A&P exam 5

cg 24, 26, 27

digestive functions

ingestion, secretion, mixing, digestion, absorption, defecation

myenteric plexus/ plexus of Auerbach

located between longitudinal and circular smooth muscles, control GI motility

submucosal plexus/ plexus of Meissner

regulates mucosa movement, vasoconstriction of blood vessels, innervates secretory cells of mucosal glands

GI Reflex Pathways

regulates GI secretion and motility in response to stimuli within GI tract

parasympathetic GI

vagus nerve, increases GI secretion and motility by increasing ENS activity

sympathetic GI

thoracic and lumbar spinal cord, decreases GI secretion and motility

peritoneum

largest serous membrane in body, simple squamous epithelium and alveolar CT, contains large folds that weave between organs for support, binding, and contain blood, lymph, and nerves

peritoneal folds

greater omentum, falciform ligament, lesser omentum, mesentery, and mesocolon

mouth

formed by cheeks, hard and soft palate, lips, tongue, extends from gum, teeth to fauces

fauces

opening between oral cavity and pharynx

salivary glands

lubricate mouth, dissolve food and starts chemical digestion of carbs; 99% H2O, solutes; under nervous control by n. facials and n. glossopharyngeous; parotid, submandibular, sublingual

tongue

forms oral cavity floor, skeletal muscle covered in mucous membrane for chewing, swallowing, speech

muscles of tongue

extrinsic: hypoglossus, genioglossus, styloglossus; intrinsic: longitudinalis s., longitudinalis inf. transverse linguae, vertical linguae.

teeth

project into mouth for mechanical digestion, contain dentin, enamel, cementum; parts are crown, root, and neck

dentin

principal substance of tooth, calcified CT for shape and ridgity

enamel

covers dentin, hardest substance in body, protects tooth from chewing wear

cementum

bone like substance covers dentin of root, attaches root to periodontal ligament

pharynx

funnel shape tube from internal nares to esophagus and larynx; skeletal muscles lined by mucus membrane

esophagus

collapsible, muscular tube lies posterior to trachea, connects pharynx to stomach; contains upper skeletal and lower smooth muscle sphincters; no serosa only adventitia

deglutition

swallowing; receptors in oropharynx stimulate deglutition center of medulla and lower pons

stomach

J shaped enlargement of GI tract beginning at esophagus and ends at pyloric sphincter; mixing and holding area for food, begins protein digestion and contds digestion of carbs; creates chyme; cardia, fungus, body, pyloric; simple columnar epithelium in mucosa

gastric juice

HCl, pepsin, intrinsic factor, gastric lipase

mucosa neck cells

secrete mucus in stomach

chief zymogenic cells

secrete pepsinogen and gastric lipase

parietal oxyntic cells

secrete HCl and intrinsic factor for B12

enteroendocrine cells / G cells

hormone producing cells in gastric glands, secrete gastrin into blood stream

gastric lipase

splits triglycerides into fatty acids and monoglycerides

pancreas

gland posterior to stomach, connected to duodenum by pancreatic duct and accessory duct; head, body and tail

pancreatic duct/ duct of Wiring

joins common bile duct from liver and gallbladder

hepatopancreatic ampulla/ ampulla of Vater

opens at major duodenal papilla

Sphincter of Odd

responsible for control over passage of pancreatic juice into ampulla of Vater

pancreatic juice

contains pancreatic amylase, trypsin, chymotrypsin, carboxypeptidase, elastase, pancreatic lipase, ribonuclease, deoxyribonuclease, sodium bicarbonate

liver

heaviest gland and second largest organ, makes bile

ligamentum teres

remnant of umbilical vein

gallbladder

sac located in depression on posterior surface of liver; stores and contains bile; fungus, body, and neck; absent submucosa

hepatocytes

major functional cells that perform array of metabolic, secretory, and endocrine function

bile canaliculi

small ducts between hepatocytes that collect bile, pass to bile ductules to bile ducts which merge to hepatic duct to exit liver as common hepatic duct

common hepatic duct

contains bile to exit liver, joins cystic duct from gallbladder to form common bile duct which exits to duodenum

hepatic sinusoids

highly permeable blood capillary rows between hepatocytes, receive oxygenated blood from hepatic artery and deoxygenated blood from hepatic vein; converge to central vein to hepatic veins to inf. vena cava

portal triad

bile duct, hepatic artery branch, hepatic vein branch

hepatic lobule

hexagon with central vein in center, portal triad at three corners

portal lobule

bile ducts are center

hepatic acinus

smallest structural and functional unit; 3 zones which provide interpretation of glycogen storage and release; zone 1 close to portal triad, zone 3 furthest

liver blood supply

supply fro hepatic artery and hepatic portal vein; all blood leaves via hepatic vein

bile

excretory product of worn out RBC and digestive secretion, emulsification of triglycerides, alkaline

small intestine

location of majority of digestion and absorption, extends from pyloric sphincter to ileocecal sphincter; duodenum, jejunum and ileum

circular folds / plicae circulars

permanent ridge in mucosa enhances absorption by increased surface area, causes chyme to swirl around instead of moving straight through

s cells

secrete secretin in SI

CCK cells

secrete cholecystokinin in SI

K cells

glucose dependent insulin trophic cells

paneth cells

secrete lysozyme, bactericidal enzyme, and are capable of phagocytosis

crypts of Liberkuhn

intestinal glands formed by cavities in mucosa lined by glandular epithelium, secrete intestinal juice

brush border enzymes

found on surface of microvilli, include a-dextrinase, maltase, sucrase, lactase, peptidase, aminopeptidase, dipeptidase, nucleosides, and phosphatase

absorption

passage of digested end products from GI tract into blood or lymph, occurs via diffusion, facilitated diffusion, or active transport; absorbed nutrients enter venous blood from SI then travel to liver via hepatic portal vein

large intestine

extends from ileocecal sphincter to anus; includes cecum, appendix, colon, rectum, anal canal

teniae coli

3 bands thicken longitudinal muscle layer which contracts and gathers colon into pouches called hausfrau

haustral churning

haustra remain relaxed and become distended when full, then contract to squeeze contents onward

mass peristalsis

strong peristaltic wave begins in transverse colon to quickly drive contents into rectum

renal fascia

dense CT anchors kidneys to surroundings

adipose capsule

protective fatty tissue of kidneys

renal capsule

smooth irregular CT as trauma barrier

renal cortex

outer superficial red region

renal medulla

inner deep darker red brown region, consists of renal pyramids

renal pyramids

secreting apparatus and tubules, base faces cortex and apex faces hilum

renal papilla

at apex of renal pyramid, opening of collecting ducts

renal columns

anchor cortex

nephron

\~1M functional units of kidney, forms filtrate to create urine; functions in glomerular filtration, tubular reabsorption, and tubular secretion

calyces

both 8-18 minor and 2-3 major; passes filtrate from nephron into renal pelvis to ureter

renal sinus

expansion inward of hilum, contains renal pelvis, calyces and branches of renal blood vessels and nerves

renal corpuscle

blood filtering component of nephron

renal tubule

tube into which filtered fluid passes

glomerular filtration

blood plasma and dissolved substances filtered into glomerular capsule

tubular reabsorption

all renal tubule, H2O and ions reabsorbed into blood

tubular secretion

along renal tubule and collecting duct; wastes, drugs, excess ions, secreted from blood into tubule ultimately into urine

cortical nephron 80-85%

glomerulus in superficial cortex and short nephron loop in outer medulla; creates urine with osmolarity similar to blood

juxtamedullary nephron 15-20%

glomerulus in deep cortex and long nephron loop that stretches through medulla almost to renal papilla; receives blood through peritubular capillaries and vasa recta

glomerulus

mass of capillaries fed by afferent arteriole to efferent arteriole

mesangial cells

contractile cells help regulate glomerulus filtration

glomerular capsule

simple epithelium, visceral layer of podocytes that wrap around capillaries; filtrate collected between layers

juxtaglomerular apparatus

consists of juxtaglomerular cells of afferent arteriole and macula dense; regulates BP and rate of renal filtration

distal convoluted tubule

principal cells are receptors for ADH and aldosterone; intercalated cells maintain blood pH homeostasis

glomerular filtrate

fluid that enters capsular space; 150-180L; 99 reabsorbed

filtration membrane

filtering unit of nephron in glomerulus includes endothelial and capsular membranes; glomerular epithelium, glomerular basement membrane, and slit membrane between podocytes

pedicels

thousands of foot like processes formed by podocytes

filtration slit

lies between pedicels, permits passage of substances

myogenic mechanism of renal auto regulation

occurs from stretching, which causes contraction of smooth muscle cells in walls of afferent arteriole in response to increased BP

tubuloglomerular feedback of renal auto regulation

occurs as macula dense provides feedback to glomerulus; increase GFR diminishes reabsorption

macula densa

inhibits release of nitric oxide from juxtaglomerular apparatus, vasconstriction occurs

Neural Regulation of Kidney

sympathetic fibers stimulation cause afferent arterioles to constrict, release of norepinephrine on A1 receptors cause vasoconstriction; decrease urine output, increase available blood

angiotensin 2

constricts afferent and efferent arterioles, decrease GFR, increase BV and BP, increase vasoconstriction, increase NaCl reabsorption, regulates electrolytes, increase aldosterone release

atrial natriuretic peptide

relaxes mesangial cells, increases capillary surface area and increase GFR; secreted in response to cardiac atria stretch; inhibit H2O and Na reabsorption, decrease ADH and aldosterone secretion

reabsorption

returns most filtered H2O and solutes to blood via active and passive transport, accomplished by epithelial cells in proximal convoluted tubule

paracellular reabsorption

passive fluid leakage between cells

transcellular reabsorption

directly through tubule cell

pathway of tubular reabsorption

tubular lumen: apical membrane: tubule cell: cytosol: basolateral membrane: interstitial fluid

obligatory H2O reabsorption

solute reabsorption drives water reabsorption; 90% occurs in proximal tubule and descending loop limb

facultative H2O reabsorption

remaining 10% of reabsorption, regulated by ADH and occurs in collecting duct

Na transporter

promote reabsorption of all organic solutes, 80-90% bicarbonate ions, 65% H2O, Na, K; 50% Cl;

Na glucose symporters

located in apical membrane, electrical potential difference caused by diffusion of Cl into institial fluid via paracellular route; tubular fluid is more positive than interstitial fluid

Na/H antiporter

achieve Na and HCO3 reabsorption to peritubular capillaries and secrete H into tubule