The Nervous System (Revision) Flashcards
1
Q
Overview of the Nervous System
A
Central Nervous System (CNS)
- Brain and spinal cord
- Processes, stores, and retrieves information
Peripheral Nervous System (PNS)
- Carries signals to and from the CNS
- Afferent Sensory Division: Transmits signals to the CNS
- Efferent Motor Division: Sends signals from the CNS to muscles and gland
- Somatic Nervous System: Voluntary movements.
- Autonomic Nervous System: Involuntary functions
2
Q
Cells in the Nervous System
A
Neurons
- Functional units of NS
- Excitability, conductivity, secretion
- Sensory (Afferent) Neurons: Carry signals from sensory receptors to the CNS
- Interneurons: Integrate information within the CNS (90%)
- Motor (Efferent) Neurons: Transmit signals to muscles and glands
Glial Cells (Neuroglia)
- CNS
- Oligodendrocytes: Myelinate CNS axons
- Ependymal Cells: Line ventricles and produce cerebrospinal fluid (CSF)
- Microglia: Immune cells
- Astrocytes: Maintain the blood-brain barrier
- PNS
- Schwann Cells: Myelinate PNS axons, facilitate nerve regeneration
- Satellite Cells: Support and protect neuron cell bodies in ganglia.
3
Q
Synapses and Neural Communication
A
Synapses
- Connections between neurons
- Chemical Synapses: Neurotransmitter released into a synaptic cleft
- Electrical Synapses: Direct passage of ions between cells.
Neurotransmitters
- Acetylcholine: Involved in muscle contraction
- GABA: An inhibitory neurotransmitter that reduces neuronal excitability
4
Q
Spinal Cord and Reflexes
A
Spinal Cord
- Main conduit for information traveling to and from the brain
Gray Matter
- Has neuron cell bodies, is involved in processing
White Matter
- Has myelinated axons that transmit signals
Reflex Arcs
- Rapid responses to stimuli without direct involvement of the brain
5
Q
Clinical Relevance (Spinal Cord)
A
- Multiple Sclerosis: Degeneration of myelin in the CNS
- Amyotrophic Lateral Sclerosis (ALS): Affects motor neurons, leading to muscle weakness and atrophy
- Spinal Meningitis: Inflammation of the protective membranes covering the brain and spinal cord
6
Q
Spinal Roots
A
Dorsal Roots
- Carry sensory (afferent) information from the body to the spinal cord
Ventral Roots
- Carry motor (efferent) information from the spinal cord to the muscles and glands
Pathway
- Exits the vertebral column through an intervertebral foramen and branches into:
- Dorsal Ramus: Supplies the back muscles and skin
- Ventral Ramus: Supplies the anterolateral body wall and limbs
7
Q
General Overview of the Structure of the Brain
A
Cerebrum
- Two hemispheres connected by the corpus callosum
- Frontal Lobe: Decision-making, voluntary movement control, Broca’s area (speech production), personality and behavior
- Parietal Lobe: Sensory processing of tactile information (touch, temperature, pain), spatial awareness
- Temporal Lobe: Auditory processing, Wernicke’s area (language comprehension), memory and emotion
- Occipital Lobe: Visual processing and recognition
Cerebellum
- Voluntary motor skills
- Maintain posture
- Coordinate movements
Brainstem
- Connects to the spinal cord
- Medulla Oblongata: Controls autonomic functions (heart rate, breathing) and has cranial nerve nuclei
- Pons: Connects the cerebellum and has cranial nerve nuclei.
- Midbrain: For vision and hearing reflexes
Gray Matter
- Has neuronal cell bodies
White Matter
- Has myelinated axons
- Facilitates communication between the brain and spinal cord
8
Q
Brain Meninges
A
Three protective membranes
Dura Mater
- Outermost layer
- Dense connective tissue with two layers (periosteal and meningeal)
Arachnoid Mater
- Middle layer
- Transparent and filled with cerebrospinal fluid (CSF)
Pia Mater
- Innermost layer
9
Q
Brain Ventricles
A
Hollow spaces within the brain filled with CSF
- Lateral Ventricles: In each cerebral hemisphere
- Third Ventricle: Connects to the lateral ventricles
- Fourth Ventricle: Connects to the third ventricle and continues into the spinal cord
10
Q
Functions of Cerebrospinal Fluid (CSF)
A
- Provides buoyancy to reduce the weight of the brain
- Protects the brain from impact
- Maintains chemical stability by removing metabolic waste
11
Q
Diencephalon of the Brain
A
Sensory signal relay and homeostasis
- Thalamus: Relay station for sensory information
- Hypothalamus: Autonomic functions and hormone secretion
12
Q
Higher Functions and Cranial Nerves
A
Limbic System
- Emotion and memory
Basal Nuclei
- Motor control and planning
Cranial Nerves
- Olfactory (S): Sense of smell
- Optic (S): Vision
- Oculomotor (M): Controls eye movement
- Trochlear (M): Rotation of eye downward and laterally
- Trigeminal (B): Sensory in the face, motor function for mastication
- Abducens (M): Abducts the eye
- Facial (B): Taste 2/3 of tongue, muscles of facial expressions
- Vestibulocochlear (S): Hearing and equilibrium
- Glossopharyngeal (B): Taste 1/3 of tongue, motor for swallowing
- Vagus (B): Sense of thoracic and abdominal muscles, motor function for heart, lungs, digestive tract
- Accessory (M): Head and shoulder movement
- Hypoglossal (M): Muscles of tongue for speech and swallowing
13
Q
The Autonomic Nervous System
A
Sympathetic
- “Fight or flight”
- Prepares for stressful situations
- Increases heart rate and blood flow to muscles
Parasympathetic
- “Rest and digest”
- Conserves energy and facilitates bodily maintenance functions
14
Q
Sensory Receptors
A
Mechanoreceptors
- Respond to mechanical forces (e.g., touch, pressure)
Thermoreceptors
- Detect changes in temperature
Nociceptors
- Respond to pain
Photoreceptors
- Detect light (rods and cones in the retina)
Chemoreceptors
- Respond to chemical stimuli (e.g., taste and smell)
15
Q
The Eye
A
Anatomy
- Outer Layer: Sclera (white part) and cornea (transparent front)
- Middle Layer (Uvea): Iris (controls light entry), ciliary body (focuses lens), and choroid (provides nutrients)
- Inner Layer (Retina): Photoreceptors (rods for low light, cones for color), converts light into neural signals
Function
- Light enters through the cornea
- Passes through the lens (which focuses it)
- Projected onto the retina
- Photoreceptors convert it to electrical impulses
- Sent to the brain via the optic nerve
