2.5 Endocrine System Flashcards
What is the endocrine system?
The endocrine system is made up of glands which secrete chemicals called hormones directly into the bloodstream
How are hormones carried?
Where are hormones carried to?
Hormones are carried by the blood to a target organ, which produces an effect
How does the target organs detect hormones?
Target organs have receptors on the cell membranes that pick up hormone molecules, triggering a response
Why do hormonal responses act slower than nervous responses?
Hormonal responses are slower than nervous responses because they travel through the bloodstream, so they take time to reach the target organ
Why do hormonal responses last longer than nervous responses?
Hormones remain in the bloodstream for some time after release
Define and explain the role of the pituitary gland
- The pituitary gland in the brain is the ‘master gland’, which secretes hormones into the blood in response to body conditions
- The hormones act on other glands to stimulate other hormones to be released to bring about effects
Why is the pituitary gland known as the “master gland”
Because it coordinates and controls other endocrine glands through hormones
How is the blood glucose concentration is monitored and controlled?
The blood glucose concentration is monitored and controlled by the pancreas
When does blood glucose concentration typically rise?
Blood glucose concentration typically rises after you have eaten a meal
What happens when the blood glucose concentration is too high?
The pancreas produces insulin
What is insulin?
Insulin is a hormone that allows glucose to move from the blood into the cells where it is used
Explain how glycogen is stored
Excess glucose is converted to glycogen for storage in liver and muscle cells
What happens when the blood glucose concentration is too low?
When the blood glucose concentration is too low, the pancreas produces glucagon
What is glucagon?
Glucagon is a hormone that causes the liver to break down glycogen and convert it back into glucose
What is type 1 diabetes?
Type 1 diabetes is a disorder in which the pancreas fails to produce enough or any insulin
What are the effects of type 1 diabetes?
- The blood glucose levels become very high after you eat
- The kidneys excrete glucose in urine
- Lack of energy and tiredness
How is type 1 diabetes usually treated?
Type 1 diabetes is usually treated with insulin injections
What is type 2 diabetes?
Type 2 diabetes is when the body cells no longer respond to insulin
What is the effect of type 2 diabetes?
Blood glucose levels are high all the time
How is Type 2 diabetes commonly treated?
Type 2 diabetes is commonly treated through a carbohydrate controlled diet and an exercise regime
Why is obesity a risk factor for type 2 diabetes?
There is excess blood glucose from the diet, so the body cells become resistant to insulin
What happens if body cells lose or gain too much water by osmosis?
If body cells lose or gain too much water by osmosis they do not function efficiently
What leaves the body via the lungs during exhalation
Water leaves the body via the lungs during exhalation
What happens if there is too much water in the blood?
Too much water in the blood results in cells swelling as water moves into them, which can lead to cell bursting
What happens if there is too little water in the blood?
Too little water in the blood results in cells losing water by osmosis, causing dehydration
Give 3 ways water, ions and urea are lost?
Water, ions and urea can be lost from the:
- Skin in sweat
- Lungs
- Kidneys
Which two organs have no control over water, ion or urea loss?
- Skin
- Lungs
Which organ has control over water, ion or urea loss?
The kidney has control over water, ion and urea loss
How is excess water, ions and urea in the blood removed?
Excess water, ions and urea are removed via the kidneys in the urine
What is deamination?
Deamination is the process of breaking down excess amino acid molecules to form ammonia
When does deamination occur?
Deamination occurs when the blood contains excess amino acids through diet
What happens to ammonia in the body?
Ammonia is toxic and so it is immediately converted to urea for safe excretion
What is the function of the kidneys?
The function of the kidneys is to filter the blood and control and maintain the water content of the body and the concentrations of other substances by selective reabsorption
How do the kidneys maintain a balance of water and other substances?
Give 2 examples
By adjusting the amounts lost in the urine
* When you are short of water the kidneys conserve it
* If you drink too much water, then the kidneys will produce lots of dilute urine to conserve it
Describe how the kidney works
- The kidney contains millions of tiny filters through which blood continuously flows through
- Glucose, ions, urea and water are filtered out of the blood and into the kidney
- Larger molecules such as blood cells and proteins are too big to pass out of the filter
- The kidney then selectively reabsorbs substances needed by the body back into the bloodstream via diffusion and active transport
- Anything not reabsorbed forms urine, which is then stored in the bladder until it is excreted
What is selectively reabsorbed back into the blood?
All of the glucose, some water and some ions depending on if they are needed to maintain the osmotic conditions of bodily fluids
Name the 2 substances that may not always be selectively reabsorbed?
Water and Ions
Why is urea never selectively reabsorbed?
It is a waste product
What are kidney tubules?
Kidney tubules are tiny structures in the kidney which filtrate passes through on its way to the bladder
What happens along the kidney tubules?
Along the kidney tubules, selective reabsorption of water and mineral ions take place
What is ADH?
ADH is a hormone that helps to maintain the amount of water in the blood at an almost constant level
Which gland secretes ADH?
The pituitary gland secretes ADH and controls how much ADH is released
How does ADH affect the kidney tubules?
ADH increases the permeability of kidney tubules to water, which leads to water being reabsorbed
How does the pituitary gland control how much ADH is released?
The receptor cells in the brain detect the concentration of solutes in the blood plasma
What happens if the blood is too concentrated?
- If the blood becomes too concentrated, the receptor cells in the brain will detect the low concentration of solutes in the blood plasma
- The pituitary gland then releases lots of ADH into the blood
- This causes the kidney tubules to reabsorb more water
- So then a small volume of very concentrated urine is produced
- The blood solute concentration returns back to normal
What happens if the solute concentration in the blood is too dilute?
- If the solute concentration becomes too dilute, the receptor cells in the brain will detect the high concentration of solutes in the blood plasma
- The pituitary gland then releases less ADH into the blood
- This causes the kidney tubules to reabsorb less water
- So then a large volume of dilute urine is produced
- The blood solute concentration returns back to normal
How are people who suffer from kidney failure usually treated?
People who suffer from kidney failure treated are usually treated by:
- Kidney Transplant
- Kidney Dialysis
What is a kidney transplant?
A kidney transplant is when a failed kidney is replaced with a healthy one
What is kidney dialysis?
Kidney dialysis is an aritifical machine that carries out the function of the kidney
Explain how kidney dialysis works?
- In a dialysis machine, a person’s blood leaves their body and flows through tubes made of partially permeable membranes
- On the other side of these membranes is the dialysis fluid, containing the same concentration of useful substances (glucose and ions) as the blood of a healthy person
- Urea and excess ions diffuse out of the blood into the dialysing solution
Explain why the dialysing fluid contains contains the same concentration of glucose and ions as the blood of a healthy person?
To prevent glucose from diffusing out of the blood
What is the advantage of using a dialysis machine?
It is an effective life-saving treatment if kidney fails
What are the disadvantages of using a dialysis machine?
- Heavily restricted and controlled diet
- Have to regularly visit the hospital several times a week or perform it at home
- Much more expensive in the long term
*
What is the advantage of using a kidney transplant?
- They can resume a normal healthy life
- No diet restrictions
What are the disadvantages of using a kidney transplant?
- There is a danger of rejection, in which you have to take life-long immunosuppressant drugs
- You have to wait for a suitable donor kidney
How can we reduce the risk of rejection from a kidney transplant?
A patient can take immunosupressant drugs that supress their immune systems
What is the disadvantage of taking immunosupressant drugs?
It prevents the immune system from dealing with infectious diseases effectively
