Homeostasis 2 Flashcards
Endocrine system (blood glucose levels, kidneys, osmoregulation, fertility).
What are hormones?
Chemical molecules released directly into the bloodstream.
They are carried into the blood to specific cells in specific organs (target organs) which they bind to, producing an effect.
What do hormones control?
Things in organs and cells which need constant adjustment.
What does the endocrine system contain?
Endocrine Glands
(which secrete chemicals called hormones directly into the bloodstream.)
Endocrine system in comparison to the nervous system.
The effects are slower but act for longer.
Pituitary gland
-In the brain
-A ‘master gland’
-Secretes several hormones into the blood in response to body conditions
-These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.
Thyroid gland
-Located in the neck
-Produces thyroxine, which is involved in regulating heart rate, temperature, and the rate of metabolism
Adrenal glands
-Located above the kidneys
-Produce adrenaline, which is used to prepare the body for a ‘fight or flight’ response
Pancreas
-Produces insulin, which is used to regulate blood glucose level
Ovaries
-Female only
-Produce oestrogen, which is involved in the menstrual cycle
Testes
-Male only
-Produce testosterone, which controls puberty and sperm production in males
Nerves vs hormones
-Nerves have very fast action, whereas hormones have slower action
-Nerves act for a very short time, whereas hormones act for a long time
-Nerves act on a very precise area, whereas hormones act more generally across the body
Which organ (gland!) is blood glucose concentration monitored and controlled by?
The pancreas
-Using the hormones insulin and glucagon in a negative feedback cycle.
Briefly describe what happens if the blood glucose concentration is too high.
-If the blood glucose concentration is too high, the pancreas produces the hormone insulin
-Insulin causes glucose to move from the blood into the cells
-In liver and muscle cells, excess glucose is converted to glycogen for storage
Briefly describe what happens if the blood glucose concentration is too low.
-If the blood glucose concentration is too low, the pancreas produces the hormone glucagon
-Glucagon causes glycogen to be converted
into glucose and released into the blood
How does glucose enter the bloodstream?
Eating food containing carbohydrates puts glucose (a type of sugar) into the blood.
It’s absorbed from the gut (small intestine!),by active transport.
What processes remove glucose from the blood?
The normal metabolism of cells (respiration etc.)
Vigorous exercise removes much more glucose from the blood.
How can excess glucose be stored?
As glycogen in the liver and in the muscles.
How does insulin control blood glucose
(sugar) levels in the body?
-When blood glucose levels get too high, it’s detected by the pancreas.
-This causes the pancreas to release the hormone insulin into the blood stream.
-This hormone then travels around the body, and stimulates the liver and muscles to absorb glucose from the blood.
-In the liver, the glucose is converted to glycogen for storage
-This decreases blood glucose levels so they go back to normal
What does the term ‘high blood glucose concentration’ mean?
That there are lots of glucose molecules dissolved in the blood plasma.
What is the problem with a low blood glucose concentration?
There won’t be enough glucose for cells to respire.
How does glucagon work?
-When blood glucose levels fall too low, it’s detected by the pancreas.
-This causes the pancreas to release the hormone glucagon into the blood stream.
-Glucagon stimulates liver cells to break down their stored glycogen into glucose and release it into the blood.
-This extra glucose increases blood glucose levels back up to normal.
What is type 1 diabetes?
A disorder in which the pancreas fails to produce sufficient insulin.
It is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections
What is type 2 diabetes?
A disorder where the body cells no longer respond to insulin produced by the pancreas.
Obesity is a risk factor for Type 2 diabetes
What is the risk of having diabetes?
A person’s blood glucose level can rise to a level that can kill them.