Week 5 - Endocrine System Flashcards
What is the endocrine system?
Group of tissues and glands that secrete hormones. Capillaries pick up the hormones and carry them by bulk flow.
If the secreting cell is a neuronal cell, what kind of signalling is it?
Neuroendocrine signalling
Describe classic endocrine signalling
Secreting cell secretes hormones into surrounding interstitial fluid. Blood vessels pick it up and brings them to target tissues.
Cells of target tissues have receptors for the hormone
Name two water soluble hormones
Insulin
Epinephrine
Where are the receptors of water-soluble hormones
On the surface of the cell, since it cant cross the lipid membrane of cells
Where are the receptors of lipid-soluble hormones
Inside the cell, since it can cross the membrane
Name an example of lipid-soluble hormones
Steroidal hormones
Describe paracrine signalling. Name examples
TRAVELS BY DIFFUSION
Secreting cell releases signalling molecules that travel to nearby crlls to trigger a response
Mast cells and neutrophils
Describe autocrine signalling. Name an example
TRAVELS BY DIFFUSION
Secreting cell releases signalling molecules that trigger a response on itself.
Cytokines from helper T cells
Describe synaptic signalling
TRAVELS BY DIFFUSION
Secreting cell is a neuron and the route traveled is the synaptic cleft
What is gastrin?
Hormone that makes parietal cells secrete hydrochloric acid to lower stomach PH
What are secretin and CCK
Two hormones that slow the rate of peristalsis and promote the secretion of bicarbonate ions from the pancreas.
Additionally, CCK is responsible to trigger gallbladder to secrete bile into duodenum
Describe blood glucose homeostasis
Blood sugar rises
Beta cells of pancreas secrete insulin
Insulin binds to surface receptors of cells:
liver and muscle cells respond to the insulin and store the glucose for later use.
Blood glucose levels fall
Alpha cells releases glucagon
Glucagon initiates the release of glycogen, gets turned into glucose
Describe blood calcium homeostasis
Calcium levels fall
Parathyroid gland secrete PTH
PTH stimulate osteoblasts to release calcium
PTH targets kidney cells to reabsorb vitamin D (vitamin D triggers epithelial cells in villi to absorb more calcium)
PTH gets nephron to reabsorb calcium
What happens if you have too much calcium
It can calcify in soft tissues
What is the command center of the endocrine system?
Hypothalamus and Pituitary gland
What does the posterior pituitary gland do?
Receives hormones from hypothalamus and then blood capillaries soak them up to take them away
What does the anterior pituitary gland do?
Neurohormones from hypothalamus go to anterior pituitary gland capillaries, triggering a response.
SYNTHESIZES HORMONES
CLASSIC ENDOCRINE SIGNALLING
What is oxytocin
Hormone involved in the release of milk from mammillary glands
Describe the short-term response to stress
Nervous system secretes epinephrine and norepinephrine.
Blood vessels bring to liver
Epinephrine tells liver to break down glycogen to get glucose
Epinephrine tells muscles to dilate for more energy
Epinephrine constricts arterioles of digestion, excretion, etc
Describe the long-term response to stress
Persistently high blood pressure bc of high production of aldosterone (which causes reabsorption of salt)
Production of cortisol
Endocrine vs exocrine glands?
Exocrine secrete substances (fluids)
Endocrine produce hormones
What is particular about oogenesis cytokinesis
It’s asymmetrical- polar body and oocyte
Where does spermatogenesis take place?
Seminiferous tubules
How long does it take for spermatids mature?
24 days
What stimulates follicle growth?
FSH and LH
What hormone triggers ovulation?
Luteinizing hormone (LH)
What does estradiol do?
Makes endometrium get thicker
In what phase does the endometrium get thicker?
Proliferation stage
What happens during the luteal phase?
More blood flow, Secrete fluids
