Ibhl Endocrine System

Front 1

What is a hormone?

Back 1

Hormones are chemical messengers secreted by endocrine glands nto the blood and transported to specific target cells

Front 2

What are the three major types of hormones? Discuss the solubility of each and give an example of each.

Back 2

1) Steroids (lipid-soluble) (Example: estrogen, testosterone, progesterone) 2) Proteins (water soluble) (Example: ADH, TRH, insulin, glucagon) 3) Tyrosine derivatives (water soluble) (Example: thyroxin)

Front 3

Distinguish between the mode of action of steroid hormones and protein hormones

Back 3

Steroid hormones enter cells(possible because lipid soluble so can go through cell membrane) and form a receptor-hormone comlex that interacts with the gene directly as a transcriptional regulator. Protein hormones bind to receptors in the cell membrane (they can't go through the membrane because they are water-soluble), which causes the release of a second messenger in the cell which will cause the cell's response.

Front 4

Outline the relationshipbetween the hypothalamus and the pituitary gland

Back 4

Refer to the picture in your notes. Things to notice: 1) hypothalamus: receives information from nerves throughout the body, makes oxytocin, ADH, TRH & other hormones that regulate the anterior pituitary 2) posterior pituitary: stores ADH and oxytocin until needed 3) neurosecretory cells: connect hypothalamus and posterior piruitary, allowing the hormones made in the hypothalmus to travel to the posterior pituitary 4) anterior pituitary: makes many hormones including TSH, FSH, and LH 5) portal vein connecting hypothalamus and anterior pituitary, allowing regulating hormones to travel from the h. to the a.p.

Front 5

Explain the control of ADH (vasopressin) secretion (H.1.5) and the effects of ADH on the body.

Back 5

This is an example of negative feedback. ADH is made by the hypothalamus The ADH is transported by neurosecretory cells in the hypothalamus to the posterior pituitary gland. It is attached to a carrier protein called neurophysin. ADH is then stored in the posterior pituitary gland. Osmoreceptors are stimulated by high blood plasma concentration and/or low blood pressure. If the blood plasma has too little water, osmoreceptor cells cause cells in the posterior pituitary to release ADH (anti-diuretic hormone). ADH travels through the blood to the kidney, causing the kidney to increase water reabsorption and therefore make more concentrated urine. The ADH does this by affecting the collecting duct. (ADH makes the collecting duct produce aquaporins, pores that will allow water to pass through)ADH also promotes constriction of blood vessels, which causes an increase in blood pressure. If the blood becomes too dilute, the osmoreceptors stop signaling cells to release ADH, so ADH levels drop. (As a result, a

Front 6

Under what conditions will ADH be released?

Back 6

Low blood pressure, high blood plasma concentration (a sign of dehydration)

Front 7

What does the endocrine system consist of?

Back 7

The endocrine system consists of glands that release hormones that are transported in the blood

Front 8

What is homeostasis?

Back 8

maintaining the internal environment between limits (to keep stable internal conditions)

Front 9

What are some body factors that are kept in homeostasis?

Back 9

blood pH, carbon dioxide concentration, blood glucose concentration, body temperature, water balance (plus others in H1)

Front 10

How is homeostasis maintained (in general)

Back 10

1. Variables are monitored (the variables are blood glucose concentration, body temperature, etc) 2. If the variable changes outside its acceptable limits, correcting changes are made by negative feedback mechanisms (be able to explain with diabetes example)

Front 11

What is negative feedback?

Back 11

Negative feedback=”a primary mechanism of homeostasis, whereby a change in a physiological variable triggers a response that counteracts the initial fluctuation”

Front 12

Where is insulin made?

Back 12

β cells in the pancreatic islets make insulin

Front 13

Where is glucagon made?

Back 13

α cells in the pancreatic islets make glucagon

Front 14

How is homeostasis maintained for blood glucose concentration?

Back 14

insulin decreases blood sugar, glucagon increases blood sugar; insulin promotes uptake of glucose by cells, glucagon does not have an effect on glucose uptake; insulin promotes change of glucose to glycogen, glucagon promotes change of glycogen to glucose; insulin promotes cell respiration, glucagon does not have an effect on cell respiration; insulin promotes change of glucose to fat, glucagon promotes breakdown of fats; both are involved in the homeostatic/feedback control of blood glucose;

Front 15

What is the difference between type I and type II diabetes?

Back 15

1. Type I diabetes—your body makes little to no insulin, treated by insulin injections, insulin-dependent, often starts in childhood. 2. Type II diabetes—your body can make insulin but your body can’t use the insulin it makes (the cells don’t respond properly to insulin), insulin can be a part of therapy but may not help, obesity is a cause, often starts in adulthood although childhood cases are possible.

Front 16

What does the body do when you are cold?

Back 16

Increased shivering, increased metabolic rate (increases heat generation), vasoconstriction (routes blood away from body's surfaces by reducing the diameter of arterioles thus reducing heat loss), stop sweatin (reduce heat loss from evaporative cooling), neurosecretory cells in hypothalamus make TRH (which will cause release of TSH then thyroxin, which causes the increase in metabolic rate)

Front 17

What does the body do when you are too hot?

Back 17

No shivering, decreased metabolic rate (decreases heat generation), vasodilation (routes blood towards body's surfaces by increasing the diameter of arterioles thus increasing heat loss), start sweating (increase heat loss from evaporative cooling), neurosecretory cells in hypothalamus stop making/releasing TRH

Front 18

Discuss the roles of hormones and thr hypothalamus in thermoregulation (regulation of body temperature)

Back 18

Body temperature is monitored by the hypothalamus. When body temperature drops the neurosecretory cells produce TRH. TRH travels to the anterior pituitary via the portal vein. The anterior pituitary releases TSH. TSH travels through the bloodstream to the thyroid. The thyroid secretes thyroxin(e) in response. There are two forms of Thyroxin…T3 and T4. Thyroxin increases metabolic rate. The increased metabolic rate produces more heat, which increases body temperature. The increased heat inhibits the production of TRH . Blood levels of thyroxin are monitored by both the hypothalamus and the anterior pituitary; high levels of thyroxin inhibit TRH secretion. Thus, thyroxin levels are regulated by negative feedback. Thyroxin levels are maintained within narrow limits.

Front 19

What hormones are used in the control of the reproductive system?

Back 19

You need to know: FSH, LH, (GnRH), testosterone, estrogen, progesterone, HCG, oxytocin. Go study the reproductive system to review these :)