Adrenal Gland + pancreas Flashcards
What are teh parts of the adrenal gland from the inside out?
- Medulla
- Zona reticularis (produces mineralocorticoids)
- Zona fasiculata (produces glucocorticoids)
- Zona glomerulosa (produces adrenal androgens)
What is the most prominent steroids released from the adrenal cortex?
- Zona reticularis - mineralocorticoids - aldosterone (from corticosterone)
- Zona fasiculata - Glucocorticoid - Cortisol (from corticosterone)
- Zona glomerulosa - Androgens and Estrogens
What is released by the adrenal medulla?
- Epinephrine (80%)
- Norepinephrine (20%)
What are the parent molecules of adrenal hormones?
- Pregnane: produces pregnenalone
- Androstane: produces testosterone
- Estrane: produces estradiol
How are androgens synthesized?
DHEA creates androstenedione which creates testosterone which creates DHT
How are estrogens synthesized?
Estrone = androstenedione + aromatase
Estradiol = estrone OR testosterone + aromatase
Estriol = Estradiol
What is aldosterone’s function?
Regulates body fluid volume by promoting Na+ retention and K+ excretion in the distal and collecting tubules of nephron in kidney
What controls aldosterone?
- Renin angiotensin system
- Circulating K+ concentrations
What is hyperaldosteronism?
Primary (Conn’s syndrome) or secondary; results in hypernatremia, hypokalemia and hypertension
What is adrenogenital syndrome?
Adult biological females: masculinisation, facial hair, deepening of voice
Newborn biological females: pseudohermaphrodism
Adult biological males: no effect
Pubertal biological males: pseudopuberty
What is adrenarche
part of puberty that involves gradual maturation of the adrenal glands and the production of more androgens
What is the cortisol stress pathway?
- Stress/diurnal rhythm triggers hypothalamus to produce CRH
- CRH stimulates anterior pituitary to release ACTH
- ACTH triggers adrenal cortex to release cortisol
What does cortisol do?
- increase blood glucose by stimulating gluconeogenesis and glucose uptake by muscle
- Increase blood AA by stimulating protein degradation
- Increase blood fatty acids by stimulating lipolysis
What are glucocorticoids’ actions outside energy generation?
- vascular collapse during stressful events
- atrophy of lymphatic system
- anti inflammatory effects
What is cushings syndrome?
Hypersecretion of CRH or ACTH, symptoms include excess glucose, fat depostiion and facial hair excess
What is addisons disease?
hyposecretion of cortisol, symptoms include weakness, weight loss, hypotension and hypoglycemia
What is the primary alarm response?
- surge of catecholamine (eye dilation, heart rate)
- increase in basal metabolic rate
- increase blood flow
- hypatic glycogenolysis
What is the secondary resistance response?
- continued mobilisation of glucose for central organs
- breakdown of alternative energy stores (lipids, proteins)
- continued primary alarm response
What is the tertiary exhaustion response?
- muscle wasting, hyperglycemia
- atrophy of immune system and gastric ulcers
- vascular derangements
What is the function of the adrenal medulla?
Release norepinephrine and epinephrine and act as extension of sympathetic nervous system.
What is the difference of epinephrine inding to alpha receptor and beta receptor?
alpha: constricts blood vessel
beta: dilates blood vessel
What are hormones released by the pancreas?
- insulin and amylin (from B or beta cells)
- glucagon (from alpha cells)
- somatostatin (released from D or delta cells)
- pancreatic polypeptide, released from PP or F cells
What does amylin do?
Released with insulin and slows down appearance of glucose in the blood
WHat does somatostatin do?
Released in response to increased glucose and amino acid levels; inhibits digestive absorptive processes
What does the pancreatic polypeptide do?
inhibits the secretion of pancreatic enzymes including somatostatin
What is the pathway of insulin secretion?
- Glucose taken up by GLUT
- Glucose undergoes glycolysis to make ATP/ADP
- ATP fuels Katp channel which allows release of K+
- Release of K+ hyperpolarizes the cell which cuases Calcium channel to open
- Intake of calcium triggers insulin secretion
What’s the difference between Type I and type II diabetes?
I: lack of insulin secretion
II: lack of insulin sensitivity
How does insulin facilitate glucose transport?
- Insulin creates a signal cascade in a hepatocyte that triggers the conversion of intracellular glucose to glucose-6-phosphate, which lowers intracellular concentration shifting the gradient to move inwards through GLUT2
- Insulin creates a signal cascade that triggers the exoctyosis of GLUT4 transporters into the membrane to increase glucose permeability
What are two ways blood glucose is increased and ways blood glucose is decreased?
Increased: glucose absorption from digestive tract + hepatic glucose production (glycogenolysis, gluconeogenesis)
Decrease: transport of glucose into muscle (storage), energy production, urinary excretion of glucose
How is insulin first synthesized?
Proinsulin cleaves connecting peptide (C-peptide) to form A chain and B chain connected by disulfide bonds.
How does insulin affect carbohydrate concentrations?
- Facilitiates glucose transport into the cell by keeping intracellular concentrations low and exocytosing GLUT vesicles
- Inhibits glycogenolysis in liver
- Inhibits gluconeogenesis by reducing circulating amino acids
What are insulin’s actions on fat?
- Inhibits lipolysis
- Stimulates fatty acid uptake in adipose tissue
- Stimulates glucose uptake and conversion to triglycerides
What are insulins actions on protein?
- Promotes amino acid uptake
- stimulate protein synthesis
- inhibits protein degradation
What is the pathway of insulin deficiency in the liver?
- Increase in glycogenolysis
- Hyperglycemia
- Glucosuria (glucose in urine)
- Pull of water into nephron
- constant urination
- dehydration
- low blood volume, increase in drinking, cell shrinkage
- Low blood volume + nervous system malfunction
What is the pathway of insulin deficiency in the cell?
- Decreased glucose uptake in cells
- intracellular glucose deficiency + hyperglycemia
- Polyphagia (constant hunger)
What is the insulin deficiency pathway in terms of fats?
- Increased lipolysis, low triglyceride synthesis
- increased blood fatty acids
- utilization oof ketone bodies as energy
- ketosis
- metabolic acidosis
- increased ventilation to maintain blood pH, diabetic coma
What is the pathway of insulin deficiency in terms of protein?
- decrease in amino acid uptake + increase in protein degradation
- increase in blood amino acids + muscle wasting
- increase in gluconeogenesis from amino acids
- aggravation of hyperglycemia
What is glucagon’s effect on carbohydrates?
Stimulates hepatic glycogenolysis (via phosphorylase) and gluconeogenesis (via glycogen synthase)
What is glucagon’s effect on fats?
- promotes fat breakdown and release of tri/di/monoglyceride lipase’s from fats
- inhibits hepatic ketogenesis (conversion of free fatty acids to ketone bodies)
What is glucagon’s relationship to proteins?
Promotes hepatic protein catabolism to free amino acids for gluconeogenesis.
How do alpha and beta cells respond to a high concentration of amino acids in the blood?
Beta: increase in production of insulin to take up amino acid into cells
Alpha: increase in production of glucagon to release glucose to fuel insulin-induced protein synthesis
