Animal Coordination, Control and Homeostasis

Question 1

Where are hormones produced?

Answer 1

the endocrine glands

Question 2

What is the general role of hormones in the body?

Answer 2

to control things in organs and cells that need constant adjustment

Question 3

How are hormones transported around the body?

Answer 3

In the bloodstream

Question 4

Describe the production and release of hormones from the pituitary gland.

Answer 4

The pituitary gland produces many hormones which regulate body conditions. It is sometimes called the master gland as these hormones act on other glands to release hormones that bring about change

Question 5

Describe the production and release of hormones from the thyroid gland.

Answer 5

Produces thyroxine, which is involved in regulating rate of metabolism, heart rate, temperature, etc…

Question 6

Describe the production and release of hormones from the pancreas.

Answer 6

Produces insulin and glucagon, used to regulate blood glucose level

Question 7

Describe the production and release of hormones from the adrenal glands.

Answer 7

Produce adrenaline, used to prepare the body for a fight or flight response

Question 8

Describe the production and release of hormones from the ovaries.

Answer 8

Produce oestrogen, involved in the menstrual cycle.

Question 9

Describe the production and release of hormones from the testes.

Answer 9

Produce testosterone, which controls puberty and sperm production in males.

Question 10

What are the effects of adrenaline on the body?

Answer 10

It prepares the body for fight or flight by activating processes which increase flow of oxygen to cells. E.g. Adrenaline binds to specific receptors in the heart, causing the heart muscle to contract more frequently & with more force so heart rate & blood pressure increase, increasing blood flow to muscles so cells receive more oxygen & glucose for respiration. Adrenaline also binds to receptors in the liver so it breaks down glycogen stores to release glucose, increasing blood glucose level to aid respiration.

Question 11

What is metabolic rate?

Answer 11

The speed at which chemical reactions in the body occur.

Question 12

What is the effect of thyroxine on metabolic rate?

Answer 12

More thyroxine causes metabolic rate to rise.

Question 13

How does a negative feedback system work and why is it important?

Answer 13

A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback. In general, if the level of something rises, control systems reduce it again; if the level of something falls, control systems raise it again

Question 14

How does negative feedback control the production of thyroxine?

Answer 14

When blood thyroxine lovel is lower than normal the hypothalamus is stimulated to release thyrotropin releasing hormone (TRH). TRH stimulates the pituitary gland to release thyroid stimulating hormone (TSH) which stimulates the thyroid gland to release thyroxine so blood thyroxine level rises. When it is too high release of TRH from the hypothalamus is inhibited, reducing production of TSH so blood thyroxine level falls.

Question 15

What happens during the menstrual cycle?

Answer 15

Stage 1- Day 1: menstruation starts- uterine lining breaks down and is released
Stage 2- uterus lining is repaired (day 4-14) until it is a thick spongy layer full of blood vessels ready for a fertilised egg to implant there
Stage 3- Ovulation (day 14)
Stage 4- Lining is then maintained for about 28 days until day 28, whereupon, if no fertilised egg has implanted,the uterine lining breaks down and menstruation occurs.

Question 16

How can barrier methods be used as contraception?

Answer 16

A barrier is put between the sperm and egg so they don’t meet. E.g. male and female condoms and diaphragms (with spermicide)

Question 17

How can hormones be used as contraception?

Answer 17

If oestrogen is taken daily to keep levels of it high, it inhibits FSH production so egg development and production stop. Progesterone stimulates production of thick cervical mucus, preventing sperm breaching the entrance to the uterus (the cervix). Some hormonal contraceptives contain both oestrogen and progesterone e.g. the combined pill and the contraceptive patch (worn on the skin). Some contain progesterone only e.g. mini-pill and contraceptive injection.

Question 18

What is the difference between hormonal and barrier methods?

Answer 18

Hormonal methods are more effective when used correctly and mean the couple don’t have to stop and think about contraception before intercourse. However, they can have unpleasant side effects (e.g. headaches, acne and mood swings) and don’t protect against STIs.

Question 19

How do oestrogen, progesterone, FSH and LH interact in the menstrual cycle?

Answer 19

FSH (released by the pituitary gland) causes a follicle to mature in an ovary and stimulates oestrogen production. Oestrogen (released by the ovaries) causes the lining of the uterus to thicken and grow. A high level stimulates an LH (lutenising hormone) surge. The LH (released by the pituitary gland) surge stimulates ovulation at day 14 - follicle ruptures and egg is released- and stimulates the remains of the follicle to develop into a corpus luteum which secretes progesterone. Progesterone maintains uterine lining and inhibits release of FSH and LH. When level of progesterone falls and oestrogen level is low the uterus lining breaks down and FSH level increases, allowing the cycle to restart.

Question 20

How is clomifene used to stimulate ovulation?

Answer 20

Some women are infertile as they don’t ovulate or don’t ovulate regularly. The clomifene drug causes more FSH and LH to be released by the body, stimulating egg maturation and ovulation. By knowing when the woman will be ovulating , the couple can have intercourse during this time period to improve chances of becoming pregnant.

Question 21

How does IVF work?

Answer 21

Eggs are collected from the woman’s ovaries and fertilised in a lab using the man’s sperm. These are then grown into embryos. Once the embryos are little balls of cells, 1 or 2 of them are transferred to the woman’s uterus to improve chances of pregnancy. FSH and LH are given before egg collection to stimulate egg production so more than 1 egg can be collected. IVF is an example of Assisted Reproductive Technology (ART) as it involves eggs being handled outside the body.

Question 22

What is homeostasis and why is it important?

Answer 22

Maintaining a constant internal environment.

Cells need the right conditions in order to function properly, including the right conditions for enzyme action.

Question 23

Why do blood glucose levels change?

Answer 23

Eating carbohydrate-containing foods puts glucose into the blood from the small intestine. Normal cell metabolism removes glucose from the blood. Vigorous exercise removes more glucose from the blood. Excess glucose can be stored as glycogen in the liver and muscles. When these stores are full the excess glucose is stored as lipid (fat) in the tissues.Changes in blood glucose are monitored and controlled by the pancreas

Question 24

How do insulin and glucagon regulate blood glucose concentration?

Answer 24

When blood glucose concentration is too high, the pancreas secretes insulin, which stimulates the liver to take in glucose and store it as glycogen. When blood glucose concentration is too low, the pancreas secretes glucagon, which stimulates the liver to break down glycogen into glucose and release it into the bloodstream.

Question 25

How is type 1 diabetes caused?

Answer 25

A condition where the pancreas produces little or no insulin. It is an immune condition usually developed in childhood.

Question 26

How is type 1 diabetes controlled?

Answer 26

Injecting insulin, usually into subcutaneous tissue, often at mealtimes. Also, lifestyle factors- limiting intake of foods containing simple carbohydrates, regular exercise.

Question 27

How is type 2 diabetes caused?

Answer 27

Either where the pancreas doesn’t produce enough insulin or when a person becomes resistant to insulin. Strongly influenced by lifestyle factors.

Question 28

How is type 2 diabetes controlled?

Answer 28

Healthy diet, regular exercise, losing weight. Also medication and insulin injections.

Question 29

What is the correlation between body mass and type 2 diabetes?

Answer 29

Obese people are more likely to develop type 2 diabetes. This is likely to be a true correlation as obese people consume more foods containing simple carbohydrates so are more likely to become resistant to insulin.

Question 30

How are BMI and waist:hip ratio related to body mass?

Answer 30

People are classified as obese if their BMI is over 30. A high waist to hip ratio (above 1.0 for men and above 0.85 for women) is associated with a high risk of developing type 2 diabetes as a lot of fat is stored around the abdomen.

Question 31

What is thermoregulation?

Answer 31

The process the body uses to keep its internal temperature steady.

Question 32

What is the importance of thermoregulation in enzyme activity?

Answer 32

The optimum temperature of enzymes in the human body is 37 degrees. homeostasis maintains this core body temperature.

Question 33

What is the role of the skin in thermoregulation when the body is too hot?

Answer 33

Erector muscles relax so hairs lie flat. Lots of sweat is produced in sweat glands in the dermis and secreted through pores in the epidermis. Evaporation of sweat cools the body.

Question 34

What is the role of the skin in thermoregulation when the body is too cold?

Answer 34

Erector muscles contract so hairs stand on end. This traps an insulating layer of air near the surface of the skin. Little sweat is produced.

Question 35

What is the role of the hypothalamus in thermoregulation?

Answer 35

The thermoregulatory centre in the hypothalamus contains receptors sensitive to the blood temperature in the brain. It also receives impulses from receptors in the epidermis and dermis that provide information about external temperature. When the hypothalamus detects a temperature change it causes a response in the skin that counteracts the change.

Question 36

What is the epidermis?

Answer 36

the outer layer of skin

Question 37

What is the dermis?

Answer 37

the layer of skin just below the epidermis

Question 38

What is the role of muscles in raising body temperature?

Answer 38

Muscles contrat automatically, increasing rate of respiration and transferring energy to warm the body. This is known as shivering.

Question 39

What is the role of changing blood vessel diameter in thermoregulation?

Answer 39

When the body is too hot, blood vessels in the dermis dilate (vasodilation), which allows more blood to flow near the surface so it can transfer more energy into the surroundings, which cools you down. When the body is too cold, the blood vessels constrict (vasoconstriction), meaning less blood flows near the surface so less energy is transferred to the surroundings.

Question 40

How is the urinary system structured?

Answer 40

Blood flows to the kidneys via the renal artery and from the kidneys via the renal vein. Urine flows from the kidneys to the bladder via the ureter and is released through the urethra.

Question 41

How is urea formed?

Answer 41

In the liver from the breakdown of excess amino acids (which are themselves produced when proteins are broken down)

Question 42

What is osmoregulation?

Answer 42

regulating water content in the body

Question 43

How is kidney failure treated by kidney dialysis?

Answer 43

A dialysis machine filters blood mechanically. It 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. The barrier is permeable to ions and waste substances but not larger molecules like proteins so waste and excess substances diffuse into the dialysis fluid but cells and proteins stay in the blood.

Question 44

How is kidney failure treated by organ transplants?

Answer 44

A healthy kidney is transplanted from a donor. The donor kidney can be rejected by the patient’s immune system (treated like a pathogen and attacked). To prevent this happening, a donor with a tissue type closely matching the patient is chosen and the patient is treated with drugs that suppress the immune system so the immune system won’t attack the new kidney.

Question 45

Why is osmoregulation important?

Answer 45

If water concentration in the blood is too high, water will move into body cells by osmosis which may cause them to burst. If water concentration in the blood is too low, water will move out of body cells into the blood by osmosis which may cause them to shrink.

Question 46

What are the roles of the kidneys?

Answer 46

Removal of urea from the blood
Adjustment of ion levels in the blood
Adjustment of water levels in the blood

Question 47

What are the parts of a nephron?

Answer 47

Bowman’s capsule (larger capsule), glomerulus(looks like a net), proximal convoluted tubule(1st), capillary network, loop of Henle (larger loop), distal convoluted tubule(2nd), collecting duct (straighter)

Question 48

What does urine contain?

Answer 48

Whatever isn’t reabsorbed: urea, excess water, excess ions. It passes out of the nephron via the collecting duct.

Question 49

How does the structure of the nephron allow filtration?

Answer 49

The liquid part of the blood (containing water, urea, ions and glucose) is forced out of the glomerulus and into the bowman’s capsule at high pressure (ultrafiltration). Bigger molecules (e.g. proteins) and blood cells cannot pass through the membrane and aren’t forced out.

Question 50

How does the structure of the nephron support reabsorption?

Answer 50

As the liquid moves along the nephron, useful substances are reabsorbed: all glucose is selectively reabsorbed (moved back into the blood against the concentration gradient); sufficient ions are reabsorbed and sufficient water is reabsorbed according to the concentration of the hormone ADH.

Question 51

What is the role of ADH in regulating body water content?

Answer 51

The brain monitors blood water content and instructs the pituitary gland to release ADH into the blood according to how much water is needed. ADH makes collecting ducts in the nephrons more permeable so more water is reabsorbed into the blood, preventing dehydration. There is a negative feedback system.