Exam 2 - Lecture Notes Flashcards
thyroxine (T4) and triiodothyronine (T3) effect
stimulate basal metabolic rate
calcitonin effect
reduces blood Ca2+ levels
parathyroid hormone effect
increases blood Ca2+ levels
aldosterone effect
increases blood Na+ levels
cortisol, corticosterone, cortisone effect
increase blood glucose levels
epinephrine and norepinephrine effects
stimulate fight or flight response
insulin effect
reduce blood glucose levels
glucagon effect
increases blood glucose levels
testosterone effects
stimulates development of male secondary sex characteristics and sperm production
estrogens and progesterone effects
stimulate development of female secondary sex characteristics and prepare the body for childbirth
the release of adrenal glucocorticoids is stimulated by the release of hormones from the _________ and ________ _________
hypothalamus and pituitary gland
the signal to release glucocorticoids is ___________ (inhibited/stimulated) when glucocorticoid levels become elevated causing ________ (negative/positive) signals to the pituitary gland and hypothalamus
inhibited; negative
what class of hormones are glucocorticoids?
steroid hormones
glucocorticoids are pleiotropic. what are the many effects it can have?
- glucose metabolism
- chronic stress response
- anti-inflammatory
main glucocorticoids in mammals
cortisol and cortisone
main glucocorticoids in birds and rodents
corticosterone
_______ _______ directly accelerates the rate of protein synthesis in skeletal muscles and bones
growth hormone
what does IGF-1 stand for?
insulin-like growth factor 1
what is activated by growth hormones and indirectly supports the formation of new proteins in muscle cells and bones?
IGF-1
GH is one of the most ___________ hormones
pleiotropic
the _____ (organ) releases IGF-1, further stimulating growth effects
liver
what are the effects of GH?
- glucose-sparing effect
- growth effects
- diabetogenic effect
what is the glucose sparing effect of growth hormone?
stimulates adipose cells to break down stored fat, fueling growth effects
what are the growth effects caused by growth hormone?
it targets bone cells, muscle cells, nervous system cells, and immune cells. It increases the uptake of amino acids from the blood. enhances cellular proliferation and reduces apoptosis.
what inhibits growth hormone?
a high levels of IGF-1 is perceived by the hypothalamus and GHIH is released to inhibit the release of GH
where is the thyroid gland located?
sits on top of the cartilage of the trachea
where is the parathyroid hormone located?
imbedded in the thyroid, located int he back of the thyroid
What is this imaging showing?
thyroid follicle cells
a classic __________ feedback loop controls the regulation of thyroid hormone levels
negative
increased levels of ____ and ____ inhibits TRH and TSH
T3 and T4
_______ is required for synthesis of T3 and T4. a deficiency in it impairs ability to synthesize the hormones leading to severe disorders like goiter.
iodine
what disease is this: thyroglobulin accumulates in the thyroid gland follicles increasing the deposit of colloids increasing the overall size of the thyroid gland
goiter
what is hyperthyroidism?
the thyroid gland produces too much thyroid hormone (T3 and T4). This increases basal metabolic rate making people look very thin and shaky.
what is hypothyroidism?
the thyroid gland does not produce enough thyroid hormone (T3 and T4). This decreases basal metabolic rate causing weight gain due to stored energy.
what hormone does calcitonin regulate?
it regulates the parathyroid hormone
how does calcitonin remove Ca2+ from the blood?
- inhibits osteoclasts
- stimulates osteoblasts
- reduces Ca absorption from gut
- increase Ca lass via urine
what class of hormones is T4 and T3?
amine hormones
how many iodines does T4 have?
4
how many iodines have T3 have?
3
which one is more secreted: T3 or T4?
T4
which thyroid hormone is a pro hormone?
T4
which thyroid hormone is considered biologically active?
T3
how are T3 and T4 made?
thyroglobulin is synthesized in the follicular cells of the thyroid gland and is secreted into the colloid in the lumen . elsewhere in these cells , iodine , which is required to synthesize thyroid hormones , is taken up by membrane transporters. it is then oxidized to yield its active form bound to tyrosine residues of the protein in thyroglobulin. This forms MIT and DIT which combine to form T3 and T4 precursors. transported these precursors are then endocytosed, resulting in vesicles that combine w/ lysosome where it forms mature thyroid hormones
what is combined to make T3?
1 MIT and 1 DIT
what is combined to make T4?
2 DIT molecules
thyroid hormone binding protein in the thyroid gland
thyroglobulin
thyroid hormone binding proteins in the blood
- thyroxine-binding globulin (TBG - 75%)
- transthyretin (TTR - 15%)
- albumin (10%)
formation of MIT and DIT is catalyzed by ________
TPO - thyroid peroxidase
formation of T3 at tissue level is catalyzed by ____________
deiodinases
deiodination
a metabolic pathway that regulates the levels of thyroid hormones (T3 and T4) in the body
rT3 - reverse triiodothyronine
about 1% of thyroid hormone released, it is metabolically inactive because the “wrong” iodine is cleaved off, its purpose is that it slows down metabolism to conserve energy
what gland does this histology image show?
parathyroid gland
what are the two types of cells in a parathyroid gland?
- oxyphil
- chief / parathyroid cells
what is the purpose of the parathyroid hormone?
increase blood Ca levels when they drop too low
the parathyroid hormone produces ___________ to reduce Ca2+ when Ca2+ is too high
calcitonin
what two mechanisms are used to constantly maintain blood calcium concentration?
- parathyroid hormone
- calcitonin
what are the two parts of the adrenal gland?
- cortex
- medulla
what class of hormones does the adrenal cortex produce?
steroid hormones
what class of hormones does the adrenal medulla produce?
amine hormones
what are the 3 layers of the adrenal glands cortex? what hormones do they make?
- outer layer = MINERALcorticoids
- middle layer = GLUCOcorticoids
- inner layer = androgens
what is the purpose of mineralocorticoids?
involved in homeostasis of minerals and water
what is the purpose of glucocorticoids?
regulation of glucose metabolism, inflammation, immune function, and stress
what hormones are produced by the adrenal glands medulla?
norepinephrine and epinephrine
what is a hormone axes?
a hormonal cascade of endocrine pathways that respond to specific stimuli and/or negative feedback loops involving the hypothalamus anterior pituitary gland and target organs/cells (a regulation of the system)
hormone axes are generally ___________ feedback loops
negative
HPG axes
hypothalamus pituitary gonad
HPT axes
hypothalamus pituitary thyroid
what is the half-life of a hormone?
the time required for its concentration to decrease to half of its initial concentration
what does t 1/2 stand for?
half-life hormone
how are hormones removed from the body?
clearance and modification
a hormones half-life is inversely related to its metabolic ___________ rate
clearance
if a hormone is cleared slowly is has a _________ half life, if a hormone is cleared quickly is has a ________ half life
longer; shorter
afferent
the process of carrying signals to the nervous system
efferent
the process of carrying signals away from the nervous system
what are the 5 modes of cell-cell communication?
- endocrine
- autocrine
- paracrine
- juxtacrine
- intracrine
endocrine cell-cell communication
hormone signaling, enters the bloodstream
autocrine cell-cell communication
cell SECRETES signal and it then detects and responds to itself
paracrine cell-cell communication
cells communicating with the neighbor cell, signal diffuses in the extracellular fluid to be detected by the neighboring cell
juxtacrine cell-cell communication
cells communicating with the neighbor cell, signal diffuses in the extracellular fluid to be detected by the neighboring cell
intracrine cell-cell communication
is NOT secreted, signal is produced and detected in the cell
what color is hemoxylin? what does it bind to?
- purple
- basophils
what color is eosin? what does it bind to?
- pink
- acid
what is a chromophore?
NO stain
what are the three types of staining in histology?
- acidophils
- basophils
- chromophobes
lactotrophs make ________
prolactin
somatotrophs make _______
GH (somatotropin)
what hormones does the posterior pituitary secrete?
- antidiuretic hormone (ADH)
- oxytocin
oxytocin effect
causes uterine contractions, cervical dilation, causes milk letdown, and the love drug
oxytocin receptors in the uterus are _____ until it is near parturition, then they will ______ during parturition. the fetus pushes against the cervix stimulating the release of oxytocin from the pituitary stimulating contractions of the myometrium.
low; increase
if lactation and pregnancy occurred at the same time milk would be released but so would the conceptus. how does the body prevent this from happening?
oxytocin receptors are inactivated during pregnancy
what is the half life of oxytocin?
about 4 minutes, it is a short (acute) signal
what is Pitocin?
a synthetic form of oxytocin, used to induce labor
what is the effect of antidiuretic hormone?
stimulates water retention in the kidneys (less water excreted in urine)
pituitary endocrine disorders
- galactorrhea
- acromegaly
- gigantism/dwarfism
- cushing’s disease
- diabetes insipidus
what type of disorder are the following caused by: galactorrhea, acromegaly, gigantism/dwarfism, cushing’s disease, diabetes insipidus ?
pituitary endocrine disorders
acromegaly
too much growth hormone as an ADULT, they grow out causing large hands, big noses, a big jaw, etc.
gigantism
too much growth hormone as a CHILD
why does gigantism increase height while acromegaly does not?
gigantism affects children by making them grow taller because their growth plates are not yet fused
thyroid endocrine disorders
- hyperthyroidism / graves disease
- hypothyroidism / hashimotos disease
what is the disorder that causes the following diseases: hyperthyroidism (graves disease) and hypothyroidism (hashimotos disease) ?
thyroid endocrine disorders
what is another name for hyperthyroidism?
graves disease
what is another name for hypothyroidism?
hashimotos disease
what is graves disease?
the autoimmune antibody thyroid-stimulating immunoglobulin (TSI) that mimics TSH causing the thyroid gland to become overactive, leading to hyperthyroidism, and can also cause eye problems, known as Graves’ ophthalmopathy
what is hashimotos disease?
an autoimmune disorder where the body’s immune system mistakenly attacks the thyroid gland, leading to an underactive thyroid (hypothyroidism) and a reduced production of thyroid hormones
what is the name of the outer layer of the adrenal cortex zone? what class of hormones does it produce?
- zona glomerulosa
- mineralocorticoids
what is the name of the middle layer of the adrenal cortex zone? what class of hormones does it produce?
- zona fasciculata
- glucocorticoids
what is the name of the inner layer of the adrenal cortex zone? what class of hormones does it produce?
- zona reticularis
- androgens
what is general adaption syndrome (GAS)?
the body’s physiological response to stress, occurring in three stages: alarm, resistance, and exhaustion.
what are the three stages of the general adaption syndrome?
- alarm reaction
- stage of resistance
- stage of exhaustion
what is the first stage of general adaption syndrome?
alarm reaction, it is the fight or flight, short term
what is the second stage of general adaption syndrome?
stage of resistance, the body tries to adapt to the stressor
what is the third stage of general adaption syndrome?
stage of exhaustion, leading to health problems including depression, immune suppression, weight gain, etc.
what does RAAS stand for?
renin-angiotensin-aldosterone system
what is the purpose of RAAS?
to increase blood pressure (vasoconstriction and reabsorption in the kidneys)
describe the RAAS from start to finish
if there is a drop in blood pressure and fluid volume the kidney will produce renin which will activate angiotensinogen produced by the liver to produce angiotensin 1 which is further activates by ACE (which is produced by the lungs) to produce angiotensin 2. angiotensin 2 targets the blood vessels stimulating vasoconstriction and the adrenal gland which will then produce aldosterone which targets the kidney for reabsorption.
in RAAS, what hormone does the kidney produce?
renin
in RAAS, what hormone does the liver produce?
angiotensinogen
in RAAS, what hormone does the lungs produce?
ACE
in RAAS, what hormone does the adrenal gland produce?
aldosterone
what is galactorrhea?
hyperprolactinemia (excess prolactin produced), a condition where a person experiences milk production from their breasts outside of pregnancy or breastfeeding
what is cushings disease?
too much cortisol (glucocorticoid) due to an overproduction of ACTH
what is diabetes insipidus?
a rare disorder that affects the body’s ability to regulate water balance, leading to excessive thirst and urination
what disease causes excessive urination (polyuria), light colored urine, and constant feeling of thirst (polydipsia)?
diabetes insipidus
what are the 4 types of diabetes insipidus?
- central
- nephrogenic
- dipsogenic
- gestational
central diabetes insipidus
caused by the brain, due to the lack of ADH, this can be due to injury or disease or autoimmune or genetic
nephrogenic diabetes insipidus
an issue in the kidney due to no response to ADH, this can be due to some meds, UT block or genetics
dipsogenic diabetes insipidus
caused by drinking too much
gestational diabetes insipidus
placenta makes too much enzyme that breaks down ADH
what does the pineal gland respond to?
light/darkness
what are circadian rhythms?
- biological clock
- photoperiod
what hormone does the pineal gland secrete? what class of hormone is it?
- melatonin
- amine hormone
light _______ (inhibits/stimulates) melatonin production and is _________ (lower/elevated) in the dark or low light
inhibits; elevated
what is the type of cell that produces melatonin in the pineal gland?
pinealocytes
what hormone is most present during the follicular phase?
estrogen
what hormone is most present during the luteal phase?
progesterone
what does the LH surge cause?
ovulation and lutenization
what are the 4 types of pancreatic inslets in the endocrine pancreas?
- alpha cells
- beta cells
- delta cells
- PP cells
what type of hormone do alpha cells produce?
glucagon
what type of hormone do beta cells produce?
insulin
what type of hormone do delta cells produce?
somatostatin
what type of hormone do PP cells produce?
pancreatic polypeptide hormone
what are the types of pancreatic inslets that regulate blood glucose?
- alpha cells (glucagon)
- beta cells (insulin)
what kind of cells make up the exocrine portion on the pancreas?
acinar cells
what is the average blood glucose? how does a ruminants blood glucose differ?
- 70-110 mg/dL
- ruminants have a much lower blood glucose because they do not absorb glucose in the small intestine
_________ is released from beta cells to promote the reduction of blood glucose
insulin
_________ is released from alpha cells to promote blood glucose levels
glucagon
label these parts of the pancreas
beta cells that secrete insulin also secrete _________ which is released with insulin
serotonin
what nerve is the connection of brain and the stomach?
the vagus nerve
type 1 diabetes mellitus
autoimmune disease that attacks beta cells so the source of insulin is lost
type 2 diabetes mellitus
acquired, adult onset, insulin resistance because the beta cells keep secreting insulin and they become exhausted
what is IGT?
impaired glucose tolerance
which is the normal response? which one is the diabetes response?
the left is normal, the right has the delay
what is the ominous octet?
eight key pathophysiological defects that contribute to the development and progression of type 2 diabetes mellitus
what are the 7 organs that are apart of the ominous octet?
liver, muscles, brain, adipose, kidneys, gi tract, and pancreas
in the pancreas, what cells produce many digestive enzymes and zymogens?
acinar cells (exocrine glands)
what are incretins?
- insulin secretions (hormones that act on the pancreas to secrete insulin)
- GIP and GLP-1
what stimulates incretins release?
they are released in response to nutrient ingestion
GLP-1
- glucagon like peptide 1
- stimulates insulin secretion
what hormones are incretins?
- GLP-1
- GIP
GIP name. What does it stimulate? What is it triggered by?
- gastric inhibitory peptide
- stimulate insulin secretion
- triggered by glucose
what effect does GLP-1 have?
- Stimulating the pancreas to release insulin
- Suppressing the release of glucagon, another hormone that raises blood sugar
- Slowing down gastric emptying
- Reducing appetite
what effect does GIP have?
suppress gastric motility and acid secretion (slow rate of passage and slow digestion)
what is segmaglutide the generic name for and what does it mimic?
- ozempic and wegovy
- mimics GLP-1
what brand name drug is approved for type 2 diabetes but NOT approved for weight loss use?
ozempic
what brand name drug is approved for weight loss and is only a once a week injection?
wegovy
what is mounjaro and zepbound?
to treat obesity or overweight people with health conditions, mimics GIP and GLP-1
what is the somatomedin hypothesis?
mediates the effects of somatotropin (GH)
what are the reflexes that cause the stimulation of endocrine glands?
- chemical or nervous signals
- osmoreceptors
- thermoreceptors
what are beta endorphins?
opioid receptors (make you feel good), they are associated with hunger, thrill, pain, maternal care, sexual behavior, and reward cognition
myoepithelial cell contraction is triggered by ________ which assists in milk meltdown
oxytocin
what are the central and peripheral inhibition of milk letdown?
- central: block release of OT
- peripheral: block binding at target cells
to achieve peripheral inhibition _________ which causes vasoconstriction blocks off blood flow to the mammary glands
epinephrine
where are myoepithelial cells located?
- salivary glands
- breast
- lacrimal glands
- sweat glands
- tracheobronchial glands
oxytocin and vasopressin (ADH) have very similar structures but how are they different?
they have completely different functions, for example oxytocin decreases aggression and anxiety which vasopressin increases them
what is MSH? what secretes it?
- melanocyte stimulating hormone
- secreted by pituitary gland
different levels of MSH are NOT the major cause of variation of skin color, it is the variation in their hormone __________, so they don’t respond so they do not make melanin
receptors
how do receptors work?
protein that bings a ligand with high affinity and low capacity; must be saturable
the target cells of a hormone must express a specific _________ for it
receptor
hormone-receptor interaction is defined by the ___________ constant also known as the ____________ constant
equilibrium; dissociation (Kd)
Ka
association constant; how it goes on
Kd
dissociation constant; how it comes off
what are hormone binding proteins?
they are water soluble globular proteins in the plasma that can carry proteins through the blood
what are the hormone binding proteins CBG and SHBG used for?
steroid hormones
what are the hormone binding proteins TBR, TTR, and albumin used for?
thyroid hormones
what is insulin triggered by?
- food in the intestine (GIP released)
- blood glucose
main target cells for insulin
- skeletal muscle
- adipocytes
what is the action of insulin?
insulin activates a tyrosine kinase receptor, triggering the phosphorylation of substrates the movement of intracellular vesicles containing glucose transporters to the
cell membrane
GLUTS move glucose by _________ diffusion
facilitated
how is glucose stored in animals?
glycogen
how is glucose stored in plants?
- cellulose
- starch (amylose and amylopectin)
what glucose storage in animals has alpha 1,4 main chain and alpha 1,6 branch glycosidic bonds?
glycogen
what glucose storage in plants have alpha 1,4 main chain and alpha 1,6 branch glycosidic bonds?
amylopectin
what glucose storage in plants has alpha 1,4 glycosidic bonds?
amylose
what glucose storage in plants has beta 1,4 glycosidic bonds?
cellulose
does insulin stimulate or inhibit glycolysis?
stimulates
does insulin stimulate or inhibit glucogenesis?
stimulates
does insulin stimulate or inhibit lipogenesis?
stimulates
does insulin stimulate or inhibit protein synthesis?
stimulates
does insulin stimulate or inhibit glucogenolysis?
inhibits
does insulin stimulate or inhibit gluconeogenesis?
inhibits
functions of the digestive system
- digestion of food
- absorption of nutrients
- intake food
- excrete waste
- sensory organ
- endocrin/efffector organ
- immune defense
- immune defense
- microbiome
what is the hepatic portal system?
allows most of the absorbed nutrients to first go to the liver
what are the 4 layers of the gi tract?
- mucosa
- submucosa
- muscularis
- serosa
what are the three components of the mucosa layer?
- lining epithelium
- lamina propria
- muscularis mucosal
what are the 2 layers of the muscularis?
- inner circular smooth muscle
- outer longitudinal smooth muscle
what is the purpose of epithelial lining?
- protection (stratified squamous)
- absorption (single layer columnar or cuboidal cells)
- lubrication (goblet cells)
- hormone secretion (enteroendocrine cells)
what makes up the lamina propria?
- loose CT
- blood and lymph vessels (MALT)
MALT
mucosa associated lymphoid tissue
what are villi?
finger like projections, lots in the mucosa to increase surface area and make it distensible (to stretch)
what makes up the submucosa?
- dense irregular connective tissue
- blood and lymph vessels
- submucosal glands
- submucosal plexus
which layer is the submucosal plexus located in?
submucosa
what is serosa made up of? where is it located?
- loose connective tube
- only in the abdominal cavity
instead of serosa, the mouth, pharynx, and esophagus have ____________, a dense collagen attachment
adventitia
what are the differences of the small and large intestine showcased in this image?
- the small intestine has much greater depth in the mucosa for digestion and absorption
- the large intestine does NOT have villi, but they have crypts for passage, lubrication, and water
label this image
- mucosa
- submucosa
- muscularis
- serosa
what are the 2 broad categories of the GIT nerve supply?
intrinsic and extrinsic
what is the intrinsic nervous system?
- enteric neurons
- they are independent from the rest of the system
what are examples of enteric neurons?
- myenteric plexus
- submucosal plexus
where is the myenteric plexus located?
in the muscularis
where is the submucosal plexus located?
in submucosa
what is the purpose of the myenteric plexus?
for motility and peristalsis
what is the purpose of the submucosal plexus?
it regulates digestive secretions, it detects the presence of food and knows what has been consumed to secrete what it needs
what nerve supply ensures that the gut will continue to move after death because it has its own central nervous system?
interneurons
what is the extrinsic nervous system?
the autonomic system (classical CNS) with sympathetic and parasympathetic nervous systems
what is the purpose of the sympathetic nervous system?
fight and flight (inhibits they intrinsic neurons)
what is the purpose of the parasympathetic nervous system?
rest and digest (stimulates the intrinsic neurons)
what nutrients does the GIT blood supply transport?
proteins (amino acids) and carbohydrates
how are lipids transported from the GIT?
by lacteals (lymph vessels)
what is the hepatic portal system?
veins carry the nutrients to the liver so it is able to process and store them
why would someone be cold after a meal?
during rest and digest, 25% of the blood flow goes to the gut
what is the GIT peritoneum? what is it made up of?
the sac around/lining the gut. it is a broad serous membrane sac. made up of stratified squamous epithelium and connective tissue.
what are the two layers of the GIT peritoneum?
- parietal
- visceral
what is the parietal peritoneum?
lines abdominal walls (keeps the organs together)
what is the visceral peritoneum?
surrounds the gut organs (separates the organs)
what is the greater omentum?
fat deposition in the visceral layer of the peritoneum
what are the 6 fundamental activities of the GIT?
- ingestion
- propulsion
- mechanical/physical digestion
- chemical digestion
- absorption
- defecation
what occurs during ingestion?
biting, chewing, saliva
what occurs during propulsion?
swallowing, peristalsis (muscularis)
what occurs during mechanical/physical digestion?
increases surface area, mastication, insalivation
what occurs during chemical digestion?
enzymes, acids, salts; reduce what we consume and make it into the nutrients that can be absorbed
what is chyme?
soup of digesta, contains acid and enzymes
what is segmentation?
peristalsis of digesta, moving back and forth in the GIT
what are long reflexes?
extrinsic neurons (they are overriding)
what are short reflexes?
intrinsic neurons (local)
what is a plexus?
a network of nerves, blood, or lymph vessels
oral cavity / buccal cavity
the mouth
labia
lips
gingivae
gums
oral vestibule
space between the cheeks and teeth
fauces
the throat, the opening between the oral cavity and oropharynx
palate
roof of the mouth
hard palate vs soft palate
- hard palate is the bony part that separates the oral cavity and oropharynx
- soft palate is muscular posterior and aids in swallowing
uvula functions
block trachea during swallowing, secrete saliva, speech, airflow, gag reflex
what are the tonsils made up of?
lymphoid tissue
what is a frenulum? what is a superior labial frenulum, inferior labial frenulum, and lingual frenulum?
- frenulum = reale like tissue that connects
- superior labial frenulum = connects upper lip and gum
- inferior labial frenulum = connects bottom lip and gum
- lingual frenulum = connects tounge to mouth
what is the epiglottis function?
during swallowing the epiglottis folds down over the larynx preventing food and liquids from entering the trachea
the tongue is covered in ________ that are often called the taste buds
papillae
what are the 3 major salivary glands?
- parotid
- sublingual
- submandibular
what are the functions of the salivary glands?
- lubricates
- buffers acids
- enzymes
- moistens
what causes dental caries?
cavities are caused by eating sugar, the bacteria will eat the sugar and produce and acid, the acid can demineralize/break down the teeth causing the dental caries / cavities
what are sialolithiasis?
salivary stones, they are calcium concretions that block saliva from leaving the gland which is painful
what can help remove sialolithiasis?
sucking on citrus fruits which increases salivation to remove the stones
what are deciduous teeth?
baby teeth, teeth that are meant to be lost or shed over time
what are the 4 types of permanent teeth?
- incisors
- cuspids (canines)
- bicuspids (premolars)
- tricuspids (molars)
what is a crown on a tooth?
the top section of the tooth
what is the root of the tooth? what does it contain?
- the base, within the gum
- contains the pulp cavity
what does the pulp cavity contain?
it contains the blood vessels and nerves
what is dentin?
hard, mineralized tissue that forms the bulk of the tooth structure. it surrounds the pulp cavity and is located beneath the enamel.
what is the hardest substance in the body?
enamel
what is the hard substance that covers the tooth?
enamel
what is cementum?
glues the enamel to the dentin
the tongue is a _______ that helps with the movements and functions of the tongue
muscle
what are the 2 types of muscles in the gi tract?
- extrinsic muscles
- intrinsic muscles
what are the 3 parts of the pharynx?
- nasopharynx
- oropharynx
- laryngopharynx
what is the nasopharynx?
the connection to the nasal cavity, gives the ability to breath and speak
what is the oropharynx?
the connection to the oral cavity that assists in breathing and digestion
what is the laryngopharynx?
the connection to the larynx which assists in breathing and digestion
what is the purpose of the pharynx?
coordinates swallowing, breathing and digestion
what is the connector between the mouth and stomach?
esophagus
what is the upper esophageal sphincter? what type of muscle is it composed of?
controls the movement of food from the pharynx to the esophagus. skeletal and smooth muscle.
what is the lower esophageal (cardiac) sphincter? what type of muscle is it composed of?
controls the movement of food from the esophagus to the stomach. smooth muscles only.
what is heartburn?
stomach acid in the esophagus
what part of the diaphragm allows the esophagus to move through?
esophageal hiatus
what is deglutition?
swallowing
what are the three phases of deglutition?
- voluntary
- pharyngeal phase
- esophageal
what phases of deglutition are involuntary?
- pharyngeal phase
- esophageal
describe the voluntary phase of swallowing?
you control when you swallow food
describe the pharyngeal phase of swallowing?
stimulation of the oropharynx receptors that cause the uvula and soft palate to close off the nasopharynx and the laryngeal muscles close off the trachea
describe the esophageal phase of swallowing?
food enters the esophagus, triggers peristalsis and mucus, the cardiac sphincter relaxes
what are the 4 regions of the stomach?
- cardia
- fundus
- body
- pylorus
what is the main function of the stomach?
mechanical and chemical digestion
what is a pyloric sphincter?
connects the stomach to the duodenum
what is the purpose of the rugae / folds in the stomach?
increase surface area and to have distention
what is the greater curvature and lesser curvature of the stomach attached to?
the greater momentum and lesser omentum
what is the purpose of the inner oblique smooth muscle?
ability to vigorously churn and mix food
what are the cells of the gastric glands?
- parietal cells
- chief cells
- mucous neck cells
- enteroendocrine cells
what do parietal cells secrete?
- HCl
- intrinsic factor
what is the purpose of HCl in the stomach?
lowers stomach pH to 1.5-3.5 and assists in acid digestion as it activates pepsin
what is the purpose of the intrinsic factor?
it is a glycoprotein required for vitamin B12 absorption in the small intestine
what do chief cells secrete?
pepsinogen
what do mucous neck cells secrete?
mucus
what do enteroendocrine cells secrete?
hormones (gastrin, ghrelin, somatostatin)
gastrin: secreted by, stimulated by, target/action
- G cells
- peptides / AA
- movements of digesta along the GIT
ghrelin: secreted by, stimulated by, target/action
- mucosa
- fasting
- hypothalamus / hunger
somatostatin: secreted by, stimulated by, target/action
- mucosa and duodenum
- food, sympathetic stimulation
- stomach (decrease motility, secretions, emptying), pancreas (decrease secretions), small intestine (decrease absorption and blood flow)
.
3 phases of gastric secretion
- cephalic
- gastric
- intestinal
what is the cephalic phase of gastric secretion?
the reflex phase that occurs in the brain, there is NO food in the stomach yet
what is the gastric phase of gastric secretion?
occurs in the stomach and lasts 3-4 hours, as food enters the stomach stretches and stimulates secretions and contractions
what is the intestinal phase of gastric secretion? what are the 2 parts?
- excitatory (chyme is moved into the duodenum stimulating enteric gastrin which increases the flow of gastric juice)
- inhibitory (the duodenum is full and inhibits secretin and closes the pyloric sphincter)
what are the components of the gastric mucosal barrier?
- mucus
- bicarbonate
- tight junctions
what is the purpose of the gastric mucosal barrier?
the mucus-bicarbonate barrier have bicarbonate (HCO3-) to neutralize the acid protecting cells by making a neutral pH
what occurs during the mechanical digestive functions of the stomach?
- mixing waves
- pylorus filtering
- gastric emptying
what does it mean that the gastric emptying is rhythmic? what is it regulated by?
- a little bit is moves through at a time, a metered dose
- regulated by the duodenum and stomach
what occurs during the chemical digestive functions of the stomach?
- lipid digestion
- protein digestion
- intrinsic factor
what nutrient slows down the stomach emptying?
the digestion of lipids
how long foes full digestion take?
24-72 hours
what is pernicious anemia?
vitamin B12 deficiency, a chronic illness caused by impaired absorption of vitamin B12 because of a lack of intrinsic factor in gastric secretions
what is the treatment for pernicious anemia?
a vitamin B12 shot once a month
vitamin B12 is required for ______ synthesis, causing organs with rapid cell turnover to be impacted if there is a deficiency of B12
DNA
pernicious anemia is an example of ____________ anemia, where megaloblasts are large nucleated RBC precursors with non condensed chromatin
megaloblastic
what is the primary digestive and absorptive organ?
small intestine
what part of the digestive system is the longest but has the smallest diameter?
the small intestine
what are the 3 main anatomical features that contribute to the large surface area of the small intestine?
- plicae circulares
- villi
- microvilli
what are the 3 parts of the small intestine in order from beginning to end?
- duodenum
- jejunum
- ileum
what part of the small intestine contains the pyloric sphincter?
duodenum
what is the pyloric sphincter?
connects the stomach to the small intestine
the duodenum makes a C-shape around the __________, an accessory organ of the GIT
pancreas
what is the ampulla of Vater (hepatopancreatic ampulla)?
it is where common bile duct and pancreatic duct join dump content
what is the sphincter of Oddi (hepatopancreatic sphincter)?
it regulates when the ampulla of Vater (hepatopancreatic ampulla) opens and closes to release its contents
the exocrine pancreas _________ cells secrete digestive enzymes
acinar
what ducts form the common bile duct?
common hepatic duct + cystic duct
what ducts empty into the duodenum?
common bile duct + pancreatic duct
bile is made in the ________ and flows the the common hepatic duct and cystic duct to the _________ where it is stored
liver; gallbladder
when food is being digested, bile is released from the gallbladder and flows through the ____________ ______ duct and pancreas into the small intestine
common bile
what is the purpose of the jejunum?
absorption (little digestion)
what is the last and longest section of the small intestine that is which with many folds?
ileum
what is the ileocecal sphincter?
where the ileum joins the cecum to connect the small intestine to the large intestine
what are the 3 unique features of the mucosa and submucosa for the small intestine to increase surface area and have the most absorption?
- circular folds/plicae circularis
- villi
- microvilli
where are circular folds / plicae circularis located and what is the purpose?
- end neat mid-ileum
- forms ridges which cause the chyme to spiral through
what is contained within the villi?
absorptive cells including enterocytes, arterioles and venules, lacteals
what structure is considered the brush border?
microvilli
what are the two types of intestinal glands?
- crypts of lieberkuhn
- Brunner’s glands (duodenal glands)
what cell has the function of: digestion and absorption of nutrients in chyme
absorptive cell
what cell has the function of: secretion of mucus
goblet cell
what cell has the function of: secretion of bactericidal enzyme lysozyme; phagocytosis
paneth
what cell has the function of: secretion of the hormone intestinal gastrin
G cells
what cell has the function of: secretion of the hormone CCK (cholecystokinin), which stimulates release of pancreatic juices and bile
I cells
what cell has the function of: secretion of the hormone glucose-dependent insulinotropic peptide (GIP), which stimulates the release of insulin
K cells
what cell has the function of: secretion of the hormone motilin, which accelerates gastric emptying, stimulates intestinal peristalsis, and stimulates the production of pepsin
M cells
what cell has the function of: secretion of the hormone secretin (stimulates brunners glands)
S cells
what is the purpose of segmentation?
separates chyme and then pushes it back together, mixing it and providing time for digestion and absorption
where is segmentation most rapid?
in the duodenum
the hormone _________ from the duodenum triggers the migration motility complexes (peristalsis)
motilin
what is the gastroileal reflex?
- digestion in eh stomach triggers segmentation
- gastrin stimulates ileal motility
the chemical digestion in the stomach will ________ the digestion of proteins and carbohydrates and _______ digestion of lipids
finish; most
why does lactose intolerance occur?
lactose draws water and when fermented int eh large intestine creates gas, so without lactase to break down lactose it causes diarrhea and gas
what are the segments of the large intestine?
- cecum (+appendix)
- colon
- rectum
- anus
which part of the GIT has the function to finish nutrient absorption, absorb water synthesize vitamins, forms feces, and defecation?
large intestine
what is the ileocecal valve?
connects the small intestine and large intestine
what are the 4 parts of the colon, in order?
- ascending
- transverse
- descending
- sigmoid
what is the pneumonic to remember the sections of the color in order?
ATDS: after this defecate soon
- ascending
- transverse
- descending
- sigmoid
in the rectum there are 3 ________ _______ to help separate gas from feces
lateral bends
what is the difference between the internal anal sphincter and external anal sphincter?
- internal anal sphincter has smooth muscle so it is involuntary
- external anal sphincter has skeletal muscle so it is voluntary
what is the type of epithelium located in the anal canal? why?
stratified squamous epithelium, for protection
what are 3 unique features of the large intestine?
- teniae coil
- haustra
- epiploic appendages
what are teniae coil of the large intestine?
three bands of smooth muscle to keep it bunched up
what are haustra of the large intestine?
pouches that are called the feces formation chamber
what are the epiploic appendages of the large intestine?
fat filled sacs with unknown function
what is the image on the left vs the image on the right?
- left: small intestine
- right: large intestine
what features make these two histologies distinguishable?
- small intestine has more enzyme secreting cells that allow the entry of bile and pancreatic juice. there is an increase in surface area with plicae, villi and microvilli.
- the large intestine has a lot more intestinal glands, enterocytes (for absorption), and global cells (that produce mucus)
__________ cells open the tight junctions between epithelial cells and extend probes into the lumen of the large intestine to evaluate the microbial antigens
dendritic
the dendritic cells with antigens then travel to neighboring lymphoid follicles in the mucosa where ___ cells inspect for antigens
T cells
what are the three types of movements during mechanical digestion of the large intestine?
- haustral contaction
- peristalsis
- mass movement
gastrocolic reflex
when stretch in the stomach and chemicals in the small intestine stimulate colon motility
what are the three accessory organs in digestion?
- liver
- pancreas
- gallbladder
what is the livers digestive function?
produces bile
what is the gall bladders digestive function?
stores/concentrates and releases bile
what is the pancreases digestive function?
produces pancreatic joule (which contains digestive enzymes and bicarbonate)
what is the portal hepatis (hepatic portal)?
a vein that carries nutrients from the small intestine straight to the liver
what 3 structures make the portal triad of the liver?
- bile duct
- portal vein
- hepatic artery
what are the 3 main components the make up the liver?
- hepatocytes
- bile canaliculi
- hepatic sinusoids
what is the main cell in the liver?
hepatocytes
what is the main function of a hepatocyte?
produce bile
what is the purpose of the bile canaliculi in the liver?
they are canals that carry the bile produced by hepatocytes to the bile duct
what is purpose of the hepatic sinusoids?
the liver’s unique microvascular structure, is to facilitate the exchange of nutrients, oxygen, and other substances between the blood and the hepatocytes
kupffer cells
specialized macrophages located in the liver (immune cells)
stellate cells
in the liver they accumulate fat and vitamin A
what is the space of disse
in the liver, it is the space between the hepatocytes and sinusoidal endothelial cells
what type of capillary is found in the liver?
sinusoidal capillaries
the liver receives oxygenated blood from the ________ _____ and nutrient rich deoxygenated blood from the ______ _______ _____
hepatic artery; hepatic portal vein
what is fatty liver disease?
hepatocytes in the liver accumulate a lot of lipids making it difficult for the cells to function
bile production increases when fatty chyme enters the duodenum and stimulates the secretion of the gut hormone __________
secretin
what are chylomicrons?
large, triglyceride-rich lipoproteins produced in the small intestine to transport dietary fats and cholesterol from the intestines to the liver and other tissues via the bloodstream
describe the central vein in the liver?
a vein located at the center of each hepatic lobule in the liver, collecting blood from the sinusoids and draining it into the hepatic veins, which ultimately lead to the inferior vena cava.
pancreatic ______ cells secrete hormones
islets
pancreatic ______ cells secrete digestive enzymes
acinar
the gallbladder stores and concentrates bile by…
absorbing water
for carbohydrate digestion, what can be absorbed?
ONLY monosaccharides (glucose, galactose, fructose)
for protein digestion, what can be absorbed?
single AA, dipeptides and tripeptides
for triglycerides what can be absorbed?
monoacylglycerides, glycerol and free fatty acids
for nucleic acids what can be absorbed?
pentose sugars, phosphates and nitrogenous bases
