Homeostasis and Response

Question 1

What is Homeostasis?

Answer 1

> The regulation of the conditions inside your body to maintain a stable internal environment in response to changes in internal and external conditions.

Question 2

What 3 components is your automatic control made up of?

Answer 2

> Receptors
Co-ordinate centres
Effectors

Question 3

Explain Negative Feedback? (4)

Answer 3

> Receptors detect a stimulus if levels are too high
Coordination centre receives and processes the info and organises a response
Effector produces a response that counteracts the change, restoring the optimum level.

Question 4

What are the hormonal and communication systems?

Answer 4

> CNS, Sensory neurones, Motor Neurones, Effectors

Question 5

What is a synapse?

Answer 5

> Connections between two neurones
The nerve signal is transferred by chemicals which diffuse across the gap.

Question 6

What is a Reflex arc?

Answer 6

> They are rapid responses which don’t involve the conscious part of the brain.

Question 7

Describe how the Reflex arc works?

Answer 7

> Stimulus detected by stimuli
Impulses sent a long a sensory neurone
This triggers chemicals to be released
The impulses are sent to motor neurones and effectors, then a response takes place.

Question 8

Explain a Method for reaction time?

Answer 8

1)One student holds a ruler just above a second student’s hand.
2)The student lets go of the ruler. The second student has to catch it as soon as possible.
3)The students have to repeat this experiment seven more times.
4)The student then catches the ruler then has to drink a cup of strong caffeinated coffee.
5)Fifteen minutes after drinking the coffee the students repeated steps 1 to 3.

Question 9

What are hormones?

Answer 9

> Chemical Molecules released into the blood

Question 10

What does the pituarity gland produce?

Answer 10

> Produces many hormones that regulate body conditions

Question 11

What does the thyroid gland produce?

Answer 11

> Thyroxine which is involved in regulating metabolism, heart rate and temperature.

Question 12

What does the Adrenal gland prdouce?

Answer 12

> Produces adrenaline use to prepare for a ‘fight or flight.

Question 13

How does the body react to high levels of Blood Glucose?

Answer 13

> Glucose levels in blood will rise
Pancreas releases insulin
Glucose is converted to glycogen (in liver)
Glucose level falls or returns to normal

Question 14

Compare how each type of diabetes is caused.
Suggest how each type of diabetes can be treated. (4)

Answer 14

> Type 1 not enough / no insulin produced
Whereas type 2 cells do not respond to insulin
Type 1 is treated with injections of insulin
Whereas type 2 is treated with diet and exercise
or
loss of weight
or
drugs

Question 15

Describe how hormones control the menstrual cycle?

Answer 15

> FSH (release from pituitary) stimulates maturation of egg.
Oestrogen (release from ovary) inhibits FSH production and
stimulates LH production.
LH (release from pituitary) stimulates ovulation.
Progesterone (release from ovary) inhibits FSH and LH production
Oestrogen and progesterone maintain the uterus lining

Question 16

Evaluate the use of Non hormonal and hormonal methods as contraceptions?

Answer 16

Hormonal Methods:
>Pills are oral contraceptive’s containing oestrogen and its over 99% effective.
>It can cause side-effect and doesn’t protect against STD.

Non Hormonal Methods:
>Condoms are worn to prevent the sperm from getting to the egg.
>They protect against STD
>They can fall off
>Spermicide can be used but they’re inneffective

Question 17

What are drastic ways to avoid pregnancy?

Answer 17

> Sterilisation- cutting off the fallopian tube but small chance tube can join.
Abstinence- to not have intercourse.

Question 18

Explain why IVF increases the chance of some women becoming pregnant?

Answer 18

Identification of hormones used in IVF:
* FSH
* LH.

Role of hormones in IVF:
* FSH causes eggs to mature
* LH causes the eggs to be released.

Effect on chance of successful pregnancy:
* high levels of hormones cause many eggs to be matured and released
* sperm and eggs are collected and eggs are fertilised (so increased
probability of fertilisation)
* fertilised eggs are given time to develop into a small ball of cells
* some are transferred into the mother (uterus), to increase the probability of one successfully implanting.

Question 19

What are the Pros and cons for FSH and LH as fertility drugs?

Answer 19

Pros:
>Help a lot of women get pregnant
Cons:
>Doesn’t always/too many eggs may be stimulated

Question 20

What are the cons of IVF?

Answer 20

> Multiple births can happen
Success rate is low
Some believe it is unethical
Emotionally stressful

Question 21

Why are some people against IVF?

Answer 21

> Unused embryos are destroyed, each embryo is a potential life so it is unethical.
Genetic testing raises issues, leads to selection of preferred characteristics

Question 22

What is negative feedback?

Answer 22

> Negative feedback system keeps the amount at right level, then the level is higher than normal.

Question 23

Explain why there is too little sugar in the blood if too much insulin is taken.

Answer 23

Increase in rate of conversion of glucose to glycogen
in liver

Question 24

Explain why there is too little sugar in the blood if the person exercises more than usual.

Answer 24

Muscles use more glucose from blood in respiration to release
energy needed for exercise

Question 25

Explain how the body of a healthy person restores blood sugar level if the level drops too low.

Answer 25

Sugar soluble
Therefore absorbed
Quicker than starch
Which has to be digested

Question 26

Explain, using insulin as an example, what is meant by negative feedback.

Answer 26

Higher blood sugar level results in increased secretion of insulin
Effect of insulin is to lower blood sugar
Which in turn reduces rate of insulin secretion
Overall result is to keep fluctuations in sugar level to a minimum