ESS 3 Endocrine System

1. Steroids
2. Amino Acid peptide derivative

Receptors found in cytoplasm or nucleus of cell
Hormone-receptor binding usually causes a PROTEIN TO BE PRODUCED that creates a response in cell to take place
-result is slow acting
-made up of lipids/cholesterol
-can pass through membrane
ex: testosterone

chemical signals produced by an endocrine gland that act at some distance from the gland

are organs, tissues or cells capable of responding to the hormone due to the presence of a receptor that binds the hormone

Use 2nd messenger system ( cascading )
Receptors found on cell membrane
Hormone-receptor binding sets off cascade of events
-result is relatively faster than steroid hormone response

1. rate of synthesis and release from manufacture/storage organ
2. rate of tissue uptake or binding
3. rate of clearance

1. Modify membrane transport
2. Alter enzyme activity
3. Alter protein synthesis
4. Alter secretory dynamics

Target cells can adjust their sensitivity to a hormone
1. Up-regulation of receptors
2. Down-regulation

1. increase the number of receptors on membrane
2. takes place when less hormone is available
3. cell is MORE sensitive to less hormone (greater response)

1. decrease in the number of receptors on membrane
2. usually takes place when more hormone is available
3. less response for the same amount of hormone concentration in blood

Hypothalamus communicates to the posterior pituitary w/ nerve fibers that begin in the hypothalamus - (end in the pos. pituitary)

Those neurons synthesize and store the hormones in the pos. pituitary until a nerve signal triggers their release

hormone that releases another hormone at a different gland

1. Follicle Stimulating Hormone (FSH)
2. Luteinizing Hormone (LH)
3. Thyroid Stimulating Hormone (TSH)
4. Adrenocorticotropic Hormone (ACTH)
5. Growth Hormone (GH)

Hypothalamus communicates to the anterior pituitary through "releasing and inhibiting hormones"

-released by hypothalamic hormones-pituitary gland
Target: Ovaries, Testes
Female: stimulates release of ovarian follicle (egg) - begins mens. cycle
Male: stimulates sperm production

1. Antidiuretic Hormone (ADH)

released by hypothalamic hormones - pituitary gland
-estrogen from mature egg stimulates release of LH- 2nd part of mens. cycle
Target: Ovaries, Testes
Female: completes maturation of egg and stimulates ovulation
Male: stimulates testosterone secretion ( can be lower in males due to overtraining)

released by hypothalamic hormone-pituitary gland
Target: thyroid gland
-stimulates secretion of thyroid hormones

-released by hypothalamic hormones-pituitary gland
Target: adrenal cortex
-stimulates secretion of cortisol

released by hypothalamic hormones-pituitary gland
Target: numerous cells throughout body
-directly stimulates muscle, bone and fat
-INdirectly stimulates other tissues by releasing insulin-like growth factors (IGF's) from the liver
-GH has a short half-life in blood (6-20 min.)
-IGF's have a half-life of about 20 hrs.

1. Increase protein synthesis (enhances AA uptake by cells and decreases protein catabolism)
2. Increase lipid metabolism
(stimulates lipolysis in adipose tissue to mobilize glycerol and FFA)
-spares AA's from being used for energy
3. Carbohydrate metabolism
-GH provides a glucose sparing effect by mobilizing FFA's, increasing the utilization of FFA and decreasing utilization of carbohydrates

hypothalamic neurons in pos. pituitary gland
Target: kidneys
Stimulus: high concentration of solutes in blood ( high osmolarity)
-increases water reabsorption in the kidneys

Stimulus: thyroid stimulating hormone
Triiodothyronine and Thyroxin together make up the "THYROID HORMONES"
-differences in strength and half-life but do similar things as:
1. Increase metabolic rate (body heat production )
2. Aids in catabolism of protein, carbs and fat

Calcitonin - from thyroid gland
Parathyroid Hormone (PTH) -parathyroid gland

Target: Bone
Stimulus: high plasma Ca++
-promotes bone deposition (increase Ca++) by stimulating osteoblast activity

Target: Bone, small intestine
Stimulus: low plasma Ca++
-promotes bone resorption (release calcium) by stimulating osteoclast activity
-also increases Ca++ absorption from intestine
-if calcium in s. intestine it will help to bring it out faster

1. Insulin
2. Glucagon

Target: many cells of body, especially muscle, liver, and adipose tissue
Stimulus: high blood glucose
-increases cell uptake of glucose and AA's to store for later use - decreases glucose levels

Target: liver, adipose tissue
Stimulus: low blood glucose
-stimulates glycogenolysis (liver) gluconeogenesis and lipolysis (adipose tissue)
-increase blood glucose levels

75% epinephrine and 25% norepinephrine
Target: many cells of body
Functions:
1. increase glycogenolysis and lipolysis
2. increase heart rate and blood pressure
3. increase pulmonary air flow
4. inhibit blood flow to digestive organs and kidneys
5. increase blood flow to muscles and coronary arteries
-all of these function to prepare the body for activity (fight of flight)
-stimulated by SNS

Target: kidney
stimulus: low renal blood pressure (usually caused by low plasma volume) - leads to the renin- angiotensin mechanism which stimulates aldosterone release
-aldosterone increases Na+ reabsorption- water follows - rehydration = increase plasma volume = increase blood volume= increase BP

Target: muscle, adipose, liver
Stimulus: stress (physical, emotional, physiology tests) via adrenocorticotropic hormone
-stimulates fat and protein catabolism and gluconeogenesis to increase blood glucose

1. Estrogen
2. Progesterone
3. Testosterone

Target: many tissues (uterus, fat, bone, muscle, etc..)
Stimulus: follicle stimulating hormone
-regulates 1st half of mens. cycle and reprod. dev.
-influences fat stores on female
-men have small amts. of estrogen but come from adrenal gland

Target: uterus
Stimulus: Luteinizing hormone
-regulates 2nd half of mens. cycle and pregnancy

Target: many tissues
Stimulus: Luteinizing hormone
-stimulates bone and muscle growth, reprod. growth and libido
-women have low levels, source is from adrenal gland