Lecture: Endocrine Flashcards
Secrete products into ducts or lumens or to the outer surface of the body
Exocrine glands
Secrete products into interstitial fluid or blood
Endocrine glands
Released into one part of the body to regulate activity in other parts of the body
Chemical messengers - mediator molecules
Which hormone can act as an autocrine and paracrine signal at the same time?
IL-2
Circulating hormones…
Enter interstitial fluid and then the bloodstream
Lipid soluble hormones are…
bound to transport proteins for transport in body fluids
Water soluble hormones are…
freely dissolved in body fluids
What are steroid hormones derived from?
Cholesterol
Common steroid hormones?
- Cortisol
- Testosterone
- Estrogen
- Progesterone
- Aldosterone
Which hormones are composed of tyrosine rings with attached iodines?
Thyroid hormones
Are thyroid hormones lipid or water soluble?
Lipid
Which hormones are composed of chains of amino acids?
Peptide + protein hormones
Common peptide and protein hormones
- Hypothalamic inhibiting + releasing hormones
- ADH
- Oxytocin
- hGH
- TSH
- ACTH
- Insulin
- Glucagon
- EPO
Which hormones are composed of modified amino acids?
Biogenic amines
Common biogenic amines
- Catecholamines
- Serotonin
- Melatonin
- Histamines
When are hormones released?
In response to internal and external changes
How many target cells do hormones have?
All hormones have 1 or more target cells.
How do hormones leave secretory cells?
Exocytosis or diffusion
How to hormones target cells?
By binding to the cell surface receptors or the receptors inside the cell
How does a cell respond to a hormone?
- New molecule synthesis
- Alteration of existing molecules
- Change in membrane permeability
- Altered rates of reaction
Compared to other hormones, the response of cells to a steroid hormone is…
relatively slow
Compared to other hormones, the response of cells to water-soluble (peptide) hormones is…
Extremely fast
What is a first messenger?
A water soluble hormone (peptide) binding to a cells surface receptor
Second messengers
- cAMP
- Calcium ions
- cGMP
A hormone that regulates the function of endocrine cells or glands
Tropic hormones
The hypothalamus controls the anterior pituitary gland with special hormones called…
releasing and inhibiting hormones
Which cells secrete human growth hormone?
Somatotrophs
Which cells secrete thyroid stimulating hormone?
Thyrotrophs
Which cells secrete prolactin?
Lactotrophs
Which cells secrete FASH and LH?
Gonadotrophs
Which cells secrete ACTH and MSH?
Corticotrophs
In target cells, what does hGH increase the synthesis of?
Insulin like growth factors
Insulin growth factors characteristics
- increase cell growth + division by increasing amino acid intake
- stimulate lipolysis in adipose tissue
- decrease glucose use by body cells so glucose levels are high enough to supply the brain
How often is hGH released?
In bursts every few hours
Does the posterior pituitary gland synthesize hormones?
No
What does the posterior pituitary gland consist of?
Axon terminals from 2 groups of hypothalamic neurons
Where are OT and ADH synthesized?
Hypothalamus
Where are OT and ADH secreted?
Posterior pituitary
In which part of the hypothalamus is ADH formed?
The supraoptic nucleus
ADH is made in response to signals from which receptors?
Osmoreceptors
Actions of ADH
- prevents diuresis (decreases urine output)
- prevents water loss in sweat glands
- Causes constriction of arterioles
What happens when you are dehydrated or have a high blood osmolarity?
ADH is released by the posterior pituitary
What happens when you are overhydrated or have a low blood osmolarity?
ADH release is inhibited
What substance inhibits ADH
Alcohol
Diabetes insipidus
- Lack of ADH or nonfunctional ADH receptors
- Inability of kidneys to conserve water
- Excess urination
In hepatocytes insulin stimulates…
glycogen
