Paper 2 Biology
B5: Homeostasis
What is Homeostasis? What does it control and how?
Homeostasis: The regulation of the conditions of the body
•Controls blood glucose concentration, temperature, water levels
•Importance: to function properly
Stimuli- change in environment
Receptors- detect stimuli
Co-ordination centres- brain and spinal cord) receive, process information from receptors
Effectors- bring about responses that restore optimum levels
Negative feedback (Higher only) = returns conditions back to optimum level if they become too high or
too low
Nervous System
What is the function of the nervous system? What is a reflex action and what is the required
practical for it?
Enables humans to react their surroundings and to coordinate their behaviour
Stimulus-> receptor-> coordinator ->effector-> response
Reflex Actions= Are automatic and rapid doesn't include the conscious part of the brain
Practical Reaction time
1) Put arm on at the table with hand hanging the edge of the table
2) Your partner will hold the bottom of the ruler (0cm)
3) Your partner drops ruler without telling you
4) You catch the ruler and record results in a table
5) Repeat experiment and do both left and right
Endocrine system
What is the function of the endocrine system? What is a gland? Can you remember all the
glands?
Endocrine system: glands which secrete chemicals called hormones into the bloodstream
,Glands:
Pituitary gland-secretes several hormones Which act on other glands hormones to bring an to
stimulate effect.
Thyroid gland produces thyroxine, which regulates rate of metabolism, heart rate and
temperature
Adrenal gland = produces adrenaline, which prepares body for ‘fight or flight!!
Pancreas = produces insulin used to regulate blood glucose levels
Ovaries = produces oestrogen
Testes = produces testosterone-controls sperm production
Synapse
Connects the neurones
1)Electrical impulse travels along first axon
2) Nerve signal received
3) Chemicals diffuse across synapse
4) Stimulates new electrical signal to the next neurone
Blood Glucose Concentration
Blood glucose monitored /controlled by the pancreas.
Blood glucose too high insulin produced to make the glucose move into the cells. Liver turns
glucose into glycogen.
Blood glucose = too low -> glucagon secreted to break down glycogen. Into glucose.
Type 1 diabetes
Pancreas fails to produce insulin
Treatment: Insulin injection
Risk factors: Genetics, Diet, Obesity
Type 2 diabetes
Body no longer responds to the insulin produced
Treatments: Carbohydrate controlled diet, exercise
Risk factors: Age, High blood pressure, Genetics, Obesity
Menstrual cycle
, Monthly release of an egg from the ovaries
Day 1-4 Uterus lining sheds
Day 4-14 Uterus lining builds again
Day 14: Egg develops and is released
Day 14-28: if there is no fertilised egg, uterus in the sheds again and cycle begins
FSH
Pituitary gland => matures egg
Stimulates ovaries => produces oestrogen
Oestrogen
Ovaries =>Uterus lining grows
And stimulates LH, inhibits FSH
LH
Pituitary gland => Stimulates egg release at day 14.
Progesterone
Ovaries => maintains uterus lining Inhibits Lit and FSH release
IVF ‘in vitro fertilisation’
1) Collect eggs from ovaries, fertilised in a lab with sperm.
2) Embryos grown in incubator
3) Embryos into tiny ball of cells, then transferred
4) FSH + LH to stimulate egg maturation
Advantages: infertile couple can have a child
Disadvantages: multiple births, low success rate, emotionally and physically stressful
Contraception
Contraception: used to prevent risk of pregnancy
Hormonal
The pill – Stops development of uterus lining.
Implant- stops development of uterus lining and inhibits egg maturing
Injection-> Contains progesterone
IUD- Skills sperm
Non hormonal
B5: Homeostasis
What is Homeostasis? What does it control and how?
Homeostasis: The regulation of the conditions of the body
•Controls blood glucose concentration, temperature, water levels
•Importance: to function properly
Stimuli- change in environment
Receptors- detect stimuli
Co-ordination centres- brain and spinal cord) receive, process information from receptors
Effectors- bring about responses that restore optimum levels
Negative feedback (Higher only) = returns conditions back to optimum level if they become too high or
too low
Nervous System
What is the function of the nervous system? What is a reflex action and what is the required
practical for it?
Enables humans to react their surroundings and to coordinate their behaviour
Stimulus-> receptor-> coordinator ->effector-> response
Reflex Actions= Are automatic and rapid doesn't include the conscious part of the brain
Practical Reaction time
1) Put arm on at the table with hand hanging the edge of the table
2) Your partner will hold the bottom of the ruler (0cm)
3) Your partner drops ruler without telling you
4) You catch the ruler and record results in a table
5) Repeat experiment and do both left and right
Endocrine system
What is the function of the endocrine system? What is a gland? Can you remember all the
glands?
Endocrine system: glands which secrete chemicals called hormones into the bloodstream
,Glands:
Pituitary gland-secretes several hormones Which act on other glands hormones to bring an to
stimulate effect.
Thyroid gland produces thyroxine, which regulates rate of metabolism, heart rate and
temperature
Adrenal gland = produces adrenaline, which prepares body for ‘fight or flight!!
Pancreas = produces insulin used to regulate blood glucose levels
Ovaries = produces oestrogen
Testes = produces testosterone-controls sperm production
Synapse
Connects the neurones
1)Electrical impulse travels along first axon
2) Nerve signal received
3) Chemicals diffuse across synapse
4) Stimulates new electrical signal to the next neurone
Blood Glucose Concentration
Blood glucose monitored /controlled by the pancreas.
Blood glucose too high insulin produced to make the glucose move into the cells. Liver turns
glucose into glycogen.
Blood glucose = too low -> glucagon secreted to break down glycogen. Into glucose.
Type 1 diabetes
Pancreas fails to produce insulin
Treatment: Insulin injection
Risk factors: Genetics, Diet, Obesity
Type 2 diabetes
Body no longer responds to the insulin produced
Treatments: Carbohydrate controlled diet, exercise
Risk factors: Age, High blood pressure, Genetics, Obesity
Menstrual cycle
, Monthly release of an egg from the ovaries
Day 1-4 Uterus lining sheds
Day 4-14 Uterus lining builds again
Day 14: Egg develops and is released
Day 14-28: if there is no fertilised egg, uterus in the sheds again and cycle begins
FSH
Pituitary gland => matures egg
Stimulates ovaries => produces oestrogen
Oestrogen
Ovaries =>Uterus lining grows
And stimulates LH, inhibits FSH
LH
Pituitary gland => Stimulates egg release at day 14.
Progesterone
Ovaries => maintains uterus lining Inhibits Lit and FSH release
IVF ‘in vitro fertilisation’
1) Collect eggs from ovaries, fertilised in a lab with sperm.
2) Embryos grown in incubator
3) Embryos into tiny ball of cells, then transferred
4) FSH + LH to stimulate egg maturation
Advantages: infertile couple can have a child
Disadvantages: multiple births, low success rate, emotionally and physically stressful
Contraception
Contraception: used to prevent risk of pregnancy
Hormonal
The pill – Stops development of uterus lining.
Implant- stops development of uterus lining and inhibits egg maturing
Injection-> Contains progesterone
IUD- Skills sperm
Non hormonal
