3.3 Homeostasis Flashcards
What is homeostasis?
Maintenance of a constant internal environment
Why is homeostasis important? Which components?
Body temperature: enzymes
Blood sugar levels: respiration and blood pressure
Water: cell size
pH: enzymes
What waste products are removed from our body?
Carbon dioxide
Urea
How and why are the two waste products removed?
Carbon dioxide: breathed out via the lungs because it makes carbonic acid lowing the pH of our blood affecting enzymes
Urea: made in the liver from the breakdown of excess amino acids, removed by the kidneys in urine, temporarily stored in the bladder
Because it is toxic
What is negative feedback?
A deviation from the norm initiates corrective mechanisms to restore the norms
How is water obtained in the body?
When eating and drinking
How do we lose water?
Sweat
Breathing out
Urine
What can too much or too little water do to out cells?
Damage them causing them to burst or shrivel
What do kidneys do?
Filter the blood excreting substances you don’t want and keep substances the body needs
How is blood brought to the kidney?
Via the renal artery
What is a nephron?
Microscopic filtering units
What is the first stage of the kidney producing urine?
Filtering the blood:
The Glomerulus separates the larger molecules - red blood cells, white blood cells and carbon dioxide
From the smaller molecules - water, ions, urea, glucose and amino acids
The bowman’s capsule collects the filtrate of smaller molecules and they can pass through the renal tubial
What is the second stage of the kidney producing urine?
Reabsorbing all the sugar:
In the proximal convoluted tubal glucose and amino acids are reabsorbed by active transport as they ate against a concentration gradient
Lots of mitochondria and ribosomes- for energy and proteins (they carry certain molecules across a membrane)
What is the third stage of the kidney producing urine?
Reabsorbing dissolved ions needed:
In the loop of Henle some ions are reabsorbed by active transport
But other salts are left behind to balance what the body needs
What is the fourth stage of the kidney producing urine?
Reabsorbing as much water as the body needs:
In the distal convoluted tubal a diuretic hormone is released by the pituitary gland leading to increased reabsorption of water via osmosis
What is the fifth stage of the kidney producing urine?
Releasing urea, excess ions and water:
In the collecting duct the molecules left are water, salt and urea forming urine to be temporarily stored in the bladder leaving via the ureter
What can Kidney failure be treated with?
Kidney dialysis
Or
Kidney transplant
What does dialysis do?
Remove the blood from you body then clean out the urea before sending it back
What is an anticoagulant used for in dialysis? Example of drug?
Prevents blood clotting
Heparin
What is an air trap used for in dialysis?
Gets rid of air bubbles preventing air embolisms (blood vessels blockages due to air bubbles)
What is done to maximise amount of urea moved in the dialysis fluid?
The dialysis fluid flows in the opposite direction to the blood
How is urea removed in dialysis?
Urea moves out of the blood via diffusion as there is no urea in the dialysis fluid creating a concentration gradient
How do you not lose useful molecules in dialysis?
The fluid contains the same concentration of glucose and mineral ions as the blood so there is no no net movement of the substances needed by the body
How often is dialysis done?
Carried out regularly
Changes from person to person
What are some similarities between dialysis and a nephron?
Both remove urea
Red blood cell and white blood cells don’t leave the blood
What are some differences between dialysis and a nephron?
Glucose is removed and then reabsorbed by active transport from the blood in the nephron
What are the advantages of dialysis?
Prevents you feeling ill
Available to all kidney patients
No immunosuppressant drugs
What are the disadvantages of dialysis?
Time consuming Affects your daily life Expensive Go to hospital al lot Can't eat salt and protein in between
What does a kidney transplant do?
Enables a diseases kidney to be replaced with a healthy one from a donor (dead or living)
What are antigens?
Proteins on the surface of cells
Why can kidneys be rejected?
Antigens on someone else’s kidney will be different to the recipients antigens
White blood cells see the new kidney as a foreign object
They produce antibodies to attack the foreign antigens
How do we prevent rejection of a kidney?
They kidney must be a good tissue match
Immunosuppressant drugs must be taken to suppress your immune system
What are the advantages of a kidney transplant?
No longer need dialysis
Lead a more normal life
Overall it’s cheaper for the NHS
What are the disadvantages of a kidney transplant?
Immunosuppressant drugs have to be taken Vulnerable to common infections Waiting for an organ can be years Shortage of donors The kidney will only last 8-9 years on average Surgery carries risks
How is thermoregulation monitored in the body?
It’s detected by thermoreceptors of the thermoregulatory centre in the brain
It monitors the temperature of blood flow through the brain
What is the core temperature of must humans?
37 degrees
What responses does your body do if you are too hot?
Sweat: heat evaporates
Vasodilation: Capillaries dilate and increased blood means more heat lost at the surface
Hairs lie flat: heat isn’t insulated
Fanning yourself or finding shade
What responses does your body do if you are too cold?
Shivering: rapid muscle contractions of skeletal muscles increase respiration increasing heat energy to blood
Vasoconstriction: capillaries constrict limiting blood at the surface
Hairs on end: insulates heat
Goosebumps
Huddle: reduces surface area exposed
What is glucose monitored by?
The pancreas
What is happens if you have high levels of glucose concentration in your blood?
The hormone insulin is released
Allowing glucose to move from the blood into the cells
What other ways can glucose by removed from the blood stream?
Increased rate of respiration
Convert glucose to glycogen
Convert glucose into fat
Increase amount taken into the cells
Where is glucose converted into glycogen?
The liver
What is happens if you have low levels of glucose concentration in your blood?
The hormone glucagon is released
This caused glycogen to be converted back into glucose
What other ways can glucose be added to the blood stream?
Break down fats
What is Type 1 diabetes?
A disease where a persons blood glucose is too high because the pancreas doesn’t produce enough insulin
How do you control type 1 diabetes?
Careful attention to diet and exercise
Injections of insulin
What new methods are being tried to treat diabetes?
Pancreas transplants
Embryonic stem cells
Transplanting pancreas cells
