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Biology > Topic 7: Animal coordination, control and homeostasis > Flashcards

Topic 7: Animal coordination, control and homeostasis Flashcards

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1
Q

What are hormones?

A

Hormones are chemicals released directly into the blood. They are carried in the blood to target organs and control things that need constant adjustment

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2
Q

Where are hormones produced?

A

Endocrine glands that make up the endocrine system

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3
Q

What’s the Pituitary Gland?

A
  • Produces many hormones that regulate body conditions
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4
Q

What’s the Thyroid Gland?

A
  • Produces thyroxine
  • Thyroxine is involved in regulating rate of metabolism, heart rate and temperature
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5
Q

What are the Ovaries (in terms of the endocrine system)

A
  • Females only
  • Produces oestrogen which is involved in the menstrual cycle
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6
Q

What are the Adrenal Glands?

A
  • Produce adrenaline, which is used to prepare the body for a ‘fight or flight’ response
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7
Q

What are the Testes (in terms of the endocrine system)?

A
  • male only
  • Produces testosterone which controls puberty and sperm production in males
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8
Q

What’s the Pancreas?

A
  • Produces insulin which is used to regulate the blood glucose level
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9
Q

What’s the difference between hormones and neurons?

A

Neurons: Very fast action, act for a very short time, act on a very precise area
Hormones: Slower action, act for a long time, act in a more general way

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10
Q

How does adrenaline prepare the body for a ‘fight or flight’ scenario?

A
  • Adrenaline binds to specific receptors in the heart which causes the heart muscle to contract more frequently with more force. So, the heart rate and blood pressure increase
  • This increases blood flow to the muscles, so the cells receive more oxygen and glucose for increased respiration
  • Adrenaline also binds to receptors in the liver which causes the liver to break down its glycogen stores to release glucose
  • This increases the blood glucose level, so there’s more glucose in the blood to be transported to the cells
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11
Q

What happens in the body when you experience a stressful situation?

A
  • The brain detects a stressful situation and sends nervous impulses to the adrenal glands, which respond by secreting adrenaline
  • This gets the body ready for action
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12
Q

What is metabolic rate?

A

The speed at which chemical reactions in the body occur

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13
Q

How does the body control hormone levels in the blood?

A

Negative feedback:
- When the body detects that the level of a substance has gone above or below the normal level it triggers a response to bring the level back to normal again

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14
Q

What can an underactive thyroid cause - why?

A
  • An underactive thyroid gland can cause weight gain
  • Less thyroxine is produced, so metabolic rate drops.
  • This means that less of the glucose taken in gets broken down in respiration, so more is stored as fat
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15
Q

How does a negative feedback system regulate thyroxine levels if they are too low?

A
  • Hypothalamus in brain detects when thyroxine levels in the blood are lower than normal, so it secretes TRH (thyroxine releasing hormone)
  • TRH stimulates the pituitary gland to release TSH (thyroid stimulating hormone)
  • TSH stimulates the thyroid gland to release thyroxine, so the blood thyroxine level rises back towards the normal
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16
Q

How does a negative feedback system regulate thyroxine levels if they are too high?

A
  • Hypothalamus detects high thyroxine levels and the release of TRH is inhibited
  • This reduces the production of TSH, so the blood thyroxine level falls
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17
Q

What is the menstrual cycle?

A

The monthly sequence of events in which the female body releases an egg and prepares the uterus in case the egg is fertilised

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18
Q

What occurs during each of the stages of the menstrual cycle?

A

Stage 1: Menstruation starts - the lining of the uterus breaks down and is released
Stage 2: The uterus lining is repaired (days 4-14) - until it becomes a thick spongy layer full of blood vessels ready for a fertilised egg to implant there
Stage 3: An egg develops and is released from the ovary (ovulation day 14)
Stage 4: Lining is then maintained until day 28 - If no fertilised egg lands on the uterus wall by day 28, the lining starts to break down again ad the cycle restarts

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19
Q

Explain the role of each hormone that controls the menstrual cycle

A

FSH (follicle stimulating hormone): Released by pituitary gland, stimulates a follicle to mature in the ovary, stimulates oestrogen production

Oestrogen: Released by ovaries, causes lining of the uterus to thicken and grow, a high level stimulates a surge of LH

LH (luteinising hormone): Released by pituitary gland, LH surge stimulates ovulation on day 14, follicle ruptures and egg is released, LH stimulates the remains of the follicle to develop into a corpus luteum which secretes progesterone

Progesterone: Released by corpus luteum after ovulation, maintains uterus lining, inhibits the release of FSH and LH, when progesterone levels fall there’s a low oestrogen level so the uterus lining breaks down, low progesterone level allows FSH to increase and the whole cycle restarts

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20
Q

What happens in terms of hormones when the woman becomes pregnant?

A

If a fertilised egg implants in the uterus, the level of progesterone will remain high to maintain the uterus lining

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21
Q

What are 2 methods that infertile couples can use to become pregnant?

A

Clomifene Therapy
IVF

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22
Q

How dos Clomifene Therapy work?

A
  • Some women are infertile because they don’t ovulate/don’t ovulate regularly, so they can take a drug called Clomifene
  • Clomifene works by causing more FSH and LH to be released in the body, which stimulates egg maturation and ovulation
    -Now that they know when ovulation will occur, the couple can have intercourse during this time period to increase the chance of becoming pregnant
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23
Q

How does IVF work?

A
  • Collects eggs from the woman’s ovaries which are fertilised using the man’s sperm
  • These are grown into embryos
  • Once the embryos are tiny balls of cells, one or two of them are transferred to the woman’s uterus to improve the chance of pregnancy
  • FSH and LH are given before egg collection to stimulate egg production so that more than one egg can be collected
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24
Q

What’s Assisted Reproductive Technology (ART) ?

A

A fertility treatment that involves eggs being handles (and usually fertilised) outside of the body

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25
Q

How can oestrogen be used as a contraceptive?

A
  • If oestrogen is taken every day to keep the level permanently high, it inhibits the production of FSH so after a while, egg development and production stops and stays stopped
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26
Q

How can progesterone be used as a contraceptive?

A
  • Progesterone can be used to reduce fertility
  • It stimulates a thick cervical mucus which prevents any sperm getting through the cervix and reaching the egg
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27
Q

How do barrier methods of contraception work?

A

They put a barrier between the egg and sperm so that they don’t meet

28
Q

What are the pros and cons of hormonal and barrier contraceptive methods?

A

Hormonal method PROS - more effective at preventing pregnancy when used correctly, couple don’t have to think about contraception each time they have intercourse
Hormonal method CONS - Don’t protect against STI’s, unpleasant side effects e.g. headaches and mood changes

29
Q

What’s homeostasis?

A

Maintaining the right conditions inside the body so that everything works properly

30
Q

Why is homeostasis important?

A

Conditions in the body need to be kept steady because you cells need the right conditions in order to function properly, including the right conditions for enzyme action
If the conditions vary too much, it can be dangerous for your health

31
Q

What are 3 examples of homeostasis in action?

A

Osmoregulation (regulating water content) - need to keep a balance between the water you take in (drink/in respiration) and the water you wee, sweat and breathe out

Thermoregulation (regulating body temperature) - you need to reduce your body temperature when you’re hot, but increase it when the environment is cold

Blood glucose regulation - make sure the amount of glucose in your blood doesn’t get too high or too low

32
Q

What happens in terms of glucose in the blood when eating foods containing carbohydrates - how do you gain weight?

A
  • Eating food containing carbohydrate puts glucose into the blood from the small intestine
  • The normal metabolism of cells removes glucose from the blood, so does vigorous exercise
  • Excess glucose can be stored as glycogen in the liver and muscles
  • When the stores are full, the excess glucose is stored as lipid (fat) in the tissues
33
Q

What is blood glucose controlled by?

A

Changes in blood glucose are monitored and controlled by the pancreas using the hormones insulin and glucagon

34
Q

How does insulin control blood glucose concentration?

A
  • Pancreas detects blood glucose level is too high
  • Insulin is secreted into the blood stream by the pancreas
  • The insulin converts glucose into Glycogen which is stored in the liver, reducing blood sugar levels
35
Q

How does Glucagon control blood glucose concentration?

A
  • Pancreas detects blood glucose level is too low
  • Glucagon is secreted into the blood stream by the pancreas
  • Glycogen is converted to glucose in the liver, increasing blood glucose concentration
36
Q

Which hormone is released when blood glucose levels are too high?

A

Insulin

37
Q

Which hormone is released when blood glucose levels are too low?

A

Glucagon

38
Q

What’s the cause of Type 1 Diabetes?

A

Pancreas produces little or no insulin, causing the person’s blood glucose level to rise to a level that could kill them

39
Q

How is Type 1 Diabetes treated?

A

Insulin therapy - injecting insulin into subcutaneous tissue, from where it will enter the blood stream
This is often done at meal times to ensure that the glucose is removed from the blood quickly once the food has been digested
This stops the blood glucose level from getting too high

40
Q

How much insulin should be injected into someone with Type 1 Diabetes?

A

It depends on the person’s diet and how active they are

41
Q

What is it beneficial for people with type 1 diabetes to do?

A

Limiting the intake of foods rich in simple carbohydrates
Regular exercise to remove excess glucose from the blood
Insulin therapy

42
Q

What’s the cause of type 2 diabetes?

A

Pancreas doesn’t produce enough insulin or the person becomes resistant to insulin (their body’s cells don’t respond properly to the hormone)
SO, blood glucose level rises

43
Q

What disease increases the risk of having type 2 Diabetes?

A

Obesity

44
Q

What BMI is classified as obese?

A

Over 30

45
Q

How do you work out Body mass index? (BMI)

A

Mass (kg) / Height (m) squared

46
Q

Why is the waist-to-hip ratio important when seeing if someone may develop Type 2 Diabetes?

A

Storing a lot of fat around the abdomen is associated with an increased risk of developing Type 2 Diabetes

47
Q

How do you calculate the Waist-to-hip ratio?

A

Waist circumference (cm) / Hip circumference (cm)

48
Q

What waist-to-hip ratio increases the risk of type 2 diabetes?

A

Males - 1.0
Females - 0.85

49
Q

Can type 2 diabetes be controlled? - how?

A

Yes
- Healthy diet, regular exercise, losing weight if needed
- Or sometimes medication/insulin injections

50
Q

What’s Thermoregulation?

A

Thermoregulation is the process the body uses to maintain a constant internal temperature

51
Q

What occurs in the body when you are too hot?

A
  • Hypothalamus triggers a response to cool you down…
  • Erector muscles relax, so hairs lie flat
  • Sweat is produced in sweat glands in the dermis releases onto skin surface through pores in the epidermis. When sweat evaporates, energy is transferred from your skin to the environment which cools you down
  • Blood vessels vasodilate, allowing more blood to flow near the surface so it can transfer more energy to the surroundings (cooling you down)
52
Q

How is body temperature controlled? (in terms of the brain)

A
  • Hypothalamus detects a change in body temperature which triggers a response to counteract it
  • Thermoregulatory centre (in hypothalamus) contains receptors that are sensitive to blood temp in the brain
  • There are also receptors in the dermis and epidermis which means that the thermoregulatory centre also receives impulses from nerve endings which provide info about the external temperature
53
Q

What occurs in the body when you are too cold?

A
  • Erector muscles contract so hairs stand up on ends which traps an insulating layer of air near the skin’s surface
  • Very little sweat is produced
  • Blood vessels vasoconstrict, so less energy is transferred to the surroundings
  • Muscles contract automatically which in also known as shivering. This increases the rate of respiration which transfers more energy to warm the body
54
Q

Why is thermoregulation important?

A

Enzymes in the body have an optimal temperature in which they work best at which is 37 degrees Celsius
A temperature lower than that means that enzyme activity will slow down, and any higher means that they begin to denature

55
Q

What are the Kidneys’ main roles?

A
  • Removal of urea from the blood
  • Adjustment of ion levels in the blood
  • Adjustment of water content of the blood
56
Q

How is Urea produced?

A

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

57
Q

Why does water content in the blood need to be controlled?

A
  • It needs to be controlled to keep cells functioning normally, BECAUSE…
    If the concentration of water in the blood gets too high, water will move into the cells by osmosis and if too much water moves in, the cells may burst
    If the concentration of water in the blood is too low, water will move out of the cells into the blood by osmosis and the cells will shrink
58
Q

What occurs in each nephron?

A

(filtration units in the kidneys)
1) 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. Larger molecules like proteins and blood cells can’t pass through the membranes in the Bowman’s capsule and are not forced out (ACTS LIKE SEIVE) - this is ULTRAFILTRATION

2) in the Proximal Convoluted tube, selective reabsorption occurs and the following are reabsorbed: all glucose and all amino acids, some ions and most of the water (they are absorbed by active transport, meaning against the concentration gradient)

3) In the Loop of Henle, water is absorbed in the first descending part and ions are absorbed in the second ascending part

4) In the Distal Convoluted Tubule, the final few mineral ions are absorbed

5) In the collecting duct, the rest of the required water is reabsorbed by osmosis (the amount of water we absorb is controlled using the hormone ADH - osmoregulation occurs here!)

59
Q

How is Urea produced?

A

The breakdown of amino acids in the liver

60
Q

Explain the process of the kidneys producing urine.

A
  • Each kidney received blood from the renal artery
  • Kidneys act like filters, removing urea from the blood
  • The urea is diluted with water (and is called urine)
  • Urine is sent to the bladder for storage via the ureter
  • It exits the body through the urethrea
61
Q

What’s ADH? (Explain its role and how it works etc…..)

A

ADH = Anti Diuretic Hormone
- Controls the amount of water reabsorbed in the kidney nephrons
- It does this by making the collecting ducts in the nephron more permeable so that more water is re absorbed into the blood

62
Q

Explain how the body responds to dehydration.

A
  • Brain detects water loss
  • Pituitary Gland releases more ADH
  • ADH makes collecting ducts in nephron more permeable so the kidney re absorbs more water
  • You are now hydrated
63
Q

Explain Dialysis.

A
  • Dialysis is a machine used to filter the blood mechanically in people with kidney failure
  • It does this by having a permeable barrier to ions and waste but not to larger molecules like proteins, so Urea, water and excess ions move from the blood across the membrane to the Dialysis fluid and cells and proteins stay in the blood
  • Salts and glucose aren’t removed from the blood because the dialysis fluid has the same concentration of them as blood plasma
  • Dialysis has to be done regularly to keep dissolved substances at the right concentrations and to remove waste
64
Q

What are the methods in which people with kidney failure can use?

A

Dialysis
Kidney Transplant

65
Q

What’s the downside of Kidney Transplants? - how can this be prevented?

A

Rejection - can be prevented by using a donor with a tissue that closely matches the patient, drugs can also be taken to suppress the immune system to stop it from attacking and rejecting the kidneys

Biology (6 decks)

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