Hormonal Coordination In Humans Flashcards
What is negative feedback?
Negative feedback is a homeostatic mechanism.
It is the regulation of internal conditions to maintain conditions for function in response to an interanl or external change
What are hormones?
Chemical messangers which ae secreted by glands into the bloodstream and transmitted to a target organ
What is the function of thyroxine
Stimulates basal metabollic rate and growth
What are the differences between the nervous system and the endocrine system?
The nervous system releases electrical impulses which are transmitted along neurones. Reflexes from the nervous system are rapid and automatic,they do not last long
The endocrine system releases hormones which are transmitted along the bloodstream
The hormones are secreted slowly but they are long-lasting
Which gland detects changes in thyroxine levels in the blood?
Hypothalamus
Which gland secretes TRH into the bloodstream?
Hypothalamus
Which gland detects TRH levels in the blood stream?
Pituitary gland
Which gland secretes TSH into the bloodstream?
Pituitary gland
Which gland detects TSH levels in the bloodstream?
Thyroid gland
What is the function of the thyroid gland?
Secretes thyroxine which stimulate basal metabolic rate and growth
Which gland secretes thyroxine into the bloodstream?
Thyroid gland
Explain how thyroxine works as a part of the negative feedback loop
The hypothalamus in the brain detects the low levels of thyroxine in the bloodstream. This stimulates the secretion of TRH from the hypothalamus into the bloodstream
The TRH is detected by the pituitary gland. This stimulates the secretion of TSH from the pituitary gland
The TSH is detected by the thyroid gland. This stimulates the secretion of the thyroxine hormone, increasing basal metabollic rate
When the thyroxine levels in the bloodstream rise too high, this is detected by the hypothalamus in the brain, and this inhibits the secretion of TRH from the hypothalamus into the bloodstream.
The pituitar gland detect the low levels of TRH, this inhibits the secretion of TSH from the pituitary gland into the bloodstream
Then the thyroid gland detects the low levels of TSH, this inhibits the secretion of thyroxine into the bloodstream.
This fluctuation of thyroxine secretion about the normal is the negative feedback loop
What happens when there is a high level of the thyroxine hormone in the bloodstream
Negative feedback:
The hypothalamus in the brain detects the high levels of thyroxine in the bloodstream, this inhibits TRH secretion form the hypothalamus into the bloodstream
The reduced levelsof TRH are detected by the pituitary glands. This then inhibits TSH secretion from the pituitary gland into the bloodstream
The reduced levels of TSH are detected by the thyroid gland, this stimulates the thyroid to secrete less thyroxine into the blood stream, reducing basal metabollic rate
Which gland detects levels of thyroxine in the blood stream?
Hypothalamus
Which gland detects levels of TRH in the bloodstream?
Pituitary gland
Which gland detects levels of TSH in the blood stream?
Thyroid gland
Which gland secretes the adrenaline hormone?
Adrenal gland
Which three organs does adrenaline affect?
- Heart
- Liver
- Blood vessels
What does the adrenaline hormone do to the heart to prepare the body for the ‘‘fight or flight’ response?
Adrenaline causes the heart muscle to contract and relax rapidly.
This increases blood flow around the body.
This increases oxygen and glucose supply to muscle cells.
This increases respiration which releases energy for the ‘fight or flight’ response
What does the adrenaline hormone do to the liver to prepare the body for the ‘fight or flight’ response?
Adrenaline breaks down glycogen which is stored in the liver and converts it into glucose.
This increases the supply of glucose in cells whcih reacts with oxygen, thus increasing respiration in muscle cells
This releases energy for the ‘fight or flight’ response
What does the adrenaline hormone do to the blood vessels to prepare the body for the ‘fight or flight’ response?
Adrenaline causes the blood vessels which supply blood to the non-vital organs to constrict and become narrower toredirect the flow of blood to the muscle cells.
This increases the flow of blood to the muscle cells.
This increases the supply of oxygen and glucose in the muscle cells, increasing respiration.
This releases energy for the ‘fight or flight’ response
Why is it that adrenaline is not part of the negative feedback cycle?
Levels of adrenaline do not need to be maintained
Adrenaline is only needed in certain situations
Name two non-vital organs
Small Intestine
Large Intestine
Why is it important that adrenaline is not part of the negative feedback cycle?
It reduces the body’s energy consumption once the danger/stress is over and everything is normal
What happens to pupils when adrenaline is secreted from adrenal glands?
They dilate
Why do pupils dilate as an effect of adrenaline for ‘fight or flight?
To allow more light in, for improved vision
What causes blood glucose levels to increase?
Eating starchy/sugary foods
What causes blood glucose levels to decrease?
Not eating
Excercise
Explain how insulin controls blood glucose levels in the body
Blood glucose levels increase after eating strach/sugary foods
This triggers the pancreas to secrete insulin into the bloodstream
Insulin is transmitted along the bloodstream to the liver and muscle cells
This causes the liver and muscle cells to become more permeable to glucose. The liver and muscle cells then convert glucose into glycogen, and the glycogen is stored in the liver
This causes the blood glucose levels to reduce as the glucose is beign stored as glycogen in the liver
Explain how insulin and glucagon interact in the negative feedback cylce to control blood glucose levels
Blood glucose levels rise due to eating starchy/sugary foods
This triggers the pancreas to secrete insulin into the blood stream
The insulin is transmitted along the blood stream to the liver and muscle cells. The liver and muscle cells become more permeable to glucose, then the cells convert the glucose into glycogen, this reduces blood glucose levels as the glucose is being stored in the liver as glycogen.
When the blood glucose levels reduce too low due to excercise or not eating this triggers the pancreas to secrete glucagon into the bloodstream
The glucagon travels along the bloodstream to the liver. This causes the liver to convert tje glycogen into glucose. This increases blood glucose levels as the glucose has been released into the bloodstream
Explain what happens when blood glucose levels in the body are too low
Blood glucose levels fall too low due to excercise or not eating
This triggers the pancreas to secrete glucagon into the bloodstream
The glucagon is transmitted along the bloodstream to the liver.
This causes the liver to convert the glycogen store into glucose. This increases blood glucose levels as the glucose is released into the bloodstream
What are the two types of diabetes?
Type 1 diabetes
Type 2 diabetes
What is type 1 diabetes
A disorder when the pancreas no longer produces a sufficient amount of insulin.
So when blood glucose levels rise after eating a starchy/sugary meal, the pancreas is unable to produce sufficient insulin, so people with type 1 diabetes often have uncontrolled high blood glucose levels
Do people with type 1 diabetes have high or low blood glucose levels?
Uncontrolled high blood glucose levels because the pancreas is unable to produce sufficient insulin
How is type 1 diabetes treated?
People with type 1 diabetes will monitor their blood glucose levels and inject themselves with insulin when their blood glucose concentration is too high, this will cause the blood glucose levels to reduce
What is type 2 diabetes?
Type 2 diabetes is when cells in the body no longer respond to the insulin that is secreted from the pancreas.
This results in high blood glucose levels
What is a major risk of type 2 diabetes?
Obesity
How is type 2 diabetes treated?
People with type 2 diabetes are treated with a diet containing low levels of carbohydrates. This is in efforts too stop blood glucose levels from rising too high
People with type 2 diabetes are also encouraged to excercise
