Endo 1 Flashcards
1
Q
What are key features of the endocrine system?
A
- broadcasts hormonal messages all over body (circulate through the whole body compared to neurons which are specifically connected to each other)
- long acting (last from minutes to days while NTs work in seconds to minutes)
- slow to act (onset is seconds to minutes compared to an NT which can take milliseconds- this is important since hormones regulate growth and we don’t want muscles and bones growing instantly)
- blood borne (Released by ductless glands- no tubes opening onto open surface. Blood runs through the gland and the hormones are leaking into the capillaries)
- many hormones are NTs (ex: epinephrine- some goes into the bloodstream to cause vasodilation so here it is acting as a hormone not an NT)
2
Q
What are examples of top prescription drugs that are for hormones?
A
- synthroid: levothyroxine- used for treating hypothyroidism
- all oral contraceptives (either estrogen/progestin or progestin)
- humulin: recombinant insulin- treatment for most common endocrine disease diabetes mellitus
- various cortical steroids (prednisone, prednisolone, cortisone) commonly prescribed for inflammation
3
Q
What are examples of glands that release hormones into bloodstream that go to different areas to have their effects?
A
- hypothalamus
- pituitary gland
- thyroid gland
- adrenal gland
- pancreas
- testes/ovaries
- the circled glands all produce endocrine hormones that are simulated by drugs
4
Q
What are temporary endocrine glands? What are examples?
A
- make and lose these glands
- females have two sets: corpus luteum (after egg is ovulated hang around and make progesterone), placenta (produces estrogen, progesterone, etc. and then once the baby it is delivered it is gone)
5
Q
What effects are seen with hypersecretion of growth hormone (GH)?
A
- gigantism
- taller and larger features such as nose, fingers, ears, etc.
6
Q
What effects are seen with hypersecretion of cortisol?
A
- cortisol comes from adrenal cortex
- Cushing’s syndrome
- retain water
7
Q
What can happen from low amount of circulating thyroid hormone?
A
- hypothyroidism
- can develop goiter often due to thyroid gland malfunctioning
- recurrent laryngeal nerve is around the goiter so it’s hard to remove
- parathyroid glands are also around there so it is complicated to remove these
- diet low in iodine in renaissance people with goiter
8
Q
How do fat cells communicate satiety?
A
- fat cells send out leptin if they are full, or inhibit the release leptin if they are empty
- leptin makes you feel satiated
- when fat cells are full they tell you not to eat anymore
9
Q
What occurs with leptin deficiency?
A
- very overweight
- if fat cells do not talk to hypothalamus, you are hungry all of the time
10
Q
Describe the hormone action of endocrine cells
A
- endocrine cells release hormones into the bloodstream
- reach a distant target cell receptor to elicit their effects
- for certain lipophilic hormones, receptors are intracellular
- hydrophilic hormones tend to have cell surface receptors
11
Q
Describe the hormone action of paracrine cells
A
- paracrine hormones are made and stimulate cells that are really nearby
- these tend to break down really quickly
- ex: prostaglandins (made in uterus or gut because they degrade quickly and are important for contraction of these areas), nitric oxide
12
Q
Describe the hormone action of autocrine cells
A
- stimulate themselves (work on the cell where they are produced)
- cause a positive feedback loop
- ex: insulin growth factors release then stimulate the cell which causes the release of more IGF1
13
Q
What are the two types of receptors and most common examples?
A
- cell surface receptors for water soluble hormones; these are the most common and include oxytocin and insulin
- lipid soluble hormone receptors are intracellular and usually intranuclear; hormones bind to intracellular receptor (hormone response element) then the hormone-receptor complex binds to DNA to elicit effects including estrogen, progesterone, testerone, thyroid hormone
14
Q
How do hyrdophilic hormones elicit their effects?
A
- move easily in the blood because of their water solubility
- binding of hormone to surface cell receptor leads to manufacture of second messengers (cAMP or IP3) which alter cellular function
- water soluble hormones producing second messengers include: NE, EP, oxytocin, and many others
15
Q
Why is the manufacture of seccond messengers necessary?
A
- cell is surrounded by lipid membrane and most NT’s and hormones are not lipophilic so 2nd messengers serve to carry the signal from the surface receptor to internal structures of cell
- when hormone is bound, the receptor will produce lots of second messenger so you get amplification
- some hormones (insulin) can bind and expand the membrane so that it doesn’t need to make second messengers
17
Q
How does salbutamol dilate the bronchioles?
A
- sits in beta 2 receptor and binds to Gs receptor
- Gs stimulates the release of cAMP through adenylate cyclase (cAMP is second messenger)
- cAMP activates phosphokinase A
- PKA binds onto light chains so you can’t get contractions
19
Q
What is the blood supply to the pancreas?
A
- branch from splenic artery coming from celiac
- superior mesenteric
- superior mesenteric and celiac branches create anastomosis
21
Q
Is the pancreas mostly exocrine or endocrine?
A
- mostly exocrine
- exocrine: glands with ducts
- to neutralize stomach contents, pancreas makes bicarbonate rich fluid which it spews into duodenum from exocrine acini
22
Q
What do beta cells do? What do alpha cells do?
A
Beta cells:
- low levels of glucose they are inhibited
- high levels of glucose they release insulin
Alpha cells:
-release glucagon when glucose levels get too low
27
Q
What are the parts of the pituitary?
A
- posterior pituitary: releases hormones into the blood which are made by the neurosecretory cells in the hypothalamus (have long axons that travel to the posterior pituitary where they enter the bloodstream)
- anterior pituitary: stimulated by hormones in the blood made by the neurosecretory cells in the hypothalamus causing anterior pituitary to release hormones
28
Q
What is the system for control of the anterior pituitary?
A
- may be releasing and inhibiting hormones
- releasing hormone in the hypothalamus which goes to anterior pituitary where you then have a stimulating hormone
- this goes to an organ causing this organ to make hormones to have its effects
- once the hormones are made they inhibit the releasing and stimulating hormone
29
Q
How is thyroid hormone regulated?
A
- thyrotropin releasing hormone (TRH) produced in and released by the hypothalamus
- TRH is released everywhere but will also reach pituitary gland (pituitary has TRH receptors) where thyroid stimulating hormone (TSH) is produced and released in the anterior pituitary
- TSH stimulates thyroid gland which starts making thyroid hormone
- thyroid hormone increases metabolic rate, digestion, hair growth, fat breakdown, etc.
- when thyroid levels are up, it will turn off its own release
