B12 - Homeostasis In Action (Y11 - Autumn 1) Flashcards
(35 cards)
🟢 How Is Body Temperature Kept In Check?
Body temperature is monitored and controlled by the thermoregulatory centre in the brain. The thermoregulatory centre contains receptors sensitive to the temperature of the blood. The skin contains temperature receptors and sends nervous impulses to the thermoregulatory centre.
🟢 How Does Your Body React When Your Body Temperature Is Too High
If the body temperature is too high, blood vessels dilate (vasodilation) and sweat is produced from the sweat glands. Both these mechanisms cause a transfer of energy from the skin to the environment.
🟢 How Does Your Body React When Your Body Temperature Is Too Low
If the body temperature is too low, blood vessels constrict (vasoconstriction), sweating stops and skeletal muscles contract (shiver).
🟢 How Does The Body Cool Itself Down (How Does The Body React, What Does It Do)
When your core body temperature begins to rise, impulses are sent from the thermoregulatory centre to the body so more energy is transferred to the surroundings to cool you down:
- The blood vessels that supply your surface skin capillaries dilate (open wider). This is called vasodilation and it lets more blood flow through the capillaries. Your skin flushes, so you transfer more energy by radiation from your skin to the surroundings, cooling you down and warming the air around you
- You produce more sweat from the sweat glands in ykur skin. This extra sweat cools your body down as water evaporates from yoir skin, transferring energy to the environment. In humid wearher when the water in sweat does not evaporate it is much harder to keep cool.
As you lose more water through sweating when it is hot or you are exercising hard, it is inportant to take in more water and mineral ions through your drink and food to balance this loss.
🟢 How does the Body Warm Itself Up
If your core body temperature starts to fall, impulses are sent from your thermoregulatory centre to the body to prevent you cooling down, reducing energy transfer to the environment.
- The blood vessels that supply your skin capillaries constrict (close up) to reduce the flow of blood through the capillaries. This vasoconstriction reduces the energy transferred by radiation through the surface of the skin.
- Sweat production is reduced or stopped. Less water from sweat evaporates, so less energy is transferred to the environment.
- Your skeletal muscles contract and relax rapidly, causing you to shiver. These muscle contractions need lots of respiration, an exothermic process. The energy transferred from these exothermic reactions raises your body temperature until the shivering stops.
🟢 What is the 1st thing in the body that anticipates getting hotter or colder? (+What is the last thing that takes in the feedback)
1st Line of Defence: Peripheral Thermoreceptors detect when it’s cold so the body starts to do things to warm up/cool down before your body temperature has gone too high/too low.
The Hypothalomus is where the feedback for how the body has helped to warm up/cool down the body
🟢 What Are The Two Main Poisonous Waste Products
There are two main poisonous waste products - carbon dioxide and urea. They cause major problems for your body if their levels are allowed to build up.
🟢 Why And How Is Carbon Dioxide Removed From The Body (+ How Is It Produced)?
The carbon dioxide produced by the body cells during respiration must be removed because dissolved carbon dioxide produces an acidic solution. This would affect the working of all the enzymes in your cells. The carbon dioxide diffuses out if the cells into your blood down a concentration gracient. It diffuses from the blood into the air in the alveli of your lungs. The air containing the excreted carbon dioxide is removed from your body when you exhale (however exhaling means you lose water when the moist air from your lungs breathed out).
🟢 What Is Urea Made Up Of?
Urea is the nitrogenous waste produced by the breakdown of excess amino acids in your liver.
🟢 Why And How Is Urea Removed From The Body
The urea passes from the liver cells into your blood. Urea is poisonous and if levels build up in your body, this will cause extensive damage to the cells. Fortunately, it is filtered out of your blood by your kidneys and is then passed out of the body in the urine produced by the kidneys, along with any excess water and salt.
🟢 How Are Proteins Digested And The Waste Removed? (What Happens To Excess Amino Acids
The digestion of proteins from the diet results in excess amino acids which need to be excreted safely. In the liver these amino acids are deaminated to form ammonia. Ammonia is toxic and so it is immediately converted to urea for safe excretion. (The rest of the amnio acid molecule can then be used in respiration or to make other molecules.)
Amino Acids (deaminated) —-> (deaminated) Ammonia —-> Urea —-> Excretion
🟢 Why Is Water and Mineral Ion Balance Maintained In The Body?
The removal of urea from the body is part of the system you use to balance the concentrations of water and mineral ions in your body fluids. If the cells of your body lose or gain too much water by osmosis to the fluids surrounding them, they can’t function properly. This means that water, mineral ions, amd urea are let out if the hody to maintain the balance.
🟢 What Ways Are Water, Mineral Ions, And Urea Lost From The Body?
- Water leaves the body via the lungs during exhalation.
- Water, ions and urea are lost from the skin in sweat.
- There is no control over water, ion or urea loss by the lungs or skin.
- Excess water, ions and urea are removed via the kidneys in the urine.
- If body cells lose or gain too much water by osmosis they do not function efficiently.
🟢 What Ways Give No Control To The Amount Substances Lost To The Environment When Mainatining Water And Nitrogen Balance?
- Water leaves the lungs every time you exhale
- Water, mineral ions, and urea are lost through the skin in sweat
🟢 What Ways Give Control To The Amount Substance Lost To The Environment When Mainatining Water And Nitrogen Balance?
Urea, excess water, and excess mineral ions are removed from the body via the kidneys, then excreted in the urine. This process is very tightly regulated to:
- Maintain the water and mineral ion content of the blood within narrow limits, and
- Remove urea (the poisonous nitrigenous waste)
🟢 What Is Deamination?
Deamination is the removal of an amino group from an amino acid or other compound..
🟢 The Difference Between Excretion and Egestion
Excretion is the process where an organism excretes the byproduct of a metabolic process using the different cellular and organ functions. Egestion, on the other hand, is the term associated with the excretion or elimination of undigested food from the digestive system of an animal.
🟢 Function Of The Kidney (What Does It Do)
Your kidneys remove toxic urea from the body in your urine, along with any excess water and mineral ions not need by the body. Urine is produced comstantly by your kidneys and stored temporarily in your bladder. The exact quantities depend on what you have taken in and given out.
🟢 What Do Your Kidneys Do When You’re Short On Water (+What Effect Does This Have On The Urine)
If you are short of water, your kidneys conserve it. You produce very little, very concentrated urine and water is saved for use in your body. If you drink too much water, then your kidneys produce lots of dilute urine to get rid of the excess.
The amount of water resbsorbed into the blood is controlled by a very sensitive feedback mechanism that makes sure the water balance of your body fluids and cells is always within a narrow range.
🟢 How Do The Kidneys Produce Urine? (Filtration and Selective Reabsorption)
The kidneys produce urine by filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water.
🟢 How Is Water Level In The Body Controlled
The water level in the body is controlled by the hormone ADH which acts on the kidney tubules.
🟢 What Happens To Glucose, Water, And Mineral Ions After The Blood Has Been Filtered?
All of the glucose is reabsorbed back into the blood by diffusion and active transport. However the amount of water and dissolved mineral ions that are reabsorbed varies. It depends on what is needed by your body. This is known as selective reabsorbtion.
The amount of water reabsorbed into the blood is controlled by a very sensitive feedback mechanism that makes sure the water balance of your body fluids and cells is always kept within a narrow range.
🟢 What Does ADH Do When Blood Plasma Becomes Too Concentrated, Where Is It Secreted, And How Is It Controlled?
The water level in the body is controlled by the hormone ADH which acts on the kidney tubules. ADH is released by the pituitary gland when the blood is too concentrated and it causes more water to be reabsorbed back into the blood from the kidney tubules. This is controlled by negative feedback.
🟢 What Does ADH Do When Blood Plasma Becomes Too Dilute
If the solute concentration becomes too dilute, less ADH is released into the blood. Less water is reabsorbed in the kidney tubules, so you produce a large volume of dilute urine and the blood solute concentration returns back to normal.
