Physiology Final Study Guide!!

atrial natriuretic peptide (NAP)

peptide hormone that promotes salt and water excretion; indirectly suppresses renin, aldosterone, and vasopressin

aldosterone

steroid hormone that increases sodium resabsorption (indirectly increaing water rabsorption) and increases potassium excretion to raise blood pressure

aquaporins

membrane proteins in collecting duct that allow rapid movement of water

vasopressin (ADH)

peptide hormone that increases water reabsorption (by inserting aquaporins in collecting duct) and causes vasoconstriction; overall result of increasingn blood pressure

angiotensin II

peptide hormone that controls aldosterone release in the adrenal cortex

clearance

rate at which one solute disappears from the body by excretion or metabolism

clearance of X = excretion rate of X (mg/min) / concentration of X (mg/mL of plasma)

clearance formula

organic anion transporters (OATs)

transporters in the proximal tubule that move organic anions (such as bile salts, benzoate, salicylate, saccharine, antivirals, antibiotics) against their concentration gradient, helping these anions being excreted

type A intercalated cells

cells in collecting duct that function in acidosis; reabsorb HCO3- and K+, excrete H+

type B intercalated cells

cells in collecting duct that function in alkalosis; reabsorb H+, excrete HCO3-

respiratory acidosis

condition in which blood becomes too acidic because of too much CO2 in the body due to hypoventilation; results in increased pCO2 , H+, and HCO3-

respiratory alkalosis

condition in which blood becomes too basic because of low CO2 levels due to hyperventilation; results in decreased pCO2, H+, and HCO3-

blood plasma

what body substance is transformed into urine?

micturition

the process of releasing urine

mucus

substance secreted by goblet cells that creates a physical barrier to protect stomach lining from acid, enzymes, and mechanical damage

bicarbonate

substance secreted by goblet cells that buffers gastric acid to prevent damage to stomach epithelium

gastric acid (HCl)

secreted by parietal cells; activates pepsin and kills bacteria

intrinsic factor

secreted by parietal cells; complexes with vtiamin B12 to permit absorption in stomach

histamine

molecule secreted by enterochromaffin-like cells that stimulates gastric acid secretion

pepsin

enzyme secreted by chief cells that digests proteins

gastric lipase

enzyme secreted by chief cells that digests fats

somatostatin

hormone secreted by D cells that inhibits gastric acid secretion

gastrin

hormone secreted by G cells that stimulates gastric acid secretion

peristalsis

wave-like contractions of circular muscles that move the food bolus through the digestive tract

migrating motor complex

contractions that clear the upper GI tract and into the large intestine; serve to reset the gut between meals

segmental contractions

short segments of intestine alternatively contract and relax to mix contents

interstitial cells of cajal (ICCs)

cells in the wall of the GI tract that generate and coordinate slow electrical waves that set the rhythm of smooth muscle contractions of the GI tract

mouth

site of mechanical digestion (chewing) and chemical digestion (salivary amylase); forms a bolus for swallowing

stomach

stores food; regulates passage of food into small intestine; mechanically and chemically digests food into chyme; protects body from ingested pathogens

small intestine

primary site of digestion and nutrient absorption

large intestine

absorbs water and electrolytes; forms and compacts feces; houses gut bacteria that produce vitamins

rectum

stores feces temporarily and controls defecation reflex

liver

produces bile to emulsify fats; processes absorbed nutrients; detoxifies chemicals and drugs; stores glycogen, vitamins, and iron

gallbladder

stores and concentrates bile produced by the liver; releases bile into small intestine when fats are present

saliva

softens and lubricates food; contains salivary amylase and lipase

trypsin

enzyme in small intestine that cleaves peptides into amino acids

ghrelin

peptide hormone produced in the stomach that stimulates appetite and increases gastric motility

cholecystokinin (CCK)

peptide hormone secreted by small intestine that stimulates digestion of fats and proteins, stimulates gallbladder to release bile, and promotes feeling of fullness

motilin

peptide hormone secreted by small intestine that stimulates migrating motor complex to clear gut during fasting

leptin

peptide hormone produced by adipose cells that decreases appetite

colonic bacteria

bacteria in the colon that break down undigested carbohydrates and proteins through fermentation and produce absorbable vitamins (especially vitamin K)

emesis

forceful expulsion of gastric and duodenal contents to remove toxic materials before they can be reabsorbed

1. efferent signals from medulla initiate a wave of reverse peristalsis in small intestine

2. abdominal contraction

3. stomach relaxes and gastric and intestinal contents are forced out of mouth

steps of emesis

swallowed air or bacterial fermentation

what are the causes of intestinal gases (flatus)?

chyme

semi-fluid mixture of partially digested food and gastric secretions that is formed in the stomach

zymogen

inactive precursor of an enzyme that must be activated before it can function

microfold cells (M cells)

cells that facilitate contact between antigens passing through intestinal tract and cells of the body’s immune system

peyer’s patches

clusters of immune tissue in the small intestine that protect against GI tract infections

diarrhea

pathological state in which intestinal secretions of fluid are not balanced by absorption, resulting in watery stools

osmotic diarrhea

pathological state in which unabsorbed, osmotically active solutes (such as lactose or sorbitol) hold water in the lumen

secretory diarrhea

pathological state in which water and solutes are actively secreted into the intestinal lumen, leading to large, watery stools; often caused by bacterial toxins

constipation

decreased motility of large intestine, leading to hard stools

ulcers

erosion of the mucosal lining of the GI tract; caused by acid and digestive enzymes

lactose intolerance

inability to digest lactose due to decrease in lactase production or lactase insensitivity

gastroesophageal reflux disease (GERD)

condition in which stomach acid frequently flows backward into esophagus

SGLT and GLUT2

transporters involved in carbohydrate absorption

endopeptidases

class of enzymes that digest internal peptide bonds

exopeptidases

class of enzymes that digest terminal peptide bonds

micelle

small disk shape formed by bile salts; acts to transport digested fats through small intestine so they can be absorbed

chylomicron

large droplet formed by triglycerides, cholesterol, and proteins; transports dietary fats from the intestine to the rest of the body through lymph and bloodstream

pancreatic and intestinal enzymes

what is the mechanism by which nucleic acids are absorbed?

intrinsic factor

protein secreted by parietal cells in the stomach that is essential for absorption of vitamin B

divalent metal transporter (DMT1)

apical transporter on enterocyte which absorbs dietary iron

passive movement through paracellular pathways; mediated by vitamin D3

what is the mechanism by which calcium is absorbed?

secretion, digestion, absorption, motility

what are the four basic processes of the digestive system?

glucostatic theory

states that glucose metabolism by hypothalamic centers regulate food intake

lipostatic theory

states that signals from the body fat stores to the brain modulate eating behavior so that the body maintains a particular weight

lacteals

specialized lymphatic vessels in the villi of the small intestine that absorb and transport dietary fats

mass movement

colonic contraction that helps the chyme to move forward

gastrocolic reflex

reflex in which stretching of the stomach after eating triggers increased movement of the colon, leading to the urge to defecate

feedforward cephalic vagal reflex

anticipatory response in which brain activates digestive processes before food reaches the stomach

defecation reflex

spinal reflex that moves fecal material out of the body

hormones

chemical messengers secreted into the blood by specialized cells or groups of cell

reproduction, metabolism, growth and development, regulation of internal environment

what processes are controlled by hormones?

peptide hormones

hormones made from amino acids; transported by being dissolved in plasma; activate second messenger systems; cause fast onset and short-term effects

steroid hormones

hormones made from cholesterol; transported by being bound to carrier molecules; activate genes for transcription and translation; cause slow onset and long-lasting effects

catecholamines

hormones that are derived from tyrosine but act like peptides; includes epinephrine, norepinephrine, and dopamine

thyroid hormones

hormones that are derived from tyrosine but act like steroids; includes T3 and T4

activate genes for transcription and translation

how do steroid hormones act on their target cells?

activate second messenger systems

how do peptide hormones act on their target cells?

1. controlling rates of enzymatic reactions

2. controlling transport of ions or molecules across cell membranes

3. controlling gene expression and protein synthesis

what are the three ways hormones act on their target cells?

hypersecretion

pathology in which a hormone is present in excess

hyposecretion

pathology in which a hormone is deficient

tropic hormone

class of hormones that control the secretion of another hormone

synergism

when two or more hormones interact in their targets

functional antagonism

when hormones have opposing physiological actions

permissive

interaction in which one hormone cannot fully exert its effects unless a second hormone is present

insulin

peptide hormone released from beta cells of pancreas; stimulates uptake of glucose into muscle and fat cells; lowers blood sugar after a meal

glucagon

peptide hormone released from alpha cells of pancreas; stimulates fat breakdown and glycogenolysis; raises blood sugar during fasting

thyroid hormone

tyrosine-derived hormones released from thyroid; stimulates increase of basal metabolic rate, oxygen consumption, and thermogenesis

epinephrine and norepinephrine

peptide hormones released from adrenal medulla; activate fight-or-flight response

aldosterone

steroid hormone released from adrenal cortex; increases sodium reabsorption and water retention in kidneys to increase blood volume and blood pressure

cortisol

steroid hormone released from adrenal cortex; increases blood glucose via gluconeogenesis; helps the body repsond to long-term stress

androgens

class of steroid hormones released from adrenal cortex; contribute to sex hormone production

deiodination

process by which target cells convert T4 into its more active form, T3, by removing one iodine atom

thyrotropin (TSH)

peptide hormone released from anterior pituitary gland; stimulates thyroid gland to release T3 and T4

proopiomelanocortin (POMC)

peptide prohormone released from anterior pituitary gland; cleaved into ACTH, MSH, and beta-endorphin

adenocorticotropic hormone (ACTH)

peptide hormone released from anterior pituitary gland; stimulates adrenal cortex to release cortisol

gonadotropin releasing hormone (GnRH)

peptide hormone released from hypothalamus; stimulates release of LH and FSH from anterior pituitary

corticotropin releasing hormone (CRH)

peptide hormone released from hypothalamus; stimulates release of ACTH from anterior pituitary gland