B1.2 Flashcards
What are cells that detect stimuli called?
Receptors
What are the cells in an eye sensitive to?
Light
What are the cells in your ear sensitive to?
Change in position
Sound
What do the nerve cells (neurones) connect to?
They connect the central nervous system (spinal cord and brain) to receptors and effectors.
What is a reflex action?
Reflex actions are automatic responses that are very fast and do not involve conscious thought.
What is the first stage in a reflex action?
A receptor cell responds to a stimulus by producing an electrical impulse.
What is the second stage in a reflex action?
The impulse passes from he receptor along a sensory neurone to the central nervous system.
What is the third stage in a reflex action?
The impulse passes from the sensory neurone to a relay neurone in the central nervous system.
What is the forth stage in a reflex action?
The impulse passes from the relay neurone to a motor neurone.
What is the final stage of a reflex action?
The impulse passes along the motor neurone to the effector.
What is an effector?
Effectors are:
• muscles that respond by contracting
• glands that respond by secreting (releasing) chemicals, e.g hormones.
Where is water lost from in the body?
- lungs when we breathe out
- skin in sweat, to cool is down
- kidneys in urine
Where are ions lost from in the body?
- skin in sweat
* kidneys in urine
What are many of the processes in the body controlled by?
Hormones
How are hormones transported?
In the blood, after being secreted by a gland.
What do hormones cause, in regards to the menstrual cycle?
Maturation (ripening) and release of eggs from the ovaries, and cause changes in the thickness of the womb lining.
How many hormone are involved in the menstrual cycle each month?
3
What hormone causes the eggs in the ovaries to mature and also stimulates ovaries to hormones including oestrogen?
Follicle-stimulating hormone (FSH)
What does the Luteinising hormone (LH) do?
Causes an ovary to release an egg
What inhibits (prevents) further production of FSH so no more eggs mature this month?
Oestrogen
Where are FSH and LH secreted by?
The pituitary gland below the brain
Where is oestrogen secreted by?
Ovaries
What are oral contraceptives?
‘Birth control’ pills, as they help to prevent pregnancy.
Oral contraceptives contain hormones that prevent FSH from being released. What does this mean?
No eggs mature, therefore no eggs are ready to be released from an ovary.
