Homeostasis (glucose/hormones/temperature)

Question 1

What is homeostasis?

Answer 1

the maintenance of constants of an internal environment.

Question 2

In our bodies, what conditions does homeostasis maintain?

Answer 2

-body temperature
-water balance
-amount of waste products in our bodies
-blood sugar levels
-pH of our blood
+salt balance
+heart rate/pressure

Question 3

State the 4 relevant GCSE conditions our body maintains and its importance:

Answer 3

-body temperature - if the body is too warm, cells (such as enzymes) may denature, making them not complimentary to their substrates, disabling chemical reactions from occurring.
-water balance - if we drink too much water, the difference between our cell’s water concentrates may cause damage if they become too hyper/hypotensive.
-pH of blood - the pH affects cellular enzymes
-blood sugar - its concentration affects the amount of energy that is available for respiration.

Question 4

Define negative feedback:

Answer 4

A cyclical reaction, that responds to a stimuli to ensure that conditions remain close to their optimum levels.

Question 5

Why must our bodies remain near 37°C?

Answer 5

If the body is too hot, cells (enzymes) may permanently denature therefore not complimentary to their substrate, preventing chemical reactions from occurring.
if the body is too cold, cells may react at a slower rate.

Question 6

Explain the process of homeostasis when the body is too warm: (4)

Answer 6

1.When the body is too warm, the thermoregulatory system detects this stimulus through receptors on the skin / blood vessels.
2. Through nervous communication, the impulse is sent to the brain where a response is planned.
3.impulses are sent to effectors eg. the blood vessels to dilate and be brought to the surface of the skin to cool down quickly (vasodilatation)
4. This is the body’s response to cool the body down.

Question 7

List and explain methods our body uses to cool our core temperature:

Answer 7

vasodilation- our blood vessels (arterioles) expand their lumen to allow more blood to flow in the capillaries nearer to the skin’s surface where it is cooler. This helps cool down the blood which decreases the core temperature as it increases heat transfer to the surroundings.

sweating- our sweat glands produce sweat on the skin’s surface to evaporate and to take the heat away from the body. this cools down the core temperature as heat escapes the body.

relaxation of the hair erector muscles- when the muscles relax, the hairs lie flat on the skin. this means less air is trapped close to the skin’s surface resulting in less insulation, making heat transfer easy which reduces the core temperature as more radiation can be given off.

Question 8

List and explain methods our body uses to heat up our core temperature:

Answer 8

vasoconstriction- the blood vessels (arterioles) narrow their lumen to restrict the amount of blood exposed near the skin’s surface causing the blood to retain its heat. this conserves the heat energy with our bodies, preventing heat transfer.

shivering- our bodies involuntarily contract and relax our skeletal muscles, since our skeletal muscles respire when they contract, heat is made which helps maintain heat in our bodies, warming our core up.

contracting our of hair erector muscles- when the muscles contract, it causes the hair to stand up and trap air close to the body, acting like an insulating blanket that prevents heat transfer, this reduces the amount of radiation we give off, reserving the het inside ourselves.

Question 9

What system is responsible for releasing hormones?

Answer 9

endocrine system

Question 10

What is a hormone? (3)

Answer 10

a chemical signal/messenger that coordinates processes in the body, produced by endocrine glands into the blood stream that affect its target organs

Question 11

What are target organs?

Answer 11

certain organs that detect hormones in the blood.

Question 12

Name 6 endocrine glands:

Answer 12

-pituitary glands
-thyroid
-pancreas
-adrenal glands
-ovaries
-testes

Question 13

What hormone does the pituitary glands produce and what are their effects?

Answer 13

they produce the growth hormones, which are responsible for the body’s growth development by effecting the rate of cell division, including sex development. too much results in giantism and too little results in dwarfism.

Question 14

What hormone does the thyroid produce and what are their effects?

Answer 14

they produce thyroxine which is responsible for the rate of cellular metabolism, which can affect a person’s mental and physical well-being. too much can lead to hyper activeness and weight loss and too little results in fatigue, depression and weight gain.

Question 15

What hormone does the adrenal gland produce and what are their effects?

Answer 15

this produces adrenaline which prepares the body for a fight or flight response by increasing heart rate, dilating the bronchioles in the lungs, sweating, increases levels of glucose in the blood. Too much of this can result in stress, long term it can lead to high blood pressure and cardiovascular issues.

Question 16

What hormone does the pancreas produce and what are their effects?

Answer 16

they produce insulin which balances the levels of glucose in the blood by making glycogen. too little results in type 1 diabetes.

Question 17

What hormone do the ovaries produce and what are their effects?

Answer 17

they produce oestrogen which effects breast growth, body shape and the menstrual cycle. abnormal levels of this can lead to infertility and irregular periods.

Question 18

What hormone do the testes produce and what are their effects?

Answer 18

they produce testosterone which effects sperm production and the size of sex organs. an abnormal amount can lead to infertility.

Question 19

Explain the negative feedback loop of homeostasis to maintain glucose levels in the blood, including circumstances that may result in changes of these levels:

Answer 19

1. when we wake up, since our body hasn’t exerted itself or eaten in a while, our glucose levels are lower than normal because we didn’t need it for respiration to make energy.
2. our pancreas detects this low level of glucose and it releases the hormone glucagon into our blood stream.
3. this is received by the cells in our muscle/ liver where they convert our glycogen stores back into glucose into our bloodstream so we can use it in our cells for respiration to produce energy to sustain us, therefore increasing our glucose levels.
4. this may cause our glucose levels to go beyond our normal, and in addition to having a meal (which provided more glucose in the form of starches), our glucose levels rise.
5. this is detected by the pancreas where it releases insulin hormones into the blood.
6. these hormones target specific cells in our muscles and liver, causing them to absorb the extra glucose in our blood and convert it into glycogen stores to be used later, resulting in the levels decreasing in our blood.

Question 20

What is the endocrine gland that’s responsible for regulating glucose levels?

Answer 20

pancreas

Question 21

State and describe the two hormones produced in glucose regulation:

Answer 21

-insulin- makes target cells absorb glucose into glycogen, decreasing the levels
-glucagon- makes target cells convert glycogen back into glucose which increases the levels

Question 22

Why is it important for our glucose levels to be normal?

Answer 22

-if they are too high… then this will interfere with the osmosis in our cells, forcing our cells to become hypotensive and in risk of bursting, this damages our cells.

-if they are too low… our cells will become shrivelled due to osmosis, damaging them long term.

Question 23

What are the three types of diabetes?

Answer 23

-Juvenile diabetes (Type 1)
-Adult on-set diabetes (Type 2)
-Gestational diabetes (pregnancy)

Question 24

Whats the difference between type 1 and Type 2 diabetes?

Answer 24

Type 1 diabetes is more common in younger people and is when the pancreas doesn’t make insulin or not enough to regulate the blood’s glucose levels.

Whereas in Type 2, it is more common in older people and is when the target cells don’t respond to the chemical insulin.

Gestational diabetes occurs in pregnancy when the woman’s body can’t produce enough insulin to cope with the effects of pregnancy but goes away when she delivers whoever the diabetes can effect her child.

Question 25

Describe the difference between the levels of glucose in a healthy person’s blood and a person’s with diabetes after having a meal:

Answer 25

When a healthy person has a meal, their glucose levels rise but eventually rest back down after a while. People with diabetes will have a heightened blood glucose level which will be matinee for a longer time, or will decrease less rapidly.

Question 26

State and describe the test we’d use to see if a person may have diabetes:

Answer 26

Glucose tolerance test:

• the patient will not eat for 8 hrs prior to have a base line level of glucose in their blood.
• they’ll consume a drink which we know the exact amount of glucose it contains.
• we monitor their blood glucose levels over 2 or more hours.
• plot it on a graph and analyse data.

Question 27

How may a person with diabetes be treated?

Answer 27

• more exercise
• different / healthier diet
• injections of insulin
• medication to help target cells respond to insulin

Question 28

Explain the negative feedback loop that regulates levels of thyroxine in the body’s blood:

Answer 28

When levels of thyroxine are too low in the blood, this is detected by the pituitary in the gland which then secretes the thyroxine stimulating hormone (TSH). this travels via the blood to be detected by the target organ in the neck - the thyroid- which then secretes thyroxine in the blood, increasing its thyroxine content. The blood carries the hormones in the blood which the pituitary glands detect, which stops the release of TSH. thyroxine is responsible for adapting our basal metabolic rate, which controls how much glucose or oxygen we need for our cells to carry our chemical reactions.

Question 29

How do we use hormones for plants? (4)

Answer 29

Using gibberellins to increase fruit sizes- when we grow seedless fruits, these fruits are often very small as infertile plants don’t contain as much gibberellins (a type of auxin) which inhibits growth. By spraying gibberellins onto the fruits, we can replace the lack and allow the plant to grow.

using ethene gas to prevent bananas from ripening- plants such as bananas often arrive over ripe and damaged due to the long distances they are exported over. ethene gas prevents plants from ripening quickly. by harvesting bananas when they are underripe and transporting them under cool conditions whilst supplying ethene gas, we can prevent them from ripening during transit and when they are nearer to markets we can warm them up and reduce the ethene gas so that they can ripen perfectly by the time they reach stores.

Using auxins in horticulture- when we achieve a plant that has the desired characteristics for optimal economic benefit, cloning the plant can be expensive and unnecessary as we can take cuttings from the plant ad dip it is rooting powder containing auxins to encourage the cuttings to develop roots to grow into several identical crops, helping companies produce many from one plant.