Nerves And Hormones ~ B1.2 Flashcards
What does the nervous system consist of?
~ the brain
~ the spinal cord
~ the neurones
~ the receptors
What does the nervous system allow organisms to do?
React to their surroundings and coordinate their behaviour.
How is information passes around the body?
Information from receptors passes along neurones (nerve cells) to the brain. The brain co-ordinates the response, which is carried out by an effector. The effector responds by releasing chemicals.
What is an effector?
The effector may be a muscle, which responds by contracting, or a gland, which responds by releasing chemicals.
What is the order of the nervous system?
~receptors ~sensory neurones ~relay neuron * ~spinal cord or brain * ~motor neurones ~effector
- = central nervous system (CNS)
What are the three types of neurones and what do they do?
Motor neurone~impulse travels away from the cell body
Relay neurone~impulse travels first towards and then away from the cell body
Sensory neurone~impulse travels towards the cell body
What are neurones?
Specially adapted cells that can carry an electrical signal, e.g. A nerve impulse
What is the small gap between the neurones called?
A synapse.
What is sent across the gap between the neurones?
A chemical neurotransmitter.
What are the different receptors?
Light ~ receptors in the eyes.
Sound ~ receptors in the ears.
Change of position ~ receptors in the ears, balance.
Taste ~ receptors on the rounds are sensitive to chemicals.
Smell ~ receptors in the nose are sensitive to chemicals.
Touch, pressure, pain and temperature ~ receptors in the skin
What is a reflex action?
Reflex actions speeds up the response time by missing out the brain completely.
An example of a reflex action is removing your hand from a hot plate, how does it work?
The hot plate acts as a stimulus.
The receptor is the pain in the finger.
An impulse is sent to the sensory neurone, then to the relay neurone (in the spinal cord), then to the motor neurone, then to the effector (the muscle in the hand)
Then there is a response (the hand withdraws).
Humans need to keep their internal environment relatively constant. What things in the body needs to be controlled?
Body temperature, the levels of water, salts (ions) and blood sugar.
How are conditions in the body controlled?
Many processes within the body (including control of some internal conditions) are coordinated by hormones.
What is a hormone?
Chemicals, produced by glands, which are transported to their target organs by the bloodstream.
What do hormones do?
Hormones regulate the functions of many organs and cells.
What does FSH stand for?
Follicle stimulating hormone
Where is FSH released from and what is its job.
It is released from the pituitary gland. FSH causes eggs to mature in the ovaries and it causes the ovaries to produce oestrogen.
Where is oestrogen released and what is its job?
It is produced in the ovaries and inhibits the production of FSH and causes the production of LH. Its job is to thicken the lining of the uterus.
Where is LH produced and what is its job?
It is produced from the pituitary gland and stimulates the release of an egg from the ovaries in the middle of the menstrual cycle.
What hormones increases fertility?
LH and FSH
What does LH stand for?
Luteinising hormone.
What hormone reduces fertility?
Oestrogen.
What are plants sensitive to?
~Light~their shoots will grow towards light
~Moisture~their roots grow towards moisture
~Gravity~roots grow in the direction of gravity whilst shoots grow against the force of gravity
What are auxins?
Auxins are hormones that control the growth of plants at the tips of roots and shoots.
What does auxin do?
Auxin promotes the growth of shoots, but inhibits growth in the roots.
What happens when a shoot tip is exposed to light?
More auxin is produced on the side of the shoot that is in the shade. This causes the shoot to grow faster on the shaded side and the plant will bend towards the light. This is known as phototropism.
What happens if a plant root is growing horizontally?
Gravity will cause more auxin to be produced on the lower side. The extra auxins inhibits growth causing the root to bend downwards, this is called gravitropism or geotropism.
Plant hormones can be used in agriculture and horticulture. What can they be used for?
~Encourafe cutting to grow roots~cutting are dipped in rooting compound so they will produce roots quickly.
~Kill weeds~most weeds have broad leaves. Selective weed killers are plant hormones that will disrupt the growth patterns of broad leaved plants whilst by harming the grass or wheat.
What are the benefits of IVF?
~Can help a woman become pregnant
~Uses woman’s own eggs and partners own sperm
~Provides an alternative to adoption
What are the problems of IVF?
~Only 28% success rate ~Age restrictions ~Uses NHS resources ~Costly ~Increases expectations for babies on demand
What are the benefits of using weed killers?
~Kills weed
~Fast acting
~Many applications
What are the problems of using weed killers?
~Harmful to wildlife
~Harmful to humans
