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topic 7 Flashcards

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1
Q

what is a hormone?

A

A hormone is 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

where is thyroxine produced

A

in the thyroid gland

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3
Q

what hormone does the thyroid gland produce?

A

thyroxine

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4
Q

where is ADH produced?

A

the pituitary gland

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5
Q

what hormone does the pituitary gland produce?

A

ADH

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6
Q

where is adrenaline produced?

A

the adrenal gland

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7
Q

what hormone does the adrenal gland produce?

A

adrenaline

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8
Q

where is insulin produced?

A

the pancreas

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9
Q

what hormone does the pancreas produce?

A

insulin

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10
Q

where is testosterone produced?

A

the testes

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11
Q

what hormone do the testes produce?

A

testosterone

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12
Q

where is oestrogen produced?

A

in the ovaries

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13
Q

what hormone do the ovaries produce?

A

oestrogen

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14
Q

how are hormones transported to their target organs?

A

carried in the bloodstream

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15
Q

how do the adrenal glands react in times of fear or stress?

A
  • adrenaline is produced
  • targets vital organs
  • increases the heart rate
  • boosts the delivery of oxygen and glucose to the brain and muscles
  • preparing the body for ‘flight or fight’.
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16
Q

when adrenaline is released into the bloodstream what effects does it create?

A
  • increases breathing rate
  • heart rate
  • increased conversion of glycogen to glucose so more energy is released in the muscles (increased blood sugar levels)
  • diverts blood away from areas, such as the digestive system, towards the muscle
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17
Q

what do low thyroxine levels in the bloodstream stimulate?

A
  • stimulate the hypothalamus to release TRH
  • this causes the pituitary to release TSH so the thyroid releases more thyroxine
  • so blood levels return to normal.
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18
Q

what do normal thyroxine levels in the bloodstream stimulate?

A
  • TRH release from the hypothalamus

- this inhibits the release of TSH from the pituitary, so normal blood levels are maintained

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19
Q

negative feedback

A

A mechanism where changes to conditions cause an action to reverse the change, to keep conditions stable.

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20
Q

what is the process called that controls thyroxine levels?

A

negative feedback

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21
Q

what is the role of FSH (follicle stimulating hormone) in the menstrual cycle?

A
  • causes an egg to mature in the ovary

- stimulates the ovaries to release oestrogen

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22
Q

what is the role of oestrogen in the menstrual cycle?

A
  • stops FSH being produced (so that only one egg matures in a cycle)
  • repairs, thickens and maintains the uterus lining
  • stimulates the pituitary gland to release LH
23
Q

what is the role of LH (luteinising hormone) in the menstrual cycle?

A

-trigger ovulation (the release of a mature egg)

24
Q

what is the role of progesterone in the menstrual cycle?

A

-maintains the lining of the uterus during the latter part of the menstrual cycle and during pregnancy

25
Q

stages of the menstrual cycle with the interactions of oestrogen, progesterone, FSH and LH:

A
  • the pituitary gland produces FSH: causes the development of a follicle in the ovary
  • as the egg develops inside the follicle, the follicle produces the hormone oestrogen.
  • the oestrogen causes growth and repair of the lining of the uterus wall. oestrogen inhibits FSH.
  • when oestrogen rises to a high enough level it causes a surge in LH from the pituitary which causes ovulation where an egg is released from the follicle (day 14)
  • follicle becomes the corpus luteum and this produces oestrogen and progesterone which inhibit FSH and LH production by the pituitary.
  • progesterone maintains the uterus lining
  • if the egg has not been fertilised, the corpus luteum dies and progesterone levels drop. This causes menstruation, where the uterus lining breaks down
26
Q

hormonal methods of contraception:

A
  • oral contraceptive (the pill) contains oestrogen or progesterone or a combination of both hormones. These hormones inhibit the production of FSH, and eggs cannot mature.
  • contraceptive injections, implants or skin patches contain slow release progesterone to inhibit the maturation and release of eggs.
27
Q

non-hormonal methods of contraception:

A
  • condoms and diaphragms, which prevent the sperm reaching an egg
  • intrauterine devices (IUD) also known as a coil, prevent the implantation of an embryo or release of a hormone
  • spermicidal agents which kill or disable sperm
  • abstaining from intercourse when an egg may be in the oviduct
  • surgical methods of male and female sterilisation - i.e. vasectomy (sperm ducts are cut and tied)
28
Q

benefits and risks of non-hormonal methods of contraception:

A
  • condoms are easy and quick to use, but sometimes they can tear or rip
  • diaphragms need to be put in just before sex and left in several hours afterwards
  • IUDs need to be fitted by a health professional - can remain in position for up to 10 years, small risk of causing an ectopic pregnancy
  • spermicidal agents can be added to other physical barriers such as condoms, but some can have allergic reactions to these
  • abstaining can be used successfully, but if the timings are not accurate the chance of pregnancy is high
  • surgical methods cannot be reversed, and is considered permanent
29
Q

the stages of IVF (In vitro fertilisation):

A
  • IVF involves giving a mother FSH and LH, to stimulate the maturation of several eggs in the ovary
  • the eggs are collected from the mother and fertilised by sperm from the father in a dish in the laboratory
  • the fertilised eggs develop into embryos
  • at the stage when they are tiny balls of cells one or two embryos are inserted into the mother’s uterus (womb)
30
Q

how does clomifene therapy work?

A
  • clomifene is used as a fertility drug to stimulate ovulation, the release of eggs
  • it works by blocking the action of oestrogen’s negative feedback on LH
  • therefore more LH is released in a surge
  • this mimics the LH surge which occurs just before ovulation
31
Q

Explain the importance of maintaining a constant internal environment in response to internal and external change

A

it is important to maintain a constant internal environment to help prevent damage to the body when internal and external conditions change. this is called homeostasis

32
Q

Explain the importance of homeostasis including: thermoregulation – the effect on enzyme activity

A
  • thermoregulation is the control of body temperature which keeps the temperature of the major organs at 37°C.
  • above 38°C is hyperthermia and below 36°C is hypothermia.
  • both hyperthermia and hypothermia are dangerous they affect how well the enzymes in the body work.
33
Q

Explain the importance of homeostasis, including: osmoregulation - the effect on animal cells

A
  • osmoregulation is the control of the balance of water and mineral salts in the body.
  • if the balance of water and mineral salts is wrong, then cells may take in or lose too much water by osmosis.
  • this can damage cells because water in cells allows all the molecules in the cell’s reactions to move around.
34
Q

Explain how thermoregulation takes place

A
  • the hypothalamus receives information from temperature receptors in the dermis of the skin.
  • this process is controlled by the thermoregulatory centre, contained in the hypothalamus in the brain, and it contains receptors sensitive to the temperature of the blood. The skin also has temperature receptors and sends nervous impulses back to the hypothalamus.
  • the hypothalamus responds to this information by sending nerve impulses to effectors in the skin to maintain body temperature.
35
Q

how does thermoregulation work when the body becomes too hot?

A
  • sweat glands in the dermis release more sweat onto the surface of the epidermis
  • the sweat evaporates, transferring heat energy from the skin to the environment.
36
Q

how does thermoregulation work when we get too cold?

A
  • muscles contract rapidly and we shiver.
  • these contractions need energy from respiration, and some of this is released as heat
  • nerve impulses are sent to the hair erector muscles in the dermis, which contract
  • this raises the skin hairs and traps a layer of insulating air next to the skin.
37
Q

a response to being too hot:

A

vasodilation

  • the arterioles get wider
  • the blood flow through the skin capillaries increases
  • heat loss from the skin increases
38
Q

a response to being too cold:

A

vasoconstriction

  • the arterioles get narrower
  • blood flow through the skin capillaries decreases
  • heat loss from the skin decreases
39
Q

Explain how the hormone insulin controls blood glucose concentration

A
  • if the blood glucose concentration is too high, the pancreas produces the hormone insulin, this causes glucose to move from the blood into the cells
  • in liver and muscle cells excess glucose is converted to glycogen for storage, and will be used at a later date.
40
Q

Explain how blood glucose concentration is regulated by glucagon

A
  • when blood glucose falls, cells in the pancreas secrete glucagon
  • glucagon instructs the liver to convert glycogen to glucose, making glucose more available in the bloodstream
  • then insulin attaches to its receptors on the body’s cells and ensures that they can absorb glucose.
41
Q

explain the cause of type 1 diabetes:

A
  • type 1 diabetes is a disorder in which the pancreas fails to produce enough insulin
  • this can be detected from an early age. It is characterised by uncontrolled high blood glucose levels and it can be controlled by injecting insulin.
42
Q

explain the causes of type 2 diabetes:

A
  • in type 2 diabetes the person’s body cells no longer respond to insulin produced by the pancreas
  • it can be controlled by a carbohydrate controlled diet and an exercise regime
  • carbohydrate is digested into glucose, which raises the overall blood glucose level
43
Q

how can type 2 diabetes be controlled?

A
  • losing weight
  • eating well
  • exercising
  • diabetes medication
  • insulin therapy
44
Q

how can type 1 diabetes be controlled?

A
  • must take insulin as part of their treatment
  • their bodies can’t make insulin anymore -they need to get the right amount to keep their blood sugar levels in a healthy range
45
Q

BMI calculation:

A
46
Q

Describe the structure of the urinary system

A
  • blood brought to the kidney in renal artery
  • the kidneys filter blood and then reabsorb useful materials such as glucose
  • after it has been purified, blood returns to the circulation through the renal vein.
  • urine taken from the kidneys to the bladder by the ureters
  • the bladder stores the urine until it is convenient to expel it from the body.
47
Q

stage 1 of a nephron:

A

filtration:

  • glomerulus filters the blood and removes water, glucose, salts and waste urea from it
  • blood is under high pressure at the start of the nephron, which aids the filtration of the blood
  • these waste substances all pass from the capillaries in the glomerulus into the Bowman’s capsule
  • purifies the blood
  • waste substances then move from the Bowman’s capsule towards the loop of Henle
  • proteins are too large to pass through here and so remain in the blood
48
Q

stage 2 of a nephron:

A

selective reabsorption:

  • kidneys must now reabsorb the molecules which are needed, while allowing those molecules which are not needed to pass out in the urine
  • the kidneys selectively reabsorb only those molecules which the body needs back in the bloodstream
  • the reabsorbed molecules include:
    • all of the glucose which was originally filtered out
    • as much water as the body needs 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
49
Q

stage 3 of a nephron:

A

forming urine:

  • the molecules which are not selectively reabsorbed (the urea, excess water and ions) continue along the nephron tubule to the collecting ducts as urine
  • this eventually passes down to the bladder
50
Q

Explain the effect of ADH on the permeability of the collecting duct in regulating the water content of the blood

A
  • the hypothalamus in the brain has osmoreceptors which detect the level of water in the blood plasma as a stimulus
  • if the level of water is too low, this causes the hypothalamus to send a signal to the pituitary gland, to release the anti-diuretic hormone or ADH.
  • ADH travels in the bloodstream to its target organ, the kidneys
  • it causes the kidney tubules to become more permeable. This means more water can leave the kidney tubule to be reabsorbed back into the blood during selective reabsorption
  • different amounts of ADH are released into the bloodstream according to the concentration of water in the blood plasma. The diagrams show what happens when there is either too little or too much water in the blood
51
Q

Treating kidney failure by transplant

A

-implanting a kidney from an organ donor into the patient’s body to replace the damaged kidney

52
Q

potential dangers of kidney transplants

A
  • as with all cells, the donor kidney cells will have protein antigens on their surface
  • differences in the antigens of the donor kidney cells and those of the patient receiving the transplant would mean that the patient’s immune system would quickly form antibodies against the kidney cell antigens, and would ultimately destroy the kidney
  • this is known as organ rejection
  • this is potentially very harmful for the patient.
53
Q

how does kidney dialysis work?

A
  • unfiltered blood that is high in urea is taken from a blood vessel in the arm, mixed with blood thinners or an anti-coagulant to prevent clotting, and pumped into the dialysis machine
  • inside the machine the blood and dialysis fluid are separated by a partially permeable membrane the blood flows in the opposite direction to dialysis fluid
  • this allows exchange to occur between the two where a concentration gradient exists.

Dialysis fluid contains:
-a glucose concentration similar to a normal level in the blood
-a concentration of ions similar to that found in normal blood plasma
no urea
-as the dialysis fluid has no urea in it, there is a large concentration gradient - meaning that urea moves across the partially permeable membrane, from the blood to the dialysis fluid, by diffusion.
-this is very important as it is essential that urea is removed from the patients’ blood.

  • as the dialysis fluid contains a glucose concentration equal to a normal blood sugar level, this prevents the net movement of glucose across the membrane as no concentration gradient exists. This is very important as the patients’ need to retain glucose for respiration.
  • and, as the dialysis fluid contains an ion concentration similar to the ideal blood plasma concentration, movement of ions across the membrane only occurs where there is an imbalance.
  • if the patient’s blood is too low in ions, they will diffuse from the dialysis fluid into the blood, restoring the ideal level in the blood.
  • if the patient’s blood is too high in ions, the excess ions will diffuse from the blood to the dialysis fluid.
54
Q

how is urea produced?

A

-from the breakdown of excess amino acids in the liver

Biology (15 decks)

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