Homeostasis Flashcards
What is homeostasis ?
The process of maintaining a constant internal environment within narrow limits , despite changes that take place internally and externally
What does the negative feedback mechanism do in the human body?
Detect changes or imbalances in the internal environment and to restore balance.
What are the two glands involved in thyroxin levels ?
Thyroid and Pituitary
What happens when Thyroxin increases above normal limits ?
Thyroxin levels increase above normal limits
Pituitary gland is stimulated
Pituitary gland produces less TSH
Low TSH levels stimulates the thyroid gland
The thyroid gland secretes less thyroxin
The thyroxin levels decrease
The thyroxin levels return to normal
What happens when thyroxin levels decrease below normal limits ?
Thyroxin levels decrease below normal levels
Pituitary gland is stimulated
Pituitary gland produces more TSH
High TSH levels stimulates thyroid gland
Thyroid gland secretes more thyroxin
Thyroxin levels increase
Thyroxin levels return to normal
What happens when glucose levels in the blood increase above normal levels?
Glucose levels in the blood increase above normal levels
Pancreas is stimulated
Pancreas secretes insulin into blood
Insulin travels in blood to liver
Stimulated conversion of excess glucose to glycogen which is stored
Glucose level in blood decreases
Returns to normal
What happens when glucose levels in the blood decreases below normal levels?
Glucose levels in the blood decreases below normal levels
Pancreas is stimulated
Secretes glucagon into blood
Stimulates conversion of stored glycogen to glucose
Glucose level in the blood now increases
Returns to normal
What happens when CO2 levels in the blood increases above normal?
CO2 levels in the blood increases above normal levels
Receptor cells in the carotid artery in the neck are stimulated
Send impulses to medulla oblongata in the brain
Medulla oblongata stimulates breathing muscles and heart
Breathing muscles contract more actively which increases the rate and depth of breathing, The heart beats faster
More CO2 is taken to and exhaled from the lungs
The CO2 level in blood returns to normal
What happens when the blood has less water than normal?
Blood has less water than normal
Hypothalamus is stimulated
Sends impulses to pituitary gland to secrete more ADH
ADH travels in the blood to kidneys
ADH increases permeability of collecting ducts and distal convoluted tubules of the kidney
More water is re-absorbed and passed to the surrounding blood vessels
The water level in the blood returns to normal
What happens when blood has more water than usual?
Blood has more water than usual
Hypothalamus is stimulated
Sends impulses to pituitary gland to stop secreting or secrete less ADH
No or less ADH travels in the blood to the kidneys
Collecting ducts and distal convoluted tubules of the kidney become less permeable to water
Less water is re-absorbed and passed to the surrounding blood vessels, more water is lost
Water level in the blood returns to normal
What happens when salt level in the blood decreases ?
Salt level in blood decreases
Receptor cells in the affront and efferent arterioles of kidney detect low salt level
Adrenal gland stimulated
Secretes more aldosterone
Aldosterone increases reabsorption of sodium ions from the renal tubules in the kidney into the surrounding blood vessels
Salt levels in blood vessels increase
Returns to normal
What happens when salt levels in blood increases?
Salt levels in the blood increases
Receptor cells in the afferent and efferent arterioles of kidney detect high salt levels
Adrenal gland is stimulated
To stop secreting/secrete less aldosterone
Decreases the reabsorption of sodium ions from the renal tubules in the kidney into the surrounding blood vessels
Salt levels in blood vessels decreases
And returns to normal
What is the optimal temp for humans
37 degrees
What is epidermis made from?
Keratin
What does Malpighian layer contain?
Contains melanocytes to produce melanin
