B3.2 The Endocrine System

Question 1

What are hormones?

Answer 1

Hormones are chemical messengers

Question 2

Where are hormones produced?

Answer 2

They are produced in endocrine glands and are secreted into the blood.

Question 3

Where in the blood do hormones travel in?

Answer 3

The blood transports the hormones in the plasma around the body

Question 4

What do hormones control?

Answer 4

Hormones control body processes that need constant adjustment - such as body temperature

Question 5

Define homeostasis

Answer 5

Maintaining a controlled internal environment

Question 6

Name all the glands and the hormones they produce

Answer 6

thyroid gland produces thyroxine
adrenal glands produces adrenaline 
Pancreas produce insulin and glucogen
Reproductive glands:
- ovaries produce oestrogen and progesterone 
- testes produce testosterone

Question 7

What do the hypothalamus and pituitary gland produce?

Answer 7

These produce hormones that regulate production of other hormones

Question 8

How do hormones travel to target organs?

Answer 8

Hormones diffuse out of the blood and bind to specific receptors for that hormone, found on membranes or in the cytoplasm of cells in the target organs, known as target cells. Once bound to their receptors the hormones stimulate the target cells to produce a response

Question 9

Compares the nervous system to the endocrine system

Answer 9

The speed of communication for nerves is very fast whereas for hormones it is slower.
In the nervous system an electrical impulse travels along the axon of a neurone. In the endocrine system the hormones are transported in the blood.
The duration is response is short for nerves whereas for hormones it is long acting.
Nerves target a very precise area whereas hormones target a larger area

Question 10

Where are the adrenal glands located?

Answer 10

The adrenal glands are located just above the kidneys

Question 11

What does adrenaline do?

Answer 11

Adrenaline prepares the body for intensive action. It is called the ‘fight or flight’ response. They are secreted in times of stress.
It activates processes that increase the supply of oxygen and glucose to cells.

Question 12

How do adrenaline prepare the body for ‘fight or flight’?

Answer 12

Adrenaline binds to specific receptors in the heart. This causes the heart muscle to contract more frequently and with more force, so heart rate and blood pressure is increased.
This increases blood flow to the muscles, so the cells receive more oxygen and glucose for increased respiration.
Adrenaline also binds to receptors in the liver. This causes the liver to break down its glycogen stores to release glucose.
This increases the blood glucose level, so there’s more glucose in the blood to be transported to the cells.

Question 13

Where is the thyroid gland located?

Answer 13

In the neck

Question 14

What is thyroxine for?

Answer 14

Thyroxine plays an important role in regulating metabolic rate
It controls how much energy is available to the cells.

Question 15

How are thyroxine levels controlled?

Answer 15

When the body requires more energy, the hypothalamus causes the pituitary gland to releases thyroid-stimulating hormone (TSH). TSH stimulates the thyroid gland to release thyroxine. This increase the metabolic rate, allowing cells to transfer additional energy.
When cells have the required amount of energy, the hypothalamus inhibits TSH. The thyroid gland therefore stops releasing thyroxine.

Question 16

Testosterone

Answer 16

Main sex hormone
Produced in the testes
Stimulates sperm production and is important for the development of the male reproductive system.

Question 17

What is the menstrual cycle?

Answer 17

The menstrual cycle is a monthly cycle during which a woman’s body gets ready for pregnancy.

Question 18

How long does the menstrual cycle last?

Answer 18

28 days

Question 19

What happens in each stage of the menstruation cycle?

Answer 19

Day 1- The uterus lining breaks down and is released
From day 4 to day 14 the lining of uterus starts to thicken, to get ready to receive a fertilising egg.
About day 14 an egg develops and is released from an ovary. This is called ovulation.
The lining is then maintained for about 14 days, until day 28. If no fertilised egg has implanted into the uterus wall by day 28, the uterus lining starts to break down and then the whole cycle starts again.

Question 20

How effective is the oestrogen and progesterone pill?

Answer 20

Over 99%

Question 21

Ovary

Answer 21

Eggs mature here

Question 21

Negative tropism

Answer 21

If a part of the plant grows away from the stimulus

Question 23

cervix

Answer 23

entrance to uterus

Question 24

vagina

Answer 24

Receives sperm from the penis during sexual intercourse

Question 25

How effective is intrauterine device?

Answer 25

Over 99%

Question 26

Oestrogen

Answer 26

made and secreted by the ovaries Causes the lining of the uterus to thicken and grow Stimulates the production of LH Inhibits the production of FSH so that only one egg is released in each cycle Peaks between day 4 and day 14

Question 26

Explain the commercial use of plant hormones: | Producing seedless fruits

Answer 26

Fruits normally grow on plants which have been pollinated by insects. If the plant doesn't get pollinated, the fruit and seeds don't grow. If auxins and gibberellins are applied to the unpollinated flowers of some types of plant, the fruit will grow but the seeds won't. This produces parthenocarpio fruit- fruit without any seeds

Question 29

How effective is condom (female)?

Answer 29

95%

Question 30

LH

Answer 30

luteinising hormone Released from the pituitary gland Stimulates the release of an egg at day 14 (ovulation) Indirectly stimulates progesterone production

Question 31

Progesterone

Answer 31

Produced by the ovaries Maintains the lining of the uterus. When the level of progesterone falls and there's a low oestrogen level, the lining breaks down Inhibits the production of FSH and LH A low progesterone levels allows FSH to increase and then the whole cycle starts again If a fertilised ago implants in the uterus (i.e the woman becomes pregnant) then the progesterone level will stay high to maintain the uterus lining during pregnancy The progesterone levels stay high between day 14 and day 28 to see if the egg is going to be fertilised or not

Question 32

diaphragm or cervical cap

Answer 32

Non-hormonal Inserted into the vagina to cover the cervix. Prevents sperm cells from entering the uterus Removed after six or more house following sexual intercourse Not effective unless used in combination with a spermicide

Question 33

Define hormonal contraception

Answer 33

These use hormones to disrupt the normal female reproductive cycle.

Question 33

Explain the commercial use of plant hormones: | Ripening fruit

Answer 33

Ethene is sprayed on fruit trees and plants so that their fruits ripen quicker. This allows fruit to be ready earlier in the growing season.

Question 35

Progesterone pill

Answer 35

Hormonal Involves the hormone progesterone Thickens mucus from the cervix, stopping sperm from reaching an ovum It also thins the lining of the uterus preventing implantation, and can prevent ovulation Must be taken around the same time everyday

Question 36

How effective is condom (male)?

Answer 36

98%

Question 37

Describe the shoot's phototropism

Answer 37

Shoots are positively phototropic When a shoot tip is exposed to light, it accumulates more auxin on the side that's in the shade than the side that's in the light. This makes the cells elongate (grow) faster on the shaded side, so the shoot bend towards the lights.

Question 38

How effective is diaphragm and cap?

Answer 38

92% - 96%

Question 39

How effective is the progesterone pill?

Answer 39

Over 99%

Question 40

Define non-hormonal contraception

Answer 40

These are barrier methods that prevent a sperm contacting the egg or physical devices that release chemical compounds. These chemical kill sperm cells (spermicides) or prevent the implantation of fertilised eggs

Question 40

Condom

Answer 40

Non-hormonal Placed over the penis (male) or vagina (female). Prevents sperm entering the vagina. Prevents sperm entering the vagina Can also prevent the spread of sexually transmitted infections (STIs)

Question 40

Phototropism

Answer 40

Growing towards the light

Question 41

Explain the commercial use of plant hormones: | Controlling dormancy

Answer 41

Seeds remain dormant until conditions are ideal for growth. This normally prevents them germinating at the end of the summer so they survive the winter. Commercial growers trigger seeds to germinate in the winter by spraying them with gibberellins or auxins in the greenhouse. It also helps make sure all the seeds in a batch germinate at the same time.

Question 42

'Natural' methods of contraception

Answer 42

Not having sexual intercourse is most fertile or withdrawal where the man pulls the penis out before ejeculation Non-hormonal

Question 43

intrauterine device (IUD, coil)

Answer 43

Non-hormonal Inserted into the uterus Releases copper, which prevents sperms surviving in the uterus and fallopian tubes Can also prevent implantation of a fertilised ovum remains effective for 5-10 years

Question 44

oestrogen and progesterone pill (combined pill)

Answer 44

hormonal Prevents ovulation Thickens mucus from the cervix, stopping sperm from reaching an ovum Prevents implantation of a fertilised egg onto the uterus wall Taken daily for 21 days of the me trial cycle

Question 45

Fallopian tube (oviduct)

Answer 45

where the egg is fertilised before travelling along the tube to the uterus

Question 46

Explain the commercial use of plant hormones: | Delaying ripening

Answer 46

Auxin is sprayed on fruit trees to delay ripening. This allows a harvest to be collected all at the same time, and can prevent fruit from dropping off trees early.

Question 47

Why are natural methods least effective in preventing pregnancy?

Answer 47

They rely on getting the timing exactly right

Question 49

Describe the root's phototropism

Answer 49

Roots are negatively phototropic If a root starts being exposed to light, more auxin accumulates on the more shaded side. The auxin inhibits cell elongation on the shaded side so the root bends downwards, back into the ground

Question 54

Cause of infertility

Answer 54

Blocked Fallopian tube Blocked sperm ducts Not enough sperm being produced in the testes A lack of matured eggs produced in the ovaries A failure of the ovaries to release an egg Too low FSH levels to cause their eggs to mature

Question 55

uterus (womb)

Answer 55

the foetus develops here

Question 56

Fertility treatment

Answer 56

Infertility treated by hormones FSH can be used as an artificial fertility drug. When the woman takes this drug it stimulates eggs to mature in her ovaries. It also triggers oestrogen production. This significantly increases her chances of getting pregnant as it increases the likelihood of one or more eggs being released

Question 58

How does IVF work?

Answer 58

IVF stands for in vitro fertilisation If treatment with hormones alone is not successful people may use IVF. This technique involves doctors collecting eggs from the ovary of the mother and fertilising them with sperm from the father outside the body. FSH and LH are given to the mother to ensure that as many eggs in her ovaries mature as possible and are harvested.

Question 59

As female age increases, the success rate for IVF treatment...

Answer 59

decreases

Question 60

Describe the root's gravitropism

Answer 60

Roots are positively gravitropic A root growing sideways will have more auxin on its lower side The auxins will inhibit growth on the lower side which means the cells at the top will elongate faster so the root will bend downwards.

Question 61

What are the considerations around IVF treatment?

Answer 61

It is not a natural process It allows parents to conceive who would otherwise not be able to have a baby It enables older parent to have children though they can find the demands of bringing up a child challenging Many IVF treatments results in multiple births. This can be dangerous for both mother and the unborn babies IVF treatment is very expensive. There is only limited availability through the National Health Service (NHS) It allows younger women's to focus on their careers, and choose to have a baby later in life.

Question 62

Define tropism

Answer 62

When plants detect stimuli in their environment, and can respond by growth in a particular direction which is called tropism.

Question 63

Positive tropism

Answer 63

If a part of a plant grows towards a stimulus

Question 64

How can you investigate the effect of light on the growth of cress seeds?

Answer 64

Put 10 cress seeds into three different Petri dishes, each lined with moist filter paper. Shine a light into one of the dishes from above and two of the dishes from different directions Leave your cress seeds alone for one week until you can observe their response You will find the seeds growing towards the light Control variables- temperature, distance from lamp, type of seeds, number of seeds

Question 65

Ethane effect on fruits

Answer 65

Causes plants fruits to ripen by stimulating the conversion of starch into sugar. This is why a ripe fruit tastes sweeter than an unrepentant one. It is the only plant hormone that exists as a gas. Ethene stimulates enzymes that causes fruit to ripen Ethene is produced by aging leaves. It stimulates the cells that connect the leaf to the rest of the plant to expand. This breaks the cell walls and causes the leaf to fall of the plant.

Question 66

How effective is the intrauterine system?

Answer 66

Over 99%

Question 67

Gibberellins

Answer 67

They promote growth, particularly stem elongation. They can also end the democracy period of seeds and buds. This leads to shoots and flowers opening. Stimulates seed germination, stem growth and flowering

Question 68

Gravitopism

Answer 68

Growing in the same direction as gravity

Question 69

Explain the commercial use of plant hormones: | Killing weeds

Answer 69

Many weed killers contain auxins. Weed killers are eclecticism herbicides. They kill weeds that are broad-leaved plants (dicotyledons) but do not affect narrow leaf plants (monocotyledons eg. Grass). The auxin weed killer makes the weeds grow too fast. This rapid uncontrolled growth kills the plant.

Question 70

Intrauterine system (IUS, hormonal coil)

Answer 70

hormonal Inserted into the uterus Has the same effect on the body as the progesterone-only pill Remains effective for 3-5 years

Question 71

FSH

Answer 71

``` Follicle stimulating hormone Secreted by the pituitary gland Causes an egg to mature Stimulates the ovaries to produce oestrogen Peak on day 14 ```

Question 72

Describe the shoot's gravitopism

Answer 72

Shoots are negatively gravitropic When a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side. This causes the lower side to grow faster, bending the shoot upwards.

Question 73

Explain the commercial use of plant hormones: | Promoting root growth

Answer 73

Rooting powder contains auxins. Horticulturists and gardeners use auxin to produce identical plants, or clone, from cuttings. They cut off a plant shoot, dip it into rooting powder and plant it. After a few days roots develop from the cut stem. The new roots anchor into the soil and take up water and minerals.

Question 74

Auxins

Answer 74

They are plant hormones that enables a plant to grow towards or away from a stimulus They move through the plant in solution They are produced in the tips and diffuses backwards to stimulate the cell elongation process which occurs in the cells just behind the tips. They promote growth in shoots and inhibit growth in roots

Question 76

Sterilisation contraceptive method

Answer 76

Non-hormonal Involves a surgical procedure to cut or tie tubes in the reproductive system. In women, the procedure means eggs are prevented from traveling from the ovaries to the uterus In men, it prevents sperm from being ejaculated Over 99% effective

Question 89

IVF is not reliable. What can it result in?

Answer 89

no pregnancy | multiple pregnancies

Question 90

Which contraceptive methods involve the hormone progesterone?

Answer 90

``` Injection-effective for up to 3 months;does what a mini pill does Implant-inserted beneath the skin of the arm;effective for 3 years;does what a mini pill does Intrauterine system (IUS)-a T-shape piece of plastic inserted into the uterus. Effective for 3-5 years Mini-pill- has to be taken everyday ```