Ch 45 bio
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Difference between endocrine and exocrine glands
Endocrine glands secrete directly into surrounding fluids and don't use ducts. Exocrine glands secrete into ducts that lead to the body surface or body cavity
Body's response to short term stress. Binds to receptors on liver cells, which leads to breakdown of glycogen into glucose (which is secreted into bloodstream) and inhibition of the formation of glycogen.
What does nitric oxide (NO) do?
NO is synthesized by blood vessel walls when O2 in blood falls. This activates enzyme relaxing smooth muscle cells causing vasodilation. Also is what causes erection. Viagra prevents NO breakdown.
Modified fatty acids. In semen, contracts uterine wall allowing sperm to move to egg. During childbirth, placenta releases, causing contraction. Promotes fever and inflammation in immune system and creates lining for stomach.
How does insulin work?
It stimulates nearly all cells in body to take up glucose from blood. Also slows glycogen breakdown in liver and conversion of glycerol and amino acids to glucose.
How does glucagon work?
Mainly influences blood glucose levels by stimulating liver cells to increase glycogen breakdown, convert amino acids and glycerol to glucose, and release glucose to blood.
Insulin and glucagon are secreted by which type of islet on the pancreas?
- glucagon > alpha
- insulin > beta
What is diabetes mellitus caused by?
Deficiency of insulin or decreased responsiveness of target cells to insulin
Why is diabetes mellitus a prblem?
Fat breakdown metabolites cause blood pH to go up, which depletes K+ and Na+ ions. Also, level of glucose in blood is too much for kidneys to reabsorb it. B/c too much, water flows out, causing large volumes of urine
What is type 1 diabetes?
When immune system attacks pancreatic beta cells. Treatment is injected insulin
What are the two causes of type II diabetes?
Not really clear on what causes
1. Decreased responsiveness of target cells to insulin. May be due to genetic defect of insulin or insulin receptor or target cells may supress the activity of a response pathway. Obesity may play a role in this. Obesity causes adipose tissue to not receive enough blood. This leads to death of adipose tissue, which leads to an immune response, which leads to decreased response to insulin in certain target cells, such as cells in the liver, adipose tissue, and muscle.
2. Steady decline in production of insulin. There are a number of different causes. One might be that there is an increased rate of apoptosis in the beta cells. Another is that Beta cells might become dedifferentiated under conditions of physiological stress.
What does the hypothalamus do?
Receives info from nerv system and initiates responses through endocrine system.
What hormones released by the posterior pituitary affect nonendocrine tissues?
Oxytocin and ADH
What does oxytocin do?
Stimulates uterine contraction and stimulates milk glands. Also regulates mood and sexual arousal in males and females
How does hypothalamus control anterior pituitary?
It does so by releasing and inhibiting hormones to ant. pit.
Hypothalamus releases neurohormones into capillaries at base of hypothalamus, which drain into a portal vessel, which then branches off into capillaries in the anterior pituitary.
What functions does the anterior pituitary regulate?
Metabolism, osmoregulation, reproductive activity
What do thyroid hormones do?
Function in bioenergetics, help maintain normal blood press, heart rate, muscle tone, and regulates reproductive + digestive functions.
Symptoms of hyperthyroidism
Weight loss, irritability, high body temp
Most common form of hyperthyroidism. Autoimmune disorder. Body creates antibodies that bind to TSH receptors.
When thyroid cannot synthesize enough T3 and T4 to exert negative feedback. Body keeps producing TSH, which leads to enlarged thyroid.
Relationship b/t thyroid hormones and frogs?
Leads to metamorphisis
Secreted by anterior pituitary. In mammals leads to development of mammary glands + production of milk. Contributes to fat metabolism and reproduction in birds. Helps in osmoregulation in freshwater fish. Delays metamorphisis in amphibians. Indicates function diverged w. evolution
In amphibians, fish, reptiles, regulates skin color. In mammals, skin color, hunger, and metabolism.
What are the four tropic hormones?
TSH, FSH, LH, and ACTH
Secreted by anterior pituitary. Makes liver secrete insulin-like growth factor (IGF). Which leads to bone and cartilage growth. Plays a role in aging in some mammals. Also acts as insulin antagonist.
hypersecretion of GH in adulthood which leads to growth of skeleton in head, feet, and hands.
What does PTH do?
Breaks down bone to release Ca ion into body and makes kidney absorb more Ca ion. Also stimulates kidney to change Vit. D into active hormone which then acts on the intestines so that they absorb more Ca.
Used only during childhood. When high level of calcium ion, inhibits resorption of bone and makes kidney excrete Ca.
What does the adrenal cortex do?
Releases corticosteroids when anterior pituitary releases ACTH. Also releases small amounts of sex hormones. Mainly androgens and small amounts of estrogens and progestins.
influences glucose metabolism. Makes body use non-cabohydrate sources of energy. Cortisol --> muscle tissue. At high levels, suppresses immune system but long-term use is dangerous.
Influence mineral metabolism. Ex. aldosterone.
Female sex hormones and functions
Estrogens responsible for secondary sex characteristics + development and maintenance of female reproductive system. Progestins prepare and maintain uterus.
What is behind biorhythms?
Pineal gland >> in brain >> secretes melatonin. It has connections to the eyes, which control its secretory activity.
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