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Biology > SB7 Animal Coordination, Control and Homeostasis > Flashcards

SB7 Animal Coordination, Control and Homeostasis Flashcards

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1
Q

Define hormone

A

A chemical substance produced by a gland and carried in the bloodstream, which alters the activity of specific target organs

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2
Q

What system makes use of hormones?

A

The Endocrine System

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3
Q

What is the pituitary gland?

A

The master gland, which secrets several hormones in response to the body’s conditions, such as water levels

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4
Q

What hormones are produced in the pituitary gland?

A
  • growth hormone
  • follicle-stimulating hormone (FSH)
  • LH
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5
Q

What hormone is produced in the thyroid?

A

Thyroxine

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6
Q

What hormones are produced in the pancreas?

A
  • insulin
  • glucagon
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7
Q

What hormones are produced in the ovaries?

A
  • oestrogen
  • progesterone
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8
Q

What hormone is produced in the testes?

A

Testosterone

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9
Q

What hormone is produced in the adrenal gland?

A

Adrenaline

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10
Q

What are the effects of the growth hormone?

A
  • makes muscle and bone cells divide
  • increases ca2+ absorption from the digestive system
  • increases protein production
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11
Q

What are the effects of FSH?

A

Allows egg to mature in the menstrual cycle

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12
Q

What are the effects of LH?

A

Allows egg to be released in the menstrual cycle

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13
Q

What are the effects of thyroxine?

A
  • increases heart activity
  • regulates metabolic rate
  • increases fat, protein and carbs breakdown
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14
Q

What are the effects of oestrogen?

A
  • stops FSH release, so that the egg isn’t matured
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15
Q

What are the effects of progesterone?

A
  • thickens the mucus of the cervix
  • stops LH release
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16
Q

What are the effects of insulin and glucagon?

A
  • insulin: reduces blood glucose levels
  • glucagon: increases blood glucose levels
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17
Q

What are the effects of adrenaline?

A
  • increases blood flow to muscles
  • makes the heart work harder
  • conversion of glycogen to glucose in liver cells which increases glucose production
  • this causes more energy to be released by the muscles in respiration
  • and more glucose supplied to the muscles
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18
Q

What are the effects of testosterone?

A
  • increases muscle and bone mass
  • makes voice deeper
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19
Q

What is the metabolic rate and how is it measured?

A

The rate are which chemical reactions occur in the body. It is measured:
- at rest
- in a warm room
- after a long meal

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20
Q

Define homeostasis

A

The maintenance of constant internal conditions in an organism

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21
Q

Explain what negative feedback is

A

Responds when conditions change from the ideal or set point and returns conditions to this set point

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22
Q

What are the differences between the nervous system and the endocrine system?

A
  • Nervous system is controlled by electric signals whereas the endocrine is controlled by chemicals
  • N is transported by the nerve cells whereas hormones are transported through the bloodstream
  • N stimulates a much faster response as compared to E
  • The duration of hormones last much longer than that of the nerve impulses
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23
Q

What is the role of the hypothalamus?

A

It is the part of the brain which controls the water balance, temperature, and secretion of hormones by the pituitary gland

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24
Q

Explain the effect of the negative feedback system when the thyroxine levels in the blood are low

A
  • stimulate the hypothalamus to release TRH
  • which causes the release TSH by the pituitary gland
  • this hormone triggers the release of thyroxine by the thyroid
  • causing the blood levels to return to normal
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25
Q

Explain the effect of negative feedback when the thyroxine levels in the blood are high

A
  • hypothalamus inhibits the production of TRH
  • stopping production of TSH
  • stopping the thyroxine from being released
  • so blood levels can return to normal
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26
Q

When is adrenaline produced and what does it do?

A
  • produced during times of fear and stress
  • targets vital organs
  • increases heart rate
  • boosts oxygen delivery to brain and muscles
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27
Q

What is the menstrual cycle?

A

The process that the body undergoes every month to prepare for a potential pregnancy

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28
Q

What hormones are involved in the menstrual cycle?

A
  • FSH: maturation of the egg in the ovary
  • LH: stimulates the release of an egg cell
  • oestrogen: repairing and thickening the uterus lining + inhibiting FSH
  • progesterone: maintains uterus lining
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29
Q

Explain the interaction between all the hormones in the menstrual cycle

A
  • the pituitary gland produces FSH which causes the development of a follicle in an ovary
  • whilst developing, the follicle produces the hormone oestrogen
  • this stops the production of FSH and thickens the uterus lining
  • when the oestrogen rises high enough, the pituitary gland releases LH, which causes ovulation, wherein an egg is released from the follicle
  • the follicle becomes a corpus luteum which triggers the production of oestrogen and progesterone inhibiting FSH + LH
  • if the egg hasn’t been fertilised, the corpus luteum dies and uterus sheds its lining which is menstruation
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30
Q

What is a corpus luteum?

A

The remains of the follicle in the ovary after it has released an egg

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31
Q

Define contraception

A

The prevention of fertilisation

32
Q

State and explain some contraceptive methods

A
  • condom: placed over erect penis, prevents sperm from entering the vagina. 98% success rate
  • diaphragm or cap: placed over the cervix, prevents sperm in the vagina from entering the uterus. 92 - 96% success rate
  • hormone pill or implant placed under skin: releases hormones to prevent ovulation + thickens cervical mucus, making it difficult for sperm to pass through
33
Q

Why do some women have difficulties in pregnancy?

A
  • low FSH levels
  • very high levels of oestrogen
  • poor egg quality
  • problems with fallopian tube
  • male partner with few healthy sperm
34
Q

State two methods of fertilisation therapy

A
  • clomiphene therapy
  • IVF
35
Q

Explain Clomiphene therapy

A
  • useful for women who rarely/ never release an egg
  • clomifene is a drug that increases blood FSH + LH levels
36
Q

Explain In Vitro Fertilisation

A
  • useful for people with oviducts and sperm problems
  • egg follicle maturation stimulated by hormones
  • when egg is released, it is taken from ovary + sperm cells taken from man
  • egg and sperms combined to allow fertilisation
  • one or two healthy embryos placed in the uterus
37
Q

Define glycogen

A

What excess glucose is converted into in liver and muscle cells

38
Q

What is diabetes

A

A condition wherein blood glucose levels can’t be controlled by the body

39
Q

What is the difference between type one and type two diabetes?

A
  • type one: cannot control rising blood glucose concentration because the cells in the pancreas are destroyed by the immune system, so the kidneys end up excreting excess glucose. This is a condition that a person inherits from birth
  • type two: the person’s body cells no longer respond to the insulin produced by the pancreas. This is a condition that a person inherits through their lifestyle
40
Q

How can type one diabetes be controlled?

A
  • injecting insulin
  • monitoring diet and levels of physical activity
41
Q

How can type two diabetes be controlled?

A

By a regulated carbohydrate-based diet and frequent exercise

42
Q

What does insulin cause?

A
  • glucose to move from the blood to muscle cells for respiration
  • excess glucose to be converted into glycogen which is then stored in the liver
43
Q

What is a risk factor for acquiring type two diabetes?

A
  • obesity
  • as body mass increases, the risk of developing type two diabetes increases significantly
44
Q

Define thermoregulation and why is it important?

A

The act of keeping our internal temperature constant, important because if a body temperature of 37 degrees is increased, our enzymes will denature

45
Q

What happens to our body when we get too cold?

A
  • Skeletal muscles contract rapidly and we shiver
  • contractions require energy from respiration which sometimes releases heat
  • nerve impulses are set to the hair erector muscles in the dermis which contract
  • raises the skin hairs and traps a layer of insulating air to the skin
  • reduction of blood flow near the skin which keeps warm blood deeper inside your body, reducing the rate of thermal energy transfer
46
Q

What happens when we get too hot?

A
  • sweat glands in the dermis release more sweat onto the surface of the epidermis
  • sweat evaporates transferring heat energy from the skin to the environment
47
Q

What is the difference between vasoconstriction and vasodilation and what do they both do?

A

Control the amount of blood flowing through capillaries
- vasoconstriction: narrowing of arterioles supplying the skin’s blood capillaries, causing less blood to flow
- vasodilation: increase in diameter of the skin’s arterioles to increase blood flow and heat loss by radiation

48
Q

What is osmoregulation?

A

The control of water and mineral ions in the blood

49
Q

What will happen if blood becomes too dilute?

A

Water will move into cells through osmosis, causing them to eventually swell and burst under pressure

50
Q

What happens if the blood becomes too concentrated?

A

Water will move out of cells and they will shrink

51
Q

What is the role of the urinary system?

A

Removes impurities and waste products from our blood, which are excreted in urine

52
Q

What is the route that the blood takes to become purified?

A
  • blood is transported to the kidney through the renal artery
  • blood is filtered at a high pressure and the kidney selectively reabsorbs any useful materials, eg: glucose, mineral ions and water. Any excess is sent to the ureter for excretion and eventually the bladder
  • the purified blood eventually returns to circulation via the renal vein
53
Q

What is the role of the kidney?

A

To regulate the levels of salt, ions and urea in the blood

54
Q

What is the role of the ureters?

A

Tubes that carry urine from kidneys to bladder

55
Q

What is the role of the urethra?

A

Tube that carries urine out of the body

56
Q

What is urea and when is it produced?

A
  • produced in the liver when excess amino acids are broken down
  • main waste product removed in urine
  • as it is not reabsorbed by the kidney
57
Q

What occurs during kidney failure?

A

When both kidneys stop working, causing a build-up of waste substances

58
Q

What are the two treatments available for kidney failure?

A
  • kidney dialysis
  • organ transplant
59
Q

How does dialysis work?

A
  • unfiltered blood is taken from a blood vessel in the arm, mixed with blood thinners / an anti-coagulant to prevent clotting and pumped through the dialysis machine
  • inside the machine, blood and the dialysis fluid are separated by a partially permeable membrane
  • the blood flows in the opposite direction as compared to the dialysis fluid, allowing for the creation of a concentration gradient for the exchange of substances occur
60
Q

What is dialysis?

A

Patients are connected to a dialysis machine which acts as an artificial kidney to remove most of the urea and restore/ maintain the water and ion balance of blood

61
Q

What does dialysis fluid contain?

A
  • a similar glucose concentration to a normal level of blood
  • a concentration of mineral ions similar to that found in normal blood plasma
  • no urea
62
Q

What are the advantages of a dialysis machine?

A
  • allows a person with kidney failure to maintain their health
  • blood leaving the machine and going to the patient’s arm will be clean
  • greatly reduced levels of urea
  • no overall change in blood glucose levels
  • correct mineral ions and water balance maintained/ balanced
63
Q

What are the disadvantages of the dialysis machine?

A
  • requires highly specialised + expensive machinery
  • time-consuming (4-6 hours, 2-3 times a week)
  • restrictive, mainly occurs in a hospital
  • must monitor diet carefully
  • will only work for a limited amount of time until a transplant s required
64
Q

What occurs in a transplant?

A

Wherein the kidney is replaced altogether

65
Q

What are the two precautions that must be taken before a transplant?

A
  • tissue typing: they match the antigens on the donor kidney to the host kidney (not a perfect match, but close)
    –> takes a long time
  • immunosuppressant drugs: suppress the immune system
    –> must be taken for the rest of the patient’s life
    –> makes them more susceptible to pathogen attacks
66
Q

What are the advantages of a kidney transplant?

A
  • cheaper for the NHS
  • Patient’s can lead a normal life
67
Q

What are the disadvantages of a kidney transplant?

A
  • must take immunosuppressant drugs which decrease the risk of rejection
  • shortage of donors
  • kidney only lasts for 8-9 years
  • any operation carries risks
68
Q

What are nephrons?

A

Small units that make up the kidney

69
Q

What are the stages the kidney works in?

A
  • filtration
  • selective reabsorption
  • formation of urine
70
Q

Describe what happens in filtration

A
  • occurs in the glomerulus
  • blood passes into the kidney’s many capillaries
  • blood under high pressure at the start of the nephron, which helps the ultrafiltration of the blood
  • small molecules are squeezed out and pass into the nephron tubule called the Bowman’s Capsule
    –> Small molecules: urea, water, ions, and glucose
  • large molecules too big to fit through the wall and will remain in the blood
71
Q

Describe what happens in selective reabsorption

A
  • occurs in the proximal convoluted tubule
  • kidneys must reabsorb the useful molecules that just got filtered out
  • allows those that are not needed to pass out and form urine
  • reabsorption of water and ions occur in the loop of Henle and collecting areas of the tubule
72
Q

What molecules are reabsorbed by the kidney during reabsorption?

A
  • all of the glucose initially filtered out
  • as much water as the body requires to maintain a constant water level in the blood plasma
  • as many ions as the body needs to maintain a constant balance of mineral ions in the blood plasma
73
Q

Describe what happens during the formation of urine

A
  • molecules that aren’t reabsorbed continue along the nephron tubule as urine
  • this eventually passes down the bladder
  • urine exits in the ureter
74
Q

What are the adaptations of a nephron?

A
  • large surface area of contact between nephron and capillaries
  • cell membrane of first convoluted tube has folds (microvilli) increasing the surface area
  • cells that use active transport have lots of mitochondria
  • cells of bowman’s capsule and glomerulus capillaries have spaces making them leaky
75
Q

What does ADH affect?

A
  • affects the water potential of the collecting duct of the kidney
76
Q

What does ADH do if the water potential is too high?

A
  • less ADH is released from the pituitary gland
  • making the collecting duct less permeable to water
  • leads to more water being released in urination
77
Q

What does ADH do if the water potential is too low?

A
  • more ADH is released from the pituitary gland
  • making the collecting duct more permeable to water
  • less water remains in the tubule + more entering blood surrounding the tubule
  • less water is released in urination

Biology (18 decks)

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