The Body - B1a Flashcards
What is a stimulus?
A change in the environment in which you may need to react.
What are the 5 sense organs and their receptors?
Eyes - Light receptors (sensitive to light)
Ears - Sound receptors (sensitive to sound)
Tongue - taste receptors (sensitive to bitter,sour, sweet) - chemical stimulus
Nose - smell receptors (sensitive to chemical stimulus)
Skin - sensitive to touch, pressure, pain and temp
What is a receptor?
A group of cells which are sensitive to a stimulus.
What is the CNC?
The central nervous system - where all information from sense organs is sent and where reflexes and actions are coordinated.
The brain and spinal cord
What are the neurones in the nervous system?
Sensory - nerve cell that carries electrical impulses from the receptor to the CNS and the relay neurone
Relay - nerve cell that carry signals from sensory to motor neurone
Motor - nerve cell that carries signals from the relay neurone in CNS to the effector (muscle)
STORM
What is a synapse?
The connection between two neurones, there will be a gap between the two so the signal is diffused by chemicals across the gap.
Why is it important to have reflexes?
Reflex is an automatic response to a stimuli, which reduces the chance of injury. Your body doesn’t wait for you to decide it just does it.
Explain the reflex arc
The neurones that go through the spinal cord and brain.
^ When a stimuli is detected by receptors, impulses are sent along the sensory neurone to the CNS.
^ The impulses reach a synapse between sensory and relay neurone and are chemically diffused across the gap between them.
^ Then impulses carry along past the relay neurone and through the CNS until they reach another synapse. (same thing happens)
^Impulses are sent along the motor neurone until they reach the effector.
^ The muscle contacts and you move away from the source of pain.
What are hormones?
Chemical messages which travel in the blood to activate target cells.
They are produced and secreted by glands and travel through the blood.
What are the differences between Hormones and Nerves?
Nerves: very fast, act for a very short time and on a precise area.
Hormones: Slower action, act for a long time and in a general area.
What are the 4 stages of the menstrual cycle?
Stage 1 - day 1 is when the lining of the uterus breaks down for 4 days (women starts to bleed)
Stage 2 - The lining of the uterus build up again (day 4-14)
Stage 3 -The egg is released from the ovary on day 14.
Stage 4 - The wall is maintained for 14 days until day 28. If no fertile egg lands on the uterus the process starts again.
What are the hormones in the menstrual cycle?
FSH - Produced in the pituitary glands,
causes the egg to mature in one of the ovaries,
stimulates the ovaries to produce oestrogen.
Oestrogen - Produced in the ovaries
causes the pituitary to produce LH
Inhibits further release of FSH
LH - Produced in the pituitary glands
stimulates the release of an egg in the middle of the menstrual cycle.
Progesterone - prodcued in ovaries
How can hormones reduce fertility?
Oestrogen is used to prevent the release of an egg. If the level of oestrogen is high then it will inhibit production of FSH and eventually egg production and development will stop.
Progesterone - simulates production of cervical mucus which stops sperm reaching the egg.
Pros and cons of the pill
Pro - pill is over 99% effective
reduces the risk of get getting some cancers
Cons - not 100% effective,
Can cause side effects like headaches, nausea and bleeding,
Doesn’t prevent STD’s
How can hormones increase fertility?
Injections of FSH and LH to simulate eggs release.
