Chp 8 Nervous system Flashcards
Describe the general functions of the nervous system
The nervous system is the primary controlling and coordinating system of the body. Its main functions include:
Sensory Input: Detects internal and external changes through receptors.
Integration: Processes and interprets sensory input, determining appropriate responses.
Motor Output: Sends signals to effectors (muscles/glands) to initiate a response.
Homeostasis Regulation: Maintains stable internal conditions (e.g., temperature, heart rate, digestion).
Higher Cognitive Functions: Supports memory, learning, reasoning, and emotions.
Reflex Actions: Enables automatic responses for protection and efficiency.
Identify the anatomical divisions of the nervous system and their components
Central Nervous System (CNS): Includes the brain and spinal cord, which process and integrate information.
Peripheral Nervous System (PNS): Composed of cranial nerves, spinal nerves, ganglia, and sensory receptors that connect the CNS to the rest of the body.
Describe the functional divisions of the peripheral nervous system
Sensory (Afferent) Division: Carries sensory information from receptors to the CNS.
Motor (Efferent) Division: Transmits signals from the CNS to effectors (muscles/glands). It has two subdivisions:
Somatic Nervous System (SNS): Controls voluntary and involuntary skeletal muscle movements.
Autonomic Nervous System (ANS): Regulates involuntary functions like heart rate, digestion, and gland secretion. It is further divided into:
Sympathetic Division: “Fight or flight” response, increasing alertness and metabolic activity.
Parasympathetic Division: “Rest and digest” response, conserving energy and promoting digestion.
Describe the structure of a neuron
A neuron consists of:
Cell Body (Soma): Contains the nucleus and organelles.
Dendrites: Short extensions that receive signals from other neurons.
Axon: A long extension that transmits electrical impulses away from the cell body.
Axon Terminals: Endings of the axon that release neurotransmitters.
Myelin Sheath: Insulating layer that speeds up signal conduction, produced by Schwann cells (PNS) and oligodendrocytes (CNS).
Compare the three structural types of neurons
Multipolar Neurons: Multiple dendrites and a single axon (most common type; found in CNS and motor neurons).
Bipolar Neurons: One dendrite and one axon (found in special sensory organs like the retina and olfactory system).
Pseudounipolar Neurons: A single process that splits into two branches (found in sensory neurons of the PNS).
Compare the three functional types of neurons
Sensory (Afferent) Neurons: Transmit impulses from sensory receptors toward the CNS.
Interneurons: Process and relay signals within the CNS.
Motor (Efferent) Neurons: Send impulses away from the CNS to effectors
Explain the functions of the five types of neuroglia
Astrocytes (CNS): Provide structural support, maintain the blood-brain barrier, and regulate ion balance.
Microglia (CNS): Act as immune cells, removing debris and pathogens.
Ependymal Cells (CNS): Line brain ventricles and spinal cord, producing cerebrospinal fluid (CSF).
Oligodendrocytes (CNS): Form the myelin sheath around axons.
Schwann Cells (PNS): Form the myelin sheath and aid in axon regeneration.
Explain the formation and conduction of an action potential
Resting Membrane Potential: The inside of the neuron is negatively charged relative to the outside (-70mV).
Depolarization: A stimulus causes sodium (Na+) channels to open, allowing Na+ to enter, making the inside more positive.
Action Potential Propagation: The depolarization wave moves along the axon.
Repolarization: Potassium (K+) channels open, allowing K+ to exit, restoring the negative charge inside.
Refractory Period: The neuron temporarily cannot fire another action potential until ion balance is restored.
Describe how action potentials are transmitted across a synapse
Action potential reaches the axon terminal.
Neurotransmitters are released into the synaptic cleft.
Neurotransmitters bind to receptors on the postsynaptic neuron.
This binding triggers a response (excitation or inhibition).
Neurotransmitters are removed via reuptake, enzymatic breakdown, or diffusion.
Describe how the brain and spinal cord are protected from injury
Bones: The skull protects the brain, and the vertebrae protect the spinal cord.
Meninges: Three layers—dura mater, arachnoid mater, pia mater—provide additional protection.
Cerebrospinal Fluid (CSF): Cushions and nourishes the CNS.
Blood-Brain Barrier: Prevents harmful substances from entering the brain.
Describe the major parts of the brain and their functions
Cerebrum: Controls higher functions (thought, memory, voluntary movement). sensory, motor and association
Diencephalon: Includes:
Thalamus: Relay station for sensory/motor signals.
Hypothalamus: Regulates homeostasis, hunger, thirst, emotions.
epithalamus (Production of the hormone melatonin)
Brainstem: Includes:
Midbrain: Visual and auditory processing.
Pons: Connects brain regions and helps control breathing.
Medulla Oblongata: Controls vital functions like heart rate and breathing.
Cerebellum: Coordinates movement and balance.
Identify the functions of the lobes of the cerebrum
Frontal Lobe: Motor control, decision-making, personality.
Parietal Lobe: Sensory processing (touch, temperature, pain).
Temporal Lobe: Hearing, language, memory.
Occipital Lobe: Vision processing.
Insula: Taste and visceral sensation.
Describe the structure and function of the spinal cord
Gray Matter: Contains neuron cell bodies for processing signals.
White Matter: Contains myelinated axons for communication between brain and body.
Functions: Reflex processing and transmitting information to/from the brain
The spinal cord consists of gray matter (processing) and white matter (signal transmission) and facilitates reflexes and communication between the brain and body.
Recall the name, type, and functions of the 12 cranial nerves
1Olfactory (Sensory) - Smell
2Optic (Sensory) - Vision
3Oculomotor (Motor) - Eye movement
4Trochlear (Motor) - Eye movement
5Trigeminal (Both) - Facial sensation, chewing
6Abducens (Motor) - Eye movement
7Facial (Both) - Facial expressions, taste
8Vestibulocochlear (Sensory) - Hearing, balance
9Glossopharyngeal (Both) - Taste, swallowing
10Vagus (Both) - Autonomic functions
11Accessory (Motor) - Neck movement
12Hypoglossal (Motor) - Tongue movement
Describe the formation, circulation, absorption, and functions of cerebrospinal fluid.
CSF is formed by choroid plexuses, circulates through ventricles and subarachnoid space, absorbed into venous sinuses, and serves as a cushion and nutrient transport medium.
Describe the classification of the spinal nerves and the plexuses they form.
31 pairs divided into cervical, thoracic, lumbar, sacral, and coccygeal nerves. These form plexuses such as cervical, brachial, lumbar, and sacral, which ensure efficient nerve supply.
Explain the functions of the components involved in a reflex.
Reflex arc components: Receptor, sensory neuron, integration center, motor neuron, and effector. Reflexes are rapid and automatic responses
Compare the structure and functions of the sympathetic and parasympathetic parts of the autonomic division.
Sympathetic: “Fight or flight” response; increases heart rate, dilates pupils.
Parasympathetic: “Rest and digest”; decreases heart rate, promotes digestion.
Describe the common disorders of the nervous system.
Inflammatory: Meningitis, neuritis.
Degenerative: Alzheimer’s, Parkinson’s.
Injury-related: Concussion, paralysis.
Functional: Epilepsy, multiple sclerosis.
