Endo 1 Flashcards
What is the main function of endocrinology?
Regulate bodily function
To what system can the endocrine system be compared in terms of coordination of functions
The nervous system
What are the two kinds of long-distance signalling between cells
Endocrine signaling
Neuroendocrine signaling
What is Neuroendocrine signaling?
When neuroendocrine cells receive a signal from a neuron, they release hormones (rather than NT)
What is the typical cascade of endocrine signaling?
Hormone secretion by an endocrine gland
Circulation of hormones in blood vessels
Hormone reaches the target site
A physiological response occurs
What are the two types of short-distance signaling?
Paracrine
Autocrine
What is autocrine signaling
A cell releases hormones and binds to it’s own receptors to have a physiological response
What is paracrine signaling
A cell releases hormones that bind to (any) an adjacent cell to produce a physiological response
What are the six steps to any communication by hormones?
- Synthesis of hormones by cell
- Release of hormone by cell
- Transport of hormone in blood stream (often bound to something in blood)
- Detection of hormone by a specific receptor
- A change in cellular metabolism
- Removal of the hormone (often terminates cell response)
How does the hypothalamic-pituitary signaling system work?
The anterior pituitary gland is a source of hormones t under the control of the hypothalamus. The latter can release a releasing factor or an inhibiting factor to cause a release or not of hormones by the anterior pituitary gland
What type of communication occurs in the Hypothalamic-Pituitary signaling?
It is a neuroendocrine signaling system
What are the two classes of hormones based on structure? What is the difference between the two?
Peptides and proteins: bigger molecules that contain the necessary genome to synthesise the hormones
Steroids and amines: smaller molecules that have the genes to code the enzymes used in hormone synthesis but not the hormone itself.
What are the important hormones of this course, and where are they produced? What are the different relations between those hormones?
(7 total)
STEROID
From the Adrenal gland:
1. Cortisol
2. Aldosterone
From the Gonads
3. Testosterone (precursor of estradiol
4. Estradiol
OTHER
Thyroid hormones
(number is the amount of iodine residue)
Will bind to the thyroid hormone receptor
5. T4
6. T3
Will not bind to the thyroid hormone receptor
7. rT3
What is the basic lock and key mechanism for a hypothetical membrane receptor?
The Hormone is complementary to the receptor. The binding brings on a conformity change in the regulatory protein which leads to a physiological response
How can receptors be regulated?
Upregulation
Downregulation
What are the four important properties of hormone receptors? explain each
Specificity: recognition of a single hormone or family
Affinity: Binding at a physiological concentration for there to be an active range
Saturability: a finite # of receptors
Measurable biological effect: response due to interaction
How can a receptor be upregulated?
- Increasing their activity in response to a hormone
- Increasing their synthesis
How can a receptor be downregulated?
- decreasing their activity in response to a hormone
- decreasing their synthesis
What are the three mechanisms by which a hormone can exert an effect on a cell?
- Direct effect on function of the cell membrane
- Intracellular effect mediated by a second messenger
- Intracellular effects mediated by genomic or nuclear action
How does the direct effect of hormones work?
The receptors of the hormone tell the effectors directly to activate
How does Intracellular by a 2nd messenger work?
GPCR: There is a cascade of effects that activate protein kinase to change the activity of other proteins
How does Intracellular by a genomic signaling work?
The steroid hormone ENTERS the cell to bind with the intracellular receptor. The new complement goes into the nucleus and transcripts genes to change the protein content of a cell
How does negative feedback of a hormone work?
Excess hormone: diminution of secretion
Deficiency hormone: increase in secretion
