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Biology > CB7- Animal Coordination, Control And Homeostasis > Flashcards

CB7- Animal Coordination, Control And Homeostasis Flashcards

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1
Q

What is a hormone?

A

A hormone is a chemical messenger which is carried by the blood and sent to different parts of the body in order to control things that need constant adjustment.

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2
Q

What are some similarities between the hormonal system and nervous systemm?

A
  • both function as systems that are designed to send messages to trigger a response
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3
Q

What are some differences between the hormonal system and nervous system?

A
  • the hormonal system works much slower
  • the hormonal system sends message through chemical signalling in blood cells, rather than electrical impulses
  • the signal transmissions form the nervous system are very fast but short lived whereas the hormonal system is slow but acts for a long time
  • neurones act in one specific area whereas hormones are more general
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4
Q

What are endocrine glands?

A
  • the various glands that produce and excrete hormones all over the body
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5
Q

Hormones affect particular cells in particular organs. These are called target organs. What are they?

A
  • target organs are organs that are affected by a specific hormone
  • the said hormone will affect the body by stimulation or just changing what the target organ is doing
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6
Q

What is the pituitary gland?

A
  • the ‘master gland’ that is near the brain
  • it is the master gland because it produces many hormones that act on other glands, also directing them to release the necessary hormones
  • some of these hormones it produces includes TSH, ACTH, FSH, AND LH
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7
Q

What is the thyroid gland?

A
  • the gland that produces thyroxine
  • it is apart of a negative feedback system
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8
Q

What is thyroxine?

A
  • a hormone that is involved in regulating things such as the rate of metabolism, heart rate, temperature and it also influences growth and development
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9
Q

Explain thyroxine negative feedback when blood thyroxine levels become too low.

A
  • when blood thyroxine levels become too low, the hypothalamus is stimulated to release TRH
  • TRH then stimulates the pituitary gland to release TSH (thyroid stimulating hormone)
  • TSH stimulates the thyroid into releasing thyroxine so that the blood thyroxine levels go back to normal
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10
Q

What is negative feedback?

A
  • negative feedback is when levels of hormones are controlled when they become anything but their regular state
  • if the level of hormones become too high or low, a response will be triggered in order to bring it back to its normal conditions
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11
Q

Explain thyroxine negative feedback when blood thyroxine levels get too high.

A
  • when blood thyroxine levels are too high the release of TRH will be inhibited
  • this way the pituitary gland will be unable to produce TSH
  • High levels of blood thyroxine directly inhibit the secretion of TSH from the pituitary gland and TRH from the hypothalamus
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12
Q

What are the adrenal glands?

A
  • adrenal glands are located above the kidneys and they release Adrenalin
  • this is NOT an example of negative feedback
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13
Q

Explain the release of Adrenalin from the adrenal glands.

A
  • in normal conditions, little adrenalin in released into the blood but when excited or frightened there is a significant increase in impulses from the neurones
  • these impulses are connected to the spinal chords which are able to reach the adrenal glands, causing a large release of Adrenalin creating a fight or flight response.
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14
Q

How is the hormone Adrenalin able to create a fight or flight sense?

A
  • Adrenalin does this by targeting certain organs that are able to activate processes that increase the supply of oxygen and glucose to cells so that they can respirate and prepare for fight or flight.
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15
Q

How does Adrenalin target the liver?

A
  • Adrenalin binds to receptors in the liver causing a breakdown of glycogen stores in order to release glucose
  • this increases the blood-glucose levels so more glucose can be transported to cells to create high rates of respiration
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16
Q

How does Adrenalin target the heart?

A
  • binds to specific receptors in the heart, causing heart muscles to contract more frequently to increase the heart rate but also more strongly to increase the blood pressure.
  • this increases the blood flow to muscles so that cells receive more oxygen and glucose for respiration
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17
Q

How does Adrenalin target blood vessels?

A
  • Adrenalin causes the diameter of blood vessels, leading to muscles to widen in order to increase the blood flow to muscles providing more oxygen and glucose
  • it also causes the diameter of blood vessels leading to other organs to narrow, reducing blood flow, but also increasing blood pressure
  • makes all the blood travel to one specific area, or it could just be to make the overall pressure larger.
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18
Q

What are the ovaries?

A
  • another endocrine gland which produces the sex hormones oestrogen and progesterone
  • it’s target organ is the ovaries itself
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19
Q

What is puberty?

A
  • a period in which adolescents start to develop secondary sexual characteristics
    Eg. Boobs
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20
Q

What is the menstrual cycle?

A
  • a cycle of changes in a women’s reproductive system that lasts around 28 days
  • the menstrual cycle occurs so that the female body can release an egg and prepare the uterus for fertilisation
  • this cycle continues from puberty to menopause
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21
Q

Name and describe the 4 stages of the menstrual cycle.

A

Stage 1- day 1- menstruation starts and the thickened part of the uterus lining along with an unfertilised egg cells breaks down due to the lack of fertilisation

Stage 2- day 4-14- the uterus lining begins to thicken again until it becomes fully repaired into a thick spongy layer, full of blood vessels and ready to carry a fertilised egg, oestrogen levels will increase in this stage because it helps to thicken the lining of the uterus

Stage 3- day 14- ovulation - the ovary develops an egg and releases it, LH levels rise because it surge triggers ovulation

Stage 4- 14-28- uterus lining is maintained (progesterone levels are high since it maintains the uterus lining) and continues to thicken. Eventually if no egg is fertilised, the spongy lining will start to break down and the whole cycle will begin again, progesterone levels drop allowing FSH to increase so the whole cycle is started again

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22
Q

Describe FSH (follicle stimulating hormone)

A
  • released by the pituitary gland
  • stimulates a follicle (an egg with surrounding cells) to mature in the ovaries
  • stimulated ovaries to produce oestrogen, however when oestrogen levels are increased this inhibits FSH
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23
Q

Describe oestrogen

A
  • hormone released from the ovaries
  • causes the lining of uterus to grow and thicken
  • high levels of oestrogen inhibits FSH but also stimulates LH
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24
Q

Describe LH (luteinising hormone)

A
  • released by the pituitary gland
  • LH surge stimulates ovulation on day 14- the follicle ruptures and the egg is released
  • also stimulates the rest of the follicle to develop into a structure called corpus luteum which secretes progesterone
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25
Q

Describe progesterone

A
  • released by the ovaries and corpus luteum after ovulation
  • maintains the lining of the uterus
  • inhibits the release of FSH and LH
  • if levels of progesterone and oestrogen fall the uterus lining breaks down triggering menstruation
  • low progesterone allows FSH to increase starting the cycle from scratch
  • if a fertilised egg were to implant in the uterus, levels of progesterone would be very high in order to maintain the lining and keep in strong
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26
Q

What are the functions of each of the menstrual hormones?

A

FSH- stimulate the growth of an egg follicle
Oestrogen- help build and thicken the lining of the uterus
LH- stimulates the surge of ovulation
Progesterone- maintain the uterus lining

27
Q

How does fertilisation occur?

A
  • during sexual intercourse sperm will be deposited within the vagina, pass through the cervix, to the uterus and then into the oviducts where fertilisation occurs
28
Q

What are some physical barrier contraceptive methods?

A
  1. Male condom- place over erect penis, preventing sperm from entering the vagina, it has a 98% success rate
  2. Female condom (diaphragm)- placed over cervix preventing sperm in the vagina from entering, must also be used with a spermicide to kill sperm cells, success rate is 92-96%
29
Q

Describe how hormonal contraceptive methods work.

A

Release hormones to prevent ovulation and thicken mucus and the cervix, making it difficult for sperm to penetrate.

30
Q

How can an increase in oestrogen be used as a contraceptive method?

A
  • oestrogen prevents the release of an egg because if it is kept consistently high the production of FSH is inhibited- after a while egg development and production will stop
31
Q

How can an increase in progesterone levels be used an a contraceptive method?

A
  • progesterone can be used to reduce fertility because it stimulates the production of a thick cervical mucus, preventing sperm from getting through
  • this can come in the form of the mini pill and contraceptive injection
32
Q

What are some pros of barrier contraceptive methods?

A
  • can protect against STD’s
  • most has a high success rate
  • no hormonal side effects
  • relatively affordable
33
Q

What are some cons of barrier contraceptive methods?

A
  • do not always work
  • could be high maintenance as it always has to be thought about before every encounter
34
Q

What are some pros of hormonal contraceptive methods?

A
  • more effective
  • more low maintenance as some forms of this can be more long term
35
Q

What are some cons of hormonal contraceptive methods?

A
  • don’t protect against STD’s
  • can have unpleasant side effects like acne, headaches and mood swings
36
Q

What is ART?

A
  • assisted reproductive therapy which uses hormones and other techniques in order to help infertile women have babies and increase they chance of pregnancy
  • IVF is an example of ART
37
Q

Describe IVF

A
  • overcomes problems such as blocked ovaries and low levels of healthy sperm
  • involves collecting eggs from a women’s ovaries and fertilising them using a man’s sperm
  • once they are tiny balls of cells 1 or 2 of them are transferred into the women’s uterus to increase chances of pregnancy
38
Q

Describe each stage of the process of IVF

A
  1. Egg follicle maturation and production is stimulated by FSH and LH
  2. Egg cells will then be released to be taken from the ovaries, sperm is taken from the man
  3. Egg and sperm are combined to allow for fertilisation
  4. One or two healthy embryos are placed into the uterus
39
Q

What is clomifene therapy?

A
  • women who are infertile because they struggle to regularly ovulate or ovulate at all can use clomifene
  • this is a drug that causes more FSH and LH to be released by the body, stimulating egg maturation and ovulation
  • intercourse during times of ovulation increases the chances of falling pregnant
40
Q

What is the definition of homeostasis?

A
  • the constant maintenance of an internal environment so that your cells are in the right condition to function properly
  • to maintain these conditions the body has to be able to react to internal and external changes while balancing inputs (things going into your body) and outputs (leaving the body)
41
Q

Name three of the main examples of homeostasis.

A
  • blood glucose regulation- making sure the amount of glucose in the blood is not too high or low
  • osmoregulation- regulating water content that goes inside your body through drinking, food and respiration but also the water that leaves your body through excretement
  • thermoregulation- regulating body temperature- the body must reduce temperatures when hot, but increase when cold
42
Q

How does negative feedback play a role in homeostasis?

A
  • negative feedback plays a very large role in homeostasis because it helps the body conditions to remain normal
  • if the conditions change drastically the body will create a counter response to bring it back to normal
43
Q

How is glucose transported into the blood stream?

A
  • when eating foods containing carbohydrates, glucose is released during digestion
  • this glucose is easily absorbed by the small intestines and is put into the blood stream, then into cells who need this glucose in order to carry out respiration
44
Q

How does the body’s glucose level increase?

A
  • when eating these foods with high carbohydrates, it may take time for cells to take in glucose from digestion
  • this can cause high glucose levels that can damage organs
45
Q

How are blood-glucose levels controlled?

A
  • changes in blood glucose are monitored and controlled by the pancreas- using the hormones insulin and glucagon
  • excess glucose can also be stored as glycogen in the liver muscles and other cells, if these stores become full than the glucose can be stored as lipids (fats) in the body tissue.
46
Q

Explain what happens when blood glucose concentration is too high.

A
  • if there is too much glucose in the blood, the pancreatic cells will respond by secreting insulin
  • after this the blood will still contain too much glucose, but this time round it will also have insulin
  • when this reaches the liver, the insulin binds into receptors in the liver, muscles and other cells to take in this glucose
  • they will then turn this glucose into glycogen for storage
47
Q

What is glycogen?

A
  • a store of glucose
48
Q

What is glucagon?

A
  • a hormone found in the pancreas which promotes the breakdown of glycogen into glucose
49
Q

What happens if blood glucose concentration is low?

A
  • the blood will firstly have too little glucose
  • the pancreas will detect this and excrete glucagon
    -the blood will still contain too little glucose, but this time it will have glucagon
  • once reaching the liver, the glucagon will make the liver turn its stores of glycogen into glucose
  • this glucose will then be released into the blood by the liver
50
Q

How does type 1 diabetes occur?

A
  • the pancreatic cells may be damaged or destroyed by the bodies immune system
  • there could also be genetics that some may inherit making them more likely to develop diabetes, however this doesn’t always happen and type 1 diabetes is usually due to an environmental factor
51
Q

How do people with type 1 diabetes need to be treated?

A
  • insulin therapy
  • involves injecting insulin into the subcutaneous tissue (fat tissue underneath the skin) to enter the blood faster
  • this is done during mealtimes to ensure that when the food is digested, the glucose obtained from the carbohydrates are removed very swiftly to make sure blood glucose levels don’t increase
  • the amount of insulin injected also depends on the persons diet and physical activity
52
Q

What are some lifestyle changes people with type 1 diabetes can factor into their lives.

A
  • limit intake of foods high in simple carbohydrates
  • regular exercise to help remove glucose from the blood
53
Q

What is type 2 diabetes?

A
  • a condition where the pancreas does not produce enough insulin or when someone’s body cells become resistant to insulin altogether.
54
Q

What are some ways to treat type 2 diabetes?

A
  • some people can just eat healthy, keeping sugar in their diet low and partaking in physical activity (exercise takes glucose out of blood because it uses it for respiration)
  • people with more severe type 2 diabetes on the other hand can have medication to reduce the amount of glucose the liver releases or to increase the sensitivity of target organs that are supposed to react to insulin
55
Q

How are obesity and type 2 diabetes linked?

A
  • obesity increases the likelihood of developing type 2 diabetes
56
Q

How do you calculate BMI?

A

Weight (kg) / height (m) ^2

57
Q

What is a healthy BMI?

A

18.5-24.9

58
Q

What is an overweight BMI?

A

Above 25

59
Q

What is an OBESE BMI?

A

Above 30

60
Q

What are some negatives of using BMI as an index?

A

Doesn’t factor in the distribution of weight and also doesn’t distinguish between actual body fat and things like muscles

61
Q

How do you calculate waist:hip ratio?

A

Waist circumference (cm) / hip circumference (cm)

62
Q

Why is the waist to hip ratio more accurate?

A

It targets the abdomen which is where most stored fat goes to

63
Q

What are healthy waist to hip ratios for men and women?

A

Men over 1.0 = increased risk of type 2
Women over 0.85 = increased risk of type 2

Biology (9 decks)

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