The Peripheral Nervous System, Sensory and Motor Functions (Nervous System II) Flashcards
What do afferent neurons do?
Convey information from receptors in the periphery to the CNS.
Known as primary and sensory neurons
What is afferent information divided into?
- Sensory which does not have a conscious component
- Perception which is conscious
What is efferent information divided into
- Somatic nervous system
- Autonomic nervous system
Describe the Somatic nervous system
- Made up of all the fibres going from the CNS to the skeletal muscle
- Neurons of this system are often known as motor neurons
Describe the autonomic nervous system
- These fibres innervate cardiac muscle, smooth muscle & glands
- Is further subdivided into sympathetic and para-sympathetic components
What movement does the somatic nervous system produce?
Conscious, voluntary movement
What are somatic efferent neurons known as?
Motor neurons
Activated by: local reflex mechanisms & pathways that descend from higher brain centers
The activation always leads to contraction
What are autonomic efferent neurons known as
Autonomic motor neurons
They regulate activities in the effector tissues
What are the 2 main branches of the efferent division of the ANS
- Sympathetic division
- Parasympathetic division
What is the function of the automatic nervous system (ANS)
- Most organs receive instructions from both divisions of the ANS, which typically oppose each other
- The balance between the 2 maintains tone (regulated by hypothalamus)
- Some structures only receive sympathetic innervation (sweat glands, hair follicles, blood vessels)
What is the function of sympathetic activity
- Produce high sympathetic tone during stress
- Responsible for E situations (exercise, emergency, excitement, embarrassment)
- Fight or flight response
What is the function of parasympathetic activity
- Rest & digest activity
- SLUDD are some of the parasympathetic responses
( salivation, lacrimation, urination, digestion, defaecation)
Give an example of when the sympathetic nervous system comes into place
E.G. fight or flight:
- heart rate increases
- increased force of ventricular contraction (increase in bp)
- pupils dilate
- air-passages increase in diameter
- sweating occurs
Give an example of when the parasympathetic nervous system comes into place
E.G. rest & digest:
- slows heart rate
- lowers blood pressure
- constricts pupils
- speeds up digestion of food
What is a human’s awareness of the world determined by?
The physiological processes involved in the processing of afferent information - initially converting the stimulus into action potentials in the nerve fibres
What are sensory functions split into?
1) Somatic sensation
- perceptive (heat, cold, touch, pressure, joint position and pain)
- visceral (unconscious response to stimulus)
2) Special senses (vision, hearing, chemical, vestibular)
Describe how the sensory system works
- Consists of thermo-, mechano-, chemo-receptors (these accord to modality)
- according to their location:
exteroceptors: located in skin & organs of special senses
proprioceptors: respond to stimuli in joints, muscles & tendons
interoceptors: sensitive to stretch
What do sensory nerves do and how do they carry nerve impulses
They bring info from receptors to the central nervous system. After entering the CNS, the afferent nerve fibres go to the somato-sensory cortex via the brainstem & thalamus.
What are the special senses
1) Olfaction (smell)
2) Gustation (taste)
3) Vision
4) Hearing
5) Vestibular (equilibrium)
Describe the vestibular (equilibrium sense)
- Controls balance
- mechano-receptors of the semi- circular canals are hair cells
- the hair cells detect motion
- connected to afferent nerves
- info from the vestibular apparatus
enable the eyes to remain fixed
maintains upright posture
