Endocrine System Flashcards
How do the nervous and endocrine system interact?
The hypothalamus-pituitary axis, HPA
What is the pituitary gland?
The “master gland” however the hypothalamus is actually in charge.
Small recap of nervous system
-electrical impulses transmit signals quickly over short distances (movement of ions across membranes)
-neurotransmitters at synapses to communicate with other neurons or target cells (muscles or glands)
-rapid responses to immediate changes in internal or external environment (muscle contraction or reflexes)
Small recap of endocrine system
-Hormones: chemical messengers released into bloodstream by endocrine glands or cells
-hormones travel to specific target cells and bind to specific receptors, initiating a response
-acts more slowly but have longer lasting effects (adrenaline seconds to minutes, steroids days to weeks)
-regulate processes that require gradual adjustments (homeostasis, growth, development, metabolism, and reproduction)
How do hormones travel?
Through blood
Can female elephant seals have testosterone?
Yes, they just have a significantly lower amount that males.
What does it mean if a hormone is Lipophilic (fat soluble)
It needs a protein carrier through blood
What type of hormone is a testosterone?
A steroid hormone
What is endocrine signalling?
Secreted molecules (H) travel with blood and trigger responses in specific target cells in the body.
What is paracrine signalling?
Secreted molecules diffuse locally and trigger a response in neighbouring cells. (not with blood)
What is autocrine signalling?
Secreted molecules diffuse locally and trigger a response in the cells that secrete them (not with blood)
What are prostaglandins?
They promote inflammation and pain sensation; their synthesis can be blocked by aspirin and ibuprofen (COX inhibitors).
What does nitric oxide do in the body?
Signals low oxygen levels in blood by causing vasodilation (the widening of blood vessels) Viagra enhances NOs effects by prolonging the relaxation of blood vessels, increasing blood flow.
Paracrine and Autocrine signalling signals through…
Local regulators.
What is synaptic signalling?
when neurotransmitters diffuse across synapses and trigger responses in target tissues (neurons, muscles, or glands)
What is neuroendocrine signalling?
when neurohormones diffuse into bloodstream and trigger responses in target cells anywhere in the body (oxycotin) or locally (HPA) via portal veins.
Where does neuroendocrine signalling occur?
hypothalamus-pituitary axis (HPA)
What is an exocrine gland?
a gland the releases secretions into external environment through ducts ( saliva, sweat, milk)
What is an endocrine gland?
glands that are ductless and secrete hormones into the blood stream.
What do portal veins do?
carry neurohormones to 2nd capillary bed in anterior pituitary.
what are the advantages of a portal system in the HPA?
-portal veins carry a tiny amount of blood
-only a small amount of neurohormones from few neurons is needed to control the secretion of anterior pituitary gland
-short distance = rapid response and no unwanted effects on rest of body.
how does testosterone work?
-it diffuses across the lipid layer of the cell membrane.
-once inside a cell it binds to the androgen receptor (AR) in the cytoplasm.
-after binding the testosterone-receptor complex transolcates to the nucleus.
-it then binds to specific DNA sequences hormone response elements (HRE)
-this activates or represses the transcription of specific target genes.
-the resulting mRNA is translated into proteins that mediate testosterones effects, promoting muscle growth, secondary sexual characteristics, or sperm production.
What hormones are secreted by the anterior pituitary?
tropic/ trophic hormones
what hormone is produced by the adrenal gland?
adrenaline
