W8 Nervous system Flashcards
PICDescribe the general structure of a nerve
A bundle of axons (unmyelinated or myelinated) located outside the CNS, by a connective tissue layer called endoneurium. These groups of axons are connected to fascicles
State the 12 cranial nerves by both name and number
Olfactory Nerve (I) Optic Nerve (II) Occulomotor Nerve (III) Trochlear Nerve (IV) Trigeminal (V) Abducens Nerve (VI) Facial Nerve (VII) Vestibulocochlear (VIII) Glossopharyngeal Nerve (IX) Vagus Nerve (X) Accessory nerve (XI) Hypoglossal Nerve (XII)
What is the function of Olfactory Nerve (I) ?
Olfactory Nerve (I) Composed of entirely sensory axons, conducts nerve impulses for the sense of smell
What is the function of Optic Nerve (II)?
Composed of entirely sensory axons conducts nerve imuplses releated to vision
What is the function of Occulomotor Nerve (III)?
Is a mixed nerve. Sensory convey info related to proprioception Motor axon convey info for the movement of eyeball PSN alter lens and pupil size
What is the function of Trochlear nerve (IV)?
Mixed nerve
Sensory axons: convey info to the position in proprioception
Motor: convey info for the movement of eyeball
EDITWhat is the function of Trigeminal (V)
Mixed nerve: Largest of cranial nerves, mixed nerve Sensory axons: convey info related to touch, pain, temp, chewing Motor axons: Convey info related to chewing
What is the function of Abducens Nerve (VI)?
Mixed nerve: Sensory axon: converys info to the position of eye ball Motor axons: movement of eye ball
What is the function of Facial Nerve (VII)?
Mixed nerve
Sensory: info related to taste
Motor: movement of face
Autonmoic axons: control salivary glands
What is the function of Vestibulocochlear (VIII) Nerve?
Sensory nerve (two branches)
Vestibular branch: carries info for balance
Cochlear branch: carries in related to hearing
What is the function of Glossopharyngeal Nerve (IX)?
Mixed nerve
Sensory axon: swallowing, blood pressure
Motor axons: controls swallowing
Autonomic: controls saliva secretion
What is the function of Vagus Nerve (X)?
Mixed nerve, only nerve that extends beyond head
Sensory axons: convey info for taste, respiration, blood pressure, organs of abdominal cavities
Motor axons: controls muscles in speech and swallowing
Autonomic axons: heart, lungs, respiratory
What is the function of Accessory nerve (XI)?
Mixed nerve
Sensory axons: conveys info related to preconception of neck muscles
Motor axons: convey info related to swallowing and head movements
What is the function of Hypoglossal Nerve (XII)?
Mixed nerve
Sensory axons: convey info related to proprioception of tongue muscles
Motor axons: convey info related to control of tongue muscles related to speech and swallowng
What are spinal nerves?
Apart of the PNS, they connect the CNS to sensory receptors, muscles and glands in all parts of the body. There are 31 pairs
List the origins of the spinal nerves and name their branches
- There are 8 pairs of cervical nerves (C1-C8)
- There are 12 pairs of thoracic nerves (T1-T12)
- There are 5 pairs of lumbar nerbe (L1-L5)
- There are 5 pairs of sacral nerves (S1-S5)
- There is one pair on coccygeal nerves (Co1)
Describe a nerve plexus
A network formed by axons from adjacent nerves called a plexus, found on both LHS/RHS.
Name the 5 nerve plexuses and the regions they innervate
- The Cervical plexus 2. The brachial plexus 3. The lumbar plexus 4. The saccral plexus
What are groups of axons wrapped in endoneurium collected into?
Fascicles, nerves bunched together strengtehn the nerve fibers. Each fascicle is wrapped in a connective tissue called a perineurium. A final connective tissue layer called the epineirium forms the outer surface of the nerve
What are the two groups of nerves?
Cranial Nerves Spinal Nerves
What are cranial nerves?
Nerves that arise from the brain they pass through foramina in the cranial bones to innervate parts of the body
How are nerves compiled?
Most nerves are mixed, they contain axons from both motor and sensory neurons, sometimes autonomic
Name 3 Sensory nerves
- Olfactory nerve (I)
- Optic nerve (II)
- Vestibulocochlear nerve (VIII)
What are spinal nerves made up of?
Spinal nerve roots are where bundles of axons make up the spinal nerves that connect with the spinal cord. A spinal nerve is where the anterior and posterior roots come together
What are the two types of spinal nerve roots?
Anterior (ventral) root Posterior (dorsal) root
What is the anterior roots function?
Axons of motor neurons are found here, they make connections with skeletal muscle, cardiac muscle, smooth muscle and glands
What is SAP?
Sensory, Afferent, Posterior
What is MEA?
Motor, Efferent, Anterior
What is MEA?
Motor, Efferent, Anterior
What are the 2 branches of the ramus and functions?
Anterior ramus - Serves muscles anf structure of UPP/LWR limbs, skin, lateral and anterior trunk Posterior ramus - serves muscle and skin of the posterior trunk of body
What do Rami contain?
Sensory Afferent Posterior and more neurons
What is the advantage of a plexus?
Axons derived from a number of different spinal nerves, ending up at a the same peripheral structure
What region does the Cervical plexus innervate?
Supplies the skin and muscles of the head, neck, and superior portions of the shoulders, chest, & diaphram
What region does the the brachial nerve innervate?
Provides nerve supply for the shoulders and upper limbs
What region does the lumbar plexus innervate?
Provides nerve supply to the anterior/lateral/abdominal wall/external genitals/ parts of lower limb
What region does the saccral plexus innervate?
Provides nerve supply to the buttocks, perineum and lower limbs
What spinal nerves DO NOT form a plexus?
The ventral rami of spinal nerves T2-T12, they’re refered to as intercostal nerves
What spinal nerves DO NOT form a plexus?
The ventral rami of spinal nerves T2-T12, they’re refered to as intercostal nerves
What is the main source of sensory input to the autonomic nervous system?
Autonomic sensory neurons, they’re largely associated with interoceptors that maintain homeostasis
What is the main output from the autonomic nervous system?
Autonomic motor neurons, these act to regulate the effect of cardiac muscle, smooth muscle, and glands.
Seperated into two system: PNS, SNS
Where are the cell bodies of ‘first order’ autonomic motor neurons located?
Axons from somatic motor neurons project from the CNS to the skeletal muscle fibres
Where are the cell bodies of ‘first order’ autonomic motor neurons located?
Located within the CNS, a myelinated axon from the preganglionic neuron extends into an autonomic ganglion
Where are the cell body of ‘second order’ autonomic motor neurons located?
The second autonomic motor neuron is located within the autonomic ganglion, the un-myelinated axon from this neuron extends to the effector called a postganglionic neuron
What neurotransmitter is released by ALL preganglionic autonomic neurons
Acetylcholine (ACh) they’re called cholingergic neurons
EDITPICWhat neurotransmitter is released by MOST sympathetic post-ganglionic neurons?
Noradrenaline (NAd) also called norepinephrine (NE)
What is the exception to ACh being released in the sympathetic system?
When the sympathetic postganglionic sweat glands release acetylcholine (ACh)
What neurotransmitters is used by ALL parasympathetic post-ganglionic neurons?
Acetylcholine (Ach)
When would you expect the SNS activated
1.Exercise 2. Arousal 3. Exercise 4. Reduces body functions, therefore releasing more energy 5. Pupil dilate 6. Heart rate
When would you expect to see sympathetic nervous system activation?
- Quiet intervals 2. Rest and digest
What are 5 processes that are stimulated by parasympathetic NS activations
SLUDD Salivation Lacrimation Urination Digestion Defacation
What is the effect of the parasympathetic NS on heart rate, air way diameter and pupil diameter?
Decreased heart rate Decreased airway diameter Decreased pupil diameter
What are the 5 components of an autonomic reflex? How do they interact?
- Receptor - responds to receptor 2. Sensory neuron - conducts impulse from recepter to CNS 3. Integrating centre - process sensory neuron info and activates motor neuron 4. Motor neuron - sends nerve impulses to the effector organ 5. Effector organ - elicits response
Define sensation & discuss the process of sensation
Sensation is the conscious or subconscious awareness of a change in the external and internal environment. - The nature of this sensation and the response it elicits is dependant on where the sensory info in processed
Outline way in which receptors can be classified
- By structure 2. By location 3. By modality (what they detect)
Describe the process of sensory adaption
Is where the response produced by the sensory receptor, becomes smaller when the stimulus is presented over a period of time
Describe somatic sensation
Sensation that arise from receptors in places such as : The skin Mucousal membranes Muscles, tendons, joints, the inner ear (balance). The primary somatosensory cortex is organised into a somatic sensory map of the body
Describe tactile sensation
Encapsulated mechanoreceptors - Touch Pressure Vibration Free nerve endings - Itch Tickle
List the different types of somatosensory receptors
xx?
Describe nociception
Free nerve endings found everywhere except the brain, intense thermal, mechanical or chemical stimuli elicit the nociception response
Describe proprioception and the different types of proprioceptors
Enables us to determine the location of our body in space, specialised structures in hair cells, and inner ear
Describe encapsulated nerve ending
Dendrite enclosed in connective tissue capsule.
Designed to detect pressure
Describe cells
Some receptors for special senses (taste) are actually separate cells, they synapse with sensory neurons
How are sensory receptors grouped based of their location?
- Interoreceptors - located in blood vessels, muscles and NS. They monitor the internal environment 2. Proprioceptors - located in muscles, tendons, joints and inner ear
How can sensory receptor be grouped bases on the type of stimuli they response to?
- Mechanoreceptors - respond to mechanical stimulation (pressure stimulus) 2. Thermoreceptors - respond to changes in temp 3. Nociceptors - respond to painful stimuli resulting from chemical or physical damage to tissue
How can sensory receptors be grouped based on the type of stimuli that they respond to?
- Photoreceptors - responds to light
- Chemoreceptors - responds to chemicals in the mouth, nose and body fluids
- Osmoreceptors - responds to changes in the osmotic pressure of body fluids edit(dehydration)
How can sensory receptors be grouped based on the type of stimuli that they respond to?
Photoreceptors - responds to light
Chemoreceptors - responds to chemicals in the mouth, nose and body fluids
Osmoreceptors - responds to changes in the osmotic pressure of body fluids edit(dehydration)
What receptors in the skin or subcutaneous layer respond to touch?
Corpuscles of touch (Meissner corpuscles) Located in the dermis of hairless skin
Hair root plexuses - free nerve endings wrapped around hair follicles which detect movements that disturb hairs
Merkel type I cutaneous mechanoreceptors (or merkle discs - makes contact with merkel cells
Type II cutaneous mechanoreceptors - sensitive to stretch
What receptors in the subcutaneous layer respond to pressure?
Corpuscles of touch Type I cutaneous mechnoreceptors Lamellated corpuscles (multiple layers of contecting tissue surrounding the dendrites)
What somatic sensory receptors in the subcutaneous layer respond to vibration?
Corpuscles of touch Lamellate corpulscles
What somatic sensory receptors in the subcutaneous layer respond to itch and tickle?
Free nerve endings
What somatic sensory receptors respond to thermal sensation?
Free nerve endings called thermoreceptors
What are the proprioceptors in muscles?
The proprioceptors located with skeletal muscles are called muscle spindles, they monitor changes in the length of skeletal muscles, participating in stretch reflexes
What are the proprioceptors in tendons?
Tendon organs provide info related to muscle tension
What are the proprioceptors in joints?
Kinesthetic receptors, sensing joint position and movement
What are the proprioceptors in joints?
Kinesthetic receptors, sensing joint position and movement
What is a reflex?
Is a fast involuntary, unplanned sequence of actions that occur to a specific stimulus
What is a cranial reflex?
Is a reflex where the integration of info performed by the CNS occurs in the brain stem
What is a spinal reflex?
The integration of info performed by the CNS occurs in the grey matter of the spinal cord
What is the difference between a somatic and an autonomic reflex?
Somatic reflex involves the contraction of a skeletal muscle Autonomic reflex: responses of muscle, cardiac muscle and glands, heart rate etc
What is a reflex arc?
Pathway followed by nerve impulses that result in a reflex response
PICWhat are the 5 components of a reflex arc?
- Sensory receptor - responds to specific stimulus
- Sensory neuron - transmitting info
- Integration centre - neurons in the grey matter process sensory input and elicit motor neuron output
- Motor neuron -
- The effector - the part of the body that responds to signals sent by the motor neuron
What is a stretch reflex? Give an example
Results in the contraction of a skeletal muscle in response to the stretching of that muscle
What is a stretch reflex? Give an example
Results in the contraction of a skeletal muscle in response to the stretching of that muscle involves a monosynaptic reflex arch (single motor neuron)
What is the neural circuitry of the patella stretch reflex?
- A stretch of the tendon activates sensory receptors that monitor the length of muscles 2. Stimulation of muscle spindle activates sensory neuron 3. Integration occurs in the grey matter 4. Impulses travel down the motor neuron axon towards the effector
What is reciprocal innervation?
- Stretch of the tendon activates sensory receptors (muscle spindles) 2. Simulation 3, Processed in spinal cord, neuron activates, an inhibitory interneuron 4. Due to inhibitation the motor neuron innervating the hamstring muscle does not send signals to these muscles 5. Hamstring muscle relaxs due to lax of input from the motor neuron
