Topic 7 - Animal Coordination, Control And Homeostasis Flashcards
What are hormones?
Chemical messengers that are sent in the blood
What does the pituitary gland do?
Produces many hormones which act on other glands that then release hormones e.g. progesterone
What does the thyroid gland produce?
Thyroxine, which regulates metabolism, heart rate and temperature
What hormone does the ovaries produce?
Oestrogen
What hormone does the testes produce?
Testosterone - controls puberty and sperm production in men
What hormone does the pancreas produce?
Insulin, which is used to regulate blood glucose (sugar) levels
What hormone does the adrenal glands produce?
Adrenaline, which is used in the ‘flight or fight’ immune response
What is the endocrine system?
Endocrine glands. These are various different glands that hormones are produced in
What are neurones and what do they do?
Neurones have a very fast response to stimuli, last for a short time and act on a precise area
What are hormones and what do they do?
Hormones have a slower response, but act for a longer period of time than a neurone response does. They do not have a specific target in the body, and act on a more generalised way
If the response if quick, what is the response most likely to be?
Nervous response with neurones
If the response lasts for a long time, what is it most likely to be?
Hormonal - e.g. ‘fight or flight’ from adrenaline, adrenal glands
What does adrenaline prepare you for?
The ‘fight or flight’ immune response
Where are the adrenal glands located?
Above the kidneys
Hormone release can be affected by what kind of feedback?
Negative feedback
What are the four stages of the menstrual cycle?
Stage 1: when menstruation starts
Stage 2: the uterus lining is repaired
Stage 3: an egg develops and is released
Stage 4: the lining is then maintained
What are the four hormones that control the menstrual cycle?
FSH (follicle stimulating hormone)
Oestrogen
LH (luteinising hormone)
Progesterone
What does FSH do?
Released by the pituitary gland
Causes a follicle (egg and surrounding cells) to mature in an ovary
Simulates oestrogen production
What does oestrogen do?
Released by the ovaries
Causes the lining of the uterus to thicken and grow
A high level stimulates an LH surge
What does LH do?
Released by the pituitary gland
The LH surge stimulates ovulation at day 14 - the follicle ruptures and the egg is released
Stimulates the remains of the follicle to develop into a structure called a corpus luteum - which secretes progesterone
What does progesterone do?
Released by the corpus luteum after ovulation
Maintains the lining of the uterus
Inhibits the release of FSH and LH
When the levels of progesterone falls, and there’s a low oestrogen level, the uterus lining breaks down
A low progesterone levels allows FSH to increase, and then the whole cycle starts again
What is ART?
Assisted Reproductive Technology
What is clomifene therapy?
Women who do not ovulate / do not ovulate regularly can take a drug called clomifene
This causes more FSH and LH to be released by the body, which stimulate egg maturation and ovulation.
This gives women a better chance of conceiving naturally
What is IVF, and what does it stand for?
IVF = “In Vitro Fertilisation”
IVF collects eggs from a woman’s ovaries and fertilising them outside the uterus using the man’s sperm
They are grown into embryos, and implanted back into the uterus in hope that they will implant and grow further
FSH and LH are given before egg collection so that more than one egg can be collected
How can hormones be used as contraceptives?
For example, oestrogen can be used to prevent the release of an egg. If oestrogen is taken every day to keep the levels permanently high, then it inhibits the production of FSH and after a while, egg production stop and stay stopped
Progesterone can also be used. E.g. stimulating the thickening of cervical mucus, which stops sperm from entering the uterus and fertilising an egg
Which contraceptive methods are usually more effective:
Physical or hormonal?
When used correctly, hormonal methods are generally more effective as contraception never needs to be considered
However, hormonal methods can have some side effects, such as headaches, acne and mood swings
Hormonal methods do not protect agains STI’s - condoms are the only form of contraception that do this
Define homeostasis
The maintenance of a constant internal environment, such as temperature, blood glucose and water content
Give three examples of how homeostasis is carried out
Osmoregulation (water content)
Thermoregulation (temperature)
Blood glucose (blood sugars)
What controls blood glucose concentration?
Insulin and glucagon
If the blood glucose is too high, what is added into the blood stream?
Insulin
If the blood glucose is too low, what is added to the blood stream?
Glucagon
What is type 1 diabetes caused by?
A lack of insulin
The pancreas produces little to no insulin. This causes blood glucose levels to rise which can kill them
Can type 1 diabetes be cured? How can it be maintained?
Type 1 diabetes cannot be cured
It can be maintained by injecting insulin into the blood, and this is often done at mealtimes to make sure that the glucose is removed from the body quickly once the food has been digested
What is type 2 diabetes caused by?
A resistance to insulin
The pancreas does not produce enough insulin, or when someone becomes resistant to insulin. In both cases, it causes their blood glucose levels to rise
What kind of correlation is there between obesity and type 2 diabetes?
A positive correlation - this means that obese people have an increased risk of developing type 2 diabetes
How can you calculate BMI?
BMI = weight (kg / (height, m) ^2
^2 = squared
What BMI does someone have to have in order to be classified as obese?
30 or over
Is BMI accurate?
BMI is not always accurate, as someone with a high muscle mass could be seen as overweight, even through they have little body fat.
What is a more accurate way of determining obesity?
Waist : hip ratio
How do you work out the wait : hip ratio?
waist circumference (cm) / hip circumference (cm)
Using the waist : hip ratio, what values for men and women are considered to put them at a risk of type 2 diabetes?
- 0 for men
0. 85 for women
How can diabetes be controlled?
By eating a healthy diet, regularly exercising, losing weight
Some people may also require medication and insulin injections
What controls body temperature?
The hypothalamus
What happens when you are too hot?
The erector muscles cause hairs lie flat on the skin
Sweat is produced which evaporates and takes away heat energy, cooling you down
Blood vessels close to the surface dilate (vasodilation). It allows more blood to flow near the surface so it can transfer more energy into the surroundings, which cools you down
What happens when you are too cold?
Erector muscles causes hairs to stand up which traps an insulating layer of air around the body
Very little sweat is produced
Blood vessels on the surface of the skin constrict (vasoconstriction), which means that less blood flows towards the surface, and less energy is therefore being transferred to the surroundings
Shivering increases the rate of respiration, which transfers more energy to the body to keep it warm
What happens to cells if water content is too high?
The cells will swell and burst - osmosis causes water to go from a high to low concentration
What happens to cells if water content is too low?
They will shrink
Name the parts of the urinary system
Renal vein Renal artery Kidneys Ureter Bladder Urethra
What are the three main roles of the kidneys
1) Removal of urea - a toxic substance produced in the breakdown of amino acids in the liver
2) Adjustment of ion levels in the blood
3) Adjustment of water content in the blood
What filters substances in the kidneys?
Nephrons
What does ADH stand for and what does it do?
ADH = anti-diuretic hormone
It controls how much water is reabsorbed back into the blood. It makes the collecting ducts of nephrons more permeable so that more water can be reabsorbed
If water content it to high ADH would not be released so a more dilute urine is produced
If water content is too low, more ADH would be produced so that the body retains as much water as possible, resulting in a darker, more concentrated urine
What happens in each nephron?
The liquid part of the blood containing things like urea, water, ions and glucose enter the Bowman’s capsule after being forced out the the glomerulus
Bigger molecules and blood cells cannot pass through the membranes and are not forced out
All of the useful substances such as glucose and some water is selectively reabsorbed into the blood against the concentration gradient
What system controls water content?
A negative feedback system
What does dialysis do?
It filters the blood mechanically outside of the body
How does dialysis work?
Has to be done regularly to keep dissolved substances at the right concentrations, and to remove waste
Dialysis fluid has the same concentration of salts and glucose as blood plasma, so they are not removed from the blood
The barrier is permeable to ions and waste substances, but not big molecules like proteins.
So, waste substances like urea are removed from the blood and enter the dialysis fluid
Apart from dialysis, what other way can kidney disease be cured?
Kidney transplants
What are advantages and disadvantages of kidney transplants?
Advantages are that it allows patients to live a life like they did before, and do not have to rely on a machine
However, the antigens on the surface of the donor kidney will be different and therefore the body may detect it as a foreign invader and attack it: rejection
How can rejection of organs be reduced?
Right now, transplants are the only cure for kidney disease
To prevent rejection, precautions may be taken, such as:
- A donor with a tissue type that closely matches the patient will be chosen
- The patient is treated with drugs that suppress the immune system, so their immune system will not attack the transplanted kidney
However, if on drugs, the patient are at a higher risk of diseases as their immune defence is weakened
