What two systems is the nervous system split into - answer-- The central nervous system: made up of the brain and the spinal cord
- The peripheral nervous system: made up of the that connect the CNS to the rest of the body
What are the two functional systems of the peripheral nervous system? - ...
OCR A-Level Biology - Animal Responses
What two systems is the nervous system split into - answer-- The central nervous system: made up of
the brain and the spinal cord
- The peripheral nervous system: made up of the that connect the CNS to the rest of the body
What are the two functional systems of the peripheral nervous system? - answer-- The somatic nervous
system: controls conscious activities, eg. running and playing video games
- The autonomic nervous system: controls unconscious activities, eg. digestion
What are the two divisions of the autonomic nervous system? - answer-- The sympathetic nervous
system: gets the body ready for action. It's the 'fight or flight' system.
- The parasympathetic nervous system calms the body down.
What do sympathetic nerves do? - answer-raise heart rate by secreting noradrenaline
What do parasympathetic nerves do? - answer-slow heart rate by secreting acylcholine
what is the difference between the anterior pituitary and posterior pituitary gland? - answer-the
posterior pituitary only stores and releases hormones sent from the hypothalamus such as ADH and
oxytocin. the anterior pituitary produces and releases hormones.
Where is the cerebrum found in the brain and what is it's function? - answer-- The cerebrum is the
largest part of the brain
- It's divided into two parts called cerebral hemispheres
- The cerebrum has a thin outer layer called the cerebral cortex, which is highly folded
- The cerebrum is involved in hearing, vision, learning and thinking
Where is the hypothalamus found in the brain and what is it's function? - answer-- The hypothalamus is
found just beneath the middle part of the brain. It monitors temperature of blood flowing through it.
The hypothalamus produces hormones that control the pituitary gland
Where is the medulla oblongata found in the brain and what is it's function? - answer-- It's at the base of
the brain, at the top of the spinal cord
- It automatically controls breathing rate and heart rate
Where is the cerebellum found in the brain and what is it's function? - answer-- Found underneath the
cerebrum and it also has a folded cortex
- It's important for muscle coordination, posture and coordination of balance
What is a reflex? - answer-responses to the environment that are not processed by the brain
Explain the blinking reflex - answer-- Sensory nerve endings in the cornea are stimulated by touch
- A nerve impulse is sent along the sensory neurone in the trigeminal nerve to a relay neurone in the
medulla oblongata
, - The impulse is then passed from the relay neurone to the motor neurones in the oculomotor nerve.
this sends impulses to the superior levator neurone.
- The motor neurones also sends impulses to the orbicularis oculi muscles from the facial nerve root that
move your eyelids
- These muscles contract causing your eyelids to clsoe quickly and prevent your eye from being damaged
what are the two effectors in the blinking reflex? - answer-orbicularis oculi muscle - pulls eyes inward
superior levator palpebrae - lowers the eyelid
Explain the knee-jerk reflex - answer-- Stretch receptors in the quadriceps muscle detect that the muscle
is being stretched
- A nerve impulse is passed along a sensory neurone, which communicates directly with a motor
neurone in the spinal cord (there is no relay neurone involved)
- The motor neurone carries the nerve impulse to the effector (the quadriceps muscle) causing it to
contract so the lower leg moves forwards quickly
How do the nervous and hormonal systems coordinate 'fight or flight'? - answer-- Nerve impulses from
sensory neurones arrive at the hypothalamus activating both the hormonal system and the sympathetic
nervous system
- The pituitary gland is stimulated to release a hormone called ACTH. This causes the cortex of the
adrenal gland to release steroidal hormones
- The sympathetic nervous system is activated, triggering the release of adrenaline from the medulla
region of the adrenal gland
- Heart rate is increased so blood is pumped round the body faster
- The muscles around the bronchioles relax, so breathing is deeper
- Glycogen is converted to glucose, more respiration
- Erector pili muscles contract, making hairs stand on end so that the animal looks bigger
- Muscles in the arterioles supplying the skin and blood constrict, and muscles in the arterioles supplying
the heart, lungs and skeletal muscles dilate
How does the nervous system help control heart rate? - answer-- The sinoatrial node (SAN) generates
electrical impulses that cause the cardiac muscles to contract
- The rate at which the SAN fires (heart rate) is unconsciously controlled by a part of the brain called the
medulla
- Animals need to alter their heart rate to respond to internal stimuli eg. to prevent fainting due to low
blood pressure
- Stimuli are detected by pressure receptors and chemical receptors, eg. baroreceptors in the aorta and
vena cava which are stimulated by high and low blood pressure
How does the medulla respond to high/low blood pressure? - answer-- High blood pressure: detected by
baroreceptor. Impulses are sent to the medulla, which sends impulses along the vagus nerve. This
secretes acetylcholine, which binds to receptors on the SAN
- Low blood pressure: detected by baroreceptor. Impulses are sent to the medulla, which sends impulses
along the accelerator nerve. This secretes noradrenaline, which binds to the receptors on the SAN
How does the medulla respond to high/low pH levels? - answer-- High pH: detected by chemoreceptors.
Impulses are sent to the medulla which sends impulses along the vagus nerve. This secretes
acetylcholine, which binds to receptors on the SAN
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