5.5.8 Mammalian Nervous System Flashcards
What is the structural organisation of the nervous system in the peripheral and central nervous systems?
The human nervous system consists of the:
Central nervous system (CNS) – the brain and the spinal cord
Peripheral nervous system (PNS) – all of the nerves in the body
The human nervous system allows us to make sense of our surroundings and respond to them, as well as to coordinate and regulate body functions
Information is sent through the nervous system as nerve impulses – electrical signals that pass along nerve cells known as neurones
A bundle of neurones is known as a nerve
Neurones coordinate the activities of sensory receptors (eg. those in the eye), decision-making centres in the central nervous system, and effectors such as muscles and glands
What is the functional organisation of the nervous system in the somatic and autonomic nervous systems?
Functionally, the nervous system can be divided into two parts:
The somatic nervous system
The autonomic nervous system
The somatic nervous system is required for the voluntary control of body movements
The somatic nervous system consists of three types of nerves:
Sensory nerves - these consist of sensory neurones and carry impulses from sense organs to the CNS
Motor nerves - the consist of motor neurones and carry impulses from the CNS to muscles and glands
Spinal nerves - found in the spinal cord, these are mixed nerves that consist of both sensory and motor neurones
The autonomic nervous system is a self-controlling system that is required for involuntary actions and functions, such as heart rate, regulation of blood vessel diameter, and peristalsis in the gut
The autonomic nervous system can itself be divided into two parts:
The sympathetic nervous system, which controls ‘flight-or-fight’ responses
The parasympathetic nervous system, which controls the ‘rest and digest’ system
How is the ‘fight or flight’ response controlled by the sympathetic nervous system?
The sympathetic nervous system controls the release of adrenaline, a hormone produced by the adrenal glands
This hormone is released during a fight-or-flight response
For example, when a zebra sees a lion starting to chase it
It causes the heart rate to increase
The increase in heart rate is beneficial as it allows for a rapid increase in blood supply to respiring muscles
This means the muscles will have more oxygen and glucose for respiration
It enables high-intensity activities like running away from a predator to be an immediate response
