Module 5: Section 3 Animal Responses Flashcards
What structures is the nervous system split into
The central nervous system
The peripheral nervous system
What is the central nervous system made up of?
The brain and spinal cord
What is the peripheral nervous system split into?
The somatic nervous system
The autonomic nervous system
What is the function of the somatic nervous system?
The somatic nervous system controls conscious activities eg running and playing video games
What is the function of the autonomic nervous system?
The autonomic nervous system controls unconscious activities eg digestion and heart rate
What is the autonomic nervous system split into?
The sympathetic nervous system
The parasympathetic nervous system
What is the function of the sympathetic nervous system?
It is the “fight or flight” system that gets the body ready for action. Sympathetic neurones release neurotransmitter noradrenaline.
What is the function of the parasympathetic nervous system?
It is the “rest and digest” system that calms the body down. Parasympathetic neurones release the neurotransmitter acetylcholine.
What are the five brain structures you have to know?
1) cerebrum
2) hypothalamus
3) medulla oblongata
4) cerebellum
5) pituitary gland
What is the location and function of the cerebrum?
Cerebrum is the largest part of the brain and is divided into two halves called cerebral hemispheres. The cerebrum has a thin outer layer called the cerebral cortex, which is highly folded. The cerebrum is involved in vision, hearing, learning and thinking.
What is the location and function of the hypothalamus?
The hypothalamus is found just beneath the middle part of the brain. It automatically maintains body temperature at a normal level. It also produces hormones to control the pituitary gland.
What is the location and function of the medulla oblongata?
The medulla oblongata is at the base of the brain, at the top of the spinal cord. It automatically controls breathing rate and heart rate.
What is the location and function of the cerebellum?
The cerebellum is underneath the cerebrum and it also has a folded cortex. It’s important for muscle coordination, posture and coordination of balance.
What is the location and function of the pituitary gland?
The pituitary gland is found beneath and is controlled by the hypothalamus. It releases hormones and stimulates other glands eg the adrenal glands to release their hormones.
What is a reflex action?
Where the body responds to a stimulus without making a conscious decision to respond.
What is the pathway for a reflex action?
1) stimulus to receptors
2) receptors to CNS (via sensory neurone)
3) CNS to effectors (via relay and motor neurone)
4) effectors to response
Why do you have a blinking reflex?
The body detects something that could damage your eye, so you quickly close your eyelid to protect the eye.
What is the pathway of communication for the blinking reflex?
1) stimulus - something touches your eye
2) receptors - sensory nerve endings in the cornea detect the touch stimulus. A nerve impulse is seng along the sensory neurone to a relay neurone in the CNS.
3) CNS - the impulse is then passed from the relay to motor neurones
4) effectors - the motor neurone send impulses to the obicularis oculi muscles that move your eyelids.
5) response - these muscles contract causing eyelids to close quickly and prevent them from being damaged.
Why do we have the knee-jerk reflex?
It works to quickly straighten your leg if the body detects your quadriceps is suddenly stretched. It helps to maintain posture and balance.
What is the pathway of communication for the knee-jerk reflex?
1) stimulus- your quadricep muscle is stretched
2) receptors - stretch receptors in quadricep muscle detect that the muscle is being stretched and a nerve impulse is passed along the sensory neurone
3) CNS - the sensory neurone communicates directly with a motor neurone in the spinal cord (no relay neurone involved)
4) effectors - the motor neurone carries the nerve impulse ti the quadricep muscle
5) response - the quadriceps muscle contracts so the lower leg moves forward quickly.
When does the fight or flight response happen?
When an organism is threatened it responds by preparing the body for action.
When your body is placed under stress what happens?
Nerve impulses from sensory neurones arrive at the hypothalamus, activating both the hormonal (endocrine 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, which have a range of effects on the body, helping to respond to stress both short and long-term.
What happens during the fight or flight response?
The sympathetic nervous system is activated, triggering the release of adrenaline from the medulla region of the adrenal gland. The sympathetic nervous system and adrenaline produce a faster response than hormones secreted by the cortex of the adrenal gland.
What are the effects of adrenaline?
1) heart rate increases- the heart contracts with more force causing blood to be pumped around the body faster.
2) the muscles around the bronchioles relax, so airways widen and breathing is deeper
3) the intercostal muscles and diaphragm also contract faster and with more strength , increasing rate and depth of breathing.
4) glycogen is converted in glucose by glycogenesis so more glucose available for cells to respire.
5) muscles in the arterioles supplying skin and gut constrict, and muscles in the arterioles supplying the heart, lungs and skeletal muscles dilate so blood is diverted from the skin and gut to longs and skeletal muscles. This increases blood flow to these areas making them ready for action.
6) erector pili muscles in the skin contract, this makes hairs stand on end so the animal looks bigger.
How is heart rate controlled by the nervous system?
The SAN generates electrical impulses that cause the cardiac muscles to contract. The rate at which the SAN fires (ie heart rate) is unconsciously controlled by the cardiovascular centre in the medulla oblongata.