SB7 - Animal Coordination, Control and Homeostasis ✓ Flashcards Preview

Edexcel GCSE Biology > SB7 - Animal Coordination, Control and Homeostasis ✓ > Flashcards

Flashcards in SB7 - Animal Coordination, Control and Homeostasis ✓ Deck (47)
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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 - What is your metabolic rate?

The rate at which energy stored as food is transferred by all of the reactions that take place in your body


SB7b - How do you measure resting metabolic rate?

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


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 - Define homeostasis

Maintaining constant conditions in the body, typically through negative feedback


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

  • 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


SB7g - What is thermoregulation?

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


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 - 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 - When the body is too cold, what will happen?

  • Shivering: Muscles rapidly contract and expand. Some of the energy released form cell respiration warms you up
  • Vasoconstriction: Nerve signals from the hypothalamus tell the blood vessels near the surface of the skin (in the dermis) will narrow. This reduces thermal energy lost to surroundings as blood flows past
  • Erector muscles contract: Erector muscles in the dermis of the skin contract causing hair to stand upright. While it may not work for humans, on other mammals it traps air next t the skin for insulation


SB7g - When the body is too warm, what will happen?

  • Sweating: Your body secretes a thin layer of sweat on the epidermis of your skin. When this evaporates, it transfers energy from the body to the surroundings
  • Vasodilation: Nerve signals from the hypothalamus tell the blood vessels in the dermis widen. As more blood flows near the surface of the skin, more energy is transferred to the surroundings
  • Erector muscles relax: Hair lies flat meaning no air can be trapped and reducing the insulation (again it doesn't make a difference for humans)


SB7h - What is osmoregulation?

  • The negative feedback system involving the balance of water and minerals in the body.
  • The wrong balance will result in cells taking in the wrong amounts through osmosis and being damaged


SB7h - Describe how to urinary system works

  • The urinary system removes excess amounts of substances from the blood inc. water mineral salts and urea
  • Renal arteries carry blood from the body to the kidney.
  • Once it is 'cleaned' renal veins carry the blood to the rest of the body
  • The kidneys remove excess substances from the blood to form urine
  • Ureters carry urine to the bladder where it is stored
  • Once the muscle keeping the bladder closed is released, the urine passes through the urethra to outside the body


SB7h - What is kidney failure and why is it dangerous?

  • Kidney failure is when both of the kidneys stop working properly
  • This means that there will be high concentration of waste products in their blood which will need to be removed by dialysis


SB7h - What is urea?

Urea is produced from the breakdown of excess amino acids in the liver. This is passed into the blood


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 - 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 - What is the relationship between T2 diabetes and average body mass?

  • The higher your body mass, the higher the risk of T2 diabetes.
  • These factors are correlated


SB7f - How do you calculate BMI?

BMI = mass (kg) ÷ height (m²)


SB7f - How do you calculate waist:hip ratio?

waist measurement ÷ hip measurement


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.


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


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


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