Topic 7 - Animal Coordination, Control, Homeostasis✅

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How is type 1 diabetes caused

When the pancreas does not produce enough insulin

How can type 1 diabetes be controlled

• Insulin injections at mealtimes

  • Results in glucose being taken up from the bloodstream

How is type 2 diabetes caused

When body cells no longer respond to insulin

What is the effect of type 2 diabetes on the body

• Cells stop responding to insulin

• Blood glucose levels are high

• Liver does not convert glucose to glycogen

How it type 2 diabetes controlled

• Treatments include reducing the number of simple carbohydrates in diet, losing weight and increasing exercise

• To control blood glucose levels

What is urea produced by + where

Urea is produced from the breakdown of excess amino acids in the liver

How does IVF work

• The mother is given FSH and LH to encourage the release and maturation of eggs

• These are extracted from the mother and fertilised in the lab using sperm

• The fertilised eggs develop into embryos and then one or two are inserted in the uterus

How does clomifene therapy work

• Clomifene is used to stimulate ovulation, so that eggs can be released.

• It blocks oestrogen’s negative feedback on LH, therefore more LH is released.

When is IVF used

• When the man has poor quality of sperm

• Or a woman has blocked oviducts

When is clomifene therapy used

If a women cannot ovulate / release eggs

How is blood glucose concentration regulated by glucagon

• Activity like exercise uses glucose for respiration, meaning there is less in the blood

• If glucose levels decrease, the pancreas produces glucagon

• Glucagon binds to liver cells causing glycogen to be broken down into glucose

• Glucose is released into the blood, increasing blood glucose concentration

What are the two communication systems in the human body

○ Endocrine system

○ Nervous system

What are the main glands in the endocrine system

○ Pituitary gland

○ Pancreas

○ Thyroid

○ Adrenal gland

○ Ovary

○ Testes

What does the pituitary gland produce

○ It produces TSH which targets the thyroid gland

○ Produces ADH targeting the kidney

○ And produces FSH and LH targeting the ovaries

What does the thyroid gland produce

Thyroxine that targets the thyroid

What does the pancreas produce

Insulin and glucose, targeting the liver

What do the adrenal glands produce

• Adrenalin

• Targeting the heart, blood vessels, and liver

What do the ovaries produce

Oestrogen and progesterone targeting the uterus

What do the testes produce

Testosterone, targeting the male reproductive organs

When is adrenaline produced by the adrenal glands

It is produced to prepare the body for fight or flight

What does adrenaline do

○ Increase heart rate

○ Increase blood pressure

○ Increase blood flow to muscles

○ Raise blood sugar levels

How does adrenaline increase heart rate

○ Adrenalin binds to heart receptors

○ Heart muscle cells contract more rapidly

How does adrenaline increase blood pressure

Heart muscle cells contract more strongly

How does adrenaline increase blood flow to muscles

Diameter of blood vessels that lead to muscles widen

How does adrenaline raise blood sugar levels

○ The liver changes glycogen to glucose

○ Glucose is released into the blood

Describe the stages of the menstrual cycle

• 0-5 days: The uterus lining breaks down and the woman has her period

• 5-14 days: The layer builds up again

• At 14 days, an egg is released from the ovary and moves to the uterus

• 14 - 28 days: If the egg is not fertilised after 28 days, the lining breaks down and the cycle continues.

  • If the egg is fertilised then the lining is maintained and no periods happen

What does FSH do in the menstrual cycle

• Produced in the pituitary gland

• Stimulates ovaries to produce oestrogen

• Causes maturation of egg in the ovary

What does oestrogen do in the menstrual cycle

• Produced in ovaries

• Secreted as a result of FSH

• Stimulates LH

• Inhibits FSH

• Causes the lining of the uterus to grow again

What does LH do in the menstrual cycle

• Produced in the pituitary gland

• As a result of oestrogen

• Causes ovulation

What does progesterone do in the menstrual cycle

○ Produced in the ovaries

○ Secreted from egg follicle

○ Inhibits FSH and LH

○ Maintains lining of uterus and supports a pregnancy is egg is fertilised

Why is it important to retain a constant internal environment

○ Mechanisms are in place to keep conditions optimal despite internal and external changes

○ Homeostasis is important for enzyme action and cell function like growth and replication

How does thermoregulation affect enzyme activity

○ Thermoregulation is the act of keeping the internal body temperature (37^o) constant

○ This is because if the temperature goes above the optimum, enzymes will become less effective and eventually denature

○ This means the enzyme and substrate cannot bind

What would happen if we did not have osmoregulation

• Osmoregulation is keeping a constant concentration of blood

• If blood becomes too dilute, water will move into cells by osmosis and cells will burst under pressure

• If the blood is too concentration, water will move out of cells and they will shrink

• In both cases, cells cannot perform their function

Explain how sweating helps regulate temperature in humans

• Sweat is released onto the surface of the skin, which evaporates.

• This cools the body

Explain how thyroxine controls metabolic rate

• Low levels of thyroxine stimulate production of TRH in hypothalamus

• This causes the release of TSH from pituitary gland

• TSH stimulates the release of thyroxine

• When thyroxine levels are normal, thyroxine inhibits the release of TRH and the production of TSH

Explain how hormonal contraception influences the menstrual cycle

• The combined contraceptive pill contains oestrogen and progesterone

• Oestrogen levels are high, inhibiting FSH, meaning no egg matures

• This stops the lining of the uterus from developing

Advantages and disadvantages of hormonal contraception

• Advantages = 99% effective

• Disadvantages = can cause side effects like weight gain, doesn't protect against STIs

Advantages and disadvantages of barrier contraception

• Advantages = protect against STIs

• Disadvantages = condoms can break or slip - less effective

Explain how insulin controls blood glucose levels

• If glucose levels are too high, the pancreas produces insulin

• Insulin binds to cells in target organs

• This causes glucose to more from the blood, into muscle cells for respiration

• Excess glucose is converted to glycogen and stored in the liver

What is the purpose of the urinary system

• The urinary system is a bodily system that removes impurities and waste products from are blood.

• These impurities are excreted in the urine

Route that blood takes to be purified

1. Blood containing impurities travels in the renal artery to the kidney

2. The kidneys regulate levels of salt, ions and urea in the blood

3. Any excess is sent to the ureter and bladder for excretion

4. The purified blood returns to the circulation through the renal vein

What is the structure of the kidney

• Each kidney contains millions of nephrons

• These are made up of a glomerulus, a region for selective reabsorption, and a kidney tubule where water and salt is regulated

Where does ultrafiltration occur and what happens during it

• Ultrafiltration occurs in the glomerulus at the start of the nephron

• Urea, water, ions and glucose are small enough to pass out of capillaries into the Bowman's capsule

• Proteins and blood cells remain in the blood because they are too large

What happens to substance once they are filtered into the Bowman's capsule

• They move into the tubule

• When they reach the proximal convoluted tubule, all the glucose that was lost during ultrafiltration is selectively reabsorbed into the blood

Where does water and ion reabsorption take place

Water and ions are reabsorbed in the loop of Henle and collecting duct

How does the collecting duct regulate urine concentration

• The collecting duct reabsorbs water based on how much the body needs

• This is controlled by ADH

What is the effect of ADH on the permeability of the collecting duct - when you have too much water in the blood

• If water potential of the blood is too high, less ADH is released from the pituitary gland and the collecting duct becomes less permeable

• This leads to more water being released in urination

What is the effect of ADH on the permeability of the collecting duct - when you have too little water in the blood

If water potential of the blood is too low, more ADH is released from the pituitary gland and the collecting duct becomes more permeable This leads to less water remaining in the tubule, and more entering the surrounding blood vessels Less water is released during urination

Describe how dialysis removes unwanted substances from the blood

• Kidney dialysis is used when a person's kidneys are damaged

• Blood taken from arm passes into the dialysis machine

• Blood is separate from the dialysis solution by a partially permeable membrane

• Unwanted substances like urea move into the dialysis fluid by diffusion down a concentration gradient

• Whereas glucose and ions stay in the blood and don't go into the dialysis fluid

• Fresh dialysis fluid is pumped through to maintain the concentration gradient

Pros and cons of dialysis

• Pros = keeps patients alive while waiting for a transplant

• Cons = requires frequent trips to hospital, can cause side effects like infections

Describe how kidney transplants work

• A kidney transplant is used to replace a damaged kidney with a healthy one

• The new kidney is placed into the patient's body during surgery

• Tissue typing ensures the donor kidney is a good match, reducing the risk of rejection

• Immunosuppressant drugs are taken for life to prevent rejection

Pros and cons of kidney transplant

• Pros = permanent solution

• Cons = risk of organ rejection, can be hard to find a matching donor

What are the three types of thermoregulation

• Shivering

• Vasoconstriction

• Vasodilation

Explain shivering

• Shivering is rapid muscle contraction

• Some energy is released from an increased rate of respiration

• Helps warm you up

Explain vasoconstriction

• Vasoconstriction is when blood cells narrow

• The hypothalamus detects cold and sends nerve impulses to skin arteries, causing them to narrow

• Blood flow in capillaries is reduced

• Energy transfer to surrounding is reduced, warming the body

Explain vasodilation

• Vasodilation is the widening of blood vessels

• When the hypothalamus detects warmth, it sends nerve impulses to skin arteries, causing them to widen

• Blood flow in capillaries near the skin is reduced

• Energy transfer to the surroundings is reduced, cooling down the body

What is the formula for BMI

Mass / height²

What is the correlation between body mass and type 2 diabetes

○ A BMI over 30 is generally considered obese

○ Obesity is a risk factor for developing type 2 diabetes

○ There is a direct correlation between body mass and type 2 diabetes

What might doctors do if someone is at risk of getting type 2 diabetes

○ They will give them a glucose tolerance test to examine how well their body can produce insulin when it is needed

How do hormones act when you are pregnant

• FSH remains low as no egg would mature

• LH levels remain low so no ovulation occurs

• Progesterone inhibits FSH and LH

• Progesterone levels remain high to maintain lining of uterus

How does the dermis help thermoregulation take place TOO COLD

• Nerve impulses are sent to the hair erector muscles in the dermis

• The hair erector muscles contract, raising the skin hairs

• This traps a layer of insulating air next to the skin

• Which warms the body

How does the dermis help thermoregulation take place TOO HOT

• The hair erector muscles relax

• This causes the hair on the skin to trap less air

• This means that the skin is less insulated and heat can be lost more easily

• Which cools the body

How does the epidermis help thermoregulation take place TOO HOT

• Sweat is produced from the sweat glands in the dermis

• Sweat is released onto the surface of the epidermis

• When the sweat evaporates, the body cools