Module 5: Animal Responses Flashcards
What are the 2 main structural system that the nervous system is split into?
1) The central nervous system (CNS)
2) The peripheral nervous system. (PNS)
What is the CNS and PNS made up of?
The CNS is made up of the brain and spinal cord.
The PNS is made up of neurones that connect the CNS to the rest of the body.
What are the 2 main functional systems that the PNS can split into?
1) The somatic nervous system (SNS)
2) The autonomic nervous system (ANS)
What does are the roles of SNS and ANS?
The somatic nervous system controls conscious activities. e.g. running and playing video games.
The autonomic nervous system controls unconscious activities e.g. digestion and heart rate.
What is the autonomic nervous system split into?
1) Sympathetic nervous system
2) Parasympathetic nervous system.
What is the role of the parasympathetic and sympathetic nervous system.
The sympathetic nervous system stimulates the ‘flight or fight’ response. It releases the neurotransmitter noradrenaline.
The parasympathetic system is the ‘rest and digest’ system that calms the body down. Parasympathetic neurones release the neurotransmitter acetylcholine.
What are the 5 main brain structures called?
1) Cerebrum
2) Hypothalamus
3) Medulla Oblongata
4) Cerebellum
5) Pituitary gland.
Describe the Cerebrum.
It is the largest part of the brain. It is divided into two halves called cerebral hemispheres.
The cerebrum has a thin outer layer called the cerebral cortex, which is highly folded, giving it a large surface area.
The cerebrum is involved in vision hearing, learning, thinking and processing language.
Describe the Hypothalamus.
It is found beneath the middle part of the brain.
It is involved in homeostatic responses such as maintaining body temperature (thermoregulation).
It also produces hormones that control the pituitary gland.
Describe the Medulla oblongata.
This is at the base of the brain, at the top of the spinal cord.
It is involved in unconscious processes such as automatically controls breathing and heart rate.
Describe the cerebellum.
The cerebellum is a leaf-shaped structure found towards the back of the brain. It is positioned underneath the cerebrum and is highly folded.
It is important for muscle coordination, posture and coordination of balance.
Describe the pituitary gland.
It is found beneath and is controlled by the hypothalamus.
It releases hormones and stimulates other glands to release their hormones.
What is a reflex action?
Reflexes are rapid, unconscious actions that protect the body from harm.
This is because the pathway of communication doesn’t involve conscious parts of the brain- instead it goes through unconscious parts of the brain or the spinal cord, which stops us from having to think about the action, which would waste time.
Explain the eye reflex.
To prevent damage to the eye, you automatically blink if something touches it.
Sensory receptors in the cornea are stimulated when something touches the eye, sending an electrical impulse along a sensory neuron to the central nervous system (CNS).
In the CNS, a relay neuron passes the impulse between the sensory neuron and a motor neuron, which passes the impulse to the orbicularis oculi muscles in the eyelids. These contract and cause the eyelid to close.
Explain the knee-jerk reflex.
If your quadriceps muscle stretches suddenly, you automatically straighten your leg to help keep your balance.
Stretch receptors in the quadriceps muscle detect that the muscle is being stretched and send an electrical impulse along a sensory neuron to the spinal cord.
In this case, the impulse is passed directly onto a motor neuron, which carries the impulse to the quadriceps muscle. The muscle contracts and causes the leg to straighten.
What is the ‘fight or flight’ response?
It prepares our body for action in response to a threat.
Describe the neural process of the ‘fight or flight’ response.
Nerve impulses from the sensory neurone arrive at the hypothalamus, activating both the hormonal endocrine system and the sympathetic nervous system.
The pituitary gland is simulated to release a hormone called ACTH which acts on the adrenal glands, stimulating the release of steroid hormones (e.g. cortisol) from the adrenal cortex.
Then, the sympathetic nervous system is activated which signals to the adrenal glands to release adrenaline from the adrenal medulla.
What are the effects of the sympathetic nervous system and adrenaline when activated?
1) Heart rate is increased.
2) Breathing rate increases
3) Glycogen is hydrolysed into glucose via glycogenolysis.
4) Increased muscle tension
5) Decreased digestion
6) Decreased salivation
7) Pupils dilate
8) Erector pili muscles in the skin contract- this makes the hair stand on end so the animal looks bigger and scarier.
How is heart rate controlled via the nervous system?
The medulla oblongata is a brain region found at the bottom of the brain, in the brain stem. It is involved in unconscious processes, such as controlling heart rate and breathing rate.
A part of the medulla oblongata called the cardiovascular control centre is responsible for changing heart rate according to our body’s needs.
It works by sending impulses along sympathetic or parasympathetic neurones which release different neurotransmitters onto the sino-atrial node (SAN) - the SAN then modifies its rate of firing to slow down or speed up the heart rate.
What are the two types of receptors found in the heart?
1) Baroreceptors
2) Chemoreceptors
What are the roles of baroreceptors and chemoreceptors?
Baroreceptors: these are pressure receptors in the aorta and the carotid arteries. they are stimulated by high and low blood pressure.
Chemoreceptors: are chemical receptors in the aorta, carotid arteries and in the medulla oblongata. they monitor the oxygen level in the blood and also carbon dioxide and pH.
Explain the control of heart rate in response to high blood pressure.
The baroreceptors detect high blood pressure and send impulses along sensory neurones to the cardiovascular centre, which sends impulses along parasympathetic neurones.
These secrete acetylcholine, which binds to receptors on the SAN. This causes the heart rate to slow down in order to reduce blood pressure back to normal.
Explain the control of heart rate in response to low blood pressure
Baroreceptors detect low blood pressure and send impulses along sensory neurones to the cardiovascular centre, which sends impulses along sympathetic neurones.
These secrete noradrenaline, which binds to receptors on the SAN. This causes the heart rate to speed up in order to increase blood pressure back to normal.
Explain the control of heart rate in response to high blood O2, low CO2 or high blood pH levels.
Chemoreceptors detect chemical changes in the blood and send impulses along sensory neurones to the cardiovascular centre, which sends impulses along parasympathetic neurones.
These secrete acetylcholine, which binds to receptors on the SAN. This causes the heart rate to decrease in order to return oxygen, carbon dioxide and pH levels back to normal.
