Peripheral Nervous System - Nervous System 2 Flashcards
1
Q
Peripheral Nervous System
A
Consists of:
- all nerves outside the brain and spinal cord
- 31 pairs of spinal nerves and 12 pairs of cranial nerves
- the autonomic part of the nervous system
2
Q
2 nerve types
A
- sensory or afferent - coneys impulses from sensory organs to brain
- motor or efferent - conveys impulses from brain through spinal cord and to effector organs e.g. skeletal and smooth muscles, glands etc
- each nerve consists of numerous nerve fibres collected into bundles, each bundle has several coverings of protective connective tissue
3
Q
Endoneurium
A
- delicate tissue - surrounds each individual fibre which is continuous with the septa (dividing wall or membrane) that passes inwards from the perineurium
4
Q
Perineurium
A
- smooth tissue - surrounds each bundle of fibres
5
Q
Epineurium
A
- tissue which surrounds and encloses a number of bundles of nerve fibres
- most large nerves are covered in epineurium
6
Q
Spinal nerves
A
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Each one is formed by a sensory and motor nerve root - therefore they are mixed nerves
7
Q
Mixed nerves
A
- within spinal cord - sensory and motor nerves are seperate
- outwith spinal cord - may run together within the same tube of connective tissue, then termed mixed nerves e.g. Trigeminal Nerve.
8
Q
Cranial nerves
A
- 1 olfactory - sensory
- 2 optic - sensory
- 3 occulomotor - mixed
- 4 trochlear - motor
- 5 trigeminal - mixed
- 6 abducent - motor
- 7 facial - mixed
- 8 vestibulococlear (auditory) -sensory
- 9 glossopharyngeal - mixed
- 10 vagus - mixed
- 11 accessory - motor
- 12 hypoglossal - motor
9
Q
Sensory nerves
A
- specialised receptors respond to stimuli
- “common sensation” - pain, touch, heat and cold
- special sensation - sight, hearing, smell and taste
- proprioceptors - information about position of the body
- baroreceptors - monitor pressure e.g. blood
10
Q
What are the 2 parts of the autonomic nervous system or (involuntary part of the nervous system)
A
- sympathetic
- parasympathetic
Controls functions of the body e.g. increase in heart rate. (Sympathetic part of the autonomic nervous system)
11
Q
Autonomic nervous system
A
- essential for homeostasis - includes stimulation or depression of glandular secretion and contraction of muscle tissue
- both antagonise each other enabling and restoring balance of involuntary actions
- sympathetic - predominates during stress
- parasympathetic - predominates during rest
- parasympathetic- responsible for increased gastric activity
12
Q
What are your special senses?
A
Taste and smell
13
Q
Taste buds
A
- microscopically approx 9000 on dorsum of tongue, soft palate, pharynx and epiglottis
- consists of small bundles of cells - one end hair like processes project through pores in mucous membrane and other end continuous with nerve fibres forming sensory portions of 7th and 9th cranial nerve
14
Q
Physiology and nerve supply (sensory) of taste?
A
- four basic tastes: bitter, salty, sweet and sour
- chemical sensation = must be dissolved
- other factors affecting flavour - texture, irritation, smell
Nerve supply: - Anterior 2.3 of tongue
- Lingual branch of Chord Tympani to the facial
- posterior 1/3 tongue-glossopharyngeal
- Soft Palate –posterior palatine nerve
15
Q
Special sense of smell
A
- Sensory nerves of smell-Olfactory 1st
- Chemical particles carried to nose with inhaled air, dissolve in mucous
- Secretions stimulate nerve cells of Olfactory when in solution
- Interpreted in Cerebral Cortex
- Continued exposure to odour leads to decreased perception.
