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Questions and Answers
What causes voltage-gated Ca2+ channels to open at the presynaptic terminal?
What causes voltage-gated Ca2+ channels to open at the presynaptic terminal?
Action potentials
What diffuses into the cell causing synaptic vesicles to release neurotransmitter molecules?
What diffuses into the cell causing synaptic vesicles to release neurotransmitter molecules?
Neurotransmitter molecules combine with their receptor sites and cause chemically-gated Na+ channels to open, leading to the diffusion of Na+ into or out of the cell, resulting in a change in __________ potential.
Neurotransmitter molecules combine with their receptor sites and cause chemically-gated Na+ channels to open, leading to the diffusion of Na+ into or out of the cell, resulting in a change in __________ potential.
membrane
Gray matter in the spinal cord looks like a letter W.
Gray matter in the spinal cord looks like a letter W.
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Match the following components of a reflex arc:
Match the following components of a reflex arc:
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What are the main functions of the nervous system? (Select all that apply)
What are the main functions of the nervous system? (Select all that apply)
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The central nervous system includes the brain and spinal cord.
The central nervous system includes the brain and spinal cord.
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What is the primary function of dendrites in a neuron?
What is the primary function of dendrites in a neuron?
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The _____ is a fatty, protective wrapping around axons.
The _____ is a fatty, protective wrapping around axons.
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Match the type of neuron with its description:
Match the type of neuron with its description:
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Which type of cells produce myelin sheath in the central nervous system?
Which type of cells produce myelin sheath in the central nervous system?
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What is the function of the medulla oblongata?
What is the function of the medulla oblongata?
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Which brainstem component is responsible for coordinated eye movement and pupil diameter?
Which brainstem component is responsible for coordinated eye movement and pupil diameter?
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The thalamus influences moods and detects pain.
The thalamus influences moods and detects pain.
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The __________ cortex controls thinking, communicating, remembering, understanding, and initiates involuntary movements.
The __________ cortex controls thinking, communicating, remembering, understanding, and initiates involuntary movements.
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Match the lobes of the brain with their functions:
Match the lobes of the brain with their functions:
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What is the main function of the Basal Nuclei?
What is the main function of the Basal Nuclei?
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Which area of the brain is responsible for motor speech?
Which area of the brain is responsible for motor speech?
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Delta waves are associated with deep sleep.
Delta waves are associated with deep sleep.
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_________ is the protective wrapping around the brain and spinal cord.
_________ is the protective wrapping around the brain and spinal cord.
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Match the following divisions of the Peripheral Nervous System with their functions:
Match the following divisions of the Peripheral Nervous System with their functions:
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Study Notes
Functions of the Nervous System
- Receives sensory input through sensory receptors
- Integrates stimuli through the brain and spinal cord
- Controls muscles and glands
- Facilitates mental activity in the brain
- Maintains homeostasis
Main Divisions of the Nervous System
- Central Nervous System (CNS): consists of the brain and spinal cord
- Peripheral Nervous System (PNS): consists of all neurons outside the CNS
Neuron Characteristics
- Receive input, process input, and produce a response
- Require oxygen and glucose
- Have three main parts: dendrite, cell body, and axon
Neuron Structures
- Dendrite: receives stimulus from other neurons or sensory receptors
- Cell body: processes stimulus and contains a nucleus
- Axon: transmits stimulus to a gland, muscle, organ, or other neuron
Myelin Sheath
- A fatty, protective wrapping around axons
- Excellent insulator
- Has gaps called nodes of Ranvier where action potentials develop
- Allows for saltatory conduction, where action potentials "jump" from node to node
Action Potential Conduction
- Action potentials are generated when the inside of the membrane becomes positive and the outside becomes negative
- Depolarization occurs when the inside of the membrane becomes positive, causing the generation of a new action potential
- Local currents are generated, causing the action potential to propagate along the axon
Types of Neurons
- Multipolar: has many dendrites and a single axon (e.g. CNS and most motor neurons)
- Bipolar: has one dendrite and one axon (e.g. eye and nasal cavity)
- Pseudo-unipolar: has one axon and no dendrites (e.g. sensory neurons)
Neuroglia Characteristics
- Supporting cells for neurons
- More numerous than neurons
- Can divide to produce more cells
- There are 5 types: astrocytes, ependymal cells, microglia, oligodendrocytes, and Schwann cells
Types of Neuroglia
- Astrocytes: star-shaped, most abundant, and form the blood-brain barrier
- Ependymal cells: produce and circulate cerebrospinal fluid (CSF)
- Microglia: help remove bacteria and cell debris from the CNS
- Oligodendrocytes: produce myelin sheath in CNS
- Schwann cells: produce myelin sheath in PNS
Organization of Nervous Tissue
- Gray matter: collection of dendrites and cell bodies
- White matter: collection of axons and their myelin sheath
- CNS: oligodendrocytes produce myelin sheath, while PNS: Schwann cells produce myelin sheath
Electrical Signals and Neural Pathways
- Resting membrane potential: outside of cell is more positive (Na+), inside of cell is more negative (K+)
- Leak ion channels: always open, K+ channels
- Gated ion channels: closed until opened by specific signal, Na+ channels
Action Potentials
- "Electricity" that causes depolarization and repolarization
- Change resting membrane potential by activating gated ion channels
- Local current: movement of Na+ which causes inside of cell to be more positive (depolarize)
Synapse
- Where an axon attaches to a muscle, gland, organ, or other neuron
- Involved with release of neurotransmitters
- Example: neuromuscular junction
Reflexes
- Involuntary response to a stimulus
- Reflex arc: path reflex travels
- Components of reflex arc:
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- Sensory receptors: pick up stimulus
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- Sensory (afferent) neurons: send stimulus to interneurons in spinal cord
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- Interneurons (Association) neuron: process stimulus
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- Efferent (motor) neurons: send response to effector
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- Effector: muscle, gland, or organ
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Neuronal Pathways
- Converging: two or more neurons synapse with the same neuron
- Diverging: axon from one neuron divides and synapses with more than one neuron
Central Nervous System
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Consists of brain and spinal cord
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Spinal cord: extends from foramen magnum to 2nd lumbar vertebra, protected by vertebral column, and allows for movement
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Gray and white matter in spinal cord: gray matter is in the center, looks like letter H or a butterfly, and white matter is outside, contains myelinated fibers### Gray Matter in Spinal Cord
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Posterior horns contain axons that synapse with interneurons
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Anterior horns contain somatic neurons
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Lateral horns contain autonomic neurons
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Central canal is a fluid-filled space in the center of the cord
Spinal Nerves
- Arise along the spinal cord from the union of dorsal and ventral roots
- Contain axons of sensory and somatic neurons
- Located between vertebrae
- Categorized by region of the vertebral column from which they emerge (e.g., C for cervical)
- There are 31 pairs of spinal nerves
- Organized into 3 plexuses: cervical, brachial, and lumbosacral
Plexuses
- Cervical plexus: spinal nerves C1-4, innervates muscles attached to the hyoid bone and neck, and contains the phrenic nerve which innervates the diaphragm
- Brachial plexus: originates from spinal nerves C5-T1, supplies nerves to the upper limb, shoulder, and hand
- Lumbosacral plexus: originates from spinal nerves L1-S4, supplies nerves to the lower limbs
Cerebrospinal Fluid
- Fluid that bathes the brain and spinal cord
- Provides a protective cushion around the CNS
- Produced in the choroid plexus of the brain
Brainstem
- Components: medulla oblongata, pons, and midbrain
- Medulla oblongata: regulates heart rate, blood vessel diameter, breathing, swallowing, vomiting, hiccupping, coughing, sneezing, and balance
- Pons: regulates breathing, chewing, salivation, and swallowing
- Midbrain: coordinates eye movement, pupil diameter, and turning head toward noise
Reticular Formation
- Location: scattered throughout the brainstem
- Function: regulates cyclical motor function, respiration, walking, chewing, arousing and maintaining consciousness, and regulates sleep-wake cycle
Diencephalon
- Located between the brainstem and cerebrum
- Components: thalamus, hypothalamus, and epithalamus
- Thalamus: influences moods and detects pain
- Epithalamus: involved in emotional and visceral response to odors
- Hypothalamus: controls body temperature, thirst, hunger, fear, rage, and sexual emotions
Cerebrum
- Characteristics: largest portion of the brain, divided into right and left hemispheres, and has four lobes: frontal, parietal, occipital, and temporal
- Cerebral cortex: surface of the cerebrum, composed of gray matter, controls thinking, communicating, remembering, understanding, and initiates involuntary movements
- Left hemisphere: controls right side of the body, responsible for math, analytic, and speech
- Right hemisphere: controls left side of the body, responsible for music, art, and abstract ideas
- Corpus callosum: connects the two hemispheres
Lobes of the Brain
- Frontal lobe: controls voluntary motor functions, aggression, moods, and smell
- Parietal lobe: evaluates sensory input such as touch, pain, pressure, temperature, and taste
- Occipital lobe: vision
- Temporal lobe: hearing, smell, and memory
Cerebellum
- Location: below the cerebrum
- Characteristics: means little brain, cortex is composed of gyri, sulci, and gray matter
- Functions: controls balance, muscle tone, and coordination of fine motor movement
Sensory Functions
- CNS constantly receives sensory input
- We are unaware of most sensory input
- Sensory input is vital for our survival and normal functions
Ascending Tracts
- Pathways in the brain and spinal cord
- Transmit information via action potentials from the periphery to the brain
- Each tract has a limited type of sensory input
- Tracts are named according to their origin and termination
Sensory Areas of the Cerebral Cortex
- Primary sensory areas: where ascending tracts project, where sensations are perceived
- Primary somatic sensory cortex: general sensory area, in the parietal lobe, receives sensory input such as pain, pressure, and temperature
Motor Areas of the Cerebral Cortex
- Primary motor cortex: frontal lobe, controls voluntary motor movement
- Premotor area: frontal lobe, where motor functions are organized before initiation
- Prefrontal area: motivation and foresight to plan and initiate movement
Descending Tracts
- Project from upper motor neurons in the cerebral cortex to lower motor neurons in the spinal cord and brainstem
- Control different types of movements
Basal Nuclei
- Group of functionally related nuclei
- Plan, organize, and coordinate motor movements and posture
- Corpus striatum: deep in the cerebrum
- Substantia nigra: in the midbrain
Speech
- Mainly in the left hemisphere
- Sensory speech (Wernicke's area): parietal lobe, where words are heard and comprehended
- Motor speech (Broca's area): frontal lobe, where words are formulated
Brain Waves and Consciousness
- Used to diagnose and determine treatment of brain disorders
- Electroencephalogram (EEG): electrodes placed on the scalp to record brain electrical activity
- Alpha waves: person is awake in a quiet state
- Beta waves: intense mental activity
- Delta waves: deep sleep
- Theta waves: in children
Memory
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Encoding: brief retention of sensory input received by the brain, also called sensory memory, lasts less than a second
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Consolidated: data that has been encoded, temporal lobe, short-term memory
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Storage: long-term memory, can last for a few minutes or permanently
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Retrieval: how often info is used
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Types of memory:
- Short-term memory: info is retained for a few seconds or minutes, limited to 7 bits of info
- Long-term memory: can last for a few minutes or permanently
- Episodic memory: places or events
- Learning: utilizing past memories### Protective Wrapping Around Brain and Spinal Cord
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Meningitis is an infection of the meninges, which can be caused by bacteria or viruses.
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The three types of meninges are:
- Dura mater: the superficial and thickest layer
- Arachnoid mater: the 2nd layer
- Pia mater: the 3rd layer that covers the surface of the brain
Subarachnoid Space and Epidural Space
- The subarachnoid space is where cerebrospinal fluid sits.
- The epidural space is located in the vertebral column between the dura and vertebra, and is an injection site for epidural anesthesia.
Spinal Block and Spinal Tap
- A spinal block and spinal tap involve injecting anesthetic into the subarachnoid space or removing cerebrospinal fluid, which numbs the spinal nerves.
Ventricles
- Ventricles are cavities in the CNS that contain fluid.
- The fourth ventricle is located at the base of the cerebellum and is continuous with the central canal of the spinal cord.
- The lateral ventricle has three horns: anterior, posterior, and inferior.
Cranial Nerves
- There are 12 pairs of cranial nerves, named by Roman numerals.
- The two categories of cranial nerve functions are sensory and motor.
Peripheral Nervous System
- The peripheral nervous system consists of all neurons outside the brain and spinal cord.
- It collects input from different sources, relays input to the CNS, and performs action.
Divisions of Peripheral Nervous System
- The two main divisions of the peripheral nervous system are:
- Afferent (Sensory): collects input from the periphery and sends it to the CNS
- Efferent (Motor): carries processed input from the CNS to effector organs
Divisions of Efferent (Motor)
- The two divisions of the efferent system are:
- Autonomic: response is automatic (involuntary), controls smooth and cardiac muscles and glands
- Somatic: response is voluntary, controls skeletal muscles
Autonomic Nervous System
- The autonomic nervous system has two divisions:
- Sympathetic: activated during times of stress, part of the fight or flight response
- Parasympathetic: activated under normal conditions, involved in digestion, urine production, and other functions
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Description
This quiz covers the functions of the nervous system, including sensory input, integration, control of muscles and glands, mental activity, and homeostasis.
