B12 Homeostasis in Action Flashcards
Where is your thermoregulatory system and how does it monitor temperature
Hypothalumus senses the temperature of the blood flowing through it
It also receives information via the sensory neurones from heat receptors in the skin
How does blood play an important part in thermoregulation
Blood carries heat from the core around the body
As blood flows throw capilleries close to the surface of the skin, heat is lost to the bodies surroundings
The arteriole ( which supply the capilleries in the skin ) have smooth muscle walls which means they can constrict or dilate to control the flow of blood into the capilleries
What happens in vasodilation
If core temperature of the body rises
Smooth muscle in the arteriole walls relaxes and the arteriole dilates
More blood flows through capillaries nervthe surface of the skin
This increases the rate of heat loss from the body
What happens in vasoconstriction
The core temperature of the body drops
Smooth muscles in the arteriole walls contract which constricts the arteriole
Less blood flows through the capilleries close to the skin as blood is redirected through the shunt vessel which are found in the layers of the skin
How do the pili erector muscles and goosebumps work
Each of our body hairs has a small muscle attached to the base
When this muscle contracts, the hair is pulled upright
When the rate of heat loss from the body increases, these muscles contract so that the hairs stand on end creating an insulating layer of still air. This decreases the rate of heat loss
How does sweating cool the body
Skin produces sweat if temperature rises
Water is sweat evaporates. In oder to do so, it must absorb heat from the body
This increases the rate of heat loss
How does shivering work in thermoregulation
Muscles require energy to contract. This energy is supplied by respiration
During respiration some energy is lost as heat energy
When we shiver, the muscles contract repeatedly so the rate of respiration in the muscles increases, and more heat is generated
What is the negative response for when the body temperature rises
Blood temperature rises
Change detected by hypothalamus
Vasodilation, sweating
Temperature falls again
What is the negative response loop for when the body temperature drops
Blood temperature falls
Change detected by hypothalamus
Vasoconstriction, goosebumps, shivering
Temperature rises
How are lungs involved with excretion
Remove carbon dioxide, a product of respiration
How is the liver involved with excretion
Converts excess protein ( amino acids ) into urea
How is the skin involved in excretion
Provides a surface area for small amounts of water and salt to move out of the body
How are the kidneys involved in excretion
Remove unwanted substances such as urea, excess water and salt
What are the steps for how excess amino acids are excreted in the urine
Excess amino acids cannot be used for fuel so they are broken down by the liver
Liver removes the amino group from the amino acids ( deamination ), forming toxic ammonia which is then immediately converted into urea
Once formed, urea is transported by circulatory system to kidneys
Kidneys filter blood, removing urea and excess water and salt which forms urine
Urine is stored in the bladder before being excreted
The remaining part of the amino acid molecule can be used in respiration or to make other molecules
Why does carbon dioxide have to be excreted and how
Dissolved CO2 produces carbonic acid. This affects the working of all enzymes in your cells
CO2 diffuses out of the blood down a concentration gradient to the alveoli and exhaled
You may lose water when moist air from the inside of your lungs is forced out of the body
Why does urea have to be excreted and how is it done
Urea is poisonous and if levels build up then it will cause damage to cells
Urea is filtered out of the blood by your kidneys and is passed out in the urine
Where does the water and mineral ions in your body come from and why does it have to be excreted
Water comes from respiration and food/ drink and mineral ions come from the diet
If the cells lose too much water by osmosis to the fluids surrounding them they can be crenated and if they gain too much water from from the surrounding fluids, they undergo lysis which means they do not function efficiently
What are the methods of water excretion that you can’t control
Water leaves lungs when exhaling
Mineral ions and urea are lost through the skin in sweat
What are the methods of water excretion that you can control
Urea, water and mineral ions are removed from the body via the kidneys and excreted in urine
What does water and mineral ions removal regulate
Maintains water and mineral ion content of blood Remove urea ( poisonous waste )
What do the kidneys do
Send the wastes to your bladder to be excreted
Removes wastes from our blood
Adjusts the amount of water and mineral ions in the blood
What is urine made from
Water
Urea (nitrogenous wastes )
Salts ( mineral ions )
How do the kidneys work
- Glucose, salts, urea and water all move out kf the blood into the kidney. Blood cells and large proteins are too big to pass through the filtering process
- Any useful substances like glucose, some ions and the right amount of water will be reabsorbed into the blood through selective reabsorbtion
- Anything not needed is removed in the urine
How is the concentration of urine controlled
Conc of urine is controlled by ADH Anti Diuretic Hormone
Brain monitors water content of blood and tells pituitary gland to release ADH into the blood depending on how much is needed
This is a negative feedback loop
What is the negative feedback loop for too high water concentration
Too much water not enough salts in the blood Pituitary gland releases less ADH Kidneys tubules reabsorb less water Blood restored to normal ( lots of urine produced, pale yellow )
What is the negative feedback loop for too low water concentration
Too many salts not enough water Pituitary gland releases more ADH kidney tubules reabsorb more water Blood restored to normal ( little urine produced, dark yellow)
What are 2 problems with the kidney
Kidney stones: high salt and minerals in your diet can lead to stones precipitating out, have to be passed in the urine which is painful
Renal damage/ failure: kidney no long able to filter the blood effectively
What are methods to fix a kidney
Dialysis
Transplantation
What is dialysis
Blood goes through a dialysis machine where urea and excess salt diffuse out of a partially permeable membrane
For this reason the dialysis fluid keeps moving so there is a constant urea flow of low concentration for the waste to move out
What are disadvantages of dialysis
Have to do it 3 - 4 times a week and for 4 hours each session
Disadvantages of kidney transplant
Risk of rejection
Risk of infection
