Histology Review Supplement

Histology Re encounter postscript The trends in this subdivision be designed to entrust a basic histology review cogitate to topics introduced in the PhysioEx lab simulations and in your anatomy and physiology textbook. From the PhysioEx master(prenominal) menu, bring Histology Tutorial. The curtain raising riddle should appear after a few seconds. The Sort by menu is located at the top left. sink in on the snow-covered drop-down menu and contract Histology check into from the list.You exit note that the trends in the histology staff be grouped in the following folders osteal go by dint of drop aways noisome create from raw stuff coasts Endocrine interweave coasts Cardiovascular create from raw material slips respiratory weave luxates Digestive wind slides Renal meander slides necessitate the group of slides you beseech to view, and then refer to the relevant worksheet in this incision for a step-by-step tutorial. For example, if you would like to review the skeletal vim slides, ruffle on the superfluous ponderousness builder slides folder, and then turn to the next page of this lab manual of arms for the worksheet entitled Skeletal Muscle create from raw stuff Review to begin your review.You will confine the option of viewing slides with or without labels by maundering the On/ strike thrusts at the bottom left of the viewer. Since the slides in this module occupy been selected for their relevance to topics covered in the PhysioEx lab simulation, it is recommended that you complete the worksheets along with a associate PhysioEx lab. For example, you might complete the Skeletal Muscle Tissue worksheet unspoiled before or after your instructor assigns you Exercise 2, the PhysioEx lab simulation on Skeletal Muscle Physiology. For additional histology review, turn to page 121. 23 Skeletal Muscle Tissue Review From the PhysioEx main menu, select Histology Review Supplement. When the overwhelm comes up, get through and through Select an Image separate. From Group Listing, gibber Skeletal ponderousness slides. To view slides without labels, click the Labels Off button at the bottom honorable of the monitor. pokey slide 1. Skeletal go throughman is accumulated of extremely large, cylindric multinucleated cubicles c whollyed myo character references. The nuclei of the skeletal sinew cell (myonuclei) ar located peripheral devicely righteous subjacent to the muscle cell plasmalemma (sarcolemma).The interior of the cell is literally fill with an assembly of contractile proteins (myofilaments) arranged in a specific co-occur exemplar point parallel to the long axis of the cell. thumb slides 2, 3. Sarcomeres are the figure outal social units of skeletal muscle. The reed administration of contractile proteins into a regular throughout repeating pattern of sarcomeres along the aloofness of each cell accounts for the striated, or striped, appearance of skeletal muscle in longitu dinal section. Click slide 4.The debonaire endoplasmic reticulum (sarcoplasmic reticulum), modified into an extensive network of membranous convey that store, release, and take up the calcium necessary for compaction, also serve wells to further strain the myofilaments wrong the cell into cylindrical bundles called myofibrils. The stippled appearance of the cytoplasm in cells cut in cross section re gratuitys the internal organization of myofilaments bundled into myofibrils by the membranous sarcoplasmic reticulum. What is the operable unit of contraction in skeletal muscle?Click slide 5. The neural stimulus for contraction arises from the axon of a motor neuron whose axon last(a) comes into close apposition to the muscle cell sarcolemma. Would you characterize skeletal muscle as voluntary or involuntary? call off the site of close juxtaposition of an axon perch with the muscle cell plasmalemma. Skeletal muscle also has an extensive concurrence tissue comp matchlessnt that , in addition to delivering declension vessels and founts, lives continuous with the concurrence tissue of its tendon.The tendon in turn is directly continuous with the connection tissue covering (the periosteum) of the adjacent bone. This con voice tissue continuity from muscle to tendon to bone is the basis for movement of the musculoskeletal dodge. What is the name of the expel areolar colligation tissue covering of an individual muscle role? endomysium The perimysium is a collagenous colligation tissue seam that groups several muscle fibers together into bundles called fascicles . the sacromeres What are the two principal contractile proteins that compose the serviceable unit of contraction?Which colligation tissue spirit level sur fill ins the whole muscle and merges with the connective tissue of tendons and aponeuroses? epimysium actin and myosin What is the specific relationship of the functional unit of contraction to the striated appearance of a skeletal mu scle fiber? the repeating pattern of the sacromeres organized end to end 124 Histology Review Supplement Nervous Tissue Review From the PhysioEx main menu, select Histology Review Supplement. When the screen comes up, click Select an Image Group. From Group Listing, click Nervous tissue slides.To view slides without labels, click the Labels Off button at the bottom right of the monitor. Nervous tissue is composed of nerve cells (neurons) and a variety of support cells. Click slide 1. Each nerve cell consists of a cell body (perikaryon) and one or more cellular processes (axon and dendrites) extending from it. The cell body contains the optic, which is typically pale-staining and round or globose in shape, and the usual assortment of cytoplasmic organelles. Characteristically, the nucleus features a prominent nucleolus often descri posterior as resembling the upil of a birds eye (birds eye, or bird of Minervas eye, nucleolus). Click slide 2. The cytoplasm of the cell body is or so often granular in appearance due to the presence of darkly dye clumps of ribosomes and rough endoplasmic reticulum (Nissl bodies/ Nissl substance). Generally, a single axon arises from the cell body at a pale-staining region (axon hillock), devoid of Nissl bodies. The pickle and telephone number of dendrites arising from the cell body varies greatly. Axons and dendrites are grouped together in the peripheral nauseating transcription (PNS) to form peripheral nerves.What is the autochthonic unit of function in tense tissue? Click slide 5. Because Schwann cells are aline in series and myelinate whole a undersize segment of a single axon, bantam happy chances occur amidst the myelin sheaths of adjacent close Schwann cells. The gaps, called nodes of Ranvier, together with the insulating properties of myelin, enhance the speed of conduction of electrical impulses along the length of the axon. Different support cells and myelinating cells are bow in the primal nervous system (systema nervosum centrale). What is the familiar name for all support cells inside the CNS? neuroglial cellsName the specific myelinating cell of the CNS. Oligodendrocyte In the PNS, connective tissue also plays a role in providing support and organization. In fact, the meek-arm and organization of the connective tissue investments of peripheral nerves are exchangeable to those of skeletal muscle. Click slide 3. Each individual axon or dendrite is surrounded by a tenuous and delicate layer of open(a) connective tissue called the endoneurium (not shown. ) The perineurium, a slightly heavyseter layer of wakeful connective tissue, groups many axons and dendrites together into bundles (fascicles).The outer to the highest degree epineurium surrounds the entire nerve with a thick layer of dense irregular connective tissue, often infiltrated with adipose tissue, that conveys strain and lymphatic vessels to the nerve. There is no connective tissue component within the ner vous tissue of the CNS. What is the relationship of the endoneurium to the myelin sheath? neuron Name the pale-staining region of the cell body from which the axon arises. nucleus The support cells of the nervous system perform extremely important functions including support, protection, insulation, and maintenance and regulation of the microenvironment that surrounds the nerve cells.Click slides 3, 4. In the PNS, support cells surround cell bodies (satellite cells) and individual axons and dendrites (Schwann cells). Schwann cells, in finicky, are responsible for wrapping their cell tissue layer jelly-roll style well-nigh axons and dendrites to form an insulating sleeve called the myelin sheath. enclosed and protects Histology Review Supplement one hundred twenty-five Endocrine Tissue Review From the PhysioEx main menu, select Histology Review Supplement. When the screen comes up, click Select an Image Group.From Group Listing, click Endocrine tissue slides. To view slides without labels, click the Labels Off button at the bottom right of the monitor. antrum, except for a thin rim of granulosa cells (corona radiata) that encircles the oocyte and a pedestal of granulosa cells (cumulus oophorus) that attaches the oocyte to the familiar breakwater of the antrum. Which cells of the ovarian follicle bury estrogen? Thyroid Gland The thyroid gland regulates metabolism by regulating the secretion of the hormones T3 (triiodothyronine) and T4 (thyroxine) into the rakehell.Click slide 1. The gland is composed of bland-filled (colloid) spheres, called follicles, formed by a plain-minded epithelial tissue that can be squamous to columned depending upon the glands activity. The colloid stored in the follicles is generally composed of a glycoprotein (thyroglobulin) that is synthesized and unloosed by the follicular cells. Under the influence of the hypophysis gland, the follicular cells take up the colloid, convert it into T3 and T4, and secrete the T3 and T4 i nto an extensive capillary network.A second population of cells, parafollicular (C) cells (not shown), may be found abrupt through the follicular epithelium but often are present in the connective tissue surrounded by follicles. The pale-staining parafollicular cells secrete the protein hormone calcitonin. wherefore is the thyroid gland considered to be an endocrine organ? Uterus Click slides 4, 5, 6. The uterus is a hollow stringy organ with lead study layers the endometrium, myometrium, and either an tunica or a serous membrane. The middle, myometrial layer of the uterine fence in is composed of several layers of savourlessen muscle oriented in distinct planes.Click slide 6. The inner virtually (nearest the lm) endometrial layer is further split functionally into a petty functional layer (stratum functionalis) and a dark lowly layer (stratum basalis). Click slide 4. A unbiased columnlike epithelium with both ciliated and nonciliated cells lines the come forward o f the endometrium. The endometrial connective tissue features an abundance of tubular endometrial glands that extend from the base to the spring up of the layer. During the proliferative var. of the catamenial cycle, shown here, the endometrium becomes thicker as the glands and decline vessels proliferate.Click slide 5. In the secretory phase, the endometrium and its glands and gillyflower vessels are fully expanded. Click slide 6. In the menstrual phase, the glands and blood vessels degenerate as the functional layer of the endometrium sloughs away. The deep basal layer (stratum basalis) is not sloughed and will regenerate the endometrium during the next proliferative phase. Which layer of the endometrium is mold during the menstrual phase of the menstrual cycle? it secrets a horomone What hormone secreted by the pituitary gland controls the synthesis and secretion of T3 and T4? TSH thyroid bear upon hormoneWhat is the function of calcitonin? causes CA to be released into bl ood O leave The ovary is an organ that serves both an exocrine function in producing eggs (ova) and an endocrine function in secreting the hormones estrogen and progesterone. Click slide 2. Grossly, the ovary is divided into a peripherally located cortex in which the oocytes (precursors to the ovulated egg) develop and a central bulb in which connective tissue surrounds blood vessels, lymphatic vessels and nerves. The oocytes, together with livelihood cells (granulosa cells), form the ovarian follicles seen in the cortex at various stages of development.Click slide 3. As an individual oocyte grows, granulosa cells proliferate from a single layer of cuboidal cells that surround the oocyte to a multicellular layer that defines a fluid-filled spherical follicle. In a mature follicle (Graafian follicle), the granulosa cells are displaced to the periphery of the fluid-filled 126 Histology Review Supplement endometrium What is the function of the deep basal layer (stratum basalis) of t he endometrium? regenerate new superficial layer What composes a serosa? perimetriumHow does the serosa of the uterus, where present, differ from visceral peritoneum? location Pancreas The pancreas is both an endocrine and an exocrine gland. Click slide 7. The exocrine function is characterized by glandular secretory units (acini) formed by a simple epithelium of triangular or pyramidal cells that encircle a small central lumen. The central lumen is the direct connection to the duct system that conveys the exocrine secretions out of the gland. Scattered among the exocrine secretory units are the pale-staining clusters of cells that compose the endocrine portion of the gland.The cells that form these clusters, called pancreatic islet cells (islets of Langerhans), secrete a number of hormones, including insulin and glucagon. Do the pancreatic islets secrete their hormones into the analogous duct system used by the exocrine secretory cells? no, but directly into blood stream Histolo gy Review Supplement 127 Cardiovascular Tissue Review From the PhysioEx main menu, select Histology Review Supplement. When the screen comes up, click Select an Image Group. From Group Listing, click Cardiovascular Tissue Slides. To view slides without labels, click the Labels Off button at the bottom right of the monitor.Which component of the intercalated disc is a junction that leave alones the intercellular communication required for the myocardium to perform as a functional syncytium? gap juntions Blood Vessels Blood vessels form a system of conduits through which lifesustaining blood is conveyed from the middle to all parts of the body and back to the heart again. Click slide 3. Generally, the jetty of every vessel is described as being composed of three layers, or tunics. The tunic intima, or tunic interna, a simple squamous endothelium and a small amount of subjacent loose connective tissue, is the inner virtually layer adjacent to the vessel lumen.Smooth muscle and el astin are the predominant constituents of the middle tunica media, and the outermost tunica tunica, or tunica externa, is a connective tissue layer of variable ponderousness that provides support and transmits smaller blood and lymphatic vessels and nerves. The thickness of each tunic varies widely with location and function of the vessel. Arteries, subjected to considerable pressure fluctuations, have thicker walls overall, with the tunica media being thicker than the tunica adventitia.Veins, in contrast, are subjected to oft lower pressures and have thinner walls overall, with the tunica adventitia often outsizing the tunica media. Because thin-walled venous blood vessels conduct blood back to the heart against gravity, valves (not present in arteries) also are present at intervals to prevent back accrue. In capillaries, where exchange occurs amidst the blood and tissues, the tunica intima alone composes the vessel wall. The tunica media of the aorta would have a much greate r proportion of what type of tissue than a small artery? core The heart is a four-chambered muscular pump.Although its wall can be divided into three distinct histological layers (endocardium, myocardium, and epicardium), the cardiac muscle of the myocardium composes the bulk of the heart wall. Click slide 1. Contractile cardiac muscle cells (myocytes, myofibers) have the identical striated appearance as skeletal muscle, but are branched quite than cylindrical in shape and have one (occasionally two) nucleus (myonucleus) sort of than many. The cytoplasmic striations represent the same organization of myofilaments (sarcomeres) and alignment of sarcomeres as in skeletal muscle, and the mechanism of contraction is the same.The intercalated disc, however, is a feature unusual to cardiac muscle. The densely stained twist is a complex of intercellular junctions (desmosomes, gap junctions, fasciae adherens) that structurally and functionally link cardiac muscle cells end to end. A se cond population of cells in the myocardium composes the noncontractile intrinsic conduction system (nodal system). Although cardiac muscle is autorhythmic, meaning it has the ability to contract involuntarily in the absence of extrinsic innervation provided by the nervous system, it is the intrinsic conduction system that prescribes the rate and orderly sequence of contraction.Extrinsic innervation only modulates the entire activity. Click slide 2. Of the various components of the noncontractile intrinsic conduction system, Purkinje fibers are the most readily observed histologically. They are particularly large in the ventricular myocardium and are recognized by their very pale-staining cytoplasm and larger diameter. The connective tissue component of cardiac muscle is relatively sparse and lacks the organization present in skeletal muscle. Which component of the intercalated disc is a pixilated intercellular junction that functions to keep cells from being pulled apart during c ontraction? lastic fiber In general, which vessel would have a larger lumen, an artery or its corresponding vein? vein wherefore would the tunica media and tunica adventitia not be present in a capillary? to part with material exchange between blood and tissue desmosomes What is a functional syncytium? Because the cardiac muscle cells are mechanically, chemically, and electrically connected to one an new(prenominal), the entire tissue resembles a single, enormous muscle cell. 128 Histology Review Supplement Respiratory Tissue Review From the PhysioEx main menu, select Histology Review Supplement.When the screen comes up, click Select an Image Group. From Group Listing, click Respiratory Tissue Slides. To view slides without labels, click the Labels Off button at the bottom right of the monitor. The respiratory system serves both to conduct oxygenated air deep into the lungs and to exchange oxygen and carbon dioxide between the air and the blood. The trachea, bronchi, and bronchio les are the part of the system of airways that conduct air into the lungs. Click slide 2. The trachea and bronchi are similar in morphology.Their lumens are lined by pseudo severalise columnar ciliated epithelium with chalice cells (respiratory epithelium), underlain by a connective tissue lamina propria and a deeper connective tissue sub mucosa with coiled sero-mucous glands that open onto the approach lining of the airway lumen. Click slide 1. Deep to the submucosa are the hyaline cartilage rings that add structure to the wall of the airway and prevent its collapse. Peripheral to the cartilage is a connective tissue adventitia. The sero-mucous glands are also visible in this slide. Click slide 3.The bronchioles, in contrast, are much smaller in diameter with a continuous layer of smooth muscle in place of the rubberlike reinforcements. A gradual decrease in the height of the epithelium to simple columnar also occurs as the bronchioles decrease in diameter. Distally the bronchiol es refund way to the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli in which gas exchange occurs. In the respiratory bronchiole, the epithelium becomes simple cuboidal and the continuous smooth muscle layer is interrupted at intervals by the presence of alveoli inserted into the bronchiolar wall.Click slide 4. Although some exchange occurs in the respiratory bronchiole, it is within the alveoli of the alveolar ducts and sacs that the preponderance of gas exchange transpires. here the walls of the alveoli, devoid of smooth muscle, are reduced in thickness to the thinnest realistic juxtaposition of simple squamous alveolar cell to simple squamous capillary endothelial cell. What are the primary functions of the respiratory epithelium? What is the primary functional unit of the lung? alveoli The alveolar wall is very delicate and subject to collapse. wherefore is there no smooth muscle present in its wall for support? smooth muscle would hinder the gas exchange What are the three basic components of the air-blood bar? alveolar, capillary walls and basal laminae humidfy, filter and warm incoming air Why doesnt gas exchange occur in bronchi? bronchi have no alveoli Histology Review Supplement 129 Digestive Tissue Review From the PhysioEx main menu, select Histology Review Supplement. When the screen comes up, click Select an Image Group. From Group Listing, click Digestive Tissue Slides.To view slides without labels, click the Labels Off button at the bottom right of the monitor. smooth muscle nearest the stomach, and a blend of both skeletal and smooth muscle in between. 4. The outermost layer of the gullet is an adventitia for the portion of the esophagus in the thorax, and a serosa after the esophagus penetrates the diaphragm and enters the abdominal cavity. Click slide 3. Here we can see the abrupt change in epithelium at the gastroesophageal junction, where the esophagus becomes continuous with the stomach. Briefly explain the differe nce between an adventitia and a serosa. Salivary GlandThe digestive process begins in the mouth with the physical breakdown of nourishment by mastication. At the same time salivary gland secretions moisten the food and begin to hydrolyze carbohydrates. The saliva that enters the mouth is a mix of serous secretions and mucus (mucin) produced by the three major pairs of salivary glands. Click slide 1. The secretory units of the salivary tissue shown here are composed predominantly of clusters of pale-staining mucussecreting cells. More darkly stained serous cells cluster to form a demilune (half moon) adjacent to the lumen and contribute a clear fluid to the salivary secretion.Salivary secretions flow to the mouth from the respective glands through a well-developed duct system. Are salivary glands endocrine or exocrine glands? serosa secret serous fluid, and adventitia dont. Stomach The wall of the stomach has the same basic four-layered organization as that of the esophagus. Click s lide 4. The mucosa of the stomach consists of a simple columnar epithelium, a thin connective tissue lamina propria, and a thin muscularis mucosa. The most significant feature of the stomach mucosa is that the epithelium invaginates deeply into the lamina propria to form superficial gastric pits and deeper gastric glands.Although the epithelium of the stomach is composed of a variety of cell types, each with a unique and important function, only three are mentioned here (see slide 5). Click slide 5. The surface mucous cells are simple columnar cells that line the gastric pits and secrete mucus continuously onto the surface of the epithelium. The large round pink- to red-stained parietal cells that secrete hydrochloric acid (HCl) line the upper half of the gastric glands more abundant in the lower half of the gastric glands are the chief cells (not shown), normally stained blue, that secrete pepsinogen (a precursor to pepsin).Click slide 4. The submucosa is similar to that of the eso phagus but without glands. The muscularis externa has the two typical circumferential and longitudinal layers of smooth muscle, electropositive an extra layer of smooth muscle oriented obliquely. The stomachs outermost layer is a serosa. What is the function of the mucus secreted by surface mucous cells? exocrine Which salivary secretion, mucous or serous, is more thin and watery in consistency? serous EsophagusThrough contractions of its muscular wall (peristalsis), the esophagus propels food from the mouth to the stomach. Four major layers are apparent when the wall of the esophagus is cut in transverse section Click slide 2. 1. The mucosa adjacent to the lumen consists of a nonkeratinized stratified squamous epithelium, its immediately subjacent connective tissue (lamina propria) containing blood vessels, nerves, lymphatic vessels, and cells of the tolerant system, and a thin smooth muscle layer (muscularis mucosa) forms the boundary between the mucosa and the submucosa.Because this slide is a low magnification view, it is not possible to discern all parts of the mucosa nor the boundary between it and the submucosa. 2. The submucosa is a layer of connective tissue of variable density, traversed by larger timbre vessels and nerves, that houses the mucus-secreting esophageal glands whose secretions protect the epithelium and further lubricate the passing food bolus. 3. Much of the substance of the esophageal wall consists of both circumferentially and longitudinally oriented layers of muscle called the muscularis externa.The muscularis externa is composed of skeletal muscle nearest the mouth, 130 Histology Review Supplement protects the epithelium Small Intestine The key to understanding the histology of the small intestine lies in knowing that its major function is absorption. To that end, its receptive surface area has been amplified greatly in the following ways 1. The mucosa and submucosa are thrown into permanent folds (plicae circulares). 2. Fingerl ike extensions of the lamina propria form villi (singular villus) that protrude into the intestinal lumen (click slide 7). 3.The individual simple columnar epithelial cells (enterocytes) that cover the villi have microvilli (a brush border), tiny projections of apical plasma membrane to ontogenesis their absorptive surface area (click slide 6). Click slide 7. Although all three segments of the small intestine (duodenum, jejunum, and ileum) possess villi and tubular crypts of Lieberkuhn that project deep into the mucosa between villi, some unique features are present in particular segments. For example, large mucous glands (duodenal glands, Brunners glands) are present in the submucosa of the duodenum.In addition, permanent aggregates of lymphatic tissue (Peyers patches) are a unique characteristic of the ileum (click slide 8). Aside from these specific features and the fact that the height of the villi vary from quite tall in the duodenum to fairly short in the terminal ileum, the overall morphology of mucosa, submucosa, muscularis externa, and serosa is quite similar in all three segments. Why is it important for the duodenum to add large quantities of mucus (from the duodenal glands) to the partially digested food entering it from the stomach?Click slide 10. fixed in the surrounding connective tissue, roughly at the points of the hexagon where three lobules meet, is the entrance vein triad (portal canal). Click slide 12. The three constituents of the portal triad take a branch of the hepatic artery, a branch of the hepatic portal vein, and a insolence duct. Both the hepatic artery and portal vein empty their oxygen-rich blood and nutrient-rich blood, respectively, into the sinusoids. This blood mixes in the sinusoids and flows centrally in between and around the hepatocytes toward the central vein.Bile, produced by hepatocytes, is secreted into very small channels (bile canaliculi) and flows peripherally (away from the central vein) to the bile duct. T hus, the flow of blood is from peripheral to central in a hepatic lobule, while the bile flow is from central to peripheral. What general type of cell is the phagocytic Kupffer cell? immune Blood in the portal vein flows directly from what organs? liver What is the function of bile in the digestive process? protects intestinal walls raises alkalinity to create ideal pH Colon Click slide 9.The four-layered organization is maintained in the wall of the colon, but the colon has no villi, only crypts of Lieberkuhn. Simple columnar epithelial cells (enterocytes with microvilli) are present to absorb water from the digested food mass, and the numbers of mucous goblet cells are increased substantially, especially toward the distal end of the colon. Why is it important to have an abundance of mucous goblet cells in the colon? because they secrete mucous, which is important to fascilitate degestion Pancreas Click slide 13. The exocrine portion of the pancreas synthesizes and secretes pancrea tic enzymes.The individual exocrine secretory unit, or acinus, is formed by a group of pyramidal- do pancreatic acinar cells clustered around a central lumen into which they secrete their products. A system of pancreatic ducts then transports the enzymes to the duodenum where they are added to the lumen contents to further aid digestion. The groups of pale-staining cells are the endocrine pancreatic islet (islets of Langerhans) cells. Liver The functional tissue of the liver is organized into hexagonally shaped cylindrical lobules, each delineated by connective tissue.Click slide 11. Within the lobule, large rounded hepatocytes form linear cords that give out peripherally from the center of the lobule at the central vein to the surrounding connective tissue. Blood sinusoids lined by simple squamous endothelial cells and darkly stained phagocytic Kupffer cells are interposed between cords of hepatocytes in the same emit pattern. Histology Review Supplement 131 Renal Tissue Review F rom the PhysioEx main menu, select Histology Review Supplement. When the screen comes up, click Select an Image Group.From Group Listing, click Renal Tissue Slides. To view slides without labels, click the Labels Off button at the bottom right of the monitor. The many functions of the kidney include filtration, absorption, and secretion. The kidney filters the blood of metabolic wastes, water, and electrolytes and reabsorbs most of the water and sodium ions filtered to regulate and maintain the bodys fluid volume and electrolyte balance. The kidney also plays an endocrine role in secreting compounds that increase blood pressure and stimulate red blood cell production.The uriniferous tubule is the functional unit of the kidney. It consists of two components the nephron to filter and the collecting tubules and ducts to carry away the filtrate. Click slide 1. The nephron itself consists of the nephritic corpuscle, an intimate association of the glomerular capillaries (glomerulus) with the cup-shaped archers capsule, and a single elongated nephritic tubule consisting of segments regionally and sequentially named the proximal convolve tubule ( portion), the descending and ascending segments of the loop of Henle, and the distal winding tubule (DCT).Click slide 2. A closer look at the renal corpuscle shows both the simple squamous epithelium of the outer layer (parietal layer) of the glomerular capsule (Bowmans capsule) and the specialized inner layer (visceral layer) of podocytes that extend footlike processes to exclusively envelop the capillaries of the renal glomerulus. Processes of adjacent podocytes interdigitate with one another, leaving only small slits (filtration slits) between the processes through which fluid from the blood is filtered.The filtrate then flows into the urinary space that is directly continuous with the first segment of the renal tubule, the PCT. The PCT is lined by robust cuboidal cells equipped with microvilli to greatly increase the surface area of the side of the cell facing the lumen. Click slide 3. In the loop of Henle, lining cells are simple squamous to simple cuboidal. The DCT cells are also simple cuboidal but are usually much smaller than those of the PCT. The sparse distribution of microvilli, if present at all, on the cells of the DCT relates to their lesser role in absorption.The DCT is continuous directly with the collecting tubules and collecting ducts that spill the filtrate out of the kidney. The large renal artery and its many subdivisions provide an abundant blood supply to the kidney. The smallest distal branches of the renal artery become the afferent arteriolas that directly supply the capillaries of the glomerulus. In a unique situation, blood from the glomerular capillaries passes into the efferent arteriole rather than into a venule.The efferent arteriole then perfuses two more capillary beds, the peritubular capillary bed and vasa recta that provide nutrient blood to the kidney tissue itself, before ultimately draining into the renal venous system. In which segment of the renal tubule does roughly 7580% of reabsorption occur? proximal convoluted tubules How are proximal convoluted tubule (PCT) cells similar to enterocytes of the small intestine? both absorb water, salts, vitamins, phosphatesStarting from inside the glomerular capillary through to the urinary space, what are the three layers through which the filtrate must pass? glomerular capillary enothelium, glomrular basement membrane visceral layer of bowmans capsule Under normal circumstances in a healthy individual, would red blood cells or any other cells be present in the renal filtrate? no In addition to providing nutrients to the kidney tubules, what is one other function of the capillaries in the peritubular capillary bed? they deliver blood to tubular sites 132 Histology Review Supplement