PSIO 202 Exam 3
proteases of the pancreas
trypsin, chymotrypsin, carboxypeptidase, elastase
thyroid hormones
tyrosine ring w/ attached iodines, very lipid soluble, hydrophobic, T3 + T4
smooth muscle of muscularis layer
under voluntary control, inner circular fibers and outer longitudinal fibers, allows motility for mixing and propulsion
congenital hypothyroidism/cretinism
under-active thyroid gland, during development, infancy or early childhood results in dwarfism and severe intellectual disabilities
edema
underactive thyroid gland in adults, can also have low heart rate, muscle weakness, sensitivity to cold, low body temp, weight gain and mental dullness
esophageal stage of swallowing
upper esophageal sphincter relaxes, peristalsis pushes food down: circular fibers contract behind bolus, longitudinal fibers contract in front of bolus to shorten the distance of travel, travel time: 4 to 8 sec for solids, 1 sec for liquids, lower esophageal sphincter relaxes as food approaches
hGH release is regulated by which two hormones?
GHRH and GHIH
low blood glucose levels stimulates release of ____, which stimulates secretion of ___ by somatotrophs, hGH and IGFs ____ the breakdown of liver glycogen into glucose, which enters blood more rapidly, blood glucose levels ____, if ____ too much, the release of GHRH is ____-
GHRH, hGH, speed up, increase, increase, inhibited
sources of electrolytes
GI secretions, ingested foods and liquids
Luteinizing Hormone (LH)
GnRH from hypothalamus stimulates gonadotrophs in anterior pituitary to produce LH
what are the high energy electrons captured by during cellular respiration?
NAD+ and FADH
oxidation reduction in ETC
NADH and FADH2 are oxidized while electrons are reduced
functions of large intestine
SM for mechanical digestion, peristaltic waves (3 to 12 contractions/minute), haustral churning, gastroilial reflex, gastrocolic reflex, defecation reflex, bacteria ferment undigested carbs into CO2 + methane gas, and undigested proteins into simpler substances
gonadotrophs
anterior pituitary cell that secretes Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
thyrotrophs
anterior pituitary cell that secretes Thyroid Stimulating Hormone (TSH)
somatotrophs
anterior pituitary cell that secretes human Growth Hormone (hGH)
lactotrophs
anterior pituitary cell that secretes prolactin (PRL)
cephalic phase of digestion
anticipation phase, prepare the mouth and stomach for food, cerebral cortex- sight, smell, taste + thoughts of food stimulate the parasympathetic NS to stimulate salivation (facial and glossopharyngeal) and gastric glands to secrete gastric juice (vagus)
neurosecretory vesicles
antidiuretic hormone and oxytocin made in the hypothalamus are transported here where they are stored until a signal comes to stimulate release
Growth Hormone Releasing Hormone regulates which anterior pituitary hormone?
growth hormone (GH or somatotropin)
what are the primary cells of the liver?
hepatocytes
liver lobule
hepatocytes, hepatic laminae, central vein surrounded by smooth muscle, hepatic sinusoids, portal triad
different target cells may respond to the same ________ differently
hormone
secretin
hormone decreases stomach secretions
oxytocin
hormone of posterior pituitary, produced by cells in paraventricular nucleus of the hypothalamus, target tissues: uterus during labor, mammary glands after delivery
message of endocrine system
hormones
the density of a lipoprotein is determined by
how much protein is present, higher protein= higher density
what is adventitia layer?
consists of areolar CT without the epithelium
Where are the parathyroid glands located?
embedded in the posterior facing side of the thyroid gland
lactic acid role in glycolysis
enables glycolysis to continue in the absence of O2 by regenerating NAD+ in the cytoplasm
goiter
enlarged thryoid gland usually due to lack of iodide in the diet, associated w/ hyperthyroidism, hypothyroidism, or euthyroidism; hypothryoidism: low T3/T4 hormone levels stimulates TSH release by negative feedback, stimulates growth of thyroid gland
absorption of electrolytes
enter epithelial cells by diffusion and secondary active transport, Na and K move by active transport, chloride, iodide and nitrate follow passively, iron, magnesium and phosphate ions use active transport, intestinal Ca2+ absorption requires vitamin D and parathyroid hormone
circulating hormones
enter interstitial fluid and then the blood stream, includes lipid soluble hormones and water soluble hormones
where is the adventitia located?
esophagus
polyphagia
excessive eating
polydipsia
excessive thirst
polyuria
excessive urination
pancreatic juice
exocrine secretion of pancrease, 2L produced per day, colorless liquid (pH 7.1 to 8.2) consisting of: water, salts, sodium bicarbonate, several enzymes
brain prefers ketone bodies when
extreme starvation occurs
how does fructose move into epithelial cells in small intestine?
facilitated diffusion through carrier protein
true/false: hGH is continuously released by the body
false, hGH is released in bursts every few hours
absorption of vitamins
fat soluble vitamins A, D3, E, K travel in micelles and are absorbed by simple diffusion with lipids, water soluble vitamins are absorbed by diffusion, vitamin B12 must combine with intrinsic factor from the stomach parietal cells before it is transported into the cells of the ileum, and absorbed by receptor mediated endocytosis
how does CCK regulate pancreatic secretion?
fats and proteins cause increased digestive enzyme release
do fatty acids or glucose allow for more ATP production?
fatty acids
glucose cannot be formed from
fatty acids
beta oxidation
fatty acids undergo this in mitochondria to produce acetyl coA and lots of ATP
thyroid follicles
follicular cells, parafollicular cells, thryoglobulin (colloid)
brush border enzymes
found on surfaces of microvilli participate in chemical breakdown of carbs, proteins, and nucleosides; pancreatic juice is present in the lumen with chyme, and it contains amylase, proteases, lipase and nucleases, no brush border lipases or nucleases present
water soluble hormones
freely dissolved in body fluids, circulating hormones
stimuli for GHIH by hypothalamus
hyperglycemia, REM sleep, increased fatty acids and decreased amino acids in blood, obesity, low levels of thyroid hormones, high levels of hGH
diabetes mellitus
hyperglycemia, excessive urine production, excessive thirst, excessive eating, type I and II
cushing's syndrome
hypersecretion of glucocorticoids, redistribution of fat to face, spindly arms and legs due to muscle loss, poor wound healing, greater susceptibility to bruising, suppression of immune system, extreme endocrine status, patient is overwhelmingly stressed and muscle loss reflects the mobilization of energy reserves
grave's disease
hyperthyroidism, autoimmune disorder in which unusual antibodies are produced that mimic the action of TSH, stimulating excess production of T3 and T4
stimuli for GHRH by hypothalamus
hypoglycemia, deep sleep, decreased fatty acids and increased amino acids in the blood, increased sympathetic stimulation (due to stress)
where is energy found?
in the bonds btwn atoms
krebs cycle occurs
in the mitochondria
aerobic cellular respiration
in the presence of O2, glucose is completely broken down (oxidized) into CO2, H2) and captured high energy electrons (by NAD+ and FADH), high energy electrons are used by the ETC to pump H+ ions which are used to make ATP via chemiosmosis, the 3 products CO2, ATP and H2) move out of mitochondria into the cytoplasm
hormones are released in response to
internal or external changes
large intestine glands and cells
intestinal gland, absorptive cells, goblet cells, lymphatic nodules, lamina propria, muscularis, submucosa
where do circulatory hormones go after released from endocrine cell?
into venous end of capillary, to the heart, through pulmonary system, and back into systemic circulation
euthyroidism
normal thryoid
is ENS controlled by CNS?
not directly
what lines bile canaliculi?
nothing
haustral churning
occurs in large intestine, relaxed pouches are filled from below by muscular contractions; when full, they contract and move contents to next pouch
ketogenesis
occurs in liver cells, ketone bodies are used by heart muscle and kidney cortex for ATP production
salivary glands
parotid, submandibular and sublingual glands; all have ducts that empty into oral cavity; sight, smell, sounds, memory of food, tongue stimulation increase salivation; fear and anxiety decrease salivation (dry mouth)
hormones
mediator molecules released in one part of the body that regulate activity in other parts of the body
functions of the liver
metabolism of carbs, proteins, lipids; detoxifies the blood by removing or altering drugs + hormones, removes bilirubin, releases bile salts to help digestion by emulsification of lipids, stores fat soluble vitamins, iron, copper and B12, phagocytosis of worn out blood cells + bacteria, plays a role in vitamin D activation pathway
message speed and duration for nervous system
milliseconds to seconds
where does the formation of acetyl co-a occur?
mitochondria
electron transport chain occurs in the
mitochondrial inner membrane
biogenic amines
modified amino acids, catecholamines (TYR modified) : NE, epinephrine, dopamine; serotonin (TRP), melatonin, histamine (HIS)
smooth muscle
modulates luminal pressure/tension, present in sheets, bundles, or sheaths around tissues
functions of saliva
moistens food (swallow), dissolves food (taste), HCO3- buffers acidic foods, protects mouth from infection w/ rinsing action, lysozyme helps destroy bacteria
types of water soluble hormones
peptide and protein hormones, biogenic amines
GI tract organs
mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus
digestion of proteins
mouth- mechanical, in stomach, HCl denatures proteins, and pepsin breaks proteins into smaller polypeptides, pancreatic enzymes (proteases) in pancreatic juice continue to split peptide bonds btwn amino acids, brush border enzymes aminopeptidase and dipeptidase in small intestine split off amino acids at the amino end of polypeptides (aminopeptidase) and split apart two amino acid chains (dipeptidase)
layers of GI tract
mucosa, submucosa, muscularis, serosa
are kidneys protected by visceral peritoneum?
no
does large intestine have villi?
no
does the posterior pituitary contain cells which make decisions regarding hormone secretion?
no
involuntary stages of swalloing
pharyngeal stage (pharynx to esophagus), esophageal stage (esophagus to stomach)
thromboplastin
phospholipids and tissue factor
lipids can be synthesized to become....
phospholipids of plasma membranes, lipoproteins that transport cholesterol, thromboplastin for blood clotting, myelin sheaths to speed up nerve conduction, cholesterol used to synthesize bile salts and steroid hormones
lactation
process of milk production and ejection
follicular cells
produce "thyroid hormones" T3 and T4
functions of hormones
produce wide-reaching, co-ordinated effects on multiple target tissues, and help to maintain homeostasis, regulate aspects of organ function
Human Growth Hormone (hGH)
produced by somatotrophs in anterior pituitary, target cells include liver, skeletal muscle, cartilage, and bone, causes increase in synthesis of insulin-like growth factors that act locally or enter bloodstream at target cells
nucleases of pancreas
ribonuclease and deoxyribonuclease
bile pathway
right hepatic duct and left hepatic duct into the common hepatic duct from liver, common hepatic duct and cystic duct of gallbladder go into common bile duct, common bile duct and pancreatic duct from pancreas go into duodenum
chemical digestion in the mouth
salivary amylase and lingual lipase
digestion of carbohydrates
salivary amylase in the mouth, mechanical in stomach, pancreatic amylase in pancreatic juice from pancreas, brush border enzymes maltase, sucrase, and lactase in small intestine act on disaccharides (maltose, sucrose, lactose) to produce monosaccharides- fructose, glucose, galactose
structure of smooth muscle cells
sarcoplasmic reticulum is poorly developed relative to skeletal muscle, thick filaments of SM have actin-gripping heads along their entire length, thick and thin filaments are arranged diagonally w/in the cell contraction results in twisting motion
message speed and duration for endocrine system
seconds to minutes, days to weeks
peritoneal cavity
space containing serous fluid
How does the hypothalamus control the anterior pituitary?
special hormones called releasing hormones and inhibiting hormones, hypothalamus releases other hormones directly into circulation through the posterior pituitary
hormone receptors
specific membrane or intracellular proteins that allow hormones to affect target cells
what do the numbers in T1 and T2 represent?
the number of iodine atoms attached to the tyrosine rings
adipocytes
insulin stimulates triglyceride synthesis
4 steps of glucose catabolism
1. glycolysis 2. formation of acetyl coenzyme A 3. krebs cycle 4. electron transport chain
about how many ATP molecules in a cell?
1 billion
triglycerides composed of
1 glycerol and 3 fatty acids
how long is the jejunum?
1 m
chemiosmosis
1. high energy electrons are delivered to ETC complexes, 2. electrons are passed from ETC complex to ETC complex, releasing energy with each transfer that is used to pump H+ ions into the space between the inner and outer membranes of mitochondria, 3. H+ ions are only permitted to move back into matrix thru H+ channels which use the energy of H+ diffusion to power synthesis of ATP from ADP and Pi
absorption of amino acids and dipeptides
1. absorption into epithelial cells of duodenum and jejunum using active transport with Na+ or H+ ions (symporters using secondary active transport), 2. movement out of epithelial cell into blood by facilitated diffusion
absorption of monosaccharides
1. absorption into epithelial cells of small intestine, 2. movement out of epithelial cell into bloodstream by facilitated diffusion
fuel sources for lipogenesis
1. amino acids, glycolysis metabolites, and ketone bodies for fatty acid production from acetyl-CoA, 2. glycolysis metabolites for glycerol production
peptide hormone action
1. binding of hormone to its cell surface receptor activates a specific G protein, which activates adenylate cyclase, 2. activated adenylate cyclase converts ATP to cAMP, 3. cAMP serves as a 2nd messenger to activate protein kinases, 4. activated protein kinases phosphorylate cellular proteins, 5. millions of phosphorylated proteins cause reactions that produce physiological responses, 6. phosphodiesterase inactivates cAMP; the response by target cells to water-soluble hormones is very fast
regulation of digestion phases
1. cephalic phase, 2. gastric phase, 3. intestinal phase
regulation of aldosterone release
1. dehydration, Na+ deficiency or hemorrhage, decrease in blood volume, decrease in BP, increased renin from juxtaglomerular cells of kidney, increased angiotensin I from liver, increased angiotensin II from lungs, increased K+ in ECF of adrenal cortex, vasoconstriction of arterioles, increase in BP, increased aldosterone, increased Na+ and water reabsorption in kidneys + increased secretion of K+ and H+ into urine
negative feedback regulation of calcium levels
1. high levels of Ca2+ in blood stimulates thyroid gland parafollicular cells to release more CT, 2. calcitonin inhibits osteoclasts, thus decreasing blood Ca2+ level, 3. low levels of Ca2+ in blood stimulates parathyroid gland chief cells to release more PTH, 4. PTH promotes resorption of Ca2+ from bone ECM into blood and retards loss of Ca2+ in urine, increasing Ca2+ levels, 5. PTH also stimulates kidneys to release calcitriol, 6. calcitriol stimulates increased absorption of Ca2+ from foods, which increases blood Ca2+ levels
functions of aldosterone
1. increases absorption and reabsorption of Na+ with Cl-, bicarbonate and water following it, 2. promotes excretion of K+ and H+, secretion in kidney
steroid hormone action
1. lipid soluble hormone diffuses into cell, 2. activated receptor-hormone complex alters gene expression (acts as transcription factor), 3. newly formed mRNA directs synthesis of specific proteins on ribosomes, 4. new proteins alter cell's activity; receptors can be found in the cytoplasm or nucleoplasm of target cells, work by changing the level of specific gene expression, relatively slow response by target cells
thyroid hormone regulation
1. low blood levels of T3 and T4 or low metabolic rate stimulate release of 2. TRG, carried by hypophyseal portal veins to anterior pituitary, stimulates release of TSH by thyrotrophs, 3. TSH released into blood stimulates thyroid follicular cells, 4. T3 + T4 released into blood by follicular cells, 5. elevated T3 inhibits release of TRH and TSH (negative feedback)
regulation of bile secretion by enteroendocrine cells (secretin and CCK)
1. parasympathetic impulses along vagus nerve stimulates bile production by liver, 2. fatty acids + amino acids in chyme entering the duodenum stimulate secretion of CCK into blood, 3. CCK causes contraction of gallbladder, 4. secretin enhances flow of bile rich HCO3- from liver
3 ways surface area of small intestine is increased for digestion and absorption
1. plicae circularis, 2. villi, 3. microvilli
absorption of lipids
1. short chain fatty acids are absorbed by simple diffusion, 2. long chain fatty acids and monoglycerides (pdts of lipases) are sequestered w/in tiny micelles after emulsification by bile; will also enter cells by simple diffusion, leaving bile salts behind, bile salts are also reabsorbed and later recycled (into bile) by the liver, fat soluble vitamins (A, K, D3 and E) are able to enter cells w/ lipids, 3. inside epithelial cells fats are rebuilt and coated with protein to form chylomicrons, 4. chylomicrons leave intestinal cells by exocytosis into interstitial fluid where they can only enter lacteals (too big for capillaries), travel in lymphatic system to reach subclavian veins, removed from the blood by the liver and fat tissue
5 types of cells of the anterior pituitary
1. somatotrophs, 2. thyrotrophs, 3. lactotrophs, 4. gonadotrophs, 5. corticotrophs
how long is the duodenum?
10 in
VLDLs
10% protein, 50% triglycerides; form in hepatocytes to transport triglycerides to adipose cells
how many carbons in an acetyl group?
2
how long is the ileum?
2 m
how many net ATP molecules are produced by glycolysis
2 net
during glycolysis, one glucose molecule becomes
2 pyruvic acids
chylomicrons
2% proteins, 85% triglycerides; form in intestinal epithelial cells to transport dietary fats to adipose cells, enter bloodstream through thoracic duct
LDLs
25% protein, 50% cholesterol; bad cholesterol, carry blood cholesterol to body cells
anatomy of small intestine
3 m in total length, 2.5 cm in diameter, large surface area, site of most digestion and most absorption, divided into 3 sections
postabsorptive state metabolism
4 hours after meal when absorption of all nutrients is complete, maintaining normal blood glucose level (70 to 110 mg/dL of blood) is major challenge--> goal is to put glucose back into the blood or use alternative fuel sources
HDLs
40% protein, 20% cholesterol; good cholesterol from liver, carry cholesterol from cells to liver for elimination, associated with low cardiovascular disease risk
absorption of water
9L of fluid enters the GI tract per day, small intestine absorbs 8L, large intestine absorbs last 90% of the last liter, absorption is accomplished by osmosis- thru cell membranes into cells and then from the cells into the capillaries inside the intestinal villi
Corticotropin Releasing Hormone (CRH) regulates which anterior pituitary hormone?
Adrenocorticotropic Hormone (ACTH or Corticotropin), Melanocyte Stimulating Hormone (MSH)
antidiuretic hormone (ADH)
ADH produced by cells in supraoptic nucleus in the hypothalamus in response to signals from osmoreceptors
how is ADH affected by alcohol?
ADH release is inhibited
regulation of ADH
ADH released from posterior pituitary with dehydration of high osmolarity of blood, ADH release inhibited w/ overhydration or low osmolarity of blood
lipids are oxidized to produce
ATP
exchange of energy requires use of
ATP molecules
myenteric plexus of muscularis
Auerbach's plexus, part of ENS with some functions shared with submucosal plexus, provides parasympathetic and sympathetic innervation of circular and longitudinal smooth muscle layers, churning and swallowing
which bonds of glucose have high energy electrons?
C-C, C-H
pyruvic acid breaks down into
CO2, NADH, acetyl coenzyme A
Growth Hormone Inhibiting Hormone (GHIH or Somatostatin) regulates which hormone of the anterior pituitary?
Growth Hormone (GH or somatotropin) and/or Thyroid Stimulating Hormone (TSH)
hypothalamic hormones
Growth Hormone Releasing Hormone (GHRH), Growth Hormone Inhibiting Hormone (GHIH or Somatostatin), Gonadotropin Releasing Hormone (GnRH), Prolactin Releasing Hormone (PRH), Prolactin Inhibiting Hormone (PIH or Dopamine), Corticotropin Releasing Hormone (CRH), Thyrotropin Releasing Hormone (TRH)
ATP synthase in ETC
H+ is forced through the ATP synthase and creates ATP molecule inside the mitochondrial membrane
local hormones examples
IL-2 released from helper T cells stimulates proliferation of helper T cells and activation of cytotoxic T cells (uses both autocrine and paracrine signals), histamine released by mast cells stimulates HCl secretion from parietal cells in stomach
which antibody is ideally suited for secretion in the mucosal lining of our airway and in breast milk?
IgA
Gonadotropin Releasing Hormone (GnRH) regulates which anterior pituitary hormone?
Lutenizing Hormone (LH) and/or Follicle Stimulating Hormone (FSH)
submucosal plexus of the submucosa
Meissner's plexus, part of ENS, receives input from sympathetic (thoracic and lumbar spinal cord) and parasympathetic neurons (vagus nerve and sacral spinal cord), regulates blood vessel diameter, secretion from glands and neurosecretory neurons, and local motility caused by muscularis mucosae
Prolactin Releasing Hormone (PRH) regulates which anterior pituitary hormone?
Prolactin (PRL)
Prolactin Inhibiting Hormone (PIH or dopamine) regulates which anterior pituitary hormone?
Prolactin (PRL), Melanocyte Stimulating Hormone (MSH)
is T3 or T4 more affective?
T3
Thyrotropin Releasing Hormone (TRH) regulates which anterior pituitary hormone?
Thyroid Stimulating Hormone (TSH or Thyrotropin)
what does a cell have to have in order to be considered a target cell for a hormone?
a receptor for that hormone
large intestine function
absorption of electrolytes and some vitamins
cells of small intestine
absorptive cell, goblet cell, enteroendocrine cell, paneth cell
how does secretin regulate pancreatic secretions?
acidity in intestine causes increased sodium bicarbonate release
local hormones
act on neighboring cells (paracrine) or on the same cell that secreted them (autocrine) without first entering the blood stream
message of nervous system
action potentials and neurotransmitters
kinases
add phosphate groups
excess lipids are stored where?
adipose tissue or liver VLDLs
regulation of low blood glucose
alpha cells are stimulated to secrete glucagon which acts on hepatocytes to convert glycogen to glucose, form glucose from lactic acid and certain amino acids, glucose released by hepatocytes raises blood glucose level to normal, if blood glucose continues to rise, hyperglycemia inhibits release of glucagon
proteins are broken down into
amino acids which are transported to the lvier
formation of glycogen from glucose
anabolic reaction
corticotrophs
anterior pituitary cell that secretes Adrenocorticotropic Hormone (ACTH) and Melanocyte Stimulating Hormone (MSH)
serosa
areolar CT, epithelium, simple squamous
digestion of lipids
begins in the mouth with lingual lipase in saliva, continues in stomach with gastric lipase, pancreatic lipase in pancreatic juice continues to split triglycerides into fatty acids and monoglycerides, bile from liver emulsifies lipids to form tiny micelles, no digestion of lipids by the small intestine itself bc no lipase enzymes in membranes of brush border cells
salivary amylase
begins starch digestion in the mouth (ph 6.5-7) but when the bolus hits the acidic gastric juices (pH 2.5) digestion stops, enzyme is destroyed
regulation of high blood glucose
beta cells are stimulated to secrete insulin which acts on body cells to accelerate facilitated diffusion of glucose into cells, speed conversion of glucose to glycogen, increase uptake of amino acids and increase protein synthesis, speed synthesis of fatty acids, slow glycogenolysis, slow gluconeogenesis, if blood glucose continues to fall, hypoglycemia inhibits release of insulin
pathway of bile secretion
bile canaliculi join to form bile ducts at portal triads which form hepatic ducts, L+R hepatic ducts form the common hepatic duct, cystic duct from gallbladder and common hepatic duct join to form common bile duct, common bile duct + main pancreatic duct empty into duodenum
cystic duct
bile is stored here until it is ready to move and be used
intermediate molecule involved in electron transfer of oxidation-reduction
coenzyme NAD+ and FADH
mechanism of action for hormones
bind to cell surface receptors or receptors inside target cells
blood flow through the liver
blood from hepatic arteries and hepatic portal vein mix, the mixed blood flows through the sinusoidal capillaries of the liver then returns to central vein, then hepatic vein, then inferior vena cava, then right atrium of the heart
hypophyseal portal system
blood leaving capillary beds in hypothalamus travels to a capillary bed in anterior pituitary to allow for paracrine secretion of releasing hormones, drained by one or more posterior hypophyseal veins
endocrine and nervous system similarities
both systems act together to control and co-ordinate body activities, both systems use chemical messengers for intercellular communication
lipid soluble hormones
bound to transport proteins for transport in body fluids, circulating hormone
catabolic reactions
break down complex organic compounds, providing energy
glycolysis
break down of glucose to pyruvate/lactate
gastric phase of digestion
breakdown of material; neural: stretch receptors + chemoreceptors increased pH signal bolus entry, vigorous peristalsis + gastric gland secretions, chyme periodically released into duodenum; endocrine: distention + presence of food in stomach cause G cells (enteroendocrines) to secrete gastrin into bloodstream, which increases gastric gland hormone secretions and motility, and causes pyloric sphincter relaxation
second messengers examples
cAMP, calcium ions, cGMP
special features of smooth muscle
capable of sustained contraction w/out fatigue and at very little energy cost, maintains a low level of tension or tone even in the absence of APs, stress relaxation response: stretch causes initial increase in tension, tension decreases within 1-2 mins, allows smooth muscle to change length but maintain ability to contract (important for storage organs)
increase in K+ is a danger to the proper functioning of....
cells
peptide and protein hormones
chains of amino acids, hypothalamic releasing and inhibiting hormones, ADH, oxytocin, hGH, TSH, ACTH
small intestine function
chemical and mechanical breakdown with major absorption
digestion in mouth
chemical and mechanical digestion
CCK
cholecystokinin, decreases stomach emptying
which lipoprotein circulates through lymphatic system?
chylomicrons
major classes of lipoproteins
chylomicrons, very low density, low density, high density lipoproteins
muscularis
circula and longitudinal muscle
krebs cycle
citric acid is produced, CO2 leaves cycle while NADH and H+ are being created
muscosa
closest layer, epithelium, lamina propria, muscularis mucosae
submucosa
connective tissue
loose CT of submucosa
containing blood vessels, glands and lymphatic tissues
intestinal phase of digestion
controlled release of chyme; entry of chyme into duodenum slows gastric activity and increases intestinal activity; neural: distention of duodenum + chemical contents of the chyme activate sympathetic nerves which slow gastric activity; endocrine: distention of duodenum + contents of chyme trigger hormonal release from enteroendocrine cells in the duodenum--> secretin + CCK
transamination
converts one amino acid into another
hypothalamus receives input from...
cortex, thalamus, limbic system and internal organs
Adrenocorticotropic Hormone (ACTH)
corticotropin releasing hormone (CRH) from the hypothalamus stimulates corticotrophs through the bloodstream in the anterior pituitary to release ACTH, ACTH stimulates release of glucocorticoids (mainly cortisol) from adrenal cortex, ACTH release is also stimulated by hypoglycemia, physical trauma, and IL-1
gluconeogenesis is stimulated by
cortisol and glucagon
oxidation reduction reactions
coupled within the body, sometimes use intermediate molecule
glycolysis occurs in the
cytoplasm
fate of amino acids
deaminated to enter krebs cycle, donate amino group to form new amino acids, used to synthesize new proteins throughout the body
protein metabolism liver
deamination, transamination, synthesis of plasma proteins utilized in the clotting mechanism and immune system
oxidation
decrease in the energy content of a molecule: electrons are lost, plus H+
rectum and anus function
defecation
type I diabetes
deficiency of insulin, typically juvenile onset, glucose level high outside cells
oral and pharyngeal stages of swallowing
deglutition starts w/ voluntary stage, food bolus pushed by the tongue into the oropharynx, the involuntary stages begin when sensory nerves in the pharynx that signal the deglutition center in brain stem: breathing stops, soft palate + uvula rise closing off nasopharynx, vocal chords adduct, larynx rises, epiglottis covers the larynx
steroid hormones
derived from cholesterol, chemical groups attached to core of structure makes it unique, cortisol, testosterone, estrogens, progesterone, aldosterone
absorption of amino acids into body cells is stimulated by
insulin-like growth factors + insulin
how does a hormone cause one type of response in one target cell but then also cause a completely different in another target cell?
different types of receptors generate different second messengers
unitary smooth muscle cells line the
digestive tract, gall bladder, urinary bladder
endocrine regulation of stomach function
distention and presence of food in stomach cause G cells to secrete Gastrin into the bloodstream, gastrin increases gastric gland secretions and motility, and causes pyloric sphincter relaxation
posterior pituitary gland
does not synthesize hormones, consists of axon terminals from 2 groups of hypothalamic neurons which release two peptide hormones that enter capillaries- antidiuretic hormone(vasopressin), and oxytocin (OT)
sections of small intestine
duodenum, jejunum, ileum
exophthalmos
edema behind eyes due to hyperthyroidism
oxytocin regulation after delivery
effect on mammary glands: suckling + hearing baby's cry stimulates oxytocin release, oxytocin causes muscle contraction + milk ejection; milk production is stimulated by Prolactin, prolactin and oxytocin work together in lactation, oxytocin controls ejection
what are spaces btwn hepatocytes filled with?
either blood filled sinusoids or bile canaliculi
what powers the formation of ATP?
electrochemical gradient of H+
skeletal muscle of muscularis layer
in mouth, pharynx, upper esophagus, and anus under voluntary control, controls deglutition and defecation
mechanical digestion in the stomach
gentle mixing waves occur in the stomach to mix the bolus of food with gastric juice (enzymes, acid, water) and turn it into chyme (a thin liquid), more vigorous waves traveling from the body of stomach to the pyloric region move the chyme along, intense waves near the pylorus lead to opening of the pyloric sphincter- squirting 1-2 teaspoons into the duodenum with each wave
hormones are released from
glands
glycogenolysis is stimulated by
glucagon and epinephrine
carbohydrate metabolism liver
gluconeogenesis, glycogenesis, glycogenolysis
postabsorptive state summary
glucose enters blood from the liver- glycogenolysis, gluconeogenesis (glycerol from adipose tissue, amino acids and lactic acid from muscle), alternative fuel sources are fatty acids from adipose fed into krebs as acetyl coA for most cells, oxidation of ketone bodies by heart and kidney, most tissues switch to utilizing fatty acids, except brain still prefers glucose
excess amino acids can be converted into
glucose or triglycerides
is glycogenesis or glycogenolysis favored after a meal?
glycogenesis because insulin rises
Follicle Stimulating Hormone (FSH)
gonadotropin releasing hormone (GnRH) from hypothalamus stimulates gonadotrophs in anterior pituitary to produce FSH (also LH)
addison's disease
hyposecretion of glucocorticoids and aldosterone, hypoglycemia, muscle weakness, low BP, dehydration due to decreased Na+ in blood, mimics skin darkening effects of MSH, potential cardiac arrest
control center for feedback loops
hypothalamus
what is considered the headquarters of the ANS?
hypothalamus
which center provides a link between the external and internal environment and the endocrine system?
hypothalamus
control almost all aspects of growth, development, metabolism, and homeostasis
hypothalamus and pituitary gland
hGH: hypothalamic control of release, target tissue and downstream effects
hypothalamus inhibiting hormone GHIH, anterior pituitary cell: somatotrophs, tropic hormone: hGH, target tissues: liver, muscle, cartilage, bone, IGFs
hypothalamus control of anterior pituitary
hypothalamus makes decisions based on sensory inputs, hypothalamus may send motor impulses to various tissue effectors, may make use of endocrine system as an effector by secreting releasing/inhibiting hormones which act on target cells in anterior pituitary, in response, the 5 types of anterior pituitary cells release more or less of the 7 tropic hormones into blood for circulation throughout the body
Prolactin (PRL)
hypothalamus regulates lactotroph cells by secreting PRH and PIH (dopamine), lactotrophs in anterior pituitary produce prolactin, prolactin causes milk production under right conditions, suckling reduces levels of hypothalamic inhibition and prolactin levels rise along w milk production
Thyroid Stimulating Hormone (TSH)
hypothalamus regulates thyrotrophs (via TRH) in anterior pituitary to produce TSH (thyrotropin), TSH stimulates the synthesis and secretion of T3 and T4, metabolic rate stimulated
Regulation of ACTH release
hypothalamus releases CRH, CRH stimulates release of ACTH, ACTH stimulates release of cortisol, cortisol inhibits release of CRH and ACTH
Regulation of Thyrotropin (TSH) release
hypothalamus releases thyrotropin releasing hormone (TRH), TRH causes release of thyroid stimulating hormone (TSH) from anterior pituitary cells, thyroid gland cells activated to secrete more T3 and T4
hGH: hypothalamic control of release, target tissues, and downstream effects
hypothalamus releasing hormone: GHRH, anterior pituitary cell: somatotrophs, tropic hormone: hGH, hGH target tissues: liver, muscle, cartilage, bone, IGFs produced, causes growth of body cells, protein synthesis, tissue repair, lipolysis, elevation of blood glucose concentration
organs/tissues with endocrine cells (not considered endocrine glands)
hypothalamus, thymus, pancreas, ovaries, testes, kidneys, skin, liver, stomach, heart, adipose tissue
where does small intestine end?
ileocecal sphincter valve (connects to large intestine)
how are hepatocytes arranged?
in grids in lobules with spaces in between
deamination of amino acids
in liver, removes NH2 group from amino acids so we can use what is left as an energy source, converts resulting toxic ammonia into urea for excretion by the kidney
glycogenesis
in liver- adds excess glucose into glycogen polymer for storage
glycogenolysis
in liver- breaks off glucose from glycogen polymer in case of need
gluconeogenesis
in liver- turns certain amino acids into glucose, turns the glycerol portion of fats into glucose, to increase blood glucose
hepatocytes
insulin stimulates glycogen synthesis
cortisol
in zona fasciculata of adrenal gland, major human glucocorticoid
diabetes insipidus
inability of the kidneys to conserve water, excessive urination, due to lack of ADH
actions of thyroid hormones
increase basal metabolic rate by stimulating cellular use of O2 to produce ATP-- increased cellular catabolism of glucose, fatty acids, and triglycerides; increase synthesis of Na/K ATPase-- more ATP used to pump ions, ATP use produces heat which raises body temp., calorigenic effect; enhance some actions of sympathetic NS by up-regulating beta receptors-- increased heart rate, contractility and blood pressure; stimulate growth in conjunction w/ hGH and insulin during development
insulin-like growth factors (IGFs)
increase cell growth and cell division by increasing uptake of amino acids and synthesis of proteins, stimulate lipolysis in adipose tissue (released fatty acids are used for ATP production in most body cells), decrease glucose use by most body cells so blood glucose levels remain high enough to supply the brain
functions of villi and microvilli
increase of SA for absorption, brush border enzymes, cell division within intestinal glands produces new cells that move up to replace old cells that have been lost
reduction
increase of energy content of a molecule: electrons gained, plus H+
deglutition
initiation of swallowing
glycogenesis is stimulated by
insulin
type II diabetes
insulin insensitivity, typically adult onset, wonky insulin receptors
high levels of glucose in blood normally causes
insulin release by the endocrine pancreas, binding of insulin hormone to target cells, increased uptake of glucose by target cells
formation of thyroid hormones
iodide trapping by follicular cells, synthesis of thyroglobulin (TGB), release of TGB into colloid, iodination of tyrosine in colloid, formation of T3 and T4 by combining T1 and T2 together, uptake + digestion of TGB by follicle cells, secretion of T3 and T4 into blood, binds to thyroxine binding globulin (TBG)
aspects of organ function regulated by hormones
ion and nutrient levels in ECF and blood, metabolic pathways, biological clock, contraction of cardiac + smooth muscle, glandular secretion, some immune functions, growth and development, reproduction
enterogastric reflex
is stimulated by the presence of chyme in the duodenum, decreases gastric peristalsis + decreases gastric gland secretions
if a heart transplant patient receives prednisone to help prevent rejection of the transplanted tissues, will ACTH and CRH be high or low?
low due to negative feedback suppression of ACTH and CRH release
how are lipids transported through blood?
lipoproteins, protein portion can dissolve in water/blood
major producers of IGFS
liver
autocrine cell
local hormones, releases autocrine hormones to autocrine receptors on the same cell
paracrine cell
local hormones, releases paracrine hormones that bind to a paracrine receptor on a nearby target cell
gastro-esophageal reflux disease (GERD)
lower sphincter fails to open- distension of esophagus feels like chest pain or heart attack; lower esophageal sphincter fails to close- stomach acids enter esophagus + cause heartburn, worsened by a weak sphincter, particularly bad when laying down after large meal, smoking and alcohol make the sphincter relax, worsening the situation
kupffer cells
macrophages in the liver, phagocytize microbes and foreign matter
aldosterone
major human mineralocorticoid
mechanical digestion in the mouth
mastication (chewing), breaks food into pieces, mixes with saliva so that it forms a moist bolus
unitary smooth muscle cells
may not have direct contact w/ any motor neuron, autorhythmic- adjacent cells connect via gap junctions, cell membranes adhere to one another-- transmission of force, slowly synchronized "graded" contraction, entire sheet of muscle contracts- as a functional syncytium, desmosomes
stomach function
mechanical and chemical breakdown with some absorption
mouth function
mechanical and chemical breakdown, deglutition (swallowing)
enteropeptidase
on brush border cells, activates trypsinogen to trypsin, which then activates chymotrypsinogen, procarboxypeptidase, proelasease
lipoprotein lipase
on endothelial cell apical membranes, breaks down fats on VLDLs and chylomicrons
each anterior pituitary cell type has unique receptors for the correct releasing factor located where?
on its plasma membrane
how many target cell types are there for one hormone?
one or more types of target cells
parathyroid glands secrete
parathyroid hormone
voluntary stage of swallowing
oral cavity to oropharynx
hyperthyroidism
overacitve thyroid, symptoms: weight loss, nervousness, tremor, increased heart rate/blood pressure, exophthalamus, high body temp, sweating
the final acceptor of transferred electrons in the electron transport chain is...
oxygen
the positive feedback of childbirth is stimulated by which hormone?
oxytocin
alpha cell
pancreas islet cell that secretes glucagon
enzymes secreted by the pancreas
pancreatic amylase, trypsin, chymotrypsin, carboxypeptidase, elastase, pancreatic lipase, ribonuclease, deoxyribonuclease
hepatopancreatic ampulla
pancreatic duct and the common bile duct unite to form this
beta cell
pancreatic islet cell that secretes insulin
delta cell
pancreatic islet cell that secretes somatostatin
pancreas
pancreatic islets, alpha cells, beta cells, delta cells, F cell
major exocrine secretions of pancreas
pancreatic juice, enzymes
endocrine glands
pituitary, thyroid, parathyroid, adrenal, pineal
what makes up a portal triad?
portal vein, hepatic artery, bile duct
which portion of the pituitary gland is made of neural tissue?
posterior pituitary
neurohypophysis is another name for the
posterior pituitary gland
dehydroepiandrosterone (DHEA)
precursor to testosterone; produced in the adrenal cortex (zona reticularis)
actions of ADH
prevents diuresis- decreases urine production by stimulating the kidneys to return more water back to the blood, prevents water loss in sweat glands, causes constriction of arterioles (vasopressin)
innervation and stimulation of smooth muscle
primarily under control of ANS- "involuntary", diffuse branching of nerve fibers, transmitters include ACh (parasympathetic) and NE (sympathetic), membrane potential 50-60 mV
chemical digestion in the stomach
protein digestion begins in the stomach- HCl denatures (unfolds) protein molecules, HCl activates pepsinogen into pepsin- an enzyme that breaks peptide bonds btwn certain amino acids, fat digestion continues- gastric lipase splits the triglycerides in milk fat, although this is more effective at pH 5-6 (infant stomach), HCl kills microbes in food, mucus cells secrete mucus to protect the stomach walls from being digested
glucocorticoids
raise BP by increasing sensitivity of blood vessels to other hormones which cause vasoconstriction (permissive effects), anti-inflammatory + immunosuppressive by reducing release of histamine from mast cells, decreasing capillary permeability, depressing phagocytosis, inhibiting white blood cells
chromaffin cells
receive direct innervation from sympathetic nervous system, develop from same tissue as postganglionic sympathetic neurons, acts as a modified sympathetic ganglion
function of cortisol
regulation of metabolism during stress, increase rate of protein catabolism and lipolysis, promote gluconeogenesis, provide resistance to stress by making nutrients available
how does hypothalamus control posterior pituitary?
releases hormones directly into circulation through the posterior pituitary
phosphatases
remove phosphate groups
absorptive state
represents the time after a meal when nutrients enter the blood and need to be stored, hepatic portal system is used for absorption of glucose and amino acids, the liver acts on these first, lacteals are used for absorption of dietary fats which are transported as lipoproteins (chylomicrons) through the lymphatic system before reaching general circulation
structures of posterior pituitary
resembles neural tissue with glial cells, nerve fibers, nerve endings, and neurosecretory vesicles
aldosteronism
results from hypersecretion of mineralocorticoids, results in high BP caused by retention of Na+ and the resultant increase in plasma volume
exocrine glands
secrete products into ducts or lumens or to the outer surface of the body, not part of the endocrine system, ex. sweat
endocrine glands definition
secrete products into interstitial fluid which diffuse into blood
proteases
secreted as inactive precursors
parathyroid hormone (PTH)
secreted by chief cells of parathyroid gland, raises blood Ca2+ levels by stimulating osteoclasts, encourages Ca2+ retention by kidneys and absorption of Ca2+ in diet, inhibits reabsorption of phosphate (bone), promotes formation of calcitriol (active vitamin D) by kidney which increases absorption of Ca2+ and Mg2+ by the cells that line the GI tract
Melanocyte Stimulating Hormone (MSH)
secreted by corticotrophs in anterior pituitary, excessive levels of CRH from the hypothalamus increases MSH release from the anterior pituitary, PIH inhibits MSH release, function unclear in humans but high levels increase skin pigmentation
lingual lipase
secreted by glands in tongue and begins breakdown of triglycerides (lipids) into fatty acids and glycerol, replaced by gastric enzyme
calcitonin
secreted by parafollicular cells of thyroid gland, lowers blood Ca2+ levels by inhibiting osteoclasts
hormone release by the hypothalamus and pituitary gland
secreted in first capillary bed, travel through portal veins and exit and influence cells in anterior pituitary in 2nd capillary bed
which hormones regulate pancreatic secretions?
secretin and CCK
in females, LH stimulates
secretion of estrogen and progesterone, ovulation, formation of corpus lutem
in males, LH stimulates
secretion of testosterone, release of GnRH is inhibited by testosterone, if male receives testosterone injections, gonadotrophs would decrease in number/activity
electron transport chain
series of integral membrane protein complexes in the inner mitochondrial membrane of mitochondria, ETC complexes are capable of oxidation/reduction,
what is the serosa layer
serous membrane also called the visceral peritoneum, secretes serous fluid, consists of areolar CT covered with simple squamous epithelium
regulation of glucocorticoid release
some stimulus disrupts homeostasis by decreasing glucocorticoid level in blood, neurosecretory cells in hypothalamus are receptors, CRH is increased and cortisol is decreased, corticotrophs in anterior pituitary cause increased ACTH which causes cells in zona fasciculata in adrenal cortex to secrete glucocorticoids, causes increased glucocorticoids in blood
what lines bile ducts?
simple cuboidal epithelium
monoglyceride
single fatty acid and glycerol
type of smooth muscle cells in digestive system
single/unitary (visceral)
enteroendocrine cells
small intestine, S cells which make secretin, CCK cells which make cholecystokinin and K cells which release GIP
absorptive cell
small intestine, absorbs nutrients
paneth cell
small intestine, secretes lysozyme and is capable of phagocytosis
goblet cell
small intestine, secretes mucus
length tension relationship in smooth muscle
smooth muscles operate over a wider range of resting lengths, generally broader length-tension relationship in smooth muscle compared to skeletal muscle
how do glucose and galactose move into epithelial cells of small intestine?
sodium symporter (secondary active transport)
lipoproteins
spheres containing hundreds of molecules, surrounded by a coat of phospholipid
types of lipid soluble hormones
steroid hormones, thyroid hormones
in females, FSH
stimulates secretion of estrogen, initiates the formation of follicles w/in the ovary
in males, FSH
stimulates sperm production in testes
oxytocin regulation during labor
stimulation of uterus by baby's head causes stretch of cervix, oxytocin release from posterior pituitary, uterine smooth muscle contracts, as the baby's head is pushed into the cervix oxytocin release increases, muscle contraction occurs which pushes the baby further and elicits even more oxytocin release, positive feedback loop ceases when baby is born
where is serosa layer found?
stomach and intesstines
parietal cell
stomach cell, secretes HCl acid and intrinsic factor for B12)
chief cell
stomach cell, secretes pepsinogen and gastric lipase
G cell
stomach cell, secretes the hormone gastrin, monitors fluid in stomach and secretes hormones into blood
stomach anatomy
stomach filling triggers secretions and motility, stomach empties slowly into the duodenum as small squirts of chyme leave through the pyloric sphincter
mucus neck cell
stomach, secretes mucus
surface mucous cell
stomach, secretes mucus
absorptive state summary
storage of excess fuels occurs in hepatocytes, adipocytes, skeletal muscle; most glucose entering liver cells is converted to glycogen (10%) or triglycerides (40%), dietary lipids are stored in adipose tissue, amino acids are deaminated to enter krebs cycle or are converted to glucose or fatty acids, amino acids that are not taken up by hepatocytes are used by other cells for synthesis of proteins
excess amino acids cannot be
stored
epithelium of mucosa
stratified squamous in mouth, esophagus and anus; simple columnar in the rest of GI tract- secretes enzymes and absorbs nutrients, specialized goblet cells secrete mucous onto cell surfaces, enteroendocrine cells secrete hormones controlling organ function
neural regulation of stomach function
stretch receptors + chemoreceptors (pH) signal bolus entry, and this leads to an increase in parasympathetic nerve impulses to effectors in the stomach, vigorous peristalsis + gastric gland secretions result, chyme periodically released into the duodenum until return to homeostasis
cell types of the stomach
surface mucous cell, mucous neck cell, parietal cell, chief cell, G cell
pharynx and esophagus function
swallowing and avoiding airway
blood vessel diameter is controlled by which nervous system division and which endocrine hormone?
sympathetic division, angiotensin II
how do cells respond to hormones?
synthesis of new molecules, change in membrane permeability, altered rates of reaction
anabolic reactions
synthesize complex molecules from small molecules, requiring energy
lipid metabolism in liver
synthesizes cholesterol, phospholipids, and lipoproteins (LDL and HDL- used to transport fatty acids and cholesterol in the blood stream); stores some fat, uses fatty acids + glucose for ATP production, exports fatty acid conversion pdts called ketone bodies for use by other tissues
lamina propria of mucosa
thin layer of CT, contains blood vessels and lymphatic tissue
muscularis mucosae of mucosa
thin layer of smooth muscle causes folds to form in mucosal layer, drives local movements to increase absorption by exposing ingested material to absorptive surfaces
lactose intolerance
those w/out lactase will have bacteria ferment lactose, and the result will be gas and diarrhea
lipolysis
triglycerides are broken down into glycerol and fatty acids within liver or adipose cells in the presence of epinephrine, norepinephrine, cortisol; fatty acids cannot pass blood brain barrier
lipogenesis
triglycerides are synthesized from amino acids or glucose within the liver or adipose cells in the presence of insulin
where are circulatory hormones released from endocrine cell?
venous end of capillary
the peritoneum
visceral peritoneum covers organs, parietal peritoneum lines the walls of body cavity
external anal sphincter is voluntary or involuntary
voluntarily controlled
stages of swallowing
voluntary stage, involuntary stage
second messengers
water soluble peptide hormones bind to cell surface receptors and produce intracellular second messenger, hormones may increase or decrease the level of second messenger, the same hormone may use different second messengers in different target cells, second messengers initiate a cascade of biochemical reactions, often involving phosphorylation or dephosphorylation within target cells
composition of saliva
water, HCO3-, enzymes
absorption of nutrients by the stomach
water, electrolytes, some drugs (aspirin) + alcohol, fat content in the stomach slows the passage of alcohol to the intestine, where absorption is more rapid, alcohol is absorbed more slowly if taken with a meal
defecation reflex
when rectum fills, sensory input from stretch receptors in rectum is sent to sacral spinal cord, control center in sacral spinal cord region may activate visceral motor (parasympathetic pre-ganglionic) neuron output to rectum and anus, parasympathetic nerves contract muscles of rectum and relax internal anal sphincter to expel feces
gastrocolic reflex
when stomach fills, a strong peristaltic wave moves contents of transverse colon into rectum
gastroilial reflex
when stomach is full, gastrin hormone relaxes ileocecal sphincter so small intestine will empty into large intestine
adrenal medulla
where chromaffin cells secrete 20% NE (as a long lasting hormone) and 80% epinephrine, responds to sympathomimetic nervous system signals- mimic sympathetic NS, cause fight-flight behavior
zona reticularis
where target cells for ACTH secrete androgens
zona fasciculata
where target cells for ACTH secrete glucocorticoids, mainly cortisol
zona glomerulosa
where target cells for angiotensin II secrete mineralocorticoids, mainly aldosterone
are lipids nonpolar?
yes
can organs have both exocrine and endocrine portions?
yes, but only the endocrine portion is part of the endocrine system
subdivisions of adrenal glands
zona glomerulosa, zona fasciculata, zona reticularis, adrenal medulla
androgens
zona reticularis, dehyroepiandrosterone (DHEA), insignificant in males, may contribute to sex drive in females, converted to a form of estrogen in postmenopausal women