Coordination and control (B1.2) Flashcards
Responding to Change.
The nervous system allows humans to react to their surroundings and coordinates behaviour. receptors detect external and stimuli. (receptors are found in sense organs) > Electrical impulses pass to the brain along neutrons (nerve cells)
The brain coordinates the responses.
Reflex Actions.
Reflex actions are rapid, automatic responses to a stimulus.
Reflexes protect us from damage. At the junction between TWO neutrons is a synapse. Chemicals transmit the impulse across the gap.
Hormones and the menstrual cycle.
The menstrual cycle takes 28 days, with ovulation about 14 days into the cycle. The cycle is controlled by three hormones. Follicle stimulating hormone is made by the pituitary gland and causes the egg to mature and oestrogen to be produced. Oestrogen produced by ovaries . Luteinising hormone made by pituitary gland and stimulates mature egg to be released from ovary.
The artificial control of fertility.
Contraceptive pill contain oestrogen and/or progesterone to inhibit FSH.
FSH can be given to a woman to help her produce eggs.
FSH causes eggs to mature.
Controlling Conditions.
It is very important that the internal conditions of the body are kept within certain limits. The nervous system and hormones help do this.
Water and ion content, as well as temperate and blood sugar levels, are all carefully controlled.
We must keep our temperature constant, otherwise the enzymes in the body will not work properly.
level of sugar in our body is controlled by the pancreas.
Hormones and the control of plant growth.
Plants respond to light, gravity and moisture. SHOOTS grow towards light and away from gravity. ROOTS grow towards gravity and water. Hormones such as auxin cause these changes.
Using hormones.
It is important to evaluate the advantages and disadvantages of using hormones to control fertility.
Incorrect use of plant hormones can damage the environment.
