SB7 - Animal Coordination, Control and Homeostasis ✓ Flashcards Preview

Edexcel GCSE Biology (9-1) > SB7 - Animal Coordination, Control and Homeostasis ✓ > Flashcards

Flashcards in SB7 - Animal Coordination, Control and Homeostasis ✓ Deck (49)
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SB7a - What are hormones?

  • Hormones are chemical messengers (carried in the blood stream).
  • They are used in the hormonal response system which is typically slow-acting and long-lasting compared to the nervous system


SB7a - Where are hormones released? (Give examples)

Endocrine glands e.g:

  • Pituitary gland
  • Thyroid gland
  • Adrenals
  • Ovaries
  • Testes
  • Pancreas


SB7a - Where do hormones go to? (Give examples)

Target organs e.g:

  • Digestive system
  • Kidneys
  • Liver
  • Endocrine glands for other hormones (e.g growth hormone)


SB7b - Define homeostasis

Maintaining constant conditions in the body, typically through negative feedback


SB7b - How do you measure resting metabolic rate?

  • At a warm room
  • Body at rest
  • Long after the person has had a meal


SB7b - How does your body's fight or flight system work?

- Describe the target organs of adrenaline in your answer

  • Adrenaline is released from adrenal glands and is always in the bloodstream at a low level
  • A fight or flight situation will cause increased impulses from neurons which will trigger the release of large amounts of adrenaline into your blood
  • Adrenaline has many target organs:
    • Causes the breakdown of glycogen to glucose in the liver so that there is more for cellular respiration (more energy)
    • Heart contracts more rapidly and strongly increasing the heart rate and blood pressure. This moves glucose around the body quicker
    • Diameter of blood vessels leading to muscles or target organs are widened to allow more blood through while the rest are narrowed to allow more to be sent to the widened vessels


SB7b - How is thyroxine used as part of a negative feedback system?

  • If the concentration of thyroxine in the blood is low, the hypothalamus may release TRH
  • This will cause the pituitary gland to release TSH
  • This stimulates the thyroid gland to release thyroxine, increasing the concentration of thyroxine


SB7b - What is a negative feedback system?

A response to an increase in one condition by causing actions that will decrease it, or vice versa (e.g response to body being too hot is to sweat to cool it down)


SB7b - What is thyroxine?

  • Thyroxine is a hormone that is released by the thyroid gland.
  • It's target organs are many different types of cells of which it will increase the rate at which protein and carbohydrates are broken down.
  • This affects your metabolic rate


SB7b - What is your metabolic rate?

The overall rate at which chemical reactions occur within the body


SB7c - Describe the stages of the menstrual cycle

  • Days 1-5ish: Menstruation is when the lining of the uterus breaks down and is lost with an unfertilised egg
  • Days 10-12ish: The uterus lining starts to thicken again
  • Days 13-15: The new egg is released from the ovary
  • Days 16-28: Uterus lining continues to thicken
  • Day 23ish: The egg cell travels along the oviduct to the uterus


SB7c - How do hormone based contraceptions work?

  • Release progesterone and oestrogen-like hormones to inhibit the production of LH and FSH, therefore preventing an egg cell maturing / ovulation occuring.
  • Thickens the mucus at the cervix making it harder for sperm to pass through


SB7c - What is contraception?

The prevention of fertilisation. e.g:

  • Condom
  • Diaphragm or cap
  • Hormonal pills / implants


SB7c - What is the menstrual cycle?

  • The cycle of changes that take place in a women's reproductive system for about 28 days
  • Starts with puberty (around 12) and ends with menopause (around 50)
  • Prepares the body for the fertilisation of an egg and pregnancy


SB7d - How can problems with conception be overcome?

Using ART (Assisted reproductive technology) (Inc. IVF)


Friggin art students, this is what they're doing


SB7d - What are progesterone and oestrogen?

  • Oestrogen: Causes the uterus lining to thicken and stimulates releases of LH
    • Highest around day 13
  • Progesterone: Inhibits release of LH and FSH
  • Both reduce in concentration after the menstruation but stay constant if the egg is fertilised


SB7d - What is clomifene therapy?

Used on women who rarely or never release an egg, this uses a drug that increases levels of FSH and LH, this prepares the body for the egg by thickening the lining and stimulates the release of an egg


SB7d - What is FSH?

  • (Follicle stimulating hormone) is involved in the maturing and growth of the egg follicle
  • It is released from the pituitary gland and is inhibited by higher level of progesterone (which is released after the follicle becomes a corpus luteum)
  • Highest levels around day 4 and 12


SB7d - What is IVF and how does it work?

In vitro fertilisation is when the egg is fertilised in a lab and the embryo is re-inserted into the women's uterus:

  • Egg follicle maturation is stimulated by hormones
  • Eggs are released by many follicles and they are taken from the ovary
  • Sperm cells are taken from the man
  • The egg cells and sperm cells are allowed to combine in a petri dish for fertilisation
  • One or two healthy embryos are re-inserted into the uterus


SB7d - What is LH?

  • (Luteinising hormone) is involved in causing the egg to be release
  • It is released from the pituitary gland and is inhibited by higher levels of progesterone but stimulated by higher levels of oestrogen
  • Highest levels around day 13 (with oestrogen)


SB7e - Describe the travel of glucose through the bloodstream of a non-diabetic person?

  • Glucose is released from the small intestine after digestion. As it flows into the bloodstream, the concentration rises
  • The pancreas detects the high levels of blood glucose and releases insulin. Now the concentration of insulin also rises
  • The insulin causes the liver, muscle and other cells to take up the glucose and store it as glycogen. Thus the glucose and insulin concentration reduces
  • Once the glucose concentration is too low, the pancreas releases glucagon.
  • This causes all the cell that contain glycogen to convert this back into glucose which is released into the blood
  • This is a negative feedback system


SB7e - What is type 1 diabetes and how can it be dealt with?

  • Pancreatic cells don't produce insulin as they have been destroyed by the body's immune system
  • This means they cannot control blood glucose levels naturally
  • A type 1 diabetic would have to inject insulin into the fat layer below the skin to reduce blood glucose levels
  • (Typically non-genetic)


SB7f - How do you calculate BMI?

BMI = mass (kg) ÷ height (m²)


SB7f - How do you calculate waist:hip ratio?

waist measurement ÷ hip measurement


SB7f - What is type 2 diabetes?

  • Insulin releasing cells don't produce enough insulin or target organs don't respond to insulin
  • Can be genetic or due to lifestyle


SB7f - Why can being physically active help with type 2 diabetes?

  • Physical activity increases cellular respiration that takes place in your body
  • This takes up glucose form your blood reducing the need for insulin
  • this lowers your blood glucose level


SB7f - Why is waist:hip ratio preferred to BMI sometimes?

While both have a correlation with risk of T2 diabetes, BMI doesn't account for muscle mass.


SB7g - How does the brain detect the temperature of the body?

  • In the dermis of the skin, there are temperature receptors
  • These feed information to the receptors in the hypothalamus in the brain


SB7g - What is fever/hypothermia and why is it bad?

  • Fever is when your body is above 38°C
  • Hypothermia is when your body is below 36°C
  • These are bad because the enzymes that enact most of the processes in our body that keep us alive have an optimum temperature of 37°C
  • So straying too far from it will stop these processes from occurring (properly) as enzymes can become denatured/ineffective


SB7g - What is thermoregulation?

The negative feedback system that ensures our body stays at around 37°C