ENDOCRINE SYSTEM AND HOMEOSTASIS Flashcards
DEFINE HORMONES
- organic substances and chemical messengers
DESCRIBE THE DIFFERENCES BETWEEN THE ENDOCRINE AND NERVOUS SYSTEM
ENDOCRINE:
* made up of glands
* produces hormones
* hormones transported by the blood
* effects are slower and more general
* hormones control long-term changes
NERVOUS SYSTEM:
* made up pf nerves
* produces nerve impulses
* impulses transmitted along the nerves
* effects are very quick and very specific
* nerve impulses control short-term changes
DESCRIBE THE DIFFERENCES BETWEEN THE ENDOCRINE AND EXOCRINE GLANDS
ENDOCRINE GLANDS:
* glands are ductless, secrete directly into bloodstream
* secrete hormones
EXOCRINE GLANDS:
* secrete their substances into ducts directly at the target site and not the bloodstream
* secrete substances like enzymes, saliva, sweat, oil
DESCRIBE ALL THE HORMONES THAT ARE SECRETED BY THE PITUITARY GLAND
THE HYPOPHYSIS SECRETES:
* GH (growth hormone) - controls growth
* TSH (thyroid stimulating hormone) - stimulates thyroid gland to secrete thyroxin
* FSH (follicle stimulating hormone) - stimulates the development of the graafian follicle in the ovary and spermatogenesis
* LH (luteinising hormone) - stimulate ovulation and the development of the corpus luteum
* prolactin - stimulates the mammary glands to secrete milk, counteracts the effect of dopamine which is responsible for sexual arousal
DESRIBE THE HORMONES THAT ARE SECRETED BY THE PANCREAS
THE ISLETS OF LANGERHANS SECRETES:
* glucagon - stimulates conversion of glycogen to glucose (increases blood glucose levels)
* insulin - stimulates conversion of glucose to glycogen (reduces the blood sugar level)
DESCRIBE THE HORMONES SECRETED BY THE TESTES
THE TESTES SECRETES TESTOSTERONE WHICH:
* stimulates the maturation of sperm cells
* stimulates puberty in males
DESCRIBE THE HORMONES SECRETED BY THE OVARY
THE OVARY SECRETES REPRODUCTIVE HORMONES:
* oestrogen - stimulates puberty in femlaes. promotes the thickening of the endometrium
* progesterone - promotes thickening of the endometrium, maintains pregnancy
DESCRIBE THE HORMONES SECRETED BY THE KIDNEY
THE ADRENAL GLANDS SECRETE:
* adrenaline - increases heartbeat, blood pressure, conversion from glycogen to glucose, blood supply to the cardiac and skeletal muscles, skeletal muscle tone, rate and depth of breathing, diameter of pupils. decreases blood flow to the digestive system and skin
* aldosterone - regulates salt concentration in the blood
DESCRIBE THE HORMONE SECRETED BY THE LARYNX BELOW THE NECK
THE THYROID GLAND SECRETES:
* thyroxin - controls basic metabolic rate
DESCRIBE THE HORMONE SECRETED BY THE HYPOTHALAMUS
- ADH (antidiuretic hormone) - controls the concentration of water in the blood
DEFINE HOMEOSTASIS
the process of maintaining a constant internal environment within narrow limits, despite changes that take place internally and externally
DESCRIBE THE REGULATION OF THYROXIN LEVELS IN THE BLOOD
TOO HIGH:
1. thyroxin levels increase above normal limits
2. pituitary gland is stimulated
3. pituitary gland produces less thyroid stimulating hormone (TSH)
4. low TSH level stimulates the thyroid gland
5. the thyroid gland secretes less thyroxin
6. the thyroxin level thus decreases
7. thyroxin level returns to normal
TOO LOW:
1. thyroxin levels decrease below normal limits
2. pituitary gland is stimulated
3. pituitary gland produces more TSH
4. high TSH level stimulates the thyroid gland
5. the thyroid gland secretes more thyroxin
6. the thyroxin level thus increases
7. thyroxin level returns to normal
DESCRIBE THE REGULATION OF BLOOD GLUCOSE LEVELS
INCREASES:
1. glucose levels in the blood increase above normal levels
2. the beta cells of the Islets of Langerhans in the pancreas are stimulated
3. to secrete insulin into the blood
4. insulin is transported to the liver and muscle cells by the blood
5. where it stimulates the conversion of excess glucose to glycogen which is then stored. insulin also stimulates the absorption of glucose in the blood into the body cells
6. glucose is removed from the blood and the glucose level in the blood now decreases
7. and returns to normal
DECREASE:
1. glucose levels in the blood decrease below normal levels
2. the alpha cells of the Islets of Langerhans in the pancreas are stimulated
3. to secrete glucagon into the blood
4. glucagon is transported in the blood to the liver and muscle cells
5. where it stimulates the conversion of stored glycogen to glucose
6. the glucose level in the blood now increases
7. and returns to normal
DESCRIBE THE REGULATION OF CARBON DIOXIDE LEVELS IN THE BLOOD
INCREASE:
1. CO2 levels in the blood increase above normal levels
2. receptor cells in the carotid artery in the neck are stimulated
3. to send impulses to the medulla oblongata in the brain
4. medulla oblongata stimulates breathing muscles and heart
5. breathing muscles contract more actively - increases the rate and depth of breathing. the heart beats faster
6. more CO2 is taken to and exhaled from the lungs
7. the CO2 level in the blood returns to normal
DESCRIBE THE REGULATION OF WATER LEVELS IN THE BLOOD (OSMOREGULATION)
LESS WATER:
1. blood has less water than normal
2. the hypothalamus is stimulated
3. and sends impulses to the pituitary gland to secrete more ADH
4. ADH travels in the blood to the kidneys
5. ADH increases the permeability of the collecting ducts and the distal convoluted tubules of the kidney
6. more water is re-absorbed and passed to the surrounding blood vessels
7. the water level in the blood returns to normal
MORE WATER:
1. blood has more water than normal
2. the hypothalamus is stimulated
3. and send impulses to the pituitary gland to secrete less ADH
4. less ADH travels in the blood to the kidneys
5. the collecting ducts and the distal convoluted tubules of the kidney become less permeable to water
6. less water is re-absorbed and passed to the surrounding blood vessels. more water is now lost
7. the water level in the blood returns to normal
