Exam 3 Flashcards
The endocrine system controls body activities by…
releasing hormones.
Hormones help regulate…
- extracellular fluid
- metabolism
- contraction of cardiac & smooth muscle
- glandular secretion
- some immune functions
- growth and development
- reproduction
Which glands have primary function as an endocrine gland?
- Pituitary gland
- thyroid gland
- parathyroid gland
- adrenal gland
- pineal gland
What has secondary function as an endocrine gland?
- hypothalamus
- thymus
- pancreas
- ovaries
- testes
- kidneys
- stomach
- liver
- small intestine
- skin
- heart
- placenta
- adipose tissue
Although hormones travel throughout the body…
they only affect specific target cells (with specific protein or glycoprotein receptors)
What are endocrines?
Hormones that travel in the blood and act on distant target cells.
What are local hormones?
Hormones that act locally without entering the bloodstream.
What are the 2 types of local hormones?
Paracrines & Autocrines
Paracrines act on…
neighboring cells
Autocrines act on…
themselves (the cells that secreted them)
What types of hormones are lipid soluble?
- Steroids
- Thyroid hormones
- nitric oxide
What are the 3 groups of water soluble hormones?
- Amines
- Peptides, proteins, and glycoproteins
- Eicosanoids
What hormones are amines?
- epinephrine
- norepinephrine
- melatonin
- seratonin
What hormones fall in the group of peptides, proteins and glycoproteins?
- insulin
- growth hormone
- ADH
What hormones are eicosanoids?
- prostaglandins
- leukotrienes
Lipid soluble hormones bind to and activate receptors…
within the cell (not on the surface)
Receptors activated by lipid soluble proteins…
alter gene expression resulting in formation of new proteins.
Water soluble hormones alter cell functions by …
activating plasma membrane receptors, setting of a cascade of events inside the cell.
The cascade of events initiated by a water soluble hormone is called…
the messenger system
What is the first messenger in the messenger system?
The hormone that binds to the cell membrane receptor.
What is the second messenger in the messenger system?
A chemical activated inside the target cell.
What is a common second messenger?
Cyclic AMP (cAMP)
Which hormones increase cAMP levels?
ADH, TSH, ACTH, glucagon, & epinephrine
Which hormones decrease cAMP levels?
growth hormone inhibiting hormone (somatostatin)
What substances can act as second messengers?
- cAMP
- calcium ions
- cGMP
- PI3
- Tyrosine Kinase
What is the major integrating link between the nervous and endocrine systems?
Hypothalamus
The hypothalamus receives input from…
cortex, thalamus, limbic system, & internal organs
What does the hypothalamus control with releasing and inhibiting hormones?
Pituitary gland
What are the hormones of the anterior pituitary gland?
- Human growth hormone (hGH)
- Thyroid-stimulating hormone (TSH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
- Adrenocorticotrophic hormone (ACTH)
- Melanocyte-stimulating hormone (MSH)
Hormones stored and released by the posterior pituitary gland are made in the…
Hypothalamus
What 2 hormones are released by the posterior pituitary gland?
- Oxytocin (OT)
- antidiuretic hormone (ADH)
What is the most plentiful hormone of the anterior pituitary gland?
hGH
What cells does hGH target?
- liver cells
- skeletal muscle cells
- cartilage cells
- bone cells
What is the function of hGH?
- increase cell growth and division
- increase cellular uptake of amino acids
- increase synthesis of proteins
- stimulate triglyceride breakdown
- slows down use of glucose for ATP production to keep blood glucose levels high enough to supply the brain
What promotes the release of hGH
growth hormone releasing hormone (GHRH, somatocrinin)
What inhibits the release of hGH?
growth hormone inhibiting hormone (GHIH, somatostatin)
What is the function of TSH?
stimulate synthesis and secretion of T3 and T4 by the thyroid gland.
What promotes the release of TSH?
thyrotropin releasing hormone (TRH)
What inhibits the release of TSH?
Somatostatin and negative feedback by elevated levels of T3 & T4.
What are the functions of FSH?
- initiates the formation of follicles within the ovaries
- stimulates follicle cells to secrete estrogen
- stimulates sperm production in testes.
What promotes the release of FSH
gonadotropin releasing hormone (GnRH)
What inhibits the release of FSH?
negative feedback by elevated levels of sex hormones.
What is the function of LH in females?
- stimulates secretion of estrogen
- stimulates ovulation of 2nd oocyte from ovary
- stimulates formation of corpus luteum
- stimulates secretion of progesterone
What is the function of LH in males?
-Stimulates secretion of testosterone.
What promotes the release of LH?
(GnRH)
What inhibits the release of LH?
Negative feedback by sex hormones.
What is the function of prolactin?
-initiate and maintain milk secretion by mammary glands.
What promotes the release of prolactin?
Prolactin releasing hormone (PRH)
What inhibits the release of prolactin?
prolactin inhibiting hormone (PIH, Dopamine)
What is the function of ACTH?
controls the production and secretion of gluccocorticoids (cortisol) by the cortex of the adrenal gland.
What promotes the release of ACTH?
corticotropin releasing hormone (CRH)
What inhibits the release of ACTH?
Negative feedback by elevated levels of gluccocorticoids,
What is the function of MSH?
- it’s role in humans is unknown.
- increases skin pigmentation in animals.
What promotes the release of MSH?
Corticotropin releasing hormone (CRH)
What inhibits the release of MSH
dopamine
What are the target tissues of Oxytocin?
- uterus
- breasts
What is the function of oxytocin?
- enhance uterine contraction during delivery
- promotes expulsion of placenta after delivery
- stimulates milk let down during breast feeding.
What promotes the release of ADH?
osmotic pressure of blood
What is secreted by thyroid follicles?
thyroid hormones, thyroxine(T4) and Triiodothyronine (T3)
what is secreted by parafollicular cells of the thyroid gland?
calcitonin (CT)
Thyroid hormones are synthesized by…
TGB (thyroglobulin)
Thyroid hormones are transported in the blood by
TBG (thyroxine-binding globulin)
What is the function of thyroid hormones?
- increase basal metabolic rate
- stimulate synthesis of Na+/K+ ATPase
- increase body temperature
- stimulate protein synthesis
- increase use of glucose and fatty acids for ATP production
- stimulate lipolysis
- enhance actions of some catecholamines
- regulate development and growth of nervous tissue and bones
What is the function of calcitonin?
- responsible for building of bone
- stops resorption of bone
- lowers blood levels of calcium
What are the cells of the parathyroid gland?
- principal cells
- oxyphil cells
What is produced by principal cells of the parathyroid gland?
Parathyroid hormone
What is the function of parathyroid hormone?
- increase blood calcium levels
- decrease blood phosphate levels
- increases the number and activity of osteoclasts
- increases the rate of Ca2+ and Mg2+ reabsorption from urine
- promotes secretion of HPO42-
- promotes formation of calcitriol, which increase absorption of calcium, magnesium, and phosphate from the GI tract.
The adrenal gland is made up of…
an outer cortex and inner medulla
What are the 3 zones in the cortex of the adrenal gland?
- Zona glomerulosa (outer zone)
- Zona fasciculata (middle zone)
- Zona reticularis (inner zone)
What hormones are secreted by the zona glomerulosa?
mineralocorticoids (aldosterone)
What hormones are secreted by the zona fasciculata?
gluccocorticoids (Cortisol)
what hormones are secreted by the zona reticularis?
androgens
what is the function of aldosterone?
- increase reabsorption of Na+
- promotes excretion of K+ and H+
What is the function of cortisol?
- increase rate of protein catabolism and lipolysis
- conversion of amino acids to glucose
- provide resistance to stress by making nutrients available for ATP production
- raise blood pressure by vasoconstriction
- anti-inflammatory
What is the function of androgens?
- insignificant in males
- may contribute to sex drive in females
- converted to estrogen in postmenopausal females
What hormones are produced by the medulla of the adrenal gland?
epinephrine and norepinephrine
What cells make up the pancreatic islets?
- Alpha cells
- Beta cells
- Delta cells
- F cells
What is produced by the alpha cells of the pancreatic islets?
glucagon
What is produced by the beta cells of the pancreatic islets?
insulin
What is produced by the delta cells of the pancreatic islets?
somatostatin
what is produced by the F cells of the pancreatic islets?
pancreatic polypeptide
What is the function of glucagon?
- raise blood glucose levels
- stimulate glycogenolysis
- stimulate gluconeogenesis
What is the function of insulin?
- lowers blood glucose levels
- accelerates facilitated diffusion of glucose into cells
- speeds up glycogenesis
- increases uptake of amino acids and increases protein synthesis
- speed lipogenesis
- slows glycogenolysis
- slows gluconeogenesis
What is the function of pancreatic polypeptide?
- inhibits secretion of somatostatin
- inhibits gall bladder contraction
- inhibits secretion of pancreatic digestive enzymes
What is found in the pineal gland?
melatonin
What are the hormones produced by the thymus gland?
- thymosin
- thymic humoral factor
- thymic factor
- thymopoietin
What is the function of prostaglandins?
- alter smooth muscle contractions
- alter glandular secretion
- alter blood flow
- alter platelet function
- alter nerve transmission
- alter metabolism
What structures make up the gastrointestinal tract?
- Mouth
- Pharynx and esophagus
- stomach
- small intestine
- large intestine
- rectum and anus
What are the accessory structures of the digestive system?
- teeth
- tongue
- salivary glands
- liver
- gallbladder
- pancreas
what are the 6 processes of digestion?
- ingestion
- secretion
- mixing and propulsion
- digestion
- absorption
- defecation
What are the 2 types of digestion?
- Mechanical
- chemical
What is mechanical digestion?
Movement of the GI tract that aids chemical digestion
What is chemical digestion?
catabolic reactions that break down carbohydrate, lipid, and protein molecules into smaller molecules that can be used by the body.
What are the layers of the GI tract?
- mucosal layer
- submucosal layer
- muscularis layer
- serosa layer
what makes up the mucosal layer?
- epithelium
- lamina propria
- muscularis mucosae
What makes up the submucosal layer?
- areolar connective tissue
- Meissner’s (submucosal) plexus (parasympathetic)
What makes up the muscularis layer?
-Muscle
Auerbach’s (myenteric) plexus (parasympathetic and sympathetic)
What makes up the serosa layer?
- visceral layer of peritoneum
- areolar connective tissue with simple squamous epithelium
What is the enteric nervous system?
neurons that extend from esophagus to the gut.
Does the enteric nervous system require stimulation from the CNS & ANS to function?
No, it can function independently.
What control does the ANS have over the GI tract?
1) Parasympathetic- synapse with neurons in the ENS and increase their action.
2) Sympathetic- decreases action of ENS neurons
What are the layers of the peritoneum?
Visceral layer (covers organs) Parietal layer (lines the walls of the body cavity)
What are the parts of the peritoneum?
- greater omentum
- falciform ligament
- lesser omentum
- mesentery
- mesocolon
What digestion occurs in the mouth?
mechanical-chewing
chemical- enzymes begin digestion of carbohydrates
What is secreted by sublingual glands?
Lingual lipase
what are the parts of the teeth?
- crown
- neck
- roots
- pulp cavity
What are teeth made of?
- enamel
- dentin
- cementum
what are the two different sets of teeth?
deciduous (baby teeth)
permanent (adult teeth)
How many teeth are in a set of deciduous teeth?
20
How many teeth are in a permanent set of teeth?
32
How is salivation affected by parasympathetic stimulation.
salivation is increased
How is salivation affected by sympathetic stimulation?
salivation is decreased
What are the functions of saliva?
- wet food for easier swallowing
- dissolve food for tasting
- protect mouth from infection using rinsing action
- destroy bacteria (using lysozyme)
- buffer acidic foods using bicarbonate ions
- begin digestion of starch using salivary amylase
What parts of the pharynx have digestive functions?
- oropharynx
- laryngopharynx
What is the role of the esophagus in digestion?
- secrete mucus
- transport food to stomach
Where does the esophagus pass through the diaphragm?
esophageal hiatus
what is deglutition?
swallowing
what occurs in the voluntary stage of deglutition?
movement of bolus to oropharynx by movement of tongue.
What occurs during the pharyngeal stage of deglutition?
- nasopharynx closed by uvula and soft palate
- epiglottis closes opening to larynx
- bolus moves through oropharynx and laryngopharynx
- upper esophageal sphincter relaxes
what occurs during the esophageal stage of deglutition?
-peristalsis pushes food down the esophagus
The stomach…
- begins digestion of proteins
- continues digestion of triglycerides
- serves as mixing and holding area for food
- converts a bolus to liquid called chyme
- absorbs some substances
What is secreted by mucous neck cells in the stomach?
mucus (protects lining of stomach)
What is secreted by the chief or zymogenic cells of the stomach?
- pepsinogen
- gastric lipase (secretion decreases with age)
what is secreted by the parietal cells of the stomach?
- HCL
- intrinsic factor
What is secreted by the G cells of the stomach?
gastrin (secreted into bloodstream not stomach lumen)
What is the role of pepsin?
digestion of proteins
what is the role of gastrin?
- release more gastric juice
- increase gastric motility
- relax pyloric sphincter
- constrict lower esophageal sphincter
what mechanical digestion occurs in the stomach?
- gentle mixing waves (every 15 to 25 seconds)
- more vigorous waves (from body of stomach to pyloric region)
- intense waves near the pylorus (squirts 1-2 teaspoonfuls of chyme into small intestine with each wave)
The stomach has limited absorption of…
- water
- electrolytes
- certain drugs (especially aspirin)
- alcohol
What occurs during the cephalic phase?
mouth and stomach prepare for food that is about to be eaten.
what initiates the cephalic phase?
sensory receptors in head responding to
- sight of food
- smell of food
- taste of food
- thought of food
what nerves stimulate the production of saliva?
facial and glossopharyngeal
What occurs during the gastric phase?
the stomach is working.
what happens during nervous control of gastric phase?
- stretch receptors and chemoreceptors provide sensory information
- ENS stimulates peristalsis and gastric glandular secretions
- at the end, chyme is released into duodenum
What happens during hormonal control of gastric phase?
presence of caffeine or protein cause G cells to secrete gastrin into bloodstream.
The intestinal phase begins…
when food enters the small intestine
How does nervous control affect the intestinal phase?
- sympathetic nerves slow stomach activity and increase intestinal activity
- enterogastric reflex inhibits gastric motility and slows gastric emptying.
what hormones control the intestinal phase?
- secretin
- cholecystokinin (CCK)
- gastric inhibitory peptide (GIP)
What role does secretin have in the small intestine?
- stimulates flow of pancreatic juice (buffers the acid)
- inhibits secretion of gastric juice
What role does cholecystokinin have in the small intestine?
- decreases stomach emptying
- stimulates secretion of pancreatic juice rich in enzymes
- increases the flow of bile
What function does Gastric inhibitory peptide have?
-decreases stomach secretions, motility, & emptying
What part of the pancreas produces hormones?
Islets of Langerhans (pancreatic islets)
What part of the pancreas produces pancreatic juice?
pancreatic acini
what is in pancreatic juice?
- water
- sodium bicarbonate
- pancreatic enzymes
What enzymes are produced by the pancreas?
- pancreatic amylase
- pancreatic lipase
- ribonuclease
- deoxyribonuclease
- proteases
What is the function of proteases?
breakdown proteins
what are the proteases secreted by the pancreas?
- trypsinogen
- chymotrypsinogen
- procarboxypeptidase
- proelastase
All of the pancreatic proteases are activated by trypsin except one. What is it and what activates it?
trypsinogen, activated by enterokinase
how does enterokinase activate trypsinogen?
removes the trypsin inhibitor
trypsin and chymotrypsin digest…
most proteins
carboxypeptidase digests…
amino acids from the carboxy end of a protein
elastase digest…
elastic fibers in connective tissue
What regulates pancreatic secretions?
- Gastric inhibitory peptide (increases insulin release)
- secretin (increases sodium bicarbonate release)
- cholecystokinin (increases release of pancreatic enzymes)
What is the gallbladder?
a sac below the liver used to store bile
hepatocytes arrange around a central vein in..
lobules (hexagonal shape)
between the hepatocytes there are…
sinusoids (blood filled spaces)
Kupffer cells are…
fixed macrophage cells located in the sinusoids of the liver
What makes bile
hepatocytes
the common hepatic duct is formed
by the merging of the left and right hepatic ducts.
the common bile duct is the created by the merging of…
the common hepatic duct and the cystic duct
blood comes to the liver from…
- hepatic artery
- hepatic portal vein
blood leaves the liver through
the hepatic vein
bile is made up of…
- water
- cholesterol
- bile salts (Na & K salts of bile acids)
- bile pigments (bilirubin)
What is the function of bile?
emulsification of tiglycerides
how is bile secretion regulated?
- parasympathetic nervous system
- secretin
- CCK
What are the functions of the liver aside from producing bile, and aiding metabolism?
- detoxification of blood
- stores fat soluble vitamins (A,B12,D,E,K)
- stores iron and copper
- phagocytizes worn out blood cells and bacteria
- activates vitamin D
What are the plica circularis?
permanent folds in the small intestine (not found in ileum)
Is peristalsis in the small intestine weaker or stronger than in the stomach?
weaker. Chyme stays in small intestine between 3 and 5 hours.
besides peristalsis, what other mechanical digestion occurs in the small intestine?
segmentation (mixes chyme with intestinal juice)
What brush border enzymes contribute to the breakdown of carbohydrates in the small intestine?
- alphadestrinase
- maltase
- sucrase
- lactase
What brush border enzymes contribute to the breakdown of proteins in the small intestine?
- aminopeptidase
- dipeptidase
What brush border enzymes contribute to the breakdown of nucleic acids in the small intestine?
- nucleosidase
- phosphatase
How are carbohydrates absorbed in the small intestine?
glucose and galactose are absorbed into an epithelial cell via sodium symporter.
fructose is absorbed via facilitated diffusion.
all are moved into the bloodstream by facilitated diffusion.
How are proteins absorbed in the small intestine?
amino acids are absorbed into an epithelial cell by active transport with Na+ or H+ ions.
they are moved to the bloodstream by facilitated diffusion.
how are lipids absorbed by the small intestine?
- small fatty acids enter epithelial cells and blood by simple diffusion.
- large lipids are coated in bile salts (called micelles) lipids enter cells by diffusion and leave bile salts in the gut. inside the cells, fats are combined with proteins to form cholymicrons. cholymicrons leave cells by exocytosis into a lacteal.
how are electrolytes absorbed by the small intestine?
- sodium/potassium pumps
- chloride, iodide, and nitrate passively follow
- iron, magnesium, and phosphate ions utilize active transport.
- calcium requires vitamin D and parathyroid hormone
Does the large intestine contain villi or plica circularis?
neither
the epithelium of the large intestine is made up of…
simple columnar epithelium, absorptive cells, and goblet cells
What mechanical movements occur in the large intestine?
- peristaltic waves
- haustral churning
- mass peristalsis
What are the 2 digestive reflexes of the large intestine?
- gastroilial reflex
- gastrocolic reflex
what occurs during the gastroilial reflex?
ileocecal sphincter relaxes, small intestine empties into large intestine making room in small intestine for new material from stomach.
What occurs during the gastrocolic reflex?
when stomach fills, mass peristaltic wave moves contents of transverse colon to rectum
What enzymes are secreted in the large intestine?
None, only mucous is secreted in the large intestine.
in the large intestine, bacteria…
- ferment undigested carbohydrates into carbon dioxide and methane gas
- ferment undigested proteins into simpler substances (indoles,which are stinky)
- turn bilirubin into simpler substances the produce color (brown)
- produce vitamin K and some B vitamins
What is absorbed in the large intestine?
- water
- electrolytes
- some vitamins
What is our only source of energy for performing biological work?
The food we eat
what occurs during defecation?
- Gastrocolic reflex moves feces into rectum
- stretch receptors send signals to sacral spinal cord
- parasympathetic nerves contract muscles of rectum and relax internal anal sphincter
- external sphincter is voluntarily controlled to allow or postpone defecation
- voluntary contractions of diaphragm and abdominal muscles aid poopage.
What are the three major metabolic destinations for nutrients from food?
- energy for active processes
- synthesized into functional or structural molecules
- stored as fat or glycogen for later use
What is glycolysis?
The breakdown of glucose for ATP production
Most metabolism on the central pathway invokes…
Glucose
What organ gets the first shot at processing incoming nutrients?
Liver
In the liver and muscle, excess glucose can be stored as…
Glycogen
What four things can body cells do during metabolism?
- oxidize glucose to produce energy
- store glucose as glycogen (only in liver and muscle)
- convert glucose into fats or amino acids
- store energy as triglycerides in adipose tissue. (Limited amount in muscle as well)
How does glucose move into most cells?
GluT facilitated diffusion transporters
Where in the body does glucose move into cells via sodium/glucose symporters?
GI tract & kidney tubules
There are in a lot of GluT transporters in which organs?
Liver & brain
Does insulin increase or decrease the insertion of GluT transporters in most cell membranes?
Increase
What is glycogenesis?
The production of glycogen for glucose storage
What is glycogen?
A polysaccharide
What stimulates glycogenesis?
Insulin
How many steps are in glycogenesis?
4
What is glycogenolysis?
Breakdown of glycogen for glucose release to bloodstream
What are two enzymes of glycogenolysis?
- Phosphorylase
- glucose-6-phosphatase
Where is glucose-6-phosphatase located?
Hepatocytes
What is the only organ that can release glucose into the bloodstream?
Liver
Phosphorylase is activated by…
Glucagon or epinephrine
what stimulates gluconeogenesis?
- cortisol
- thyroid hormone
- epinephrine
- glucagon
- hGH
What is gluconeogenesis?
the conversion of protein or fat molecules into glucose.
What lipoproteins transport lipids through the bloodstream?
- cholymicrons
- VLDL’s
- LDL’s
- HDL’s
What is good cholesterol?
HDL’s
What is bad cholesterol?
LDL’s
Where do we get cholesterol?
- foods we eat
- liver synthesis
for adults, total cholesterol level should be…
below 200 mg/dl
for adults, LDL levels should be…
below 130 mg/dl
for adults, HDL levels should be
over 40 mg/dl
normally, triglycerides are in the range of…
10-190 mg/dl
How are lipids stored?
in adipose tissue (as triglycerides)
what are the two methods of lipid catabolism?
- lipolysis
- ketogenesis
what happens during lipolysis?
- Triglycerides are broken down into glycerol and fatty acids
- glycerol converted to glucose (glyceraldehyde-3-phosphate)
- Beta oxidation (fatty acids broken into carbon atom pairs)
Carbon pairs resulting from beta oxidation are
converted to acetyl-coA and enter Krebs cycle
What happens during ketogenesis?
-2 acetyl-coA’s bond to form acetoacetic acid which can be converted into beta-hydroxybutyric acid and acetone (ketone bodies)
Where does ketogenesis occur?
liver
what 2 structures prefer to use acetoacetic acid for ATP production?
- heart muscle
- kidney cortex
What is lipogenesis?
conversion of glucose or amino acids into lipids
what hormone stimulates lipogenesis?
insulin
where does lipogenesis occur?
liver and adipose cells
how do amino acids enter the liver?
hepatic portal vein
Amino acids enter cells via…
active transport
what occurs during protein anabolism?
- protein synthesis
- gluconeogensis
- lipogenesis
what occurs during protein catabolism?
liver cells convert amino acids into substances that can enter the Krebs cycle
How are amino acids deaminated?
- amino group removed (NH2)
- NH2 converted to NH3 which is converted to urea
- Urea excreted in urine
Can the body synthesize nonessential amino acids or essential amino acids?
Nonessential
How do our bodies get essential amino acids?
food intake
At some point in life, ____ out of 20 essential amino acids are required by our bodies.
10
How do our bodies synthesize nonessential amino acids?
transamination (conversion of one amino acid to another)
What occurs during the absorptive stat of metabolism?
storage
What occurs during the postabsorptive state of metabolism?
maintenance of normal blood glucose level
What hormone regulates the absorptive state of metabolism?
insulin
What hormones regulate the postabsorptive state of metabolism?
- glucagon
- epinephrine
- norepinephrine
During the postabsorptive state of metabolism, glucose enters the blood from what 3 major sources?
- glycogenolysis
- gluconeogensis of amino acids
- gluconeogenesis of glycerol
what body cells require glucose for ATP production?
Brain
What are minerals?
inorganic substances
What vitamins are fat soluble?
A,D,E, and K
can vitamins be synthesized by the body?
No
Where does the body store water soluble vitamins?
The body does not store water soluble vitamins well.
