Module 5 - Endocrinology Flashcards
Local vs Long-distance signalling
Local
- paracrine
- synaptic
Long-distance
- endocrine (hormonal)
5 types of signalling, signalling molecule and communication type
Endocrine
- signalling molecule: hormones
- long distance
Synaptic
- signalling molecule: neurotransmitters
- short distance
Neuroendocrine
- signalling molecule: neurohormone
- long distance
Paracrine
- signalling molecule: local regulators
- short distance
Autocrine
- signalling molecule: local regulators
- very short distance
Define endocrine signalling
secreted molecules diffuse into the blood stream, circulate, and trigger responses in target cells anywhere in the body
Define synaptic signalling
secreted molecules diffuse across a synapse, triggering a response in cells of the targeted tissue
Define neuroendocrine signalling
secreted molecules are released from a neurosecretory cell, diffuse into the blood stream, circulate, and trigger responses in target cells anywhere in the body
Define paracrine signalling
secreted molecules diffuse locally through the ECF, triggering a response in neighbouring cells
Define autocrine signalling
secreted molecules diffuse locally, triggering a response in the cell which secreted them
Type I vs type II diabetes mellitus
Type I
- insulin dependent
- an autoimmune disorder in which the immune system destroys pancreatic beta cells
Type II
- non-insulin dependent
- involves insulin deficiency or reduced response of target cells dues to change in insulin receptors
Posterior vs Anterior pituitary
Posterior
- houses ends of hypothalamic neurons which store hormones
- place of neurosecretion
- no cells
- ‘dry’ side
Anterior
- houses true endocrine cells which synthesise and release hormones
- portal circulation
- regulated by hormones released into portal blood vessels
- rich in blood supply, gives pink colour
- ‘wet’ side
What is portal circulation?
Capillaries to portal vessels to capillaries
What hormones does the posterior pituitary release and what are their target?
Antidiuretic hormone (ADH, Vasopressin) - kidney tubules Oxytocin - mammary glands and uterine muscles
What hormones does the anterior pituitary release?
Gonadotropins (FSH and lutropin) TSH ACTH Prolactin MSH GH
Tropic vs non-tropic hormones
Tropic - stimulate another endocrine gland to release a subsequent hormone that will act on its target cells
Non-tropic - act directly on target cell
Components of Adrenal gland
Adrenal medulla
- inside
- neural tissue
- releases amine hormones (catecholamines) including epinephrine (adrenline) and norephinephrine (noradrenaline)
- triggers fight or flight response
Adrenal cortex
- outside
- true endocrine cells
- releases steroid hormones (corticosteroids) such as mineralocorticoids (aldosterone) and glucocorticoids (cortisol)
What is the distinctive feature of steroids?
4 ring structure like cholesterol
Steroid hormones plus examples
Corticosteroids
- mineralocorticoids e.g. Aldosterone
- glucocorticoids e.g. cortisol
Amine hormones plus examples
Catecholamines
- epinephrine e.g. adrenaline
- norephinephrine e.g. noradrenaline
Short term responses to stress
Caused by epinephrine and norepinephrine
- glycogen broken down to glucose to increase blood glucose
- increased blood pressure
- increased breathing rate
- increased metabolic rate
- change in blood flow patterns leading to increased alterness and decreased digestive, excretory and reproductive system activitiy
Long term responses to stress
Effects of mineralocorticoids (aldostrone)
- retention of sodium ions and water by kidneys
- increased blood volume and blood pressure
Effects of glucocorticoids (cortisol)
- proteins and fats broken down and converted to glucose, leading to increased blood glucose
- possible suppression of immune system
What are the three types of hormones? Are they hydrophillic and hydrophobic?
Polypeptides - hydrophillic, water-soluble
Steroids - hydrophobic, lipid-soluble
Amines - both: hydrophillic
hydrophobic
How does receptor location vary with hormone type?
Water-soluble hormones bind on membrane receptors.
Lipid-soluble hormones bind to a receptor in nucleus or cytoplasm (intracellular receptors) as they can cross the membrane.
What do thyroid hormones regulate?
- homeostatsis
- development
Positive vs negative feedback
positive - reinforces stimulus, takes to an extreme
negative - reduces stimulus, restores homeostasis
What is the point of feedback loops?
Feedback loops tell if things are back to normal or not.
