LABORATORY MANUAL

BIO 329

HUMAN ANATOMY & PHYSIOLOGY I

Barbara Christie-Pope, Ph.D.

Contents

Histology

Anatomy of the Central Nervous System

Special Senses

Endocrine System

Hormonal Control of Blood Glucose

Blood

Respiratory and Cardiovascular Physiology

Anatomy of the Heart and Circulatory System

Ventilation Physiology and Respiratory Volumes

The Kidney

Role of Respiratory System in Regulation of Body pH

Histology

There are several excellent websites devoted to histology and histopathology. Not only does HistoWeb at the University of Kansas have excellent images for you to view, but it also provides text information on the subtypes of tissues.

Histoweb

Histology is the study of the microscopic anatomy of the tissues and organs of the body. An understanding of the function or physiology of an organ or system of the body has to include an examination of the cells, extracellular components and the physical relationship of cells to other cells found in the organ/system. Organs are comprised of four basic types of tissues: epithelial, connective, muscular and nervous. The four tissue types have distinctive structures and functions and can be further divided into subtypes. Knowledge of the tissue types comprising an organ will give you a good idea of how the organ functions.

Use your text as a guide and examine each of the slides contained in your slide box. Be able to identify each of the tissues listed in the following table, and any particular structures/cells associated with the tissues, and their function. Realize that these slides are from organs; therefore there may be different types of tissues on a single slide. At this point, be able to identify the location of the tissue type on the slide; you will examine these slides again when we discuss them from the aspect of the organ. You may not have a slide of each of the organs listed in your box but will have at least one representative.

Type of Tissue Slide

Epithelial Tissue:
Simple squamous	Blood vessels, lungs
Simple cuboidal	Kidney
Simple columnar	Intestine, uterine tubes
Pseudostratified	Trachea
Transitional	Bladder, ureter
Stratified squamous	Skin, esophagus, rectum
Stratified columnar	Male urethra

Connective Tissue:
Loose (Areolar)	Dermis, intestine, lung, blood vessels
Adipose	Hypodermis (skin), adipose tissue
Dense	Tendons, ligaments, white fibrous
Blood	Blood
Hyaline cartilage	Trachea, hyaline cartilage
Elastic cartilage	Pinna, epiglottis
Fibrocartilage	Intervertebral discs
Bone	Bone

Muscle Tissue:
Skeletal	Skeletal muscle
Cardiac	Heart
Smooth	Intestine, colon, blood vessels

Nervous Tissue:	Brain, spinal cord, nerves

Examine figures A and B. Although very different in appearance, these two images are of the same type of tissue. What tissue is it and why are they classified as the same tissue?

Brain: The average adult human brain weighs about 1400gm (3 lb). The brain and spinal cord are delicate, semisolid organs requiring protection and support. The brain is invested by a series of membranes (meninges) and floats in a cushion provided by a clear fluid (cerebral spinal fluid or CSF) encased in a rigid skull. The meninges include a dense connective tissue membrane next to the skull called the dura mater, a thin, translucent membrane that tightly adheres to the surface of the brain and spinal cord called the pia mater and a delicate weblike membrane located between the dura and pia called the arachnoid. The brain is divided into three major regions: the cerebral hemispheres, the brain stem and the cerebellum.

Cerebral Hemispheres: In mammals, the higher central nervous system functions including skilled movements, perception of sensations, consciousness, memory and intelligence are localized in the cerebral cortex or cerebrum. The cerebral cortex is also infolded or convoluted in higher mammals to increase the cortical surface area. The convolutions or elevated ridges are called gyri and the grooves are called fissures or sulci. The cerebrum is partially divided by a deep vertical longitudinal fissure or sulcus into halves called the cerebral hemispheres. Each cerebral hemisphere is divided into four lobes: the frontal, parietal, occipital and temporal. The central sulcus divides the frontal lobe from the parietal lobe; the lateral sulcus separates the temporal lobe from the parietal and frontal lobes, and the parietooccipital sulcus divides the parietal lobe from the occipital lobe. Specific neural functions are localized within each of the cortical lobes: the frontal lobes are concerned primarily with movement and olfaction, the parietal lobes with somatic sensation, the occipital lobes with vision and the temporal lobes with audition and memory. In addition, there are areas within each lobe devoted to the initial cortical analysis of specific sensory information or to the initiation of specific movements. The primary sensory area (postcentral gyrus) is located posterior to the central sulcus in the parietal lobe. Impulses traveling from the body's sensory receptors are localized and interpreted in this area allowing the body to recognize pain, cold or light touch. Body regions are represented according to the proportion of sensory receptors. For example, more cortical area is devoted to parts of the body where sensation is more acute (the face, mouth and hands). Body regions send impulses to neurons within the sensory cortex through crossed sensory pathways. The left side of the body sends impulses to the postcentral gyrus located in the right cerebral hemisphere and the left postcentral gyrus receives sensory information from the right side of the body. The primary motor area (precentral gyrus) concerned with conscious movement of skeletal muscles is located anterior to the central sulcus in the frontal lobe. Portions of the body are represented in the precentral gyrus proportional to degree of motor control. The axons of neurons within the precentral gyrus form the major voluntary motor tract that descends down the spinal cord (the pyramidal or corticospinal tract) and, like sensory pathways, the motor pathways are crossed.

Areas involved in higher intellectual reasoning, more complex processing of sensory input, and the integration of sensory information are found in the secondary or association areas of the cortex, and each hemisphere is concerned with only certain aspects of higher function. For example, two areas of the left cortex play a key role in speaking and understanding the spoken or written word, Wernicke's area and Broca's area. Lesions of Broca's area cause impairments of speech articulation and language production. Wernicke's area is concerned with the comprehension of speech and with writing and reading. A lesion in Wernicke's area can result in articulation of words, however, the words are inappropriate.

The cell bodies of neurons involved in the function of the cerebral hemispheres are found only in the outermost gray matter of the cerebrum. The bulk of the cerebral hemisphere is composed of white matter. White matter is composed of fiber tracts or bundles of nerve fibers that carry impulses to and from the cortex. The corpus callosum, a large fiber tract connecting the cerebral hemispheres can be seen deep within the longitudinal fissure. The corpus callosum can be seen in a midsagittal view of the brain arching over the structures of the brain stem.

Islands of gray matter within the substance of the cortex and amongst the white matter, constitute the basal ganglia. These nuclei or collections of nerve cell bodies help regulate voluntary motor activities by modifying instructions sent to the skeletal muscles by the primary motor cortex. The five nuclei of the basal ganglia can be most easily seen in a vertical section of the brain.

The brain stem is seen on the ventral surface of the brain and can also be viewed in a longitudinal section. It is composed of the diencephalon or thalamus, the hypothalamus, the midbrain, the pons and the medulla oblongata. The thalamus consists of numerous nuclei that relay sensory and motor information to the cerebral cortex. The hypothalamus and the medulla are concerned with the regulatory centers of the brain. Hypothalamic nuclei regulate eating, drinking, sexual activity, body temperature, heart rate, blood pressure, emotional behavior and hormone release from the pituitary gland. The midbrain is a relatively small part of the brain stem consisting of a roof (tectum) and a floor (tegmentum). The tectum consists of the corpora quadrigemina which includes a pair of superior colliculi and a pair of inferior colliculi. The superior colliculus is associated with optic systems, visual guidance and tracking activities related to eye and head movements. The inferior colliculus is involved with auditory and motor activities related to audition. The tegmentum is separated from the tectum by a small cerebral aquaduct that joins the third ventricle to the fourth ventricle. Prominent areas of the midbrain tegmentum include the substantia nigra (seen in vertical sections) concerned with motor control and the cerebral peduncles, a large bundle of ascending and descending fiber tracts. The pons is a rounded structure that protrudes just below the midbrain. Pons means 'bridge', and this area is composed of mostly fiber tracts. The medulla oblongata is the most inferior part of the brain stem. It is continuous with the spinal cord. The medulla contains fiber tracts and a number of nuclei involved in the regulation of vital visceral activities including heart rate, blood pressure, breathing, swallowing, vomiting, etc. The fourth ventricle can be seen posterior to the pons and medulla and anterior to the cerebellum.

The cerebellum projects dorsally from under the occipital lobe and is also divided by fissures into various lobes. The cerebellum coordinates skeletal muscle activity and controls balance and equilibrium. Fibers from the equilibrium apparatus of the inner ear, the eye and proprioceptors from skeletal muscles and tendons reaching the cerebellum allow for cerebellar monitoring of body position and the amount of tension in various muscles. Damage to the cerebellum in a human results in loss of balance and coordination of muscle activity.

Cerebrospinal fluid is formed by specialized clusters of capillaries within the roof of chambers found within the brain. These chambers or ventricles can be found within the two cerebral hemispheres (the lateral ventricles), the diencephalon (the third ventricle) and dorsal to the pons and medulla oblongata (the fourth ventricle). CSF continuously moves within the ventricles and down the central canal of the spinal cord.

Twelve pairs of cranial nerves arise from the underside of the brain. These are designated by number and name usually indicating point of innervation or origin. Some contain both sensory and motor fibers, however, some are associated only with fibers concerned with the special senses and others contain primarily motor fibers.

Vertebrate Spinal Cord: The cylindrical spinal cord is a continuation of the brain stem. It provides a two-way conduction pathway to and from the brain and it is a major reflex center. The gray matter of the spinal cord looks like a butterfly or the letter H in cross section. The two posterior projections are the dorsal or posterior horns and the two anterior projections are the ventral or anterior horns. Sensory information enters the cord dorsally, motor information exits the cord ventrally. The nerve bundles carrying this information are called the dorsal and ventral roots.

The nerve cell bodies of sensory neurons coming from the body are located in the dorsal root ganglion. Fibers from these neurons enter the cord via the dorsal roots. The ventral horns contain nerve cell bodies of motor neurons of the somatic nervous system (voluntary) that send their axons out the ventral root. The white matter of the spinal cord is composed of myelinated fibers that either ascend to the brain (sensory or afferent tracts) or descend from various areas within in the brain (motor or efferent tracts). White matter is divided into three regions: the posterior, lateral and anterior columns. Bundles of fibers having the same origin, course and terminations are known as tracts. For example, the posterior columns contain ascending fibers that convey information regarding touch, pressure and senses of position and movement. These fibers convey tactile impulses for exact localization and two point discrimination. Information concerning pain and thermal sense travel within the lateral spinothalamic tract located near the lateral and anterior columns. Tracts such as the spinothalamic tract are often named for their point of origin and termination. Hence the spinothalamic tract conveys information from the spinal cord to the thalamus. Information is then relayed to the postcentral gyrus (primary sensory cortex).

Examine the cow spinal cord. Very carefully examine the human brain specimen with the spinal cord attached. Notice the spinal nerves. Which are the dorsal roots, the ventral roots? Can you see the cervical enlargement? What is the cauda equina?

Aqueduct of Sylvius (Mesencephalic Aquaduct)

Basal nuclei (Basal Ganglia)

Brain stem

Broca’s area

Central sulcus

Cerebellopontine Angle

Cerebellum

Cerebral hemispheres

Cerebral peduncles

Corpora quadrigemina

Corpus callosum

Diencephalon

Fourth ventricle

Frontal lobe

Gyri

Hypothalamus

Inferior colliculus

Infundibulum

Interventricular foramen of Monro

Lateral sulcus

Lateral ventricles

Longitudinal fissure

Medulla oblongata

Mesencephalon

Midbrain

Occipital lobe

Parietal lobe

Pineal gland

Pituitary gland

Pons

Postcentral gyrus

Precentral gyrus

Pyramids (pyramidal tract)

Septum pellucidum

Substantia nigra

Sulci

Superior colliculus

Tectum

Tegmentum

Temporal lobe

Thalamus

Third ventricle

Wernicke’s area

Cranial Nerves:

Olfactory Bulbs

Olfactory Tract

Optic Nerve

Optic Tract

Trigeminal

Vagus

Learn the structures responsible for the sense of vision and hearing by examining your partner’s ear, a cow eye, and slides of the retina and cochlea. Before dissecting the cow eye, read about how the eye works. Instructions for dissecting the eye are located at the Exploratorium. Take a few minutes on your own to read the information on senses located at the Howard Hughes Medical Institute site, particularly the page on vision, hearing and smell, the visual pathway, a language the brain can understand (signal transduction in vision) and the disease, retinitis pigmentosa (located under of the heading of “the feared eye disease”).

The Visual Pathways: Except at the fovea centralis and the optic disk, the retina is a complicated tissue composed of a number of layers: the pigment epithelium on the outer edge; the outer and inner segments of the rods and cones; the outer nuclear layer consisting of cell bodies and fibers of rods and cones; the outer plexiform layer comprising synapses among rods, cones, bipolar cells and horizontal cells; the inner nuclear layer composed of the cell bodies of bipolar cells, horizontal cells, and amacrine cells; the inner plexiform layer, an area of synapses among bipolar cells amacrine cells and ganglion cells; the ganglion cell layer composed of cell bodies of ganglion cells and synapses similar to the inner plexiform layer; a nerve fiber layer consisting of the axons of ganglion cells. The ganglion cells give rise to axons of the optic nerve. The fovea centralis is the zone of the highest density of photoreceptors (cones). The optic disk contains only the axons of the ganglion cells.

The axons of ganglion cells pass through the optic nerves, optic chiasm and optic tracts to either the lateral geniculate body of the thalamus or to the tectum of the midbrain (superior colliculus). Each optic tract contains fibers from the lateral side of the eye on the same side and the medial side of the opposite eye. Those axons synapsing in the superior colliculus constitute an important part of the pupillary reflexes, accommodation and coordinated movements of the eye. The visual pathway leading to the lateral geniculate body extends to the visual cortex in the occipital area of the cerebrum via the optic radiations. Each side of the visual cortex receives input from the lateral field of vision of the eye on its own side and the medial field of the other eye.

The endocrine system controls a number of cellular and organismal functions including controlling the rates of chemical reactions in the body, the transport of substances across cellular membranes and aspects of growth and maintenance of body tissues. Endocrine glands secrete specific chemical messages or hormones into the blood for circulation throughout the body. Hormones elicit responses by binding to specific receptor proteins located either on the cell surface (extracellularly) or within the cytosol (intracellularly) of target cells. Peptide and most amino acid-derived hormones interact with integral membrane proteins. This extracellular hormone-receptor binding initiates a sequence of events involving an intracellular message. Types of intracellular or second messengers are cyclic nucleotide monophosphates (cAMP or cGMP), calcium ions and inositol triphosphate. General responses of a target cell to increased levels of second messengers include an increase or decrease in transport of specific substances across the cell membrane, an alteration in the rate of metabolic reactions and the secretion of substances from the target cell. Steroid and some protein hormones that readily diffuse across the cell membrane bind to intracellular, cytosolic or nuclear receptors and can directly alter gene transcription by binding to specific DNA nucleotide sequences.

Histology of the Endocrine Glands:

There are many different endocrine glands, and each of them has a distinctive gross and histological structure. Endocrine glands may be independent organs such as the pituitary, ovary, testes, thyroid and parathyroid, or hormone-producing cells may be part of predominantly nonendocrine organs such as the pancreas, liver, stomach, small intestine, heart and brain.

You will be provided the slides of the following organs: pituitary, thyroid, parathyroid, adrenal, ovary, testes, and pancreas.

Pituitary: The pituitary or hypophysis is approximately the size of a small grape in humans and hangs by a stalk from the inferior surface of the hypothalamus in the brain. There are two functional areas of the pituitary. The anterior pituitary or adenohypophysis is composed of glandular tissue. The posterior pituitary or neurohypophysis is composed of nervous tissue. The anterior and posterior pituitary can be distinguished by observing the large distribution of blood capillaries (or sinusoids) within the anterior pituitary.

The anterior pituitary releases a number of hormones into these capillaries. Within the substance (parenchyma) of the anterior pituitary different types of epithelial cells can be seen distinguished by their cytoplasmic staining. Chromophils are larger cells with deeply staining cytoplasm. Chromophils are divided into acidophils and basophils on the basis of differential staining of cytoplasmic granules. Acidophils and basophils produce different types of hormones and may be difficult to distinguish in your slides. Chromophobes are small cells with unstained cytoplasm that often appear in groups. Chromophobes are not involved in hormone production.

The posterior pituitary, the majority of which is called the pars nervosa, does not make any hormones but serves to store hormones manufactured in two areas of the hypothalamus (supraoptic and paraventricular nuclei). Oxytocin and ADH or vasopressin are produced in the hypothalamus, travel along unmyelinated nerve fibers to the posterior pituitary where these neurohormones are stored within the nerve terminals. Small pale nuclei of pituicytes can be seen amongst the nerve fibers. These cells resemble neuroglial cells found elsewhere within the central nervous system.

Thyroid: The thyroid gland is located at the base of the throat, just inferior to the "Adam's apple". It is a fairly large gland consisting of two lobes joined by a central mass or isthmus. The functional units of the thyroid are called the follicles. Follicles vary greatly in size and contain a secretion known as colloid. Each follicle is a hollow ball formed from a single layer of simple cuboidal epithelium. These follicular cells absorb iodine from the blood and synthesize several proteins including thyroglobulin, thyroxine, and triiodothronine from the amino acid tyrosine. The follicular cells are embedded within a delicate, vascular connective tissue. Collections of cells known as parafollicular cells can be seen between the follicles and secrete the hormone calcitonin.

Parathyroid: The parathyroid glands are tiny masses of tissue found on the posterior surface of the thyroid gland. Typically there are two glands on each lobe of the thyroid. Parathyroid hormone is the most important regulator of blood calcium levels. Each parathyroid gland is covered by a thin capsule of connective tissue that separates it from the thyroid gland. The parenchyma of the gland is composed of masses and irregular cords of epithelial cells of two types, chief and oxyphil. Chief cells are the most abundant. Oxyphil cells are larger than chief cells and have a pale cytoplasm.

Pancreas: The pancreas is located close to the stomach in the abdominal cavity. It is a mixed gland, i.e. it has both an exocrine and an endocrine function. Hormone producing tissues called the Islets of Langerhans are scattered among the enzyme-producing tissues of pancreas. The hormones insulin and glucagon are produced by two different cell types within the Islets, beta cells and alpha cells, respectively. Insulin is a hypoglycemic hormone and glucagon is one of several hormones that can cause hyperglycemia. Exocrine secretions of the pancreas are produced by clusters of cells, the pancreatic acini, that are arranged in around a central duct. The acini are dark-staining cells that form most of the body of the pancreas. The Islets of Langerhans can be seen as circular, lighter-staining areas interspersed between the acini. Alpha cells are smaller than beta cells and contain pink-staining granules. The larger beta cells stain blue.

Ovary: The ovaries are paired, almond-sized organs located in the pelvic cavity. Besides producing sex cells (ova) ovaries produce two types of steroid hormones, estrogens and progesterones. The ovary contains a large number of oocytes sometimes surrounded by a cluster of cells to form a follicle. The ovarian follicles become mature under the influence of the gonadotropic hormones secreted by the anterior pituitary gland. The follicle cells assist in nutrient supply to the oocyte and secrete estrogens. As the follicle and oocyte mature they increase in size. When the follicles rupture at the surface of the ovary, the ovum is released (ovulation). A mature follicle just prior to ovulation is called a Graafian follicle. After ovulation the follicle cells temporarily persist as the corpus luteum that secretes progesterone.

Testes: In the human, the paired oval testes are suspended in the scrotal sac outside the abdominopelvic cavity. A connective tissue capsule, the tunica albuginea, surround each testes. The testes produces both sperm and testosterone. Sperm are produced within highly convoluted and tightly packed seminiferous tubules. Germinal epithelium is found on the outermost region of the seminiferous tubules. This epithelium represents immature spermatogonia that will undergo a series of meiotic division progressing from the outer area of the tube to the inner area. Mature spermatozoa will be found within the tubular lumen. The Interstitial cells of Leydig are endocrine cells that produce male androgens especially testosterone. Interstitial cells are located between adjacent convolutions of the seminiferous tubules.

Adrenal Glands: The adrenal gland is composed of two different types of tissue. The central medullary region (adrenal medulla) is neural tissue and cortex (adrenal cortex) is a classical endocrine gland. The adrenal cortex produces three major groups of steroid hormones collectively called corticosteroids: the mineralocorticoids (aldosterone and deoxycorticosterone), the glucocorticoids (cortisone, hydrocortisone and cortisol) and the sex hormones (androgens and estrogens). The adrenal medulla is a part of the sympathetic nervous system and releases two neurohormones: epinephrine and norepinephrine. Under low power distinguish the medulla from the cortex. Find the outer edge of the cortex and identify the following structures: the layer of connective tissue surrounding the gland; the zones of cell cords interspersed with capillaries or sinusoids that comprise the adrenal cortex. The cortex is divided into 3 zones. The outer Zona glomerulosa is composed of a tightly packed, irregular arrangement of cells. This zone secretes the mineralocorticoids in response to angiotensin II. The next zone is the thickest part of the cortex, the Zona fasciculata. The cells in this zone are arranged in columns and secrete the glucocorticoids when stimulated by adrenocorticotropic hormone. The cells of the Zona reticularis, the innermost layer next to the medulla, form irregular dark-staining lines. This layer is also involved in the secretion of the glucocorticoids. The adrenal medulla can be readily distinguished from the Zona reticularis by the light stain.

Hormonal Control of Blood Glucose

Insulin is a peptide hormone manufactured by the beta cells of the islets of Langerhans in the pancreas. Insulin serves to increase the cellular uptake of glucose and stimulates the storage of glucose in the form of glycogen. Insulin stimulates glucose uptake in skeletal muscle and adipose tissue, however, notably does not affect glucose transport in the brain. Glucose levels in the blood of the human range from 60mg% (60mg/100ml of blood) to 140mg5 depending on the dietary intake of glucose. An increase in the level of blood glucose stimulates the beta cells to release insulin into the blood. When insulin is deficient or lacking in the blood, glucose transport is decreased. The result is a high level of blood glucose or hyperglycemia. An excess of insulin would result in the opposite effect or hypoglycemia.

Hypoglycemia: Without glucose present, most tissues rely on the metabolism of fats and proteins for cellular energy. The brain, however, requires a constant supply of glucose. Hypoglycemia therefore can greatly affect the nervous system. True hypoglycemia is rare except in the case of and insulin-producing tumor of the pancreas or an insulin overdose. Reactive hypoglycemia can occur if the beta cels secrete excessive insulin after the ingestion of a meal of carbohydrates or if the pancreatic beta cells are over-responsive to glucose. However, reactive hypoglycemia is a controversial condition since the symptoms, including tremors, weakness, sleepiness, tachycardia and nervousness, are vague and nonspecific and have not been correlated to measurements of blood glucose in most people diagnosed with this condition.

Hyperglycemia: Diabetes mellitus is a disease characterized by hyperglycemia, increased thirst (polydipsia), increased urination (polyuria), the appearance of glucose in the urine or glucosuria, excessive eating or polyphagia, and blood acidosis due to an increase in the utilization of fatty acids and fats as cellular energy sources and the formation of acidic ketone bodies. Polyuria leads to dehydration and, combined with the metabolic acidosis, can lead to coma and death.

Several tests can be used to diagnose diabetes mellitus including, urinary tests for glucose and ketones, fasting blood glucose determinations and glucose tolerance tests. The oral glucose tolerance test entails ingesting a high concentration of glucose and then measuring the level of blood glucose at various times after ingestion. The blood glucose level in a normal person would rise from around 90mg5 to 140mg5 one hour after ingestion and then would fall back to normal levels by at least 3 hours after ingestion. The rise in blood glucose levels for a diabetic person may reach 300mg% and return to pre-ingestion levels 5 to 6 hours after the glucose load.

Blood is a specialized connective tissue found within vessels of the cardiovascular system. Blood is a transport medium for nutrients, end-products of metabolism, hormones and gases. Blood also plays a significant role in the immune response to pathogens and toxins, and maintains body temperature. Blood is part of the extracellular fluid of the body, and the blood volume helps to maintain blood pressure within the cardiovascular system. Whole blood is 55% liquid, or plasma, and around 45% formed elements or cells. Plasma is the connective tissue matrix of blood. It is a straw-colored fluid that transports over 100 substances including gases, nutrients, electrolytes, wastes, hormones, enzymes and other proteins.

Blood cells include erythrocytes (RBCs), leukocytes (WBCs) and cellular fragments called platelets. Red blood cells (RBCs) are the most abundant cells in the body. RBCs contain hemoglobin that binds to oxygen in the lungs and releases oxygen to the tissues. RBCs also play a significant role in acid base balance in the body. Carbonic anhydrase found in RBCs catalyzes the reaction between carbon dioxide and water, forming carbonic acid. Carbonic acid readily dissociates releasing hydrogen ions (H⁺) and bicarbonate ion (HCO₃^-). In addition, hemoglobin itself acts as a buffer by binding H⁺. There are two general subtypes of WBCs named for the presence or absence of granules in the cytoplasm. Agranulocytes have few to no cytoplasmic granules and include monocytes and lymphocytes. Granulocytes are distinguishable by the staining patterns of their cytoplasmic granules. Neutral dyes, acidic dyes and basic dyes stain the granules of neutrophils, eosinophils and basophils respectively. Platelets function mainly in blood clotting or hemostasis. There are spindle-shaped fragments of large cells called megakaryocytes found in the bone marrow.

Histology: Examine the slides of blood time focusing on the types of cells. There are also several abnormal slides of blood. How do these slides compare to the normal slides?

Hematocrit: The thickness of the blood, or blood viscosity, depends on the concentration of red blood cells. Conditions that affect the number of RBCs will change blood viscosity and greatly alter cardiovascular physiology. For example, anemia is a deficiency of RBCs due to either blood loss or slowed production of red blood cells. Blood viscosity is normally 3-5 times that of water but with severe anemia can fall to only 1.5 times. Since the blood is “thinner”, the resistance to blood flow is less and more blood returns to the heart. This increase in the volume of blood returning to the heart, or preload, will increase the cardiac output or amount of blood the heart pumps per minute. The increased cardiac output increases the work load on the heart. In addition, the decline in oxygen delivery to the tissues will cause blood vessels to dilate also increasing preload, and therefore cardiac output, even further. This increased cardiac output will cause oxygen delivery to the tissues to approach normal. During exercise the cardiac output normally increases to meet the increased demand for oxygen delivery. When a person with anemia exercises, the heart is incapable of increasing the cardiac output any further and oxygen delivery to the tissues declines, a condition called hypoxia. This exercise induced hypoxia can lead to cardiac failure.

Several circumstances that can lead to an increase in the number of RBCs (polycythemia) and an increase in viscosity include living at high altitudes where oxygen levels in the atmosphere are low and cardiac failure. Venous return to the heart is usually close to normal since the volume of blood is high although the blood flow is sluggish. Smokers generally have a high concentration of RBCs. Smoking lowers the oxygen loading at the lung; the body responds by increasing RBC production to offset the lowered oxygen availability.

The hematocrit is a measure of the percentage of cells in the blood and, since RBCs are the most abundant blood cells, reflects the concentration of these cells. The hematocrit ranges from 40 to 45%; the hematocrit of males is higher than that of females.

CAUTION: You will be obtaining a sample of blood from your fingertip. Handle only your own blood and dispose of all strips, lancets, preps that come into contact with your blood by placing them in the biohazard bag. Remember, all body fluids are potentially infectious!

You will need a “hanging drop” of blood to determine your hematocrit. However, you must not massage or “milk” your finger prior to lancing. Milking the finger will push tissue fluid into the sample that will invalidate your hematocrit value. Hold your hand low or swing your arm to ensure maximum blood flow to the fingers. After puncturing the side of your finger using the autolet, fill a heparinized capillary tube about two-thirds full with blood and seal the clean end of the tube. Before you stop bleeding, determine your hemoglobin level using the Tallquist method described below. Place your capillary tube into the hematocrit centrifuge. Remember the number of your tube. Load everyone’s tube. Balance the centrifuge, screw on the top and shut the lid. Centrifuge for about 4 minutes. Determine your hematocrit using the hematocrit reader, or you can simply measure the total volume in the tube and the volume of RBCs, then calculate the percentage of cells.

Dividing your hematocrit by 3 is a very rough determination of your hemoglobin level is your hematocrit was normal. You can also obtain a fairly accurate hemoglobin count using the Tallquist method, a simple method based on the color of the blood: the higher the hemoglobin concentration in the blood, the darker the blood. Place a drop of blood on the Tallquist paper, wait about 15 seconds and read your hemoglobin concentration using the Tallquist scale. Unfortunately, the Tallquist method also assumes that your blood volume and RBC count is normal and does not tell you the oxygen-carrying capacity of the blood. For example, you may have an adequate amount of hemoglobin but the capacity of your hemoglobin to bind and carry oxygen might be reduced. Under what situation do you think this might occur?

Blood Typing: Blood typing is based on antigen found on your RBCs and antibodies found in your plasma. If you are blood type A, you have agglutinogen or antigen A embedded in the membranes of your RBCs and you carry anti-B agglutinins (antibodies) in your plasma. If you are type B, you have B agglutinogens and anti-A agglutinins. Blood type O indicates no agglutinogens on your RBC membranes but both plasma anti-A and anti-B agglutinins. Blood will clot or, more specifically, the RBCs will crosslink, when an antigen complexes to the appropriate antibody. Hence, type A blood will clot when exposed to anti-A, type B blood when exposed to anti-B. Type O blood will not clot when exposed to either anti-A or anti-B.

The Rh factor is actually three antigens, C, D and E. D is usually the antigen tested for in Rh typing. If you are Rh+, then your RBC membranes contain antigen D. Rh- individuals do not have antigen D. An Rh- person when first exposed to Rh+ blood will make anti-D antibodies that will remain in their blood. Any subsequent exposure to Rh+ blood will result in the clotting of the Rh+ blood.

You have access to three antibodies for A, B and D. Follow the procedure demonstrated to determine your blood type, and list your blood type on the board.

The heart is a pulsatile pump causing a rhythmic flow of blood into arteries. Arterial blood pressure is defined as the pressure exerted on the walls of arteries. Pressure within arteries rises and falls with contraction and relaxation of the heart. Systolic pressure is the pressure in the arteries at the peak of ventricular ejection. Diastolic pressure is the pressure present during ventricular relaxation. Blood pressure is reported in millimeters of mercury (mm Hg) as systolic pressure over diastolic pressure (systolic/diastolic). The difference between the systolic and diastolic pressure is called the pulse pressure and is usually about 40mm Hg.

There are a number of factors that affect the pulse pressure. Two major factors are the amount of blood pumped with each beat of the heart or stroke volume (SV) and compliance or distensibility of the arterial tree. Arterial blood pressure is therefore directly dependent on the amount of blood pumped by the heart per minute or cardiac output (CO=SV x HR) and the resistance to blood flow through the systemic circulation (peripheral resistance) especially through the so-called high resistance vessels, the arterioles. Any factor that increases either the cardiac output or the peripheral resistance causes a reflex rise in blood pressure. Factors such as age, weight, time of day, exercise, body position, emotional state, specific drugs (for example, nicotine) can alter blood pressure.

Arterial blood pressure can be measured indirectly by using a sphygmomanometer. It consists of a pressure gauge and an inflatable cuff. The inflatable cuff is wrapped around the upper arm and inflated to a pressure greater than the systolic pressure thereby occluding the blood flow to the forearm. The pressure within the cuff is gradually released while the examiner listens with a stethoscope positioned over the brachial artery.

The blood within the center of the vessel moves faster than the blood next to the vessel wall and under normal conditions the artery is silent. However, when the flow of blood is stopped and then is allowed to gradually return, the blood is pushed through the compressed walls of the artery in a turbulent flow. During turbulent flow, eddies appear with blood flowing perpendicular to the normal axial stream. This turbulence sets up vibrations in the artery that can be heard as characteristic sounds called the "sounds of Korotkoff" after the man who first described them. The first soft tapping sounds indicate the systolic pressure. As pressure against the vessel is reduced by further deflation of the cuff, blood flow becomes more turbulent and the sounds may increase in intensity. When the artery is no longer compressed and blood flows freely, without turbulence, the sounds disappear. The pressure when the sounds disappear is the diastolic pressure.

Determine your pulse rate or heart rate (HR) by placing your fingertips (not your thumb) on the radial artery located proximal to the thumb on the anterior wrist. Count the number of pulses in 30 seconds and multiply by 2 to determine "beats per minute".

Anatomy of the Heart and Circulatory System:

The adult circulation consists of a completely separate pulmonary and systemic circuit. This double circuit is due to an anatomical separation of oxygenated and deoxygenated blood. The heart has four chambers. The pulmonary circuit in the heart involves the return of deoxygenated blood from the body to the right atrium. Blood passes through the right atrioventricular valve (tricuspid valve) into the right ventricle. The right ventricle pumps blood through the pulmonary semilunar valves into the right and left pulmonary arteries that lead to the lung. The systemic circuit and distribution of oxygenated blood to the body involves the return of blood from the lungs to the heart through the pulmonary veins into the left atrium. The left atrium ejects blood into the left ventricle through the mitral valve (left atrioventricular valve or bicuspid valve). The left ventricle in turn pumps the oxygenated blood to the systemic circulation through the aorta pass the aortic semilunar valve. Pressures within the various chambers of the heart allow only one way flow of blood through the valves. Projections from the ventricular walls to the atrioventricular valves (AV valves) (the chordae tendineae and papillary muscles) prevent these valves from being forced inside-out into the atria due to the high ventricular pressures reached in systole. When the heart is relaxed blood flows into the atria and ventricles through the open AV valves. The semilunar valves (pulmonary and aortic) are closed. During atrial contraction residual blood in the atria is forced into the ventricles. As the pressure within the ventricles begins to rise the AV valves shut. When ventricular pressure exceeds the pressure within the aorta and pulmonary artery, the semilunar valves open and blood enters these vessels. During ventricular systole the atria are filling with blood. As ventricular volume and pressure decrease after ventricular systole, the semilunar valves close. When ventricular pressure is less than atrial pressure the AV valves open and ventricular filling begins again.

Examine both the microscopic and gross anatomy of the heart. Observe the following structures: Right and left atria, right and left ventricles, right and left atrioventricular valves (tricuspid and mitral valves), right and left semilunar valves (pulmonary and aortic valves), pulmonary veins, pulmonary artery, aorta, chordae tendineae, papillary muscles, intraventricular septum. Describe the flow of blood through the heart and correlate this with the events of the cardiac cycle.

Obtain a slide of cardiac muscle. Identify the branched cardiac muscle cells and intercalated discs. Why is cardiac muscle referred to as a functional syncytium?

Anterior interventricular sulcus

Aortic arch

Aortic semilunar valve

Apex of heart

Ascending aorta

Base of heart

Bicuspid valve

Chordae tendineae

Coronary sulcus and sinus

Descending aorta

Endocardium

Epicardium

Inferior vena cava

Interatrial septum

Internal carotid arteries

Interventricular branch left coronary artery

Interventricular septum

Left atrium

Mediastinum

Myocardium

Papillary muscles

Parietal pericardium

Pericardial cavity

Pericardial sac

Posterior interventricular sulcus

Pulmonary arteries

Pulmonary semilunar valve

Pulmonary trunk

Pulmonary veins

Right atrium

Right common carotid artery

Right coronary artery

Right ventricle

Superior vena cava

Tricuspid valve

Visceral pericardium

A spirometer is a device that measures the volume of air during a respiratory cycle of inspiration and expiration. Measurement of lung volumes and capacities can assist in the diagnosis of various respiratory diseases such as obstructive lung disease or restrictive lung disease.

Determine your own respiratory volumes under resting conditions and also under the condition or parameter you are investigating.

Identify on Cadaver:

Carina

Cricoid cartilage

Diaphragm

Hilus of the lung

Larynx

Left and right primary bronchi

Left lung: superior, inferior lobes

Parietal pleura

Pharynx

Pleural cavities

Pulmonary arteries

Pulmonary trunk

Pulmonary veins

Right lung: superior, middle, inferior lobes

Thyroid cartilage

Trachea

Tracheal cartilages

Visceral pleura

The Kidney

Anatomy of the Kidney:

The kidneys perform two general functions for the body: they excrete most of the waste products of metabolism and they regulate the concentrations of most of the constituents of the body fluids. Through the general processes of filtration, reabsorption, secretion and osmoconcentration, the kidneys are able to maintain a constant internal environment.

The urinary system consists of a pair of kidneys that are located on the posterior wall of the abdominal cavity, behind the parietal peritoneum (a position referred to as retroperitoneal). Each kidney is joined to the urinary bladder by a ureter that transports urine to the bladder for storage. Each kidney contains approximately two million functional units called nephrons.

A nephron is composed of two basic parts: 1. a vascular system including a tuft of capillaries called the glomerulus, afferent and efferent arterioles and an extensive system of peritubular capillaries; 2. a renal tubule that includes Bowman's capsule surrounding the glomerular capillaries, a proximal and distal convoluted tubule, a hairpin loop of variable length called the Loop of Henle, and a collecting duct that serves to collect tubular fluid from several different nephrons.

Ventilation is necessary for oxygenation and removal of carbon dioxide from the blood. Carbon dioxide is transported in the blood principally as bicarbonate ion (HCO₃). Carbon dioxide diffuses from cells into red blood cells where it combines with water in the presence of the enzyme carbonic anhydrase to form carbonic acid. Carbonic acid readily dissociates into bicarbonate and hydrogen ions (H⁺). The H⁺combine with hemoglobin molecules in the red blood cell and are neutralized or buffered. The bicarbonate ions diffuse out of the red blood cell into the plasma and constitute an essential component of the buffering capacity of plasma. Normal physiologic functions require a stable pH. Acidosis occurs if excess H⁺ are present in the blood and alkalosis occurs if excess OH^- are present. Bicarbonate ion combines with both H⁺ and OH^- thereby stabilizing plasma pH. Slow or shallow breathing (hypoventilation) causes retention of carbon dioxide in the blood and excess carbonic acid resulting in a condition known as respiratory acidosis (high blood CO₂₎. Respiratory alkalosis (low blood CO₂) is due to hyperventilation with increased removal of carbon dioxide and low carbonic acid levels in blood. The Davenport diagram summarizes the relationship between pH and bicarbonate for blood. Conditions of respiratory acidosis (RAC) and respiratory alkalosis (RAL) indicate disturbances in blood pH due to respiration. Also indicated on the Davenport diagram are disturbances in pH due to metabolic factors (MAC = metabolic acidosis; MAL = metabolic alkalosis). Some metabolic factors that cause disruption in normal pH are the adding or excreting of excess acid or base by the gills or kidneys.

Changes in respiration can compensate for metabolic induced alterations in pH. For example, metabolic acidosis causes hyperventilation (respiratory alkalosis) thereby rapidly removing carbon dioxide and lowering blood pH. Metabolic alkalosis can be compensated by hypoventilation with resultant respiratory acidosis.

Hydrogen ions directly stimulate the respiratory center of the brain that controls breathing. A decrease in pH causes hyperventilation and a pH in the alkaline range results in hypoventilation.

By consciously holding your breath for a sufficiently long time, the carbon dioxide level in your blood rises and blood pH falls. The increased concentration of hydrogen ions causes a stimulation of the respiratory center in the medulla oblongata resulting in reflex breathing. During hyperventilation the pH of the blood rises eliminating the desire to breathe until carbon dioxide and therefore hydrogen ion concentration in the blood increase.

1. Count the number of breaths you take in one minute of relaxed, normal breathing.

2. Hyperventilate for about 10 seconds. Stop if you feel dizzy!

3. Immediately after hyperventilation, count the number of breaths you take in a minute of relaxed, normal breathing.

Gross Anatomy of the Central Nervous System:

Hormonal Control of Blood Glucose

Blood Vessels: Identify in cadaver after removal of heart and digestive tract

Determine your own respiratory volumes under resting conditions and also under the condition or parameter you are investigating.

The Kidney