Histology Exam 3

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what are the components of the urinary system?: two kidneys, two ureters, a bladder, and a urethra
what is the basic structural and functional unit of the kidney?: uriniferous tubule (synonym: nephron)
uriniferous tubule - composed of?: nephron and a system of collecting ducts
Name 7 functions of the kidney: (1) excretion of waste products of metabolism
(2) elimination of foreign substances and their breakdown products
(3) regulation of TBW
(4) maintenance of extracellular fluid volume
(5) regulation of various salts to be retained or excreted by the body (renin is involved)
(6) control of acid-base balance
(7) production of the hormone, erythropoietin (for RBC production)
how much plasma is filtrated per day?: 180 liters / day
how much urine is produced a day?: 1-2 liters / day
renal hilus: verticle slit on medial concave border through which the renal artery and vein, nerves, lymphatics, and ureter pass
renal sinus: flattened cavity within the kidney that communicates with renal hilus
renal pelvis: expanded part of the ureter found in the area of the renal hilus
major calyxes: 3-4 branches of renal pelvis, lie in the renal sinus
minor calyxes: 7-14 branches arising from the major calyxes
what part of the nephron is contained within the renal cortex?: the renal corpuscles and the convoluted portions of renal tubules
renal columns: projections of cortex toward renal sinus, lie between medullary pyramids
medullary rays - what? where?: groups of straight tubules, striated appearance

form the center of the renal lobule, project into the cortex from base of each medullary pyramid
what is the apex of each renal pyramid capped with?: minor calyx
renal lobe: a medullary pyramid and the cortical substance that surrounds it
renal lobule: consists of a medullary ray at its center and the cortical tissue surrounding it
where in the kidney is the renal corpuscle located?: located in the cortex
renal corpuscle - consists of?: tuft of capillaries (the glomerulus), supporting (mesangial) cells and a Bowman's capsule
renal corpuscle - parietal layer: outer layer of capsule, simple squamous epithelium
renal corpuscle - visceral layer: simple squamous epithelial cells (podocytes) adjacent to endothelial cells of the glomerulus
renal corpuscle - Bowman's space: snifter-shaped space b/t parietal and visceral layers
renal corpuscle - vascular pole: where the afferent glomerular arteriole enters and the efferent arteriole leaves the glomerulus
renal corpuscle - urinary pole: where Bowman's space goes continous with epithelium of tubule system
what comprises the visceral layer of the Bowman's capsule?: podocytes (stellate-shaped simple squamous epithelial cell)
glomerulus - basal lamina -- location: located between podocytes and endothelial cells
glomerulus - basal lamina -- three zones: (1) lamina rare interna -- adjacent to endothelium

(2) lamina rara externa -- adjacent to podocytes

(3) lamina densa -- intermediate zone, most electron-dense
glomerulus - filtration barrier - components include? - fxn: components include: fenestrated endothelium, basal lamina, and filtration slits

filters the blood plasma, permits water, ions and small molecules to enter Bowman's space

proteins greater than 69 kD and high net negative charge are excluded
glomerulus - mesangium - comprises? - fxn: comprises the interstitial spaces of glomerulus between the capillaries, contains mesangial cells and extracellular matrix

mesangial cells phagocytose proteins and molecules caught up in filtration barrier
what is the largest and longest tubule in the cortex?: proximal convoluted tubule
proximal convoluted tubule - lined with what? - mitochondria?: lined by simple cuboidal epithelium with a well-developed brush border along the lumen

abundant mitochondria in the bases of cells, provide energy for active transport
proximal convoluted tubule - adjacent cells bound together by what?: zonule occludens junctions and lateral indigitations
what is the major function of the proximal convoluted tubule?: to reduce volume of glomerular filtrate by approx 80%
straight portion of the proximal tubule - located where: located in the medullary ray and forms the first part of the loop of henle, may extend into the medullary pyramid
Thin Limb - where? - lined with? - fxn: sometimes forms in the medullary ray although usually forms within the medullary pyramid, forms a hairpin loop in the medullary pyramid (middle portion of Henle's loop)

lined by simple squamous epithelium

plays an important role in further concentrating urine
Straight portion of the distal tubule - where? - lined with? - microvilli? - fxn?: located in the medullary ray, forms third component of a loop of Henle

lined by simple cuboidal epithelium with irregular heights and shorter than cells in proximal tubules, microvilli not prominent over luminal surface

cells transport ions from lumen into the interstitium and helps luminal fluid become hypotonic with respect to the blood
Distal Convoluted Tubule - where? - fxn?: located in the cortex and begins at the macula densa

cells actively transport sodium from the filtrate into the interstitium -- make urine more hypotonic
Macula Densa - where? - what? - fxn?: distal tubule, in the vicinity of the afferent glomerulus arteriole

is one component of the JG apparatus

cells are tall, narrow, and lined up closely so that the nuclei come closely together forming what appears to be a "dense spot"

these cells are thought to monitor fluid in distal tubule and send signals via gap jxns to the JG cells in the afferent glomerular arteriole
Juxtaglomerular Apparatus - located where? - consists of? - fxn?: located at the vascular pole of the renal corpuscle

consists of: modified smooth muscle cells of afferent arteriole, the macula densa, and mesangial cells

fxns in response to a decrease in ECF -- triggers the JG cells to release renin
Collecting Ducts - found where? - lined with? - responds to?: found in cortex and medullary ray

lined by simple cuboidal epithelium, cells with very regular height

responds to ADH
Papillary Ducts (of Bellini) - located where? - what type of epithelium? - consist of what? - responds to? - fxn?: located in medullary pyramid, near the apex

simple columnar epithelium

large, straight ducts that empty their contents into the minor calyxes

respond to ADH

play a primary role in producing a concentrated urine when affected by ADH
area cribrosa: holes through which papillary ducts of bellini empty into a minor calyx
which artery gives rise to the interlobar arteries?: renal artery
which arteries give rise to the afferent arterioles of glomeruli?: interlobular arteries
vasa recta: form hairpin loops and play a role in concentrating urine

drain into interlobular or arcuate veins, then into interlobar veins, which at the hilus form the renal vein
what is the renal pelvis lined with?: transitional epithelium
describe the muscularis of the urinary bladder: muscularis is thick, consists of smooth muscle arranged in an inner longitudinal, middle circular, and outer longitudinal layer
what are the four ways we classify glands?: product distribution, morphology, mode of release of secretory product, type of secretory product
serous demilunes: consists of a "cap" of serous cells around the end of a mucous tubule; appear half-moon shaped in section
myoepithelial cells: resemble smooth muscle cells in their fine structure but are of epithelial origin; prominent in sweat and mammary glands, they surround the secretory units and aid in the expulsion of secretory products from the gland
mucous secretion: viscous glycoprotein secretion, functions to protect and lubricate
serous secretion: water secretion, often rich in enzymes and ions
lipid secretion: oily secretion (sebum) from sebaceous glands and lipid portion of milk in mammary gland
cerumen secretion: a waxy material formed by the combination of the secretory products of sebaceous and cerumenous glands with desquamated epidermal cells in the auditory canal
merocrine secretion - aka - definition: aka eccrine

product released by exocytosis
apocrine: where part of the apical cytoplasm is released along with the secretory product
holocrine: where the entire cell (may be dead or alive) and its contents are released
diffusion: secretory product passes through the cell membrane without the formation of secretory granules (e.g. steroid hormones)
what type of glands use diffusion as a mode of secretion?: endocrine glands only
what is the most common unicellular exocrine gland?: goblet cell
goblet cells - fxn: secrete mucus to lubricate the surface epithelium
vestibule: internal to the lips and cheeks, as far back as the teeth
oral cavity proper: behind the teeth (forward and lateral), bounded above by the hard and soft palate, the tongue below, ends posteriorly at the fauces (beginning of the oropharynx)
masticatory mucosa - present where? - what type of epithelium? - fxn: present on gingiva, dorsum of tongue, and hard palate

stratified squamous keratinized (parakeratinized) epithelium

underlying connective tissue contains Meissner's corpuscles and minor salivary glands (mostly mucus-secreting)
lining mucosa - present where? - what type of epithelium? - fxn: found everywhere except gingiva, dorsum of tongue, and hard palate

stratified squamous nonkeratinized epithelium

underlying connective tissue contains Meissner's corpuscles and minor salivary glands (mostly mucus-secreting and classified morphologically as compound tubuloacinar)
what is the tooth mostly comprised of?: dentin
what is the hardest substance of the body?: enamel
what forms enamel?: amelioblasts
what forms an maintains dentin?: odontoblasts
dentin - composed of: 70% calcium hydroxyapatite and its organic component mostly collagen, proteoglycans, and glycoproteins
pulp cavity - contains what? - what is at periphery?: contains gelatinous CT with blood vessels, nerves, and lymphatics; odontoblasts at the periphery
cementum - composed of: 45-50% calcium hydroxyapatite, organic component collagen, glycoproteins, proteoglycans
what separates the anterior 2/3 from the posterior 1/3 of the tongue?: sulcus terminalis
what kind of epithelium covers the dorsal surface of the tongue?: stratified squamous keratinized (parakeratinized) epithelium
where are papillae found on the tongue?: dorsal surface, over anterior 2/3
what covers the anterior surface of the tongue?: stratified sqaumous non-keratinized epithelium
are papillae found on the anterior surface of the tongue?: NO
what is the most numerous type of papillae?: filiform
filiform papillae - ID - covered by what type of epithelium? - taste buds?: short, tapering structures, point aimed toward the back of oral cavity

covered by parakeratinized epithelium with a connective tissue core

taste buds associated with them
fungiform papillae - occur how? - shape? - epithelium? - taste buds?: occur singularly over the dorsum of the tongue, mushroom shaped, appear red due to vascularity

covered by non-keratinized epithelium with a CT core

taste buds located on apical surface
circumvallate papillae - #, location - shape? - taste buds? - glands associated with them?: 10-15 in number, located anterior to sulcus terminalis, mushroom shaped and surrounded by a deep furrow

taste buds along their lateral surface

lingual glands -- the serous glands of Von Ebner associated only with these papillae, their duct empty into furrows
what are the component cells of a taste bud?: neeuroepithelial cells and supportive cells
CN V - what tongue innervation?: general sensation
CN VII - what tongue innervation?: taste to anterior 2/3
CN IX - what tongue innervation?: taste to posterior 1/3
what nerve innervates the muscles of the tongue?: CN XII (hypoglossal)
parotid gland - general structure: compound acinar
submandibular gland - general structure: compound tubuloacinar
sublingual gland - general structure: compound tubuloacinar
intercalated ducts - epithelium? - most prominent in? - fxn: formed of a simple cuboidal epithelium

in all major salivary glands but most prominent in Parotid Glands

cells add bicarbonate ions to saliva
striated ducts - epithelium? - cell jxns? - fxn: formed of a simple columnar epithelium

extensive cell jxns

account for approx 75% of the volume of saliva, remove sodium and chloride from saliva
Compare and contrast Parotid Gland, Submandibular Gland, and Sublingual Gland with respect to gland type, acini type, and striated ducts: Parotid Gland
- compound acinar
- only serous acini
- striated ducts prominent

Submandibular Gland
- compound tubuloacinar
- serous acini dominant
- striated ducts prominent

Sublingual Gland
- compound tubuloacinar
- mucus acini dominant
- striated ducts poorly developed
how much saliva is produced per day?: 1.0 - 1.2 liters / day
parasympathetic stimulation of glands produces what type of saliva?: watery
sympathetic stimulation of glands produces what type of saliva?: thicker saliva with relatively more mucus
6 fxns of saliva: (1) protects oral cavity
(2) limits bacterial growth
(3) solubilizes food for taste
(4) contains enzymes that begin digestion
(5) buffers against noxious ingested agents
(6) helps maintain the teeth
what are the three components of the mucosa of the organs of the GI tract?: epithelium, lamina propria, muscularis mucosa
mucosa: epithelium - fxns - vascular?: conduction, absorption, and secretion

avascular and sits on a basement membrane
mucosa: lamina propria - composed of? - vascular?: loose FECT, collagen and elastic fibers along with various CT cell types; occasional areas of diffuse and nodular lymphoid tissue; some areas contain varying #s of exocrine glands

contains small blood vessels, nerves, and lymphatics
mucosa: muscularis mucosa - composed of? - thickest where? - fxns? - innervated by?: smooth muscle mostly running longitudinally

relative thickness greatest in esophagus

contraction helps empty glands of mucosa and helps transport material along the tube

innervated by postganglionic parasympathetic fibers originating from Meissner's plexus
submucosa - classified as? - contains?: dense irregular FECT

contains large plexi of blood vessels and lymphatics, nerves and Meissner's plexi
muscularis externa - layer directions - innervated by? - functions: usually inner circular and outer longitudinal layers

innervated by post-ganglionic parasympathetic fibers originating from Auerbach's (myenteric) plexus located between the two muscle layers (preganglionic fibers from Vagus Nerve)

fxns in peristalsis; circular layer controls caliber of lumen, longitudinal layer shortens tube locally
adventitia - classified as? - contains?: dense irregular FECT

contains blood vessels, lymphatics, and nerve fibers
serosa: adventitia covered with visceral peritoneum
Esophagus innervation - smooth muscle - vascular smooth muscle - skeletal muscle: smooth muscle layers innervated by postganglionic parasympathetics from Meissner's and Auerbach's plexi

vascular smooth muscle innervated by postganglionic sympathetics from cervical and thoracic sympathetic trunks

skeletal muscle supplied by spinal nerves
Esophagus 3 main fxns: (1) completes warming or cooling of food

(2) conveys food by gravity and muscular contraction

(3) glands secrete mucus for lubrication
Esophagus: mucosa - what type of epithelium?: non-keratinized stratified squamous epithelium
Esophagus: mucosa: lamina propria - contains?: esophageal cardiac glands (mucus secreting)
Esophagus: submucosa - fxn - contains: contributes to the large longitudinal folds of esophagus (smooth out during swallowing)

contains esophageal glands -- compound tubuloalveolar, mucus secreting
what are the 4 gross anatomic divisions of the stomach?: cardiac, fundic, body, and pyloric
what are the 3 histological divisions of the stomach?: cardiac, fundic, and pyloric
rugae: large longitudinal folds formed by the mucosa and submucosa, most prominent when stomach empty
what change in epithelium is evident at the esophageal-gastric jxn?: abrupt change from stratified squamous to simple columnar epithelium
gastric gland structure: simple, branched tubular glands occupy entire thickness of mucosa; each gland has a neck, body, and a base
cardiac glands - location - components - fxn: in cardiac region of stomach

mostly mucus secreting cells with a few parietal and enteroendocrine cells

function is to produce a protective mucus secretion
fundic glands - location - classifiication - orientation - fxn: located in fundic and body regions of the stomach

simple branched tubular

closely packed and oriented perpendicular to surface

major source of gastric juice
fundic gland: mucous neck cells: relatively few, located in necks of glands produce an acidic mucous secretion
fundic gland: parietal cells - mitochondria? - secrete?: abundance of mitochondria

secrete H+ and Cl-

also secrete gastric intrinsic factor (binds to vitamin B12 and this allows it to be absorbed in the small intestine)
fundic gland: chief cells: have zymogen granules in their apical cytoplasm

secrete pepsinogen -- converted to pepsin by low pH -- important enzyme in the digestion of proteins
gastrin - produced by which cells? - fxn: enteroendocrine cells

stimulates secretions of chief and parietal cells and increases gastric motility
serotonin - produced by which cells? - fxn: enteroendocrine cells

triggers contraction of smooth muscle of blood vessels - leads to a slowing of gastric activity
pyloric glands - classification - composed of: simple branched tubular glands which are very coiled

composed almost entirely of mucus secreting cells with a few parietal cells and enteroendocrine cells
which layer of the stomach muscularis externa makes up the pyloric sphincter?: middle circular layer
where is the Auerbach's plexus located in relation to the muscularis externa of the stomach?: between circular and longitudinal layers
describe the 3 structural features of the small intestine that increase the surface area 500 fold: (1) plica circulares -- permanent folds, mucosa & submucosa (x 2-3)

(2) intestinal villi -- finger-like projections 0.5-1.5 mm, core of lamina propria (x 10)

(3) microvilli -- on absorptive cells (x 20)
intestinal villi: covered with absorptive cells and goblet cells

lacteals (blind-ended lymphatic channels in lamina propria core of villi) important in absorption of products of lipid digestion
intestinal glands - structure / location - composed of - fxn: simple tubular glands formed by invaginations of epithelium into the lamina propria, lie between villi

4 cell types: goblet, absorptive, paneth, enteroendocrine

cells in the basal half of glands at at bases of villi are mitotically active
lamina propria of intestine - vascularized? - lymph?: highly vascularized with numerous CT cells and lymphatics

lymph nodular aggregates known as "Peyer's patches"
what are the four cell types of the small intestine epithelium?: enterocytes (intestinal epithelial cells), goblet cells, paneth cells, enteroendocrine cells
what is the dominant cell type of the small intestine epithelium?: enterocytes
enterocytes - surface? - cell-to-cell - fxn: well-developed surface glycocalyx -- imparts resistance to proteolytic enzymes and contains enzymes which convert pancreatic proenzymes into active forms

cells bound together by jxnal complexes

responsible for absorption of products of protein, carbohydrate, and lipid digestion
paneth cells - located where? - fxn: in bases of intestinal glands

secrete lysozyme (an antibacterial enzyme)
secretin: hormone stimulates secretion of bicarbonate by centroacinar cells of the pancreas
CCK: cholecystokinin

secretion triggered by fatty acids and L-amino acids in the duodenum, hormone stimulates the release of secretory granules by pancreatic acinar cells and also stimulates contraction of the smooth muscle in the wall of the gall bladder
duodenal glands of brunner - located where? - produce what? - stimulated by?: located in Submucosa, ducts empty into bases of intestinal glands

produce alkaline mucus (for protection)

stimulated to secrete by acidic chyme entering duodenum
what are the two principal fxns of the large intestine?: dehydration of luminal contents & vitamin reabsorption
classify the epithelium of the large intestine: tall columnar, contains absorptive, goblet, and endocrine cells
pectinate line - mucosa epithelium? - muscularis mucosa? - lamina propria? - muscularis externa?: jxn of the rectum and anal canal

mucosa epithelium is stratified non-keratinized sqaumous

no muscularis mucosa

lamina propria contains hemorrhoidal venous plexus

inner circular layer of muscularis externa forms the internal anal sphincter, while outer longitudinal layer disappears
Anus - lined by? - CT components? - external anal sphincter?: keratinized stratified squamous epithelium

hemorrhoidal vessels, apocrine sweat glands, sebaceous glands, and hairs

external anal sphincter formed by skeletal muscle -- under control of spinal nerves
endocrine pancreas: - beta cells - alpha cells - delta cells: beta cells secrete insulin, alpha cells secrete glucagon, and delta cells secrete somatostati
pancreas: centroacinar cells: produce the bicarbonate-rich component of the exocrine pancreas
name / describe the two main pancreatic ducts that enter into the duodenum: (1) main pancreatic duct leads to a duodenal papilla (ampulla of Vater) that is controlled by a sphincter (of Oddi)

(2) accessory duct (of Santorini)
what is the largest gland in the body?: liver
hepatic artery: brings 30% of blood to liver

blood is oxygenated and brings products of fat digestion absorbed by small intestine to liver
portal vein: brings 70% of blood to liver

blood is deoxygenated but carries products of carb and protein digestion absorbed by small intestine

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