endocrine system Flashcards
endocrine system
The endocrine system is a system of ‘ductless’ glands that produce hormones involved in the regulation of various body functions.
what do hormones do
Hormones are used to stabilise the body’s internal environment through homeostasis and also co-ordinate longer term processes such as growth and sexual development.
thyroid
Produces the hormone thyroxine:
- Regulates rate of metabolism.
- Excess causes hyperactivity.
- Deficiency causes overweight and sluggishness.
ADRENAL GLANDS
Produce the hormone adrenaline.
- Adrenaline causes the ‘fight or flight’ response resulting in:
- Increased heart rate and breathing rate.
- Blood diverted to the muscles.
- Increased respiration to increase the amount of glucose in the blood.
Reproductive Organs - female
n females, ovaries produce several hormones:
oestrogen
Controls the development of female secondary sexual characteristics.
Regulates menstrual cycle,
progesterone
Thickens uterine wall.
Prevents contractions until a baby is being born.
Reproductive Organs - males
In males, testes produce the hormone testosterone:
Promotes the development of male secondary sexual characteristics.
PANCREAS
Produces the hormone insulin:
-Controls the conversion of blood glucose to insoluble glycogen, which is stored in the liver.
-Increases metabolic rate by stimulating cellular glucose uptake.
-Increases protein synthesis in some cells.
-Deficiency causes the condition “sugar diabetes”, where the blood sugar level is unregulated.
Produces the hormone glucagon
PITUITARY GLAND
Produces several hormones:
growth hormone
Promotes bone and muscular growth.
antidiuretic hormone (ADH) Controls reabsorption of water into the blood by kidneys.
thyroid stimulating hormone (TSH)
Controls the endocrine function of the thyroid gland.
Pituitary Gland and Hypothalamus
Pituitary Gland is connected to the Hypothalamus.
negative feedback
It is a “Stimulus–Response Mechanism” in which the response reduces the magnitude of the original stimulus. This returns the internal environment to its original state.
e.g wate o temp
Managing blood glucose levels:
When too high: insulin is released
When too low: glucagon is released
Which of these parts of the body are involved in the negative feedback process that regulates blood glucose?
The brain, the pancreas and the liver are all involved in regulating blood glucose.
Positive Feedback Mechanisms
-Uncommon
-Creates instability (away from optimum)
-Response increases intensity of original stimulus
E.g.’s.
Uterine contractions
during birth
