endocrinology part 1 Flashcards
What is homeostasis?
Physiological processes are regulated with ranges -feedback loop and + feedback loop
What is direct feedback regulation?
Involves release of hormone by endocrine glad
no involvement of nervous system in regulation
atrial natriuretic peptide
What are examples of direct feedback regulation? (1)
stretch sensitive cells of atrium lowers bp
negative feedback
What does the pituitary gland do?
secretes many hormones
What are the two distinct anatomic sections of the pituitary?
- anterior pituitary (adenohypophysis)
- posterior pituitary (neurohypophysis)
What is the posterior pituitary an extension of?
the hypothalamus
neurons that originate in the hypothalamus terminate in the posterior pituitary
What hormones are released by the posterior pituitary?
Oxytocin and arginine vasopressin(involved in water retention)
packaged in vesicles
what is an example of the hypothalamus asking as a first order endocrine athway ?
receives sensory input
hypo. serves as intigration center
What does oxytocin regulate?
uterine contractions
more stretching in contractions means more oxytocin release
positive feedback loop
the path for a hormone to get to the Anterior pituitary
Hypothalamus synthesize and secretes neurohormone –> hypothalamic pituitary portal system –> anterior pituitary release hormones
at least a second or third order anything at effects anterior pituitary
What is a tropic hormone?
one hormone causes the release of another hormone
The pancreas is involved in what
regulation of blood glucose
Regulation of Blood glucose is performed by what?
insulin and Glucagon
What is insulin and Glucagon regulated by?
The pancreas via Direct feedback loop
What is antagonistic paring?
Homrmones that have opposing effects
ex insulin and glucagon
The Pancreas:
waht is the exocrine function?
secretes digestive enzymes
The Pancreas:
what is the endocrine function?
Secretes insulin and glucagon
The Pancreas:
what are the Islets of Langerhans?
what do the beta cells do?
what do the alpha cells do?
Cells of pancreas with endocrine function
beta: secret insulin
alpha secrete glucagon
Secretion of Insulin and its action:
When is insulin secreted?
What glucose is elevated
Secretion of Insulin and its action:
when glucose is transported into beta cells (GLUT2) what happens? (6)
- increase intracellular ATP
- shuts doen ATP dependent K channels
- depolarizes cell and activates voltage gated ca channel
- causes cesicle fusion and insulin secretion into blood
- insulin binds to insulin receptor (RTK)
- signal transduction results in phosphorylation of intracellular glucose transporters (GLUT4)- cell surface translocation
Secretion of Glucagon and its action:
when is it secreted?
when blood glucose is low
Secretion of Glucagon and its action:
Glucagon binds to what receptor?
G-protein coupled receptor
Secretion of Glucagon and its action:
when glucagon has bound to receptor what does it stimulate? (2)
Adenylate cyclase signal transduction
PKA
Secretion of Glucagon and its action:
What does PKA do?
Phosphorylates Glycogen phophorylase kinase
Secretion of Glucagon and its action:
What does GPK lead to?
Breakdown of glycogen to Glucose
Secretion of Glucagon and its action:
what are the processes and where is glucose released from?
glycogenolysis
gluconeogenesis
released from GLUT2
Why can glucose not penetrate cell membrane?
due to it being hydrophilic
Resting level of glucose
after feeding level of glucose
4-6mM
9-11mM
Where is GLUT1 and GLUT3 found
GLUT1- All tissue
GLUT3 - Brain
Both work constantly and express well on cell surface
GLUT4 characteristics
how is it phosphorylated?
Large intracellular pool in muscle and fat tissue
insulin signal transduction phosphorylates it
Glut4 translocates to cell surface
GLUT2: where is it expressed
Expressed well on cell surface in pancreatic beta cells, liver
Bidirectional transporter
What stimulates glycogenolysis and gluconeogensis
Glucagon
Anterior pituitary hormones?
Prolactin and CSH
