EXAM Flashcards
Week 9-12
What is a Ganglion?
Is a collection of Neuronal cell bodies located outside of the central nervous system.
In the Peripheral nervous system, ganglia appear as enlargements along nerves and contain cell bodies of neurons.
Where are ganglia located?
Ganglia are located in the peripheral nervous system, often near the spinal cord or target organs.
Ganglia are categorised as:
SENSORY:
- Found in dorsal roots of the spinal cord
- Contains the cell bodies of the sensory neurons entering the spinal cord
- Trigeminal Ganglion is the largest
AUTONOMIC:
- Sympathetic ganglia are located close to the spine.
- Parasympathetic ganglia are close to the end of the organ.
What are the 3 layers of connective tissue surrounding a nerve?
Epineurium: contains major blood vessels and surrounds the entire nerve
Perineurium: surrounds bundles of axons known as fascicles within the nerve.
Endoneurium: Connective tissue surrounding axons
What are the different types of Peripheral nerves?
Spinal:
somatic efferent fibres to the skeletal muscles of the trunk and limbs,
somatic afferent fibres to the skin, muscles and joints,
visceral efferent autonomic fibres, and
some spinal nerves contain visceral afferent fibres as well.
Cranial
Name All the cranial Nerves
“oh oh oh to take a family vaccation go (to) vegas after hours “
I. Olfactory
II. Optic
III. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducens
VII. Facial
VIII. Vestibulocochlear
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal
Describe the Function of each cranial Nerve
I. Olfactory: Smell.
II. Optic: Vision.
III. Oculomotor: Eye movement, eyelid elevation, and pupil constriction.
IV. Trochlear: Eye movement (superior oblique muscle).
V. Trigeminal: Sensation to face and meninges, and muscles of mastication.
VI. Abducens: Eye movement (lateral rectus muscle).
VII. Facial: Facial expression, taste (anterior 2/3 of tongue), and lacrimal and salivary gland secretion.
VIII. Vestibulocochlear: Hearing and balance.
IX. Glossopharyngeal: Taste, pharynx sensation, and parotid gland secretion.
X. Vagus: Taste, sensation in pharynx, and parasympathetic control of organs.
XI. Accessory: Controls trapezius and sternocleidomastoid muscles.
XII. Hypoglossal: Tongue movement
Understand the general role of the subtypes of motor and sensory nerves in the cranial nerves.
Sensory Types:
Somatic sensory: Sensation from the body, like skin and muscles.
Special sensory: Senses such as vision, hearing, balance, and taste.
Visceral sensory: Sensation from internal organs.
Motor Types:
Somatic motor: Motor control of skeletal muscles.
Branchial motor: Motor control of muscles derived from branchial arches (e.g., muscles of facial expression).
Visceromotor: Parasympathetic innervation to organs like glands and heart
Function of each cranial nerve as either SENSORY (S), MOTOR (M), BOTH (B)
Some - Olfactory (Sensory)
Say - Optic (Sensory)
Marry - Oculomotor (Motor)
Money - Trochlear (Motor)
But - Trigeminal (Both)
My - Abducens (Motor)
Brother - Facial (Both)
Says - Vestibulocochlear (Sensory)
Big - Glossopharyngeal (Both)
Brains - Vagus (Both)
Matter - Accessory (Motor)
More - Hypoglossal (Motor)
Origins of the SNS
Pre-ganglionic: fibers arise form the intermediolateral cell column of the T1 to L2/3 levels of the spinal cord, then travel to the paravertebral ganglia (located near the spine) before synapsing with post-ganglionic fibres which travel to the end of organ
SNS ganglia are located close to spine!
Origins of the PNS
Arises from the cranial nerves and S2-4 Sacral Segments
CRANIAL NERVES INVOLVED;
Cranial Nerve III (pupil constriction),
Cranial Nerve VII (lacrimation and salivation),
Cranial Nerve IX (salivation), and
Cranial Nerve X (controls heart rate and digestion).
PNS galglia are usually located closer to the end of organ!!!
Actions of the SNS
(Fight or Flight response)
- Increasing HR and bP
- Dilate the pupils to allow more light.
- Relax airway muscles to increase O2 intake
- Slowing digestion and repair processes.
- Releasing sugar into the bloodstream for energy.
Inducing sweating and piloerection (goosebumps). - Reducing bladder contraction and temporarily depressing immune system function.
Actions of the PNS
(Rest and Repair)
- Decrease heart rate
- Dilate the visceral blood vessels to increase blood perfusion to allow absorption of nutrients
- Inhibit SNS to dilate peripheral blood vessels (note peripheral blood vessels only have SNS innervation) – reduces blood pressure
- Constrict the pupils
- Increase digestion and repair functions
- Increase bladder contraction
- Increase immune system function
- Facilitates neuroplasticity (synaptic connections)
Neurotransmitters of the SNS
The Pre-ganglionic fibers use ACETYLCHOLINE to stimulate postganglionic neurones
The Post-ganglionic fibers use ADRENALINE (epinephrine),
Neurotransmitters of the PNS
The Pre-ganglionic fibers use ACETYLCHOLINE
The POst-ganglionic fibers also use ACETYLCHOLINE
to stimulate their respective targets
Differences Between the Somatic and Autonomic Motor Systems:
"SOMATIC"
- primarily acts on SKELETAL MUSCLE
- Voluntary control (CONSCIOUS)
- Neurotransmitter is ACETYLCHOLINE
- Muscle Contraction (EXCITATION ONLY)
- FUNCTIONS = body movement, posture, respiration, speech.
- Involves a SINGLE NEURONE PATHWAY where an alpha motor neuron directly innervates the target muscle.
Differences Between the Somatic and Autonomic Motor Systems:
"AUTONOMIC"
- Acts on SMOOTH and CARDIAC MUSCLE
- Involuntary control
- Neurotransmitter for Pre-ganglionic = ACETYLCHOLINE, Neurotransmitter for Post-ganglionic = NOREPINEPHRINE (sympathetic), ACETYLCHOLINE (parasympathetic)
- Muscle contraction (EXCITATION/INHIBITION
- FUNCTIONS - regulates HR, BP, digestion, respiration, body temp
- Utilizes a TWO-STEP PATHWAY: a preganglionic neuron projects from the CNS to a ganglion, and a postganglionic neuron projects from the ganglion to the target organ.
Enteric Nervous System:
“Structure”
- Located within the walls of the gastrointestinal tract, spanning from the esophagus to the rectum
- organized into two main plexuses:
1. Myenteric Plexus = controls gut motility
2. Submucosal Plexus = regulates blood flow, secreations, and absorption within the gut.
Functions of the ENS
- Known as the “second brain” because it operates independently of the central nervous system (CNS).
- Controls peristalsis (movement of food) and digestion.
- Plays a role in regulating local blood flow, immune response, and sensory perception within the gut.
Neurotransmitters of the ENS
Uses various neurotransmitters, including acetylcholine, serotonin, dopamine, and nitric oxide.
