F215:04:06 Organising the nervous system Flashcards
How does the nervous system co-ordinate the actions of the body?
Through electrical impulses
Describe the organisation of the nervous system
-> Receptors and sensory neuones transmit impulses to the CNS
<- Somatic motor neurones transmit impulses to voluntary muscles
What does the nervous system work in conjunction with and why?
the endocrine system
As they are both are essential in maintaining life in humans
What are the different sub-sections of the nervous system
CNS
Peripheral nervous system
What does the CNS consist of?
the brain and the spinal cord
its made up of grey matter and white matter
What is the peripheral nervous system made up of?
neurones that carry impulses into and out of the CNS
What is grey matter?
Billions of non-myelinated nerve cells
What is white matter?
Longer myelinated axons and dendrons that carry impulses
Why does white matter appear white?
Because of the myelin
What do sensory neurones do?
They carry impulses from the many receptors, in and around the body to the CNS
What do motor neurones do?
They carry impulses from the CNS to the effecter organs
How are nerves formed?
Many neurones bundled together and covered in connective tissues
How is the motor system subdivided?
The somatic and autonomic motor neurones
What does the somatic and autonomic neurones make up?
The motor system
What do somatic motor neurones do?
they carry impulses from the CNS to the skeletal muscles which are under voluntary (conscious) control
What do the autonomic motor neurones do?
They carry impulses from the CNS to cardiac muscles, to smooth muscles in the gut wall and to glands, none of which are under voluntary control
What does autonomic translate as and why?
self-governing
As the system operates to a large extent independently of conscious control
What is the autonomic nervous system responsible for?
For controlling the majority of homeostatic mechanisms and so plays a vital role in regulating the internal environment of the body within set parameters
What is the autonomic nervous system capable of doing beyond maintaining homeostatic conditions?
Controlling the heightened responses associated with the stress response
Desrcibe the makeup of the peripheral nervous system beginning from the top of the head to the feet
Cerebrum
Cranial nerves
Cervical nerves (innervate the neck and arms)
Spinal cord + intercostal muscles
Lumbar and sacral nerves (innervate the legs and pelvic organs)
What do Cervical nerves do and where are they found?
They innervate the neck and arms
Found in peripheral nervous system
How does the autonomic nervous system differ from the somatic nervous system?
- Most Autonomic nervous systems are non-myelinated, but Somatic are mostly myelinated
- Autonomic connections to effectors always consist of at least 2 neurones (Somatic only consist of 1)
Autonomic motor neurones occur in 2 types: sympathetic and parasympathetic
Which of the two subdivisions of the peripheral nervous system is subdivided into two types of motor neurone and what are they known as?
Autonomic nervous system
Autonomic and somatic motor neurones
What is the swelling known as where two neurones meet (potentially just autonomic- not sure)
a Ganglion
What are sympathetic and parasympathetic subsystems known as?
antagonistic systems- because in many cases the action of one opposes the action of the other
What rate are the impulses passing along both neurones of the para and symp systems under normal resting conditions?
A relatively low rate
What leads to an altered balance of stimulation between the para and symp systems? and what does this lead to?
a change to internal conditions or stimulation of a stress response
Leads to an appropriate response
When is the para and symp most active?
para: sleep and relaxation
Symp: times of stress
How are the neurones linked in the para and symp systems?
para: neurones of a patheway are linked at a ganglion within the target tissues so pre-ganglionic neurones vary considerably in length
Symp: Linked at a ganglion just outside the spinal cord, so the pre-ganglionic neurones are very short
What do post-ganglionic neurones secrete in the para and symp systems?
para: acetylcholine as the neurotransmitter at the synpase between the neurone and the effector
symp: noradrenaline at the synpase between neurone and effector
What are the effects of action of the para and symp systens?
Para: - decreased heart rate - pupil constriction - decreased ventilation rate - sexual arousal Symp: - increased heart rate - pupil dilation - increased ventilation rate - orgasm
Describe the differences between para and symp:
- Most active
- How pathways are linked
- What post-ganglionic neurones secrete
- Effects of action
What is the CNS?
Central nervous system
consists and of brain and spinal cord
What is the PNS?
Peripheral nervous system
Consists of all the sensory and motor neurones that are outside the CNS
and connect the receptors and the effectors to the CNS
Explain why the control of pupil diameter in the eye is described as an autonomic reflex
A reflex action involves sensory and motor neurones passing through the CNS
These actions involved a stimulus and an appropriate immediate response to that stimulus
Pupil diameter is controlled by autonomic neurones
Where too much light enters the eye, a reflex action involving those neurones leads to constriction of the pupil by contraction of the circular muscles of the iris
If a person exercises by running for 2 minutes, a number of autonomic responses will take place during and after the exercise
List the responses
During exercise:
-increased blood flow to muscles
- Increased heart and ventilation rate
- Decreased blood flow to gut
- Vasodilation in skin to accommodate sweating and increased blood flow to the surface
After: All the above are reversed during recovery
If a person exercises by running for 2 minutes, a number of autonomic responses will take place during and after the exercise
State whether the responses are sympathetically or parasympathetically controlled and why
During exercise:
- Increased activity of the symp is responsible
- As the cardiac, vasomotor and respiratory centres in the brain receive input from pH, temp, and stretch receptors in the carotid body, aortic body and medulla which leads to increased sympathetic output from these centres
After:
- Parasympathetic is responsible for returning the body back to its resting state
