Endocrine 2 Flashcards
what are acinar cells?
exocrine glands with pancreatic digestive enzymes
What do pancreatic beta cells produce?
insulin
What percentage of islet cells in the pancreas are beta cells?
60-80%
What do pancreatic alpha cells produce?
glucagon
What percentage of islet cells in the pancreas are alpha cells?
10-20%
What do delta cells in the pancreas produce?
somatostatin
What percentage of islet cells in the pancreas are delta cells?
3-5%
PP-cells (F cells) in the pancreas produce _________
pancreatic polypeptide
What percentage of islet cells in the pancreas are F cells?
3-5%
Epsilon cells in the pancreas produce ________ and account for _____% of cells
ghrelin (growth hormone releasing peptide); 1
Ghrelin is a growth hormone releasing peptide and also ______________
hunger stimulating peptide
Two things that can cause an increase in insulin production
- increased plasma glucose
- GI hormones
T/F: Insulin is a protein-bound hormone
FALSE.
It is a water-soluble hormone and so doesn’t need to bind to a protein for blood transport
Insulin and the liver
Glucose Uptake
- dec blood glucose
- increase glycogen formation
Insulin and fat cells
Fat storage
-dec blood triglycerides, fatty acids
Insulin and muscles
Protein Synthesis
- increased uptake of aa
- inhibits protein degradation
Most important factor controlling insulin release?
blood glucose
Why would oral glucose produce larger insulin response than blood glucose?
elevates insulin to try to capture as much glucose from the meal as possible
T/F: Insulin is a negative feedback method
FALSE - it’s a positive feedback!
Higher blood glucose, more insulin released
___________ decrease insulin secretion via alpha-adrenergic receptors on beta cells
Catecholamines
Cholinergic input ________ insulin release
increases
What increases glucagon synthesis? (3)
- catecholamines
- glucocorticoids
- aa
What decreases glucagon synthesis?(2)
- high plasma glucose and insulin
- high plasma free fatty acids
Glucagon has a ___________ stimulatory effect on beta cells
direct
Most actions of glucagon are opposite those of ______
insulin
What things happen d/t glucagon in the liver that lead to a net increase in blood glucose? (3)
- increased glycogenolysis
- increased gluconeogenesis
- inhibits FFA production from glucose
What happens in adipose tissue d/t glucagon?
leads to increased lipolysis
Parasympathetic NS stimulation will do what to glucagon and insulin?
Increase both of them
Why would Parasym. NS stimulation cause increased glucagon?
allows for redistribution of energy storage
The Sympathetic NS does what to glucagon and insulin?
- INCREASES glucagon
- DECREASES insulin
Why would the Sym. NS increase glucagon and decrease insulin?
Fight or Flight response
Which is the only glucose transporter that’s insulin sensitive?
GLUT4
Where is the body’s calcium?
- 99% in bone
- next largest % intracellular
- smaller pool extracellular 0.5%
What part of the body calcium is regulated?
the extracellular pool
How is calcium regulated in the body?
- absorption from gut
- loss via kidney (2%)
- general losses = gains
What receptor helps in the regulation of calcium?
PPARgamma
Peroxisome proliferator-activated receptor gamma
__________ handle the storage of calcium in bone
Osteoblasts
____________ breakdown soluble calcium from bone and move to ECF
Osteoclasts
Two Primary functions of Calcium
- structural integrity of bones and teeth
- messenger or regulator ions
Pathological effects of abnormal Ca2+
- calcification of soft tissues
- osteoporosis
- reproductive disorders
The __________ is the main organ of Ca2+ and phosphate metabolism
parathyroid
Two main cell types of the parathyroid
- chief cells
- oxyphil cells
Function of chief cells of the parathyroid?
- clear cytoplasm
- synthesize PTH
Function of oxyphil cells of the parathyroid?
function unknown
3 steps in the formation of Parathyroid Hormone (PTH)
- pre pro-PTH
- pro-PTH
- PTH
Parathyroid hormone is a _________ hormone
peptide
What causes an increase in PTH?
decrease in serum calcium
What does an increase in PTH lead to in regards to Ca2+ and phosphate?
- increased plasma Ca2+
- decreased ECF phosphate
The actions of __________ are countered by PTH
calcitonin
Vit. D is activated by _______
PTH
PTH _______ bone formation
inhibits
What does PTH do to the kidneys?
- increases absorption of Ca2+ at distal tubule
- decreases phosphate reabsorption in the proximal tubule = excretion of phosphate in urine
PTH and the small intestine
increased absorption of Ca2+ and phosphate
PTH leads to an ______ relationship between Ca2+ and Phosphorus
inverse
Calcitonin has the _________ effect on Ca2+ as PTH, but the _______ effect on phosphate
opposite; same
Effects of Calcitonin
- decreased Ca2+ in ECF
- hypopshophatemia
How does calcitonin decrease Ca2+ in the ECF?
- moves Ca2+ to bone by blocking osteoclast activity
- inhibits Ca2+ absorption by intestines
- inhibits renal tubular cell reabsorpion of Ca2+
Hypophoshatemia caused by calcitonin
- moves phosphorus from ECF to bone
- inhibits phosphate reabsorption by renal tubules
What is calcitriol? What’s it do?
- bioactive form of Vit. D (1,25-Vit. D)
- increase Ca2+ and phosphorus in blood
What secretes calcitriol?
kidneys
Where is calcitonin produced?
Parafollicular cells of thyroid
Sites of Erythropoietin (EPO) synthesis
- kidney
- liver (minor, no liver synthesis in dog!)
What is the primary site of EPO synthesis? By what cells?
Kidney; in peritubular cells
What type of feed back is in place for EPO synthesis?
classic negative feedback control
________ is a stimulus for EPO synthesis and increases the number of EPO-synthesizing cells
Hypoxia
What is the site of action of EPO?
red bone marrow
Specific actions of EPO
- increases differentiation of hemocytoblasts into reticulocytes (STEM CELL ACTIVATION)
- increases synthesis of key proteins
What key proteins have increased synthesis d/t EPO?
- alpha and beta globins
- transferrin receptor
Clinical significance of EPO?
- renal failure/ anemia relationship
- EPO therapy = use of recombinant human EPO
