Anatomy Lecture Exam #3

~1% of blood plasma

Wastes (breakdown products of metabolism) (e.g., lactic acid, creatinine, urea, bilirubin, ammonia) -urea: a nitrogen-containing waste product of body cells -bilirubin: a component of a digestive secretion called bile, which is produced by liver cells. -uric acid: a normal cellular waste product

what's in the Buffy coat

WBC and platelets

growth hormone (GH)

-All body tissue growth!-anterior pituitary gland-tropic

Area of sharpest vision? What receptors?

Fovea centralis, cones

What is a Stapedius & Tensor Tympani

Muscles attached to ossicles

Hemocytoblast

"stem" cell that produces all blood cells. -considered multipotent cells, meaning that they can differentiate and develop into many different kinds of cells. -Hemocytoblasts produce two lines for blood cell development: the myeloid (mī′ě-loyd; myelos = marrow) line forms erythrocytes, megakaryocytes, and all leukocytes except lympho- cytes; the lymphoid (lim′foyd) line forms lymphocytes. -The maturation and division of hemopoietic stem cells is in- fluenced by colony-stimulating factors (CSFs), or colony-forming units (CFUs). -These molecules are all growth factors (except erythropoietin, which is a hormone) and include the following. -Multi-colony-stimulating factor (multi-CSF) increasesthe formation of erythrocytes, as well as all classes of granulocytes, monocytes, and platelets from myeloid stem cells. -Granulocyte-macrophage colony-stimulating factor (GM-CSF) accelerates the formation of all granulocytes and monocytes from their progenitor cells. -Granulocyte colony-stimulating factor (G-CSF) stimulates the formation of granulocytes from myeloblast cells. -Macrophage colony-stimulating factor (M-CSF) stimulates the production of monocytes from monoblasts. -Thrombopoietin stimulates both the production of megakaryocytes in the bone marrow and the subsequent formation of platelets. -Erythropoietin (EPO) is a hormone that is produced primarily by the kidneys (small amounts are produced by the liver) to increase the rate of production and maturation of erythrocyte progenitor and erythroblast cells

anterior pituitary gland

-AKA anterior lobe or adenohypophysis -Most of the pituitary gland is composed of the anterior pituitary which is the part of the pituitary gland that both produces and secretes hormones. -partitioned into three distinct areas: 1. the pars distalis is the large anterior portion of the anterior pituitary. 2. A thin pars intermedia is a scant region between the pars distalis and the posterior pituitary. 3. The pars tuberalis is a thin wrapping around the in- fundibular stalk (a posterior pituitary structure), which is also called the infundibulum. -Anterior pituitary secretions are controlled by regulatory hormones secreted by the hypothalamus -These regulatory hormones reach the anterior pituitary by traveling through a blood vessel network called the hypothalamo-hypophyseal (hī′pō-thal′ă- mō-hī-pō-fiz′ē-ăl) portal system -This portal system is composed of two capillary plexuses interconnected by portal veins, which shunt blood from the hypothalamus to the pituitary, before the blood is returned to the heart. -HORMONES: 7 major hormones, 6 Tropic (Tropic hormones stimulate other endocrine glands or cells to secrete other hormones) -TROPIC: 1. Thyrotropic (thī-rō-trop′ik) cells in the pars distalis synthesize and secrete thyroid-stimulating hormone (TSH), also called thyrotropin (thī-rō-trō′pin). TSH regulates the release of thyroid hormone from the thyroid gland. Increased secretion of TSH results from pregnancy, stress, or exposure to low temperatures. 2. Mammotropic (mam′ō-trop′ik) cells, also called lactotropic cells, in the pars distalis synthesize and secreteprolactin (prō-lak′tin; lac = milk) (PRL). In females, prolactin regulates mammary gland growth and breast milk production. 3. Gonadotropic (gō′nad-ō-trōp′ik, gon′ă-dō-) cells in the pars distalis synthesize and secrete both follicle-stimulating hormone (FSH) and luteinizing (lū′tē-i-nī-zing) hormone (LH), collectively called gonadotropins. These hormones act in both females and males to influence reproductive system activities by regulating hormone synthesis by the gonads, as well as the production and maturation of gametes in both sexes 4. Corticotropic (kōr′ti-kō-trop′ik) cells are located inthe pars distalis. These cells synthesize and secrete adrenocorticotropic (ă-drē′nō-kōr′ti-kō-trō′pik) hormone (ACTH), also called corticotropin. ACTH stimulates the adrenal cortex to produce and secrete its own hormones 5. Somatotropic (sō′mă-tō-trop′ik) cells in the pars distalis synthesize and secretegrowth hormone (GH), also called somatotropin. GH stimulates cell growth as well as cell division (mitosis) and affects most body cells, including adipose connective tissue, but specifically those of the skeletal and muscular systems. GH exhibits its tropic effects by stimulating the liver to produce insulin-like growth factor 1 and 2 (IGF-1 and IGF-2), also called somatomedin (sō′mă-tō-mē′din), the hormone that stimulates growth at the epiphyseal plates of long bones -NON-TROPIC: 1. The remaining hormone produced by the anterior pituitary is not considered a tropic hormone, because it does not stimulate hormone secretion by other endocrine tissues or glands. Rather, this hormone directly affects other activities in specific cells in the body. Melanocyte-stimulating hormone (MSH) is secreted by the cells in the pars intermedia of the anterior pituitary. MSH stimulates both the rate of melanin synthesis by melanocytes in the integument and the distribution of melanocytes in the skin (see section 5.2a). Its secre- tion has little effect on humans and usually ceases prior to adulthood, except in specific diseases.

posterior pituitary gland

-AKA posterior lobe (neurohypophysis) -the neural part of the pituitary gland because it was derived from nervous tissue at the base of the diencephalon -The posterior pituitary is composed of a rounded lobe called the pars nervosa and the infundibular stalk, also called the infundibulum. -The neural connection between the hypothalamus and the posterior pituitary is called the hypothalamo-hypophyseal tract -The posterior pituitary consists primarily of the endings of unmyelinated axons that extend through the hypo- thalamo-hypophyseal tract from neuron cell bodies housed in the hypothalamus. - These hypothalamic neurons are called neurose- cretory cells because they secrete hormones. -The hormones they produce are transported through the unmyelinated axons and housed in their terminals within the posterior pituitary. -These hormones are released from the posterior pituitary when a nerve impulse passes through the neuron to the ending in the posterior pituitary. -Instead of releasing a neurotransmitter into a synaptic cleft, the posterior pituitary releases a hormone into the blood. -Two specific hypothalamic nuclei contain the neuron cell bodies whose axons extend into the posterior pituitary. -The supraoptic (sū′pră-op′tik) nucleus is located superior to the optic chiasm, and the paraventricular (par′ă-ven-trik′yū-lăr) nucleus is in the anterior-medial region of the hypothalamus adjacent to the third ventricle -The neuron cell bodies in both nuclei produce two closely related peptide hormones, antidiuretic (an′tē-dī-yū-ret′ik) hormone (ADH) and oxytocin (ok′sē-tō′sin; okytokos = swift birth). -Both hormones are transported from the hypothalamus to the posterior pituitary via the hypothalamo- hypophyseal tract. -ADH is released from the posterior pituitary in response to various stimuli, including a decrease in blood volume, a decrease in blood pressure, or an increase in the concentration of specific electrolytes (salts) in the blood. -These conditions indicate that the body is dehydrated. ADH primarily increases water retention from kidney tubules during urine production, resulting in more concentrated urine and conservation of the body's water supply -Another consequence of its release is the vasoconstriction of blood vessels, resulting in increased blood pressure; thus, ADH is also referred to as vasopressin -In females, oxytocin stimulates contraction of the uterine wall smooth musculature to facilitate labor and childbirth, and it is also responsible for milk ejection from the mammary gland -In males, oxytocin induces smooth muscle contrac- tion in male reproductive organs during ejaculation (release of semen during sexual activity, -Investigations suggest that oxytocin influences maternal behavior and pair bonding. -Oxytocin receptors have been found throughout the body in a number of organs, including the reproductive organs, pancreas, car- diovascular system, kidney, and brain. -One group of studies linked oxytocin to decreases in both heart rate and cardiac output. -Interest- ingly, other studies suggest that oxytocin can modulate stress, social behaviors, and anxiety through the activity of the limbic system

follicle-stimulating hormone (FSH)

-Act on gonads and stimulate gamete formation -anterior pituitary gland -tropic

Erythrocytes

-Although erythrocytes are commonly referred to as red blood cells, or RBCs, the term "cell" is a misnomer because mature erythrocytes lack nuclei and organelles. It is more appropriate to call it a formed element. -Erythrocytes transport oxygen and carbon dioxide between the tissues and the lungs -Their structure enables them to carry these respiratory gases proficiently. -A normal, mature erythrocyte is very small, with a diameter of about 7.5 micrometers (μm) -Its unique, biconcave disc structure (at its narrowest point about 0.75 μm and at its thickest point about 2.6 μm) allows respiratory gases to be loaded and unloaded rap- idly and efficiently. -Erythrocytes line up in single file, termed a rouleau (rū-lō′; pl. rouleaux; cylinder), as they pass through small blood vessels. The number of erythrocytes in the blood nor- mally ranges between 4.2 and 6.2 million per cubic millimeter (or microliter) of blood. -function: transport most of O2 from the lungs to the tissues and small amount of CO2 from the tissues to lungs -hemoglobin carries oxygen -O2 is carried on heme group

adrenocorticotropic hormone (ACTH)

-Cause release of corticosteroids from adrenal cortex .-anterior pituitary gland -tropic

Melanocyte-stimulating hormone (MSH)

-Melanin release= darker skin and hair-anterior pituitary gland-non-tropic

oxytocin

-Milk ejection-Uterine contraction-posterior pituitary gland

Prolactin (PRL)

-Milk production-anterior pituitary gland-tropic

thyroid-stimulating hormone (TSH)

-Release of thyroid hormones -anterior pituitary gland-tropic

antibodies of blood

-The ABO surface antigens on erythrocytes are accompanied by specific antibodies (or agglutinins) that travel in the blood plasma. -In general, an antibody is a protein that is produced by a leukocyte (specifically, a B-lymphocyte) and designed to recognize and immo- bilize a specific antigen it perceives as foreign to the body. -The ABO blood group has both anti-A and anti-B antibodies that react with the surface antigen A and the surface antigen B, respectively. -Your blood plasma does not have antibodies that recognize the surface antigens on your erythrocytes. -Within the ABO blood group, the following blood types and antibodies are normally associated: Type A blood has anti-B antibodies within its blood plasma. Type B blood has anti-A antibodies within its blood plasma. Type AB blood has neither anti-A nor anti-B antibodies within its blood plasma. Type O blood has both anti-A and anti-B antibodies within its blood plasma.

adrenal medulla

-The adrenal medulla forms the inner core of each adrenal gland -It has a pronounced red-brown color due to its extensive vascularization. -The adrenal medulla primarily consists of clusters of large, spherical cells called chromaffin (krō′maf-in; chroma = color, affinis = affinity) cells. -These chromaffin cells were formed from neural crest cells, so they are essentially modified ganglionic cells of the sympathetic division of the autonomic nervous system. -They are innervated by preganglionic sympathetic axons. -When stimulated by the sympathetic division of the ANS, one population of chromaffin cells secretes the hormone epinephrine (ep′i-nef′rin; epi = upon, nephros = kidney, also called adrena- line [ă-dren′ă-lin]). The other population secretes the hormone norepinephrine (nōr′ep-i-nef′rin, also called noradrenaline [nōr′ă-dren′ă-lin]). -These hormones work with the sympathetic division of the autonomic nervous system to prepare the body for an emergency or fight-or-flight situation. Because hormones are released more slowly than nerve impulses and their effects are lon- ger lasting, the secretion of epinephrine and norepinephrine helps prolong the effects of the sympathetic stimulation. -Thus, long after the sympathetic axons have ceased to transmit nerve impulses, the sympathetic responses continue to linger because the epinephrine and norepinephrine are still present in the blood and affecting their target cells.

pituitary gland

-The pituitary gland, or hypophysis lies inferior to the hypothalamus -housed within the hypophyseal fossa in the sella turcica of the sphenoid bone -connected to the hypothalamus by a thin stalk, the infundibulum -The infundibulum extends from the base of the hypothalamus at the median eminence, a conical pro- jection sandwiched between the optic chiasm anteriorly and the mammillary bodies posteriorly. -The pituitary gland is partitioned both structurally and func- tionally into an anterior pituitary and a posterior pituitary (sometimes referred to as just the anterior lobe and posterior lobe, respec- tively).Growth hormone, also called somatotropin (sō′mă-tō-trō′pin), is produced by the anterior pituitary gland. It affects bone growth by stimulating the liver to form another hormone called insulin-like growth factor (IGF), also calledsomatomedin (sō′mă-tō-mē′din). Growth hormone and IGF directly stimulate growth of cartilage in the epiphyseal plate. -Sometimes called the "master gland" -Produces many hormones that effect other endocrine glands. -Tropic hormomes.-•FSH •LH•ACTH•TSH•MSH •PROLACTIN•GH... -anterior: produces 7, posterior produces 0 -Anterior pituitary secretes: Adrenocorticotropic hormone (ACTH), Follicle-stimulating hormone (FSH), Growth hormone (GH), Luteinizing hormone (LH), Melanocyte-stimulating hormone (MSH), Prolactin (PRL), Thyroid-stimulating hormone (TSH) -Posterior pituitary releases: Antidiuretic hormone (ADH), Oxytocin (OT)

antidiuretic hormone (ADH)

-Water retention from kidney-posterior pituitary gland

Endocrine system: positive feedback loops

-accelerates the original process, either to ensure that the pathway continues to run or to speed up its activi- ties. -Few instances of positive feedback occur in the human body. -One example is the process of milk release from the mammary glands -The initial stimulus is the baby suckling at the breast, which sends nerve impulses to the hypothalamus. -In turn, the hypothalamus signals the posterior pituitary to release the hormone oxytocin. -When oxytocin is released into the blood, it acts on the mammary gland cells and stimulates milk release. -As milk is released, the baby continues to suckle, which continues to stimulate the hypothalamus. -This process goes on until the baby stops suckling or all the milk is expelled from the breast. Then milk release ceases. -hormone production results in increased hormone production, increased activity

pineal gland

-also called the pineal body, is a small, cone-shaped structure attached to the posterior region of the epithalamus-It is composed primarily of pinealocytes, which secrete melatonin (mel′ă-tōn′in; melas = dark hue, tonas = contraction), a hormone that makes us drowsy. -Its production tends to be cyclic; it increases at night and decreases during the day. -Melatonin secretion helps regulate a circadian rhythm (24-hour body clock).-Studies have linked low melatonin levels with mood (affective) disorders, such as seasonal affective disorder (SAD), a condition that may be treated with light therapy. -Melatonin also appears to affect the synthesis of a hypothalamic hormone (gonadotropin-releasing hormone). -This hormone is responsible for regulating synthesis of two hormones from the anterior pituitary (follicle-stimulating hormone and luteinizing hormone), which in turn regulate the reproductive system. -The role of melatonin in sexual maturation is not well understood. -However, excessive melatonin secretion is known to delay puberty in humans. -The pineal (pin′ē-ăl; pineus = pinecone-like) gland (or pineal body) is an endocrine gland. -It secretes the hormone melatonin, which appears to help regulate day-night cycles known as the body's circadian rhythm -secretes Melatonin

five tastes

-our tongue detects just five basic taste sensations: sweet, salt, sour, bitter, and umami -Sweet tastes are produced by organic compounds such as sugar or other molecules (e.g., artificial sweeteners). -Salt tastes are produced by metal ions, such as sodium (Na+) and potassium (K+). -Sour tastes are associated with acids in the ingested material, such as hydrogen ions (H+) in vinegar -.Bitter tastes are produced primarily by alkaloids such as quinine, unsweetened chocolate, nicotine, and caffeine. -Umami stimuli: Umami is a Japanese word meaning "delicious flavor." It is a taste related to amino acids, such as glutamate and aspartate, to produce a meaty flavor.

adrenal cortex

-exhibits a distinctive yellow color as a consequence of the stored lipids in its cells. -These cells synthesize more than 25 different steroid hormones, collectively called corticosteroids. -Corticosteroid synthesis is stimulated by the ACTH produced by the anterior pituitary. -Corticosteroids are vital to our survival; trauma to or removal of the adrenal glands requires corticosteroid supplementation throughout life. -The adrenal cortex is partitioned into three separate regions: the zona glomerulosa, the zona fasciculata, and the zona reticularis -Different functional categories of steroid hormones are synthesized and secreted in the separate zones. -The zona glomerulosa (zō′nă glō-mĕr′yū-lōs′ă; glomerulus = ball of yarn) is the thin, outer cortical layer composed of dense, spherical clusters of cells. -These cells synthesize mineralocorticoids(min′ĕr-al-ō-kōr′ti-koyd), a group of hormones that help regulate the composition and concentration of electrolytes (ions) in body fluids. -The principal mineralocorticoid is aldosterone (al-dos′tĕr-ōn), which regulates the ratio of sodium (Na+) and potassium (K+) ions in our blood by stimulating Na+ retention and K+ secretion. If the ratio of these electrolytes becomes unbalanced, body functions are dramatically affected; severe imbalances can result in death. -The zona fasciculata (fă-sik′yū-lă′tă; fascicle = bundle of par- allel sticks) is the middle layer and the largest region of the adrenal cortex. -It is composed of parallel cords of lipid-rich cells that have a bubbly, almost pale appearance. -Glucocorticoids (glū′kō-kōr′ti-koyd) are synthesized by these cells. -Glucocorticoids stimulate metabo- lism of lipids and proteins, and help regulate glucose levels in the blood, especially as the body attempts to resist stress and re- pair injured or damaged tissues. -The most common glucocorti- coids are cortisol (kōr′ti-sol) (hydrocortisone) and corticosterone (kōr′ti-kos′ter-ōn). -The innermost region of the cortex, called the zona reticularis (re-tik′yū-lăr′is; reticulum = network), is a narrow band of small, branching cells. -These cells are capable of secreting minor amounts of sex hormones called gonadocorticoids. -The primary gonadocor- ticoids secreted are androgens, which are male sex hormones. -In females, some of the androgens are converted to estrogen. -The amount of androgen secreted by the adrenal cortex is small compared to that secreted by the gonads.

platelets or thrombocytes

-irregular, membrane-enclosed cellular fragments that are about 2 micrometers in diameter (less than one-fourth the size of an erythrocyte). -Platelets are sometimes called thrombocytes (throm′bō-sīt; thrombos = clot), although that name is inappropriate because they are cell fragments that never had a nucleus, whereas the suffix -cyte implies a complete, nucleated cell. -In stained prepa- rations, they exhibit a dark central region. -Platelets are sometimes called thrombocytes (throm′bō-sīt; thrombos = clot), although that name is inappropriate because they are cell fragments that never had a nucleus, whereas the suffix -cyte implies a complete, nucleated cell. -continually produced in the red bone marrow by cells called megakaryocytes (meg′aˇ-kar′ē-ō-sīt; megas = big) (figure 21.8). Megakaryocytes are easily distinguished both by their large size (about 100 micrometers in diameter) and their dense, multilobed nucleus. Megakaryocytes extend long processes (called proplatelets) through the blood vessel wall. These proplatelets are spliced by the force of the blood flow into platelets. -function: blood clotting -inactive platelets are smooth but can become irregular and sticky -fibrinogen is activated to form fibrin nets and activated platelets can easily get caught to form a platelet plug

LAB EXAM #6 FOR

-lacrimal tracing -eye tracing -all the tracings

interoceptors

-origin -also called visceroceptors, detect stimuli in internal organs (viscera). -These sensory receptors are primarily stretch receptors in the smooth muscle of these organs. -Most of the time we are unaware of these sensory receptors, but when the smooth muscle stretches to a certain point (e.g., when eating a large meal stretches our stomach wall), we may become aware of these sensations. - Interoceptors also report on pres- sure, chemical changes in the visceral tissue, and temperature. -When we feel pain in our internal organs, it is usually because a tissue has been deprived of oxygen (as in a heart attack), because the smooth muscle has been stretched so much that we are uncomfortable, or be- cause the tissue has suffered trauma, and damaged cells have released chemicals that stimulate specific interoceptors.

exteroceptors

-origin -detect stimuli from the external environment. For example, the sensory receptors in your skin (generally called cutaneous receptors) are exteroceptors because external stimuli typically cause sensations to the skin. - Likewise, receptors for your special senses are considered exteroceptors because they usually interpret external stimuli, such as the taste of the food you just ate or the sound of music on the radio. -Exteroceptors are also found in the mucous membranes that open to the outside of the body, such as the nasal cavity, oral cavity, vagina, and anal canal.

proprioceptors

-origin -located in muscles, tendons, and joints. -These sensory receptors detect body and limb movements, skeletal muscle contraction and stretch, and changes in joint capsule structure. - Thus, even if you are not looking at your body joints, you are aware of their positioning and the state of contraction of your skeletal muscles, because proprioceptors send this information to the CNS. -receptor of joints and muscles and body position

Parathyroid glands

-secrete Parathyroid hormone (PTH) - located on posterior surface of thyroid --The small, brownish-red parathyroid (par′ă-thī′royd) glands are located on the posterior surface of the thyroid gland -The parathyroid glands are usually four small nodules, but some individuals may have as few as two or as many as six of these glands. - The inferior thyroid artery generally supplies all nodules of the parathyroid gland. -Rarely, the superior thyroid artery may supply the superior pair of nodules. -There are two different types of cells in the parathyroid gland: chief cells and oxyphil cells. -The chief cells, or principal cells, have a large, spherical nucleus and a relatively clear cytoplasm. -They are the source of parathyroid hormone (PTH). Oxyphil (ok′sē-fil) cells are larger than chief cells, and each oxyphil has a granular, pink cy- toplasm. -The function of oxyphil cells is not known. -PTH is secreted into the blood in response to decreased blood calcium levels, which may result from normal events such as loss of electrolytes during sweating or urine formation. -Because calcium ions are needed for many body functions, including activity at synapses and muscle contraction (see sections 14.6a and 10.3c), in- adequate levels of calcium in the blood mean that the body cannot function properly. -Thus, parathyroid hormone stimulates the release of calcium stores into the blood, ultimately raising blood calcium levels -PTH stimulates osteoclasts to resorb bone and release calcium ions from bone matrix into the blood. -PTH stimulates calcitriol synthesis from an inactive form of vitamin D as a result of increased calcium ions in the kidney. Calcitriol is a hormone that promotes calcium absorption of ingested nutrients in the small intestine. -PTH prevents the loss of calcium ions during the formation of urine in the kidneys. Calcium ions are returned to the blood from filtrate of the blood that is later modified to form urine.

Thyroid gland

-secretes Calcitonin (CT), Thyroid hormone (TH) -The largest gland entirely devoted to endocrine activities is the thyroid (thī′royd; thyreos = an oblong shield) gland -The thyroid gland in an adult weighs between 25 and 30 grams and is located immediately inferior to the thyroid cartilage of the larynx and anterior to the trachea. -It is covered by a connective tissue capsule. -The thyroid gland is butterfly-shaped, composed of left and right lobes connected at the anterior midline by a narrow isthmus (is′mŭs; constrict). -Both lobes of the thyroid gland are highly vascu- larized, giving the gland an intense reddish coloration. -The gland is supplied by the superior and inferior thyroid arteries. -Thyroid veins return venous blood from the thyroid and also transport the thyroid hormones into the general circulation. -At the histologic level, the thyroid gland is composed of numerous microscopic, spherical structures called thyroid follicles. -The wall of each follicle is formed by simple cuboidal epithelial cells, called follicular cells, that surround a central lumen. -That lumen houses a viscous, protein-rich fluid termed colloid (kol′oyd). -External to individual follicles are some cells called parafollicular cells, which we discuss later in this chapter. -The follicular cells are instrumental in producing thyroid hormone. -Follicular cells synthesize a glycoprotein called thyroglobulin (TGB) and secrete it by exocytosis into the colloid. -In brief, iodine molecules must be combined with the thyroglobulin in the colloid to produce thyroid hormone precursors, which are TGB molecules that contain immature thyroid hormone within their structure. -The precursors are stored in the colloid until the secretion of thyroid hormone is needed. -When the thyroid gland is stimulated to secrete thyroid hormone, some of the colloid with thyroid hormone precursors is internalized into the follicular cell by endocytosis. - It travels to a lysosome where an enzyme releases the thyroid hormone molecules from the precursor in preparation for its secretion into circulation from the follicular cells. -Two forms of the hormone, commonly called thyroid hormone, are produced: tetraiodothyronine (T4; thyroxine) and triiodothyro- nine (T3). For our purposes, we will continue referring to these two hormones by the general name thyroid hormone (TH). -calcitonin: Decrease Ca++ ++ in blood, Can result in bone growth.

cochlea

-snail-shaped spiral chamber within the bone of the inner ear. - the cochlea "wraps" about 2.5 times around a spongy bone axis called the modiolus (mō-dī′ō-lŭs = hub of a wheel), giving the cochlea its snail-shaped appearance. - The membranous labyrinth called the cochlear duct is housed within the cochlea. -The roof of the cochlear duct is formed by the vestibular membrane, and the floor is formed by the basilar membrane (see figures 19.26b and 19.27). -These membranes parti- tion the bony labyrinth of the cochlea into two smaller chambers on either side of the cochlear duct; both are filled with perilymph. -The chamber adjacent to the vestibular membrane is the scala vestibuli (vestibular duct), and the chamber adjacent to the basilar membrane is the scala tympani (tympanic duct). -The scala vestibuli and scala tympani merge through a small channel called the helicotrema (hel′i-kō-trē′mă; helix = spiral, trema = hole) at the apex of the co- chlea (figure 19.27).

Photoreceptors

-stimulus -are located in the eye, where they detect changes in light intensity, color, and movement.

Chemoreceptors

-stimulus -detect chemicals such as specific molecules dissolved in fluid in our external and internal environments, including ingested food and drink, body fluids, and inhaled air. -For example, the receptors in the taste buds on our tongue are chemoreceptors, because they respond to the specific molecules in ingested food. - Likewise, chemoreceptors in some of our blood vessels monitor the concentration of oxygen and carbon dioxide molecules in our blood.

Thermoreceptors

-stimulus -respond to changes in temperature. Thermoreceptors are present in both the skin and the hypothalamus. -These receptors initiate reflexes that regulate and maintain body temperature.

Mechanoreceptors

-stimulus -respond to distortion of the plasma membrane that occurs due to touch, pressure, vibration, and stretch. -The various types of mechanoreceptors include baroreceptors, proprioceptors, tactile receptors, and other specialized cells such as the hair cells in the cochlea of the ear that move in response to sound waves. - For example, baroreceptors (bar′ō-rē-sep′tōr; baros = weight) are a type of mechanoreceptor, which are stimulated by changes in stretch or distension within the wall of body structures. -Baroreceptors located within blood vessel walls monitor stretch of these structures, as part of blood pressure regulation. -baroreceptors detect pressure within organs such as blood vessels

hypothalamus

-the antero- inferior region of the diencephalon. A thin, stalklike infundibulum (in′fŭn-dib′yū-lŭm; funnel) extends inferiorly from the hypothalamus to attach to the pituitary gland -Master control of the autonomic nervous system. -Master control of the endocrine system. -Regulation of body temperature. -Control of emotional behavior. -Control of food intake. -Control of water intake. -Regulation of sleep-wake (circadian) rhythms

function of blood

-transportation: of nutrients and O2 as well as metabolic wastes to be excreted -homeostasis: temp., blood pressure, salts -specialized immune cells protect from infection and disease

formed elements

-usually slightly less than half of whole blood -the vast majority of formed elements are found at the bottom of the tube and are RBC (99.9%) -above the RBC is a Buffy coat consisting of WBC and platelets (0.1%)

hormones

A hormone's structure determines how it interacts with the target cells. Hormones are classified based upon their chemical struc- ture into three distinct groups: 1. Protein hormones are formed from chains of amino acids. Most of our body's hormones are protein hormones. Smaller chains are called peptide hormones. An example is growth hormone. 2. Biogenic amines (bī′ō-jen-ik ă-mēn′, am′in) are small molecules produced by altering the structure of a specific amino acid. An example is thyroid hormone. 3. Steroid (ster′oyd) hormones are a type of lipid derived from cholesterol. An example is testosterone.

adaptation

All sensory receptors become less sensitive to a constant stimulus and initiate a progressive decrease in nerve impulses. -This decrease in sensitivity to a continuous stimulus is called adaptation. -However, the rate of decrease is different for the various types of sensory receptors. -This difference in adaption is used to catego- rize sensory receptors as either tonic receptors or phasic receptors -not noticing a stimulus after a given time

Rh

Another common surface antigen on erythrocyte membranes is part of the Rh blood type. -The Rh blood type is determined by the presence or absence of the Rh surface antigen, often called either Rh factor or surface antigen D. -When the Rh factor is present, the individual is said to be Rh positive (Rh+). -Conversely, an individual is termed Rh negative (Rh−) when the surface antigen is lacking from the membranes of his or her erythrocytes (see figure 21.6b). -In contrast to the ABO blood group, where antibodies may be found in the blood even without prior exposure to a foreign antigen, antibodies to the Rh factor termed anti-D antibodies appear in the blood only when an Rh negative individual is exposed to Rh positive blood. -This most often occurs as a result of an inappropriate blood transfusion. -Therefore, individuals who are Rh positive never exhibit anti-D antibodies, because they possess the Rh antigen on their erythrocytes. -Only individuals who are Rh negative can exhibit anti-D antibodies, and that can occur only after exposure to Rh antigens. -The ABO and Rh blood types are usually reported together. - For example, types AB and Rh+ together are reported as AB+. -However, remember that ABO and Rh blood types are independent of each other, and neither of them interacts with or influences the presence or activities of the other group.

origin receptors

Based upon where the stimulus originates, there are three types of sensory receptors: exteroceptors, interoceptors, and proprioceptors.

What anatomy happens at the optic disc?

Blind spot where nerve fibers and blood vessels exit eye

Agglutination

Blood types become clinically important when a patient needs a blood transfusion. - If a person is transfused with blood of an incompatible type, antibodies in the plasma bind to surface antigens of the transfused erythrocytes, and clumps of erythrocytes bind together in a process termed agglutination (ă-glū-ti-nā′shŭn; ad = to, gluten = glue). -Clumped erythrocytes can block blood ves- sels and prevent the normal circulation of blood. -Eventually, some or all of the clumped erythrocytes may rupture, a process called hemolysis (hē-mol′i-sis; lysis = destruction). -The release of erythrocyte contents and fragments into the blood often causes further reactions and ultimately may damage organs. -Therefore, compatibility between donor and recipient must be determined prior to blood donations and transfusions using an agglutination test

What does ciliary muscle do to make the lens fatter, wider?

Contracts (which moves ciliary body closer to the lens)

Adrenal glands

Cortex: Corticosteroids Medulla: Epinephrine (E) Norepinephrine (NE) --The adrenal (ă-drē′năl; ad = to, ren = kidney) glands (or suprarenal glands) are paired, pyramid-shaped endocrine glands anchored on the superior surface of each kidney -The adrenal glands are embedded in fat and fascia to minimize their movement. -These endocrine glands are supplied by multiple suprarenal arteries that branch from larger abdominal arteries, including the inferior phrenic arteries, the aorta, and the renal arteries. -Venous drainage enters the suprarenal veins. The adrenal gland has an outer adrenal cortex and an inner central core called the adrenal medulla. These two regions secrete different types of hormones -HORMONES: Cortex:Mineralocorticords, Glucocorticoids, Gonadocorticoids, Medulla: Epinephrine (adrenaline) and Norepinephrine (noradrenaline)

Erythropoiesis

Erythrocyte production is called erythropoiesis (ě-rith′rō-poy-ē′sis). -Normally, erythrocytes are produced at the rate of about 3 million per second, controlled by the hormone erythropoietin (EPO). -Erythropoiesis begins with a myeloid stem cell that forms a progenitor cell. -The progenitor cell forms a proerythroblast, which is a large, nucleated cell. -This cell then becomes an erythroblast, a slightly smaller cell that is forming hemoglobin in its cytoplasm. -The next stage, called a normoblast, is a still smaller cell with more hemoglobin in the cytoplasm; at the end of this stage, the nucleus is ejected. -Eventually, a cell called a reticulocyte (re-tik′yū-lō-sīt) is produced. -The reticulocyte has lost all organelles except some ribosomes, but it continues to produce hemoglobin. The transformation from myeloid stem cell to reticulocyte takes about 5 days. - Reticulocytes enter the circulation, and within 1 to 2 days the remaining organelles degenerate, and the reticulocyte becomes a mature erythrocyte.

What are the 3 tunics of the eye?

Fibrous, vascular, neural

where is most of the O2 carried

Heme (with Fe)

feedback loop

Hormone levels are regulated by a self-adjusting mechanism called feedback, meaning that the product of a pathway acts back at an earlier step in the pathway to regulate the pathway's activities. -This pattern is circular, so is often called a feedback loop. -There are two types of feedback: negative feedback and positive feedback -Many of the body's feedback mechanisms are much more complex than the examples just given, usually involving multiple steps or multiple feedback loops. -Complex loops are the most common self-adjusting regulatory mechanisms because they permit an exquisite fine-tuning of the process, not just an all- or-none effect.

Difficulty reading? You have?

Hyperopia

parathyroid hormone (PTH)

Increase Ca++ in blood •Bone density decrease...

leukocytes

Leukocytes help initiate an immune response and defend the body against pathogens. Leukocytes are true cells in that they contain a nucleus and cellular organelles. -white blood cells are (WBC) -Leukocytes also differ from erythrocytes in that leukocytes are about 1.5 to 3 times larger in diameter and they do not contain hemoglobin. - The number of leukocytes in the blood normally ranges between 4500 and 11,000 per cubic millimeter (or microliter) of blood in adults. - Infants normally have a higher number than children or adults. -a reduced number of leukocytes causes a serious disorder called leukopenia (lū′kō-pē′nē-aˇ; penia = poverty). This condition may result from viral or bacterial infec- tion, certain types of leukemia (see Clinical View 21.4: "Leukemia" in section 21.3c.), or toxins that damage the red bone marrow. Conversely, leukocytosis (lū′kō-sī-tō′sis) results from an elevated leukocyte count (greater than 11,000 per cubic millimeter of blood) and is often indicative of infection, inflammatory reaction, or ex- treme physiologic stress. -Leukocytes are motile and remarkably flexible. In fact, most leukocytes function in body tissues (as opposed to the blood). -Leukocytes enter the tissue by a process called diapedesis (dī′aˇ-pě-dē′sis; dia = through, pedesis = a leaping), whereby they leave the vessel by squeezing between the endothelial cells of the blood vessel wall. -Chemotaxis (kē′mo-tak′sis; taxis = orderly ar- rangement) is a process whereby leukocytes are attracted to the site of infection by molecules released by damaged cells, dead cells, mast cells, or invading pathogens. The five types of leukocytes are divided into two distin- guishable classes—granulocytes and agranulocytes—based upon the presence or absence of visible organelles termed granules when stained (table 21.3). When a normal blood smear is ob- served under the microscope, erythrocytes outnumber leukocytes by 500- to 1000-fold.

interpretation of taste in insula (cerebrum)

Once the gustatory cells within taste buds have detected sensory stimuli, nerve impulses conduct this information through CN VII (facial) from the anterior two-thirds of the tongue and CN IX (glosso- pharyngeal) from the posterior one-third of the tongue -Axons within these nerves project to the medulla oblongata (specifically the nucleus solitarius) to synapse with secondary neurons. -These secondary neurons project to the thalamus, and axons of tertiary neurons project to the primary gustatory cortex in the insula of the cerebrum (see table 15.3). -The conscious perception of taste requires integrating taste sensations with those of temperature, tex- ture, and smell.

hyperopia

People with hyperopia (hī′pĕr-ō′pē-ă) have trouble seeing close-up objects, and so are called "farsighted." In this optical con- dition, only convergent rays (those that come together from distant points) can be brought to focus on the retina. The cause of hypero- pia is a "short" eyeball; parallel light rays from objects close to the eye focus posterior to the retina

phantom pain

Phantom (fan′tŏm) pain is a sensation associated with a body part that has been removed. -Following the amputation of an appendage, the patient often continues to experience pain that feels like it is coming from the removed part. -The stimulation of a sensory neuron pathway from the removed limb anywhere on the remaining intact portion of the pathway propagates nerve impulses and conducts them to the primary somatosensory cortex of the brain (see section 15.3b), where they are interpreted as originating in the amputated limb. - In other words, the cell bodies of the sensory neurons that provided sensation to the leg remain alive because they were not part of the leg. -This so-called phantom limb syndrome can be quite debilitating. -Some people experience extreme pain, whereas others have an insatiable desire to scratch a nonexistent itch.

plasma proteins

Plasma proteins make up about 7% of the plasma -Measured amounts of plasma proteins usually range between 6 and 8 grams of protein in a volume of 100 milliliters of blood (referred to as grams per deciliter [g/dL]). -The plasma proteins include albumins, globulins, fibrinogen, and regulatory proteins. -Albumins (al-bū′min; albumen = white of egg) are the smallest and most abundant of the plasma proteins, making up about 58% of total plasma proteins. They regulate water move- ment between the blood and interstitial fluid by providing some of the plasma solutes to drive osmosis. Secondarily, albumins act as transport proteins that carry ions, hormones, and some lipids in the blood. -Globulins (glob′yū-lin; globules = globule) are the second- largest group of plasma proteins, forming about 37% of all plasma proteins. The smaller alpha-globulins and the larger beta-globulins primarily bind, support, and protect certain water-insoluble (hydro- phobic) molecules, hormones, and ions. -Gamma-globulins, also called immunoglobulins or antibodies, are soluble proteins produced by some of our defense cells to protect the body against pathogens that may cause disease. -Fibrinogen (fı-̄ brin′ō-jen; fibra = fiber) makes up about 4% of all plasma proteins. Fibrinogen is responsible for blood clot formation. Following trauma to the walls of blood vessels, fibrinogen is con- verted into long, insoluble strands of fibrin, which helps form a blood clot. -Regulatory proteins form a very minor class of plasma pro- teins (less than 1% of total plasma proteins) and include enzymes (proteins that accelerate chemical reactions), proenzymes (inactive precursors of enzymes), and hormones that are being transported to other parts of the body.

pacemaker of the heart

SA node

transducers

Sensory receptors act as transducers. -Transducers (tranz-dū′sĕr; trans = across, duco = to lead) change one form of energy into a different form. -The original energy form detected is specific to the type of receptor (e.g., those forms of energy are detected within the eye, ear, and blood vessels). -However, the form the energy is transduced or changed to is always electrical energy, and it is conducted along a sensory neuron. - This sensory information is relayed to the CNS for interpretation.

stimulus receptors

Sensory receptors also may be classified according to the stimulus they perceive, called the modality of stimulus, or the stimulat- ing agent. -For example, some sensory receptors respond only to temperature changes, whereas others respond to chemical changes. -There are five groups of sensory receptors, based upon their modal- ity of stimulus: chemoreceptors, thermoreceptors, photoreceptors, mechanoreceptors, and nociceptors.

Which extrinsic eye muscle has a trochlea?

Superior oblique

What gland produces secretion that keeps eyelids from sticking together?

Tarsal gland

lifespan of erythricytes , RBC, red blood cells

The absence of both a nucleus and cellular organelles comes at a cost to the erythrocyte by reducing its life span. -A mature erythrocyte cannot synthesize proteins to repair itself or replace damaged membrane regions. -Aging and the wear-and-tear of circulation through blood vessels cause erythrocytes to become more fragile and less flexible. -Therefore, the erythrocyte has a finite life span of about 120 days (figure 21.5). -Every day, just under 1% of the oldest circulating erythrocytes are removed from circulation. -The old erythrocytes are phagocytized in the liver and spleen by cells -called macrophages. Some erythrocyte components are stored in other organs for recycling, whereas other components are excreted from the body

fibrous tunic

The external layer of the eye wall, called the fibrous tunic, is com- posed of the anterior cornea and the posterior sclera. -The avascular, transparent cornea (kōr′nē-ă) forms the anterior surface of the fibrous tunic. It exhibits a convex shape, and thus it refracts (bends) light rays coming into the eye. The cornea is composed of an inner simple squamous epithelium, a middle layer of collagen fibers, and an outer stratified squamous epithelium, called the corneal epithelium. At its circumferential edge, this epithelium is continuous with the ocular conjunctiva, and it adjoins the sclera. The structural continuity between the cornea and sclera is called the limbus (lim′bŭs) or the corneal scleral junction. -The cornea contains no blood vessels; thus, both its external and internal epithelial surfaces must obtain nutrients by alternative means. Nutrients and oxygen are supplied to the external corneal epithelium by fluid from the lacrimal glands, whereas the internal epithelium obtains needed gases and nutrients from the fluid in the anterior chamber of the eye. -Most of the fibrous tunic is formed by tough sclera (sklē′ră; skleros = hard), a part of the outer layer that is called the "white" of the eye. It is composed of dense irregular connective tissue that includes both collagen and elastic fibers. The sclera provides for eye shape and protects the eye's delicate internal components.

Gonads- testes and ovaries

The gonads (gō′nad; gone = seed) are the female and male primary sex organs—the ovaries in females and the testes in males (see sections 28.2a and 28.3c). -In addition to producing gametes, the gonads also produce sex hormones. -The ovaries produce the female sex hormones estrogen and progesterone, whereas the testes pro- duce the male sex hormones called androgens, many of which are converted into testosterone. -The gonads also produce inhibin, which inhibits follicle-stimulating hormone secretion

retina (neural tunic)

The internal layer of the eye wall, called the retina (ret′i-nă; rete = a net), or either the internal tunic or neural tunic, is composed of two layers: an outer pigmented layer and an inner neural layer (figure 19.13a). -The pigmented layer is immediately internal to the choroid and attached to it. This layer provides vitamin A for photo- receptor cells. The pigmented layer also transports all nutrients and oxygen to the photoreceptors and removes wastes, including recycling visual pigments away from the photoreceptors. Light rays that pass through the inner layer are absorbed in this outer layer. -The inner neural layer houses all of the photoreceptors and their associated neurons. This layer of the retina is responsible for receiving light rays and converting them into nerve impulses that are transmitted to the brain. -The retina extends posteriorly from the ora serrata (ōr′ă sē-ră′tă; serratus = sawtooth) to line the internal posterior surface of the eye wall. The ora serrata is the jagged margin between the photosensitive posterior region of the retina and the nonphotosensi- tive anterior region of the retina that continues anteriorly to cover the ciliary body and the posterior side of the iris (see figure 19.11b).

What controls pupil size?

The iris and its muscles.

middle ear

The middle ear contains an air-filled tympanic cavity (figure 19.19). Medially, a bony wall that houses the oval window and round win- dow separates the middle ear from the inner ear. The tympanic cav- ity maintains an open connection with the atmosphere through the auditory tube (also called the pharyngotympanic tube or Eustachian tube). This passageway opens into the nasopharynx (upper throat) from the middle ear (see section 25.2c). It has a normally closed, slitlike opening at its connection to the nasopharynx. Air movement through this tube occurs as a result of chewing, yawning, and swallowing, which allows the pressure to equalize in the middle ear. Middle ear infections result when infectious agents (e.g., a cold virus) move from the nasopharynx through the auditory tube into the middle ear

vascular tunic

The middle layer of the eye wall is the vascular tunic, also called the uvea (yū′vē-ă; uva = grape). It is composed of three distinct regions; from posterior to anterior, they are the choroid, the cili- ary body, and the iris (figure 19.11). The vascular tunic houses an extensive array of blood vessels, lymph vessels, and the intrinsic muscles of the eye. -The choroid (kor′oyd; choroeides = like a membrane) is the most extensive and posterior region of the vascular tunic. It houses a vast network of capillaries, which supply both nutrients and oxygen to the retina, the inner layer of the eye wall. Cells of the choroid are filled with pigment from the numerous melanocytes in this region. The melanin pigment is needed to absorb extraneous light that enters the eye, thus allowing the retina to clearly interpret the remaining light rays and form a visual image. -The ciliary (sil ′ē-ar′ē; cilium = eyelid) body is located anterior to the choroid. The ciliary body is composed of ciliary muscles (bands of smooth muscle) and ciliary processes (folds of epithelium that cover the ciliary muscles). Extending from the ciliary body to the lens are suspensory ligaments. Relaxation and contraction of the cili- ary muscles change the tension on the suspensory ligaments, thereby altering the shape of the lens. In addition, the ciliary body epithelium secretes a fluid called aqueous humor -The most anterior region of the vascular tunic is the iris (ī′ris; rainbow), which is the colored portion of the eye. In the center of the iris is a black hole called the pupil (pyūpīl). The pe- ripheral edge of the iris is continuous with the ciliary body. The iris is composed of two layers of pigment-forming cells (anterior and posterior layers), two groups of smooth muscle fibers, and an array of vascular and nervous structures. The iris controls pupil size or diameter—and thus the amount of light entering the eye— using its two smooth muscle layers: the sphincter pupillae and the dilator pupillae muscles (figure 19.12). The sphincter pupillae (or pupillary constrictor) muscle is arranged in a pattern that re- sembles concentric circles around the pupil. Under the control of the parasympathetic division of the ANS, it constricts the pupil. The dilator pupillae (or pupillary dilator) muscle is organized in a radial pattern extending peripherally through the iris. It is controlled by the sympathetic division of the ANS to dilate the pupil. Only one set of these smooth muscles can contract at any one time. When stimulated by bright lights, parasympathetic innervation causes the sphincter pupillae to contract and thus decrease pupil diameter, whereas low light levels activate sympa- thetic stimulation to cause pupil dilation.

Pancreas

The pancreas (pan′krē-as; pan = all, kreas = flesh) is an elongated, spongy, nodular organ situated posterior to the stomach between the duodenum of the small intestine and the spleen -The pancreas performs both exocrine and endocrine activities, and thus it is considered a heterocrine, or mixed, gland. -The pancreas is mostly composed of groups of cells called pancreatic acini (sing., acinus = grape). -Acinar cells produce an alkaline pancreatic juice that is secreted through pancreatic ducts into the duodenum of the small intestine -This pancreatic juice aids digestion.-Scattered among the pancreatic acini are small clusters of endocrine cells called pancreatic islets (ī′let), also known as islets of Langerhans (figure 20.15b). -Estimates of the number of islets range between 1.5 and 2 million; however, these endocrine cell clusters form only about 1% of the pancreatic volume. -A pancreatic islet may be composed of four types of cells: two major types (called alpha cells and beta cells) and two minor types (called delta cells and F cells). -Each type produces its own hormone Alpha cells secrete glucagon (glu ′̄ kă-gon) when blood glucose levels drop. -Glucagon causes target cells in the liver to break down glycogen into glucose and release glucose into the blood to increase blood glucose levels. -Also, this hormone stimulates adipose cells to break down lipid and secrete it into the blood.-Beta cells secrete insulin (in′sū-lin; insula = island) when blood glucose levels are elevated. -Target cells respond to insulin by taking up the glucose, thus lowering blood glucose levels -Insulin also promotes glycogen synthesis and lipid storage.-Delta cells are stimulated by high levels of nutrients in the blood. Delta cells synthesize somatostatin (sō′mă-tō-stat′in; stasis = standing still), also described as growth hormone-inhibiting hormone (GHIH) -In this context it only acts within the pancreas, not systemically. -Somatostatin slows the release of insulin and glucagon as well as the activity of the digestive organs, thereby also slowing the rate of nutrient entry into the blood. -This process gives the other islet hormones the ability to control and coordinate nutrient uptake.-F cells are stimulated by protein digestion in the digestive tract. -F cells secrete pancreatic polypeptide (PP) to suppress and regulate somatostatin secretion from delta cells. Together, these pancreatic hormones provide for orderly uptake and processing of nutrients. -Glucagon: Increases blood glucose levels, glycogen breakdown in liver cells, lipid breakdown in adipose cells -Insulin: Decreases glucose levels in body fluids, glucose transport into target cells; promotes glycogen and lipid formation and storage -Somatostatin: Slows release of insulin and glucagon to slow rate of nutrient absorption during digestion -Pancreatice polypeptide: Suppresses somatostatin secretion from delta cells

hematocrit

The percentage of the volume of all formed elements in the blood is called the hematocrit (hē′mat′ō-krit, hem′aˇ-; hemato = blood, krino = to separate). -This medical dictionary definition differs from the clinical definition, which equates the hematocrit to the percentage volume of erythrocytes only. -In practice, the true hematocrit and the clinical hematocrit are virtually the same. -Hematocrit values vary somewhat and are dependent upon the age and sex of the individual. -A very young child's hematocrit may vary from 30% to 60%, and that range will narrow to 35% to 50% as the child becomes older. - Adult males tend to have a hematocrit ranging between 42% and 56%, whereas adult females' hematocrits range from 38% to 46%. -Males typically have a higher hematocrit because testos- terone stimulates the kidney to produce the hormone erythropoietin (EPO), which promotes erythrocyte production (see section 20.9a). -An elevated hematocrit may indicate that the patient is either dehydrated or participating in blood doping (see Clinical View 21.1: "Blood Doping" in section 21.3a), whereas a lowered hematocrit often suggests the patient is suffering from anemia

ABO blood type

The plasma membrane of an erythrocyte has numerous molecules called surface antigens (or agglutinogens), that project from the plasma membrane surface. -The most commonly identified group of antigens is the ABO blood group. -This group has two surface antigens, called A and B. -The presence or absence of either the A and/or B surface antigen are the criteria that determine your ABO blood type: Type A blood has erythrocytes with surface antigen A only. Type B blood has erythrocytes with surface antigen B only. Type AB blood has erythrocytes with both surface antigens A and B. Type O blood has erythrocytes with neither surface antigen A nor B. -type O universal donor -type AB universal receiver

Rh incompatibility

The potential presence of anti-D antibodies is especially important in pregnant women who are Rh negative and have an Rh positive fetus. -An Rh incompatibility may result during the pregnancy if the mother has previously been exposed to Rh positive blood (such as can occur with a previously carried Rh positive fetus, typically at the time of childbirth). -As a result of the prior exposure, the mother has anti-D antibodies that may cross the placenta and destroy the fetal erythrocytes, resulting in severe illness or death. -The illness that occurs in the newborn is called hemolytic disease of the newborn (HDN), or erythroblastosis fetalis. -The newborn typically presents with anemia and hyperbilirubinemia (increased bilirubin in the blood) due to erythrocyte destruction. -In severe cases, the infant may develop heart failure and must be given a blood transfusion to survive. -Giving a pregnant Rh negative woman special immunoglobulins (e.g., RhoGAM) between weeks 28-32 of her pregnancy and at birth prevents the mother from developing anti-D anitbodies. -Specifically, these immu- noglobulins bind to fetal erythrocyte surface antigens—and in so doing, prevent the mother's immune system from recognizing Rh antigens and being stimulated to produce anti-D antibodies.

Leukopoiesis

The production of leukocytes is called leukopoiesis (lū′kō-poy-ē′sis). - Leukopoiesis involves three different maturation processes: granulocyte maturation, monocyte maturation, and lymphocyte maturation. 1. Granulocyte Maturation All three types of granulocytes (neutrophils, basophils, and eosino- phils) are derived from a myeloid stem cell along the myeloid line. This stem cell forms a progenitor cell, which then forms a myeloblast (mī′ě-lō-blast), which ultimately differentiates into one of the three types of granulocytes. 2. Monocyte Maturation Like granulocytes, monocytes are also derived from a myeloid stem cell. In this case, the myeloid stem cell differentiates into a progenitor cell, which then forms a monoblast (instead of a myeloblast, as with granulocytes). The monoblast matures into a promonocyte, which then forms a monocyte. 3. Lymphocyte Maturation Lymphocytes are derived from a lymphoid stem cell along the lym- phoid line. The lymphoid stem cell differentiates into B-lymphoblasts and T-lymphoblasts. B-lymphoblasts mature into B-lymphocytes, whereas T-lymphoblasts mature into T-lymphocytes. Some lymphoid stem cells differentiate directly into NK cells.

Thrombopoiesis

The production of platelets is called thrombopoiesis (throm′bō- poy-ē′sis). -From the myeloid stem cell, a committed cell called a megakaryoblast is produced. It matures under the influence of thrombopoietin to form a megakaryocyte. -Each megakaryocyte produces thousands of platelets.

receptive field

The receptive field of a sensory receptor is the entire area through which the sensitive ends of the sensory receptor cell are distributed. -An inverse relationship exists between the size of the receptive field and our ability to identify the exact location of a stimulus. - If the receptive field is small, precise localization of the stimulus and sensitivity are determined easily. - In contrast, a broad receptive field detects only the general region of the stimulus. -Although it might seem advantageous for all sensory receptors to have small receptive fields, the number of receptors in the body would have to markedly increase to detect environmental stimuli if all receptive fields were very small. -Not only would organ size and total body surface area need to increase markedly to accommodate all of these extra sensory receptors, but also the increase in energy costs to maintain activity in such a large number of sensory receptors would be enormous. -the total area that a single group of receptors senses -best discrimination = small

Vision

The sense of vision uses visual receptors (photo- receptors) in the eyes to detect light, color, movement, and to perceive detailed visual images in our environment. -The accessory structures of the eye prevent foreign objects from com- ing into contact with the eye (eyebrows, eyelashes, and eyelids); keep the exposed surface moist, clean, and lubricated (lacrimal glands); and provide a superficial covering over its anterior exposed surface (conjunctiva) -Tarsal glands, previously called Meibomian glands, are sebaceous glands that produce a secretion to prevent tear overflow from the open eye and keep the eyelids from adhering together. -lacrimal gland is located within the superolateral depres- sion of each orbit. It is composed of an orbital or superior part and a palpebral or inferior part. The gland continuously produces tears. The blinking motion of the eyelids "washes" the lacrimal fluid re- leased from excretory ducts over the eyes. -accommodation

special senses vs general senses

The sensory nervous system has two components: somatic sensory and visceral sensory. -The somatic sensory components are the general somatic senses—touch, pain, pressure, vibration, tempera- ture, and proprioception (sensing the position or movement of joints and limbs) —and the special senses (taste, vision, hearing, balance, and smell). -These functions are considered voluntary because we have some control over them and we tend to be conscious of them. -general senses: Distributed throughout the body; structurally simple *somatic sensory receptors: Located in skin and mucous membranes, joints, muscles and tendons ex: Tactile (touch receptors)Joint receptors, muscle spindles, Golgi tendon organs *visceral sensory receptors: Located within walls of viscera and blood vessels ex: Stretch receptors in stomach wall, chemoreceptors in blood vessels -special senses: Located only in the head; structurally complex sense organ, Sensory receptors for smell, taste, vision, hearing, and equilibrium

frequency

The sound waves that give rise to pressure waves in the inner ear are characterized by their frequency and intensity. - Frequency is the number of waves that move past a point during a specific amount of time. Frequency is measured in hertz (Hz), and is classified as high, medium, or low -Frequency is interpreted as the pitch of a sound. The region of the spiral organ stimulated by pressure waves in the perilymph varies according to the frequency of the sound: High-frequency sounds stimulate it near the oval window, whereas low-frequency sounds stimulate the spiral organ far away from the oval window. - Loudness, or sound intensity, is measured in units called decibels (dB). Soft sounds cause relatively small movements of the basilar membrane in a relatively smaller area of the spiral organ, whereas loud sounds cause relatively larger movement of the basilar membrane in a wider area of the spiral organ. The greater movement of the basilar membrane associated with louder sounds increases both the rate of nerve impulses that are initiated by the inner hair cells and the number of hair cells that are stimulated.

auditory ossicles

The tympanic cavity of the middle ear houses the three smallest bones of the body, called the auditory ossicles (os′i-kēl) (figure 19.20; see also figure 19.19). These bones are, from lateral to medial, the mal- leus (hammer), the incus (anvil), and the stapes (stirrup). The malleus (mal′ē-ŭs) is attached to the medial surface of the tympanic membrane, and suspended by ligaments bound to the wall of the tympanic cavity. It resembles a large hammer in shape. The incus (ing′kŭs) resembles an anvil and is the middle auditory ossicle. The stapes (stā′pēz) resembles a stirrup on a saddle. It has a cylindrical, disclike footplate that fits into the oval window, an opening that marks the lateral wall of the inner ear. The auditory ossicles are responsible for amplifying sound waves and transmitting them into the inner ear via the oval window. When sound waves strike the tympanic membrane, the three middle ear ossicles vibrate along with the tympanic membrane, causing the footplate of the stapes to move in and out of the oval window. The movement of this ossicle initiates pressure waves in the fluid within the closed compartment of the inner ear. Because the tympanic mem- brane is 20 times greater in diameter than the stapes footplate in the oval window, sounds transmitted across the middle ear are amplified more than 20-fold, and we are able to detect very faint sounds. Two tiny skeletal muscles, called the stapedius and the tensor tympani, are located within the middle ear. These muscles restrict ossicle movement when loud noises occur, and thus protect the sensi- tive receptors in the inner ear.

organization of neural layer

Three distinct layers of cells form the neural layer: photoreceptor cells, bipolar cells, and ganglion cells. Incoming light must pass almost through the entire neural layer before reaching the photoreceptors. The outermost layer of the neural layer is composed of photoreceptor cells of two types: -Rods have a rod-shaped outer part nd function in dim light, longer and narrower than cones, primarily located in the peripheral regions of the neural layer, There are more than 100 million rod cells per eye, important when the light is dim, They detect movement but exhibit poor visual acuity, rods pick up contrasting dark and light tones, but cannot distinguish color, when you are trying to see at night, it is primarily the rods that are working, rods can perceive the object, but your vision may not be particularly sharp, and you may find it difficult to see any color variation. - cones have a cone-shaped outer part and function in high-intensity light and in color vision, occur at a density of less than 10 million per eye, activated by high-intensity light and provide precise visual acuity and color recognition, when you notice the fine de- tails in a colorful picture, the cones of your neural layer are responsible. -Immediately internal to the photoreceptor layer is a layer of bipolar cells, type of bipolar neuron. -Rods and cones form synapses on the dendrites of bipolar cells. -Sandwiched between the photore- ceptor layer and the bipolar cells is a thin web of horizontal cells that form connections between the photoreceptor and bipolar cells. -There are far fewer bipolar neurons than photoreceptors, and thus informa- tion must converge as nerve impulses are directed toward the brain from the stimulated photoreceptors. Ganglion cells form the innermost layer in the neural layer that is adjacent to the vitreous humor in the posterior cavity. Neuronal convergence continues between the bipolar neurons and ganglionic neurons. Amacrine (ahm′ă-krin) cells help process and integrate visual information as it passes between bipolar and gan- glionic neurons. Axons extend from the ganglionic cells into and through the optic disc. These axons converge to form the optic nerve (CN II) as they exit the eye and extend toward the brain. The optic disc lacks photoreceptors, and consequently it is called the blind spot because there are no receptors to detect an image that might fall there (figure 19.14). Just lateral to the optic disc is a rounded, yellowish region of the neural layer called the macula (mak′yū-lă) lutea (lū′te-ă; saffron- yellow). Within the macula lutea is a pit called the fovea centralis (fō′vē-ă, pit; sen-trā′lis, central), which contains the highest proportion of cones and almost no rods. This pit is the area of sharpest vision; when you read the words in your text, they are precisely focused here.

high altitude effect on blood

To enhance their performance in endurance events, some athletes try to boost their bodies' ability to deliver oxygen to the muscles by increasing the number of erythrocytes in their blood. One way the number of erythrocytes can be increased naturally is by living and training at high altitude. The body compensates for the decreased oxygen concentration in the atmosphere by increasing the rate of erythrocyte production, thus increasing the number of erythrocytes per unit volume of blood. -High altitude living = higher hematocrit, producing more RBC

What are the functions of blood?

Transportation of of nutrients & O2 as well as metabolic wastes to be excreted .•Homeostasis: Temperature, blood pressure, salts. •Specialized immune cells protectf rom infection & disease... -transportation: Blood transports numerous elements and compounds throughout the body. For example, erythrocytes and plasma carry oxygen from the lungs to body cells and then transport the carbon dioxide produced by the cells back to the lungs to diffuse from the body. Blood plasma transports nutrients that have been absorbed from the GI tract. Plasma also transports hormones secreted by the endocrine glands. Finally, plasma carries some waste products from the cells to organs such as the kidneys, where these waste products are removed -regulation: Blood regulates many body functions including body temperature. Plasma absorbs and distributes heat throughout the body. If the body needs to be cooled, the blood vessels in the dermis dilate and dissipate the excess heat through the integument. Conversely, when the body needs to conserve heat, the dermal blood vessels constrict, and the warm blood is shunted to deeper blood vessels in the body (see section 5.1b). Blood also helps regulate pH levels in the body's tissues. The term pH is a measure of how acidic or alkaline a fluid is. A neutral pH (neither acidic nor alkaline fluid, such as water) is measured at exactly 7, whereas acidic fluids (e.g., orange juice) are between 0 and 7, and alkaline fluids (e.g., milk) are between 7 and 14. Blood plasma contains compounds and ions that may be distributed to the fluid bathing cells within the tissues (interstitial fluid) to help main- tain normal tissue pH. In addition, blood plasma pH is continuously regulated to try to maintain a value between 7.35 and 7.45 (slightly alkaline), which is the pH level required for normal cellular function- ing. If the blood pH falls much below 7.35, the condition called acido- sis results, and depresses the central nervous system; coma and death could occur. If the blood pH rises much above 7.45, alkalosis results, characterized by a hyperexcited nervous system and convulsions. Blood maintains normal fluid levels in the cardiovascular system. A constant exchange of fluid takes place between the blood plasma and the interstitial fluid. If too much fluid is absorbed into the blood, high blood pressure results. Yet if too much fluid escapes the blood and enters the tissues, blood pressure drops to unhealthy levels, and the tissues swell with excess fluid. To maintain a balance of fluid between the blood and the interstitial fluid, blood contains molecules (such as salts and some proteins) to prevent excess fluid loss from the plasma. -protection: Leukocytes help guard against infection by mounting an immune response if a pathogen or an antigen (an′ti-jen; anti = opposite, gen = producing) (a substance perceived as foreign to the body) is found. Antibodies (an′tē-bod′ē; body = main part), which are molecules that can bind to antigens until a leukocyte can completely kill or remove the antigen, are transported in plasma. In addition, platelets and plasma proteins protect the body against blood loss by forming blood clots.

Which has choroid?

Vascular

components of blood

Whole blood can be separated into its liquid and cellular components by using a machine called a centrifuge -Erythrocytes (ě-rith′rō-sīt; erythros = red, kyte = cell), sometimes called red blood cells, form the lower layer of the centrifuged blood. They typically average about 44% of a blood sample. -A buffy coat makes up the middle layer. This thin, slightly gray-white layer is composed of cells called leukocytes (or white blood cells) and cell fragments called platelets. The buffy coat forms less than 1% of a blood sample. -Plasma is a straw-colored liquid that lies above the buffy coat in the centrifuge tube; it generally makes up about 55% of blood. -Collectively, the erythrocytes and the components of the buffy coat are called the formed elements. It is best not to refer to all of these structures as "cells" because platelets are merely fragments broken off from a larger cell. The formed elements, together with the liquid plasma, compose whole blood (the substance we most com- monly refer to simply as "blood").

blood plasma

a complex mixture of water, proteins, and other solutes -When the clotting proteins are removed from plasma, the remaining fluid is termed serum (sē′rum; whey). -Water is the most abundant compound in plasma, making up about 92% of plasma's total volume. -Water facilitates the transport of materials in the plasma. -The next most abundant compounds in plasma are the plasma proteins. -Blood Composition: visible when we spin whole blood -Plasma: the liquid matrix of blood. -Plasma is usually slightly more than half of whole blood. of whole blood. The vast majority of plasma is water. -≈ 7% = blood blood proteins:albumins (transport lipids & steroids); globulins (antibodies); fibrinogen (clotting) -≈ 1% are other: : ions (Na+, Cl-, Ca++, K+, HCO3-); nutrients (glucose, fatty acids, amino acids); wastes(urea, uric acid, bilirubin)...

external ear

a skin-covered, primarily cartilaginous struc- ture called the auricle, or pinna (pin′ă; wing). The auricle is funnel-shaped, and serves to protect the entry into the ear and to direct sound waves into the bony tube called the external acoustic meatus (see section 7.1c), which extends medially and slightly superiorly from the lateral surface of the head. The external acoustic meatus terminates at the tympanic (tim-pan′ik; tympanon = drum)membrane, or eardrum, a delicate, funnel-shaped epithelial sheet that is the partition between the external and middle ear. The tym- panic membrane vibrates when sound waves hit it. These vibrations provide the means for transmission of sound wave energy into the middle and inner ear. The narrow external opening in the external acoustic meatus prevents large objects from entering and damaging the tympanic membrane. Near its entrance, fine hairs help guard the opening. Deep within the canal, ceruminous glands produce a waxlike secre- tion called cerumen, which combines with dead, sloughed skin cells to form earwax. This material may help reduce infection within the external acoustic meatus by impeding microorganism growth.

when blood cells clump its called

agglutination

hemoglobin

an oxygen-binding protein in eryth- rocytes, contributes a red or pink hue -Every erythrocyte is filled with about 280 million molecules of a red-pigmented protein called hemoglobin (hē′mō-glō′bin; haima = blood). -Hemoglobin transports oxygen and carbon dioxide, and is responsible for the characteristic bright red color of arterial blood. -When blood is maximally loaded with oxygen, it is termed oxygenated. -Conversely, when some oxygen is lost and carbon dioxide is gained during respiratory gas exchange, blood is called deoxygenated. -Deoxygenated blood has a deep red color that is perceived as blue when observed through the skin and the sub- cutaneous layer. -Each hemoglobin molecule consists of four polypeptide chains called globins. - Two of these globins are called alpha (α) chains, and the other two, which are slightly different, are called beta (β) chains (figure 21.4). -These globin chains each contain a non- protein (or heme) group that is in the shape of a ring, with an iron ion (Fe2+) in its center. - Oxygen binds to these iron ions for trans- port in the blood. -Because each molecule of hemoglobin has four rings, each hemoglobin molecule has four iron ions and is capable of binding four molecules of oxygen. -The oxygen bind- ing is fairly weak to ensure rapid attachment and detachment of oxygen with hemoglobin. -The result is that oxygen binds to the hemoglobin when the erythrocytes pass through the blood vessels of the lungs, and it leaves the hemoglobin when the erythrocytes pass through the blood vessels of the body tissues. -This gas exchange occurs by diffusion as a result of the differences in concentration of oxygen between two areas. -For example, oxygen is in higher concentration in the lungs compared to the blood, so oxygen diffuses from the lungs into the blood. -Conversely, oxygen is in higher con- centration in the blood compared to the interstitial fluid around body cells, so oxygen diffuses from the blood to the interstitial fluid. -Carbon dioxide and the globin molecule (not the iron ion) have a similar weak attachment relationship for the transport of carbon dioxide molecules.

Encapsulated tactile receptors

are either wrapped by connective tissue or covered by glial cells. -Encapsulated tactile receptors include end bulbs, lamellated corpuscles, bulbous corpuscles, and tactile corpuscles.

describe a RBC

biconcave, hemoglobin containing, enucleate, round, O2 carrying, short lived

hemopoiesis

blood cell formation -because formed elements have a relatively short life span, new ones are continually produced by the process of hemopoiesis (hē′mō-poy-ē′sis; poiesis = a making), also called hematopoiesis. -Hemopoiesis occurs in red bone marrow

Endocrine glands

ductless and secrete their molecular products directly into the blood. -All endocrine cells, whether organized into a single organ or scattered in small clusters within other organs, are located within highly vascularized areas to ensure that their products enter the blood immediately. -pituitary gland -pineal gland -thyroid gland -parathyroid glands -adrenal glands •Hypothalamus• •Thymus •Pancreas •Gonads -tropic = stimulating

Equilibrium

equilibrium refers to our awareness and monitoring of head position. Sensory receptors in the utricle, saccule, and semi- circular ducts—collectively called the vestibular apparatus—help monitor and adjust our equilibrium. Our brain receives this sensory input and, along with visual sensory input and input from our pro- prioceptors, integrates this information so we may keep our balance and make positional adjustments as necessary. -The utricle and saccule detect head position during static equilibrium—that is, when the head is stationary. So, for example, when you are standing in the anatomic position, it is the utricle and saccule that inform your brain that your head is upright. The utricle and saccule also detect linear acceleration changes of the head. This occurs, for example, when you tilt your head downward to look at your shoes. The semicircular ducts, in contrast, are responsible for detecting angular acceleration, or rotational movements of the head. The sensory receptors in the semicircular ducts are stimulated when you shake your head "no," or when a figure skater does a spin on the ice. -Both static equilibrium and linear acceleration are detected by the sensory receptors housed within the vestibule of the inner ear. -The sensory receptor, called a macula, is located along the internal wall of both the utricle and saccule -Each macula is composed of a mixed layer of hair cells and supporting cells. -Hair cells are the sensory receptors of the inner ear for both equilibrium and hearing. They continuously release neurotransmitter molecules to the sensory neurons that monitor their activity. The apical surface of each hair cell has a covering of numerous (more than 50) long, stiff microvilli, termed stereocilia (ster′ē-ō-sil′ē-ă; stereos = solid, cilium = eyelid). In the maculae of the utricle and saccule and in the semicircular ducts, each hair cell also has one long cilium, termed a kinocilium (kin′ō-sil′ē-ŭm; kino = movement) on its apical surface (figure 19.22c). Both the stereocilia and kinocilia may be physically bent or displaced, result- ing in changes in the amount and rate of neurotransmitter release from the hair cell. -Stereocilia and kinocilia projecting from the hair cells embed within a gelatinous mass that completely covers the apical surface of the epithelium. This gelatinous layer is embedded with a bunch of small calcium carbonate crystals called otoliths (o′tō-lith; lithos = stone), or statoconia. Together, the gelatinous layer and the crystals form the otolithic membrane (or statoconic membrane). The otoliths push on the underlying gelatin, thereby increasing the weight of the otolithic membrane covering the hair cells. The position of the head influences the position of the otolithic mem- brane (figure 19.23). When the head is held erect, the otolithic membrane applies pressure directly onto the hair cells, and minimal stimulation of the hair cells occurs. However, tilting the head due to ither acceleration or deceleration causes the otolithic membrane to shift its position on the macula surface, thus distorting the stereo- cilia. -Bending of the stereocilia results in a change in the amount of neurotransmitter released from the hair cells and a simultaneous change in the stimulation of the sensory neurons. Thus, distortion of the hair cells in one particular direction causes stimulation, whereas the opposing movement causes inhibition of the sensory neuron. These impulses are sent to the brain to indicate the direction the head has tilted. The semicircular canals are continuous with the superoposterior region of the utricle. -There are three semicircular canals: anterior, posterior, and lateral. The anterior and posterior canals are vertical but at right angles to each other, whereas the lateral canal is slightly off the horizontal plane. Within each semicircular canal is a semicircular duct connected to the utricle. Receptors in the semicircular ducts detect angular acceleration (rotational movements) of the head. -Contained within each semicircular duct is an expanded region, called the ampulla (am-pul′lă; pl., ampullae, located at the end furthest from the utricle connection (figure 19.24). The ampulla contains an elevated region, called the crista ampullaris (or ampullary crest), that is covered by an epithelium of hair cells and supporting cells (figure 19.25). These hair cells embed both their kinocilia and stereocilia into an overly- ing gelatinous dome called the cupula (kū′pū-lă). This accessory structure extends completely across the semicircular duct to the roof over the ampulla. -When the head rotates, it causes endolymph within the semicir- cular ducts to move and push against the cupula, causing bending of the stereocilia. Stereocilia bending results in altered neurotransmit- ter release from the hair cells and simultaneous stimulation of the sensory neurons. As described earlier in this section, fluid move- ment in one direction causes distortion of the hair cells, resulting in stimulation, whereas the opposing movement causes distortion resulting in inhibition.

platelet plug

gathering of platelets that forms a small mass at the site of an injury

Unencapsulated tactile receptors

have no connective tissue wrap- ping around them and are relatively simple in structure. -The three types of unencapsulated tactile receptors are free nerve endings, root hair plexuses, and tactile discs.

anemia is having a low

hematocrit

the blood forming stem cell

hemocytoblast

Olfaction

is the sense of smell, whereby volatile molecules (called odorants) must be dissolved in the mucus in our nasal cavity to be detected. -We use this sense to sample our environment for information about the food we will eat, the presence of other individuals in the room, or potential danger (e.g., spoiled food or smoke from a fire). -Compared to many other animals, our olfactory ability is vastly less sensitive and not as highly developed, because we do not rely as greatly on olfactory information to find food or communicate with others. -Within the nasal cavity, paired olfactory organs are the organs of smell. They are composed of several components -In our nasal cavity, an olfactory epithelium lines the superior region of the nasal cavity, including both the superior nasal conchae and the inferior surface of the cribriform plate of the ethmoid bone. -This specialized epithelium is composed of three distinct cell types: 1. Olfactory receptor cells (also called olfactory neurons), which detect odors 2. Supporting cells (also called sustentacular cells) that sandwich the olfactory neurons and sustain the receptors 3. Basal cells (which function as neural stem cells) continually replace olfactory receptor cells -Olfactory receptor cells are one of the few neuronal types that are replaced. Olfactory receptor neurons are regenerated every 40 to 60 days by basal cells within the olfactory epithelium. (This process decreases with age, and the remaining olfactory neurons lose their sensitivity to odors. Thus, an elderly individual has a decreased abil- ity to recognize odor molecules.) -Olfactory receptor cells are bipolar neurons that have undergone extensive differentiation and modification, and serve as the primary neuron in the sensory pathway for smell. - Olfactory receptor cells have both a single dendrite and an unmyelinated axon. - Projecting from the dendrites are numerous thin, nonmotile cilia called olfactory hairs, which extend into the layer of mucus. - Olfactory hairs contain chemoreceptors within their plasma membrane that detect one specific odorant molecule. -Depending upon which olfactory receptor cells are stimulated, different smells will be perceived. -Axons of olfactory receptor cells form bundles (fascicles) of the olfactory nerves (CN I) (see section 15.8). -These fascicles project through foram- ina (holes) in the cribriform plate of the ethmoid bone to enter an olfactory bulb. -bipolar neurons replaced by mitosis

which pumps blood to the body

left ventricle

visceral sensory receptors

located in the walls of the viscera (internal organs) and blood vessels. -These receptors detect stretch in the smooth muscle within the walls of internal organs (e.g., stretch of the stomach wall), chemical changes in the contents within their lumen (e.g., a change in carbon dioxide levels in the blood), temperature, and pain.

special sense receptors

located only within the head and are specialized, complex sense organs. -The five special senses are olfaction (smell), gustation (taste), vision (sight), hearing (audition), and equilibrium (head position and acceleration).

when does Rh cause a problem

mom is Rh-, baby is Rh+ and she has previously had an Rh+

which WBC becomes a macrophage

monocyte

Endocrine system: negative feedback loops

occurs when a stimulus starts a process, and eventually either the hormone that is secreted or a product of its effects causes the process to slow down or turn off. -Most hormonal systems work by negative feedback mechanisms. -One example is the regulation of the blood glucose level in the body -A normal blood glucose level exists when the body is at homeostasis for energy production. -Eating food is a stimulus that eventually causes the blood glucose level to rise. -In response, the pancreas secretes a hormone called insulin that helps reduce the blood glucose level. -Insulin acts in two ways: It causes target cells in the liver to take up glucose from the blood and store it in the form of glycogen, and it stimulates other body target cells to take up the glucose for use in metabolism. -As the blood glucose level declines, a normal blood glucose level is reached. -Once this homeostatic level is achieved, insulin secretion stops, and glucose uptake by target cells ceases. -hormone production results in decreased hormone production, decreased activity

referred pain

occurs when impulses from certain viscera are perceived as originating not from the organ, but in dermatomes of the skin (see figure 16.6). -Numerous cutaneous and visceral sensory neurons conduct nerve impulses through the same ascending tracts within the spinal cord (figure 19.3). -As a result, impulses conducted along ascending pathways may be localized incorrectly. -Consequently, the primary somatosensory cortex in the brain is unable to differentiate between the actual and false sources of the stimulus. -sensed in another area

gustatory cells

our sense of taste, gustation, permits us to perceive the characteristics of what we eat and drink. -Gustation is also referred to as contact chemoreception because we must come in contact with a substance to experience its flavor. -Gustatory (taste) cells are taste receptors housed in specialized sensory organs termed taste buds on the tongue surface. -The tongue and soft palate also house mechanoreceptors and thermoreceptors to provide information about the texture and temperature of the food we are eating. -Taste buds are cylindrical sensory organs containing taste receptors and have the appearance of an onion (figure 19.6c, d). Each taste bud is composed of three distinct cell types: 1. Gustatory cells (also called gustatory receptors), which detect tastants (taste-producing molecules and ions) in our food 2. Supporting cells, which sustain the gustatory cells 3. Basal cells, which function as neural stem cells to continually replace the relatively short-lived gustatory cells -Gustatory cells are regenerated every 7 to 9 days by basal cells within the taste bud. This process decreases with age, and our sensitivity to taste also decreases. -Beginning at about age 50, our ability to distinguish between different tastes declines. -Gustatory cells within the taste buds are specialized neu- roepithelial cells. -The dendritic ending of each gustatory cell is formed by a slender gustatory microvillus, sometimes called a taste hair. -Many gustatory microvilli extend through an opening in the taste bud, called the taste pore, to the surface of the tongue. -This is the receptive portion of the cell. Within the oral cavity, saliva keeps the environment moist; the tastants in our food dis- solve in the saliva, and then they are able to contact and stimulate gustatory receptors.

ear

partitioned into three distinct anatomic regions: external, middle, and inner - The external ear is located mostly on the outside of the body, and the middle and inner areas are housed within the petrous part of the temporal bone. Movements of the inner ear fluid result in the sensations of hearing and equilibrium (balance).

myopia

people with myopia (mī-ō′pē-ă; myo = to shut) have trouble seeing far-away objects, and so are called "nearsighted." In myopia, only rays relatively close to the eye focus on the retina. The cause of this condition is a "long" eyeball; parallel light rays from objects at some distance from the eye focus anterior to the retina within the vitreous humor.

blood flow into capillaries is controlled by

precapillary sphincters

End bulbs

previously called Krause bulbs, are dendritic end- ings of sensory neurons ensheathed in connective tissue. -They are located in the dermis of the skin near the border of the stratified squa- mous epithelium, and in the mucous membranes of the oral cavity, nasal cavity, vagina, and anal canal. -End bulbs detect light-pressure stimuli and low-frequency vibration.

Tactile corpuscles

previously called Meissner corpuscles, are large, encapsulated oval receptors. -They are formed from highly intertwined dendrites enclosed by modified neurolemmocytes, which are then covered with dense irregular connective tissue. -They are housed within the dermal papillae of the skin, especially in the lips, palms, eyelids, nipples, and genitals. -Tactile corpuscles are phasic receptors for discriminative touch to determine textures and shapes of an object and for light touch.

Tactile discs

previously called Merkel discs, are flattened nerve endings that function as tonic receptors for fine touch. -These receptors are important in distinguishing the texture and shape of a stimulating agent. - Tactile discs are associated with special tactile cells (Merkel cells), which are located in the stratum basale of the epidermis. - Tactile cells exhibit a small receptive field and commu- nicate directly with the dendrites of a sensory neuron. -(Note that tactile cells are the only specialized receptor cells; other tactile receptors are simply the dendritic endings of primary sensory neurons.)

Lamellated corpuscles

previously called Pacinian corpuscles, are composed of several dendritic endings ensheathed with an inner core of neurolemmocytes (see section 14.2b) and outer concentric layers of connective tissue. -They occur deep within the reticular layer of the dermis of the skin; in the subcutane- ous tissue of the palms of the hands, soles of the feet, breasts, and ex- ternal genitalia; in the synovial membranes of joints; and in the walls of some organs. -The structure and location of lamellated corpuscles allow them to function in coarse touch, as well as sense continuous deep-pressure and high-frequency vibration stimuli.

Bulbous corpuscles

previously called Ruffini corpuscles, are dendritic endings of sensory neurons ensheathed within connective tissue that are housed within the dermis and subcutaneous layer, as well as in joint capsules. - They detect both continuous deep pressure and distortion in the skin. These are tonic receptors that do not ex- hibit adaptation.

sensory receptors

range in complexity from the relatively simple, bare dendritic ending of a single sensory neu- ron (e.g., touch receptors; see figure 19.5) to complex structures called sense organs, whose nerve endings are associated with epithelial tissue, connective tissue, or muscular tissue (e.g., the eye; see figure 19.13). - The feature common to all sensory receptors is the ability to respond to a stimulus and initiate sensory input to the central nervous system (CNS).

Nociceptors

respond to painful stimuli, to inform the body of injury or other damage. -Somatic nociceptors detect chemical, heat, or mechanical damage tothe body surface or skeletal muscles. -For example, exposure to acid, touching a hot pan, or suffering a sprained ankle stimulate somatic nociceptors. -Visceral nociceptors detect internal body damage within the viscera due to excessive stretching of smooth muscle, oxygen deprivation of the tissue, or chemicals released from damaged tissue. -pain receptors

action potentials in the heart are conducted along

sarcolemma

inner ear

slocated within the petrous part of the temporal bone, where there are spaces or cavities called the bony labyrinth (lab′i-rinth; an intricate, mazelike passageway) (figure 19.21; see also figure 19.19). Within the bony labyrinth are membrane-lined, fluid- filled tubes and spaces called the membranous labyrinth. Recep- tors for equilibrium and hearing are housed within the membranous labyrinth. -The space between the outer walls of the bony labyrinth and the membranous labyrinth is filled with a fluid called perilymph (per′i- limf), which is similar in composition to both extracellular fluid and cerebrospinal fluid (CSF). In the inner ear, the perilymph suspends, supports, and protects the membranous labyrinth from the wall of the bony labyrinth. The membranous labyrinth contains a unique fluid called endolymph (en′dō-limf). Endolymph exhibits a low sodium and high potassium concentration similar to that of intracellular fluid. -The bony labyrinth is structurally and functionally partitioned into three distinct regions that include the cochlea, vestibule, and semicircular canals: The cochlea (kok′lē-ă = snail shell) houses a membranous labyrinth structure called the cochlear duct (or scala media). The vestibule (veśti-byūl; vestibulum = entrance court) contains two saclike, membranous labyrinth structures— the utricle (yū′tri-kēl; uter = leather bag) and the saccule (sak′yūl; saccus = sack). The semicircular canals each contain a membranous labyrinth structure called the semicircular duct.

cataracts

small opacities within the lens that, over time, may coalesce to completely obscure the lens. Cataracts are a major cause of blindness worldwide. Most cases occur as a result of aging, although other causative factors include diabetes, intraocular infections, excessive ultraviolet light exposure, and glaucoma. The resulting vision problems include difficulty focus- ing on close objects, reduced visual clarity as a consequence of clouding of the lens, "milky" vision, and reduced intensity of colors. A cataract needs to be removed only when it interferes with normal daily activities. Newer surgical techniques include phacoemulsification (or phaco), a process whereby the opacified center of the lens is fragmented using ultrasonic sound waves, thus making it easy to remove. The destroyed lens then typically is replaced with an artificial intraocular lens, which becomes a permanent part of the eye.

Root hair plexuses

specialized free nerve endings that form a weblike sheath around hair follicles in the reticular layer of the dermis. -Any movement or displacement of the hair changes the arrangement of these branching dendrites, initiating a nerve impulse. -These receptors quickly adapt; thus, although we feel the initial contact of a long-sleeved shirt on our arm hairs when we put on the garment, our conscious awareness subsides immediately until we move and the root hair plexuses are restimulated.

a contracting heart muscles is in

systole

somatic sensory receptors

tactile receptors housed within both the skin and mucous membranes, which line the nasal cavity, oral cavity, vagina, and anal canal. -These sensory recep- tors monitor several types of stimuli including texture of an object, pressure, vibration, temperature, and pain. -Somatic sensory receptors are also within joints, muscles, and tendons, and include joint recep- tors, muscle spindles, and Golgi tendon organs, respectively. -These detect stretch and pressure relative to position and movement of the skeleton and skeletal muscles. -A Golgi tendon organ, for example, monitors stretch of a tendon when a muscle contracts.

Free nerve endings

terminal branches of dendrites. -They are the least complex of the tactile receptors and reside closest to the surface of the skin, usually in the papillary layer of the dermis. -Often, some dendritic branches extend into the deepest epidermal strata and terminate between the epithelial cells. -These tactile receptors primarily detect pain and temperature stimuli, but some also detect light touch and pressure.

tactile receptors

the most numerous type of sensory receptor. - They are mechanoreceptors that react to touch, pressure, and vibration stimuli. -They are located in the dermis (see section 5.3) and the subcutaneous layer (figure 19.5). -Tactile receptors range from simple, dendritic ends that have no connective tissue wrapping (called unencapsulated) to complex structures that are wrapped with connective tissue or glial cells (called encapsulated)

auscultation of the heart is listening for

valve sounds

accommodation

when we wish to see close objects (use our near vision), the lens must become more spherical to properly refract (bend) the light rays and focus an image on the retina. - The pro- cess of making the lens more spherical to view close-up objects is called accommodation (ă-kom′ŏ-dā′shŭn; accommodo = to adapt) (figure 19.15b). -Accommodation is controlled by the parasympathetic division of the ANS (see section 18.3); specifically, originating within the oculomotor nerve (see section 15.8). -Stimulation of the ciliary muscles by parasympathetic axons causes the muscles to contract. When the ciliary muscles contract, the entire ciliary body moves an- teriorly and thus moves closer to the lens itself. -This process reduces the suspensory ligaments' tension and releases some of their "pull" on the lens, so the lens can become more spherical.

Thymus

•Numerous thymic hormones •Immune response... -The thymus, located in the mediastinum, produces several hormones called thymosins. -The thymus (thī′mŭs; thymos = sweetbread) is a bilobed structure located within the mediastinum superior to the heart and immediately posterior to the sternum (see figure 20.2). -A connec- tive tissue framework houses both the epithelial cells and maturing T-lymphocytes (a specific type of white blood cell) (see section 24.3a). -The size of the thymus varies among individuals; however, it is always relatively large in infants, continues to grow until puberty, then diminishes in size and activity. -The adult thymus is usually only one-third to one-fourth its pre-puberty size and weight. -Most of the functional cells of the thymus are lost, and the ensuing space fills with adipose connective tissue. -The thymus functions principally in association with the lymphatic system to regulate and maintain body immunity. - It produces thymopoietin (thī′mō-poy-ē′tin) and thymosins (thī′mō-sins) (a group of complementary hormones). -These hormones act by stimulating and promoting the differentiation, growth, and maturation of T-lymphocytes.