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Questions and Answers

What is the primary function of the basal ganglia?

Regulating sensory input

Coordinating emotional responses

Generating impulses for voluntary movements (correct)

Forming memories

Which lobe of the cerebral hemisphere is responsible for processing auditory information?

Parietal Lobe

Frontal Lobe

Occipital Lobe

Temporal Lobe (correct)

Which area of the brain is referred to as the 'emotional brain'?

Basal Ganglia

Cerebellum

Diencephalon

Limbic System (correct)

Which statement about Broca's area is correct?

It controls the movement of the mouth for speaking. Signup and view all the answers

What does the parietal lobe primarily interpret?

Touch and proprioception Signup and view all the answers

Which of the following functions is associated with the occipital lobe?

Interpreting visual stimuli Signup and view all the answers

What role does the thalamus play in the brain?

It acts as the main relay center for sensory impulses. Signup and view all the answers

The hippocampus is critical for which of the following functions?

Formation of memories Signup and view all the answers

What is the primary role of the cochlear branch of the vestibulocochlear nerve?

Sense of hearing Signup and view all the answers

Which cranial nerve is responsible for controlling the muscles of the throat and the secretion of saliva?

Glossopharyngeal Signup and view all the answers

Which division of the Autonomic Nervous System (ANS) is activated during stressful situations?

Sympathetic Division Signup and view all the answers

What neurotransmitter is primarily released by postganglionic neurons of the sympathetic nervous system?

Norepinephrine Signup and view all the answers

Where are the cell bodies of parasympathetic neurons located?

Brain stem and sacral spinal cord Signup and view all the answers

Which muscle groups are controlled by the Accessory nerve?

Neck and shoulder muscles Signup and view all the answers

What is the main function of the vagus nerve?

Control of the heart rate Signup and view all the answers

What characterizes the preganglionic neurons of the ANS?

They are always myelinated. Signup and view all the answers

What is the primary function of the anterior (ventral) root of a spinal nerve?

Transmits motor impulses to muscles and glands Signup and view all the answers

Which component of the reflex arc is responsible for detecting changes and generating impulses?

Receptor Signup and view all the answers

Which plexus is responsible for supplying nerve impulses to the diaphragm?

Cervical plexus Signup and view all the answers

What is the function of the spinal nerves in terms of sensory and motor neurons?

They are mixed nerves combining sensory and motor functions. Signup and view all the answers

What is the primary function of the myelin sheath?

To increase the speed of impulse conduction Signup and view all the answers

What term describes the network of nerves that supply a specific body area?

Plexus Signup and view all the answers

Which component of the nervous system primarily consists of myelinated axons?

White Matter Signup and view all the answers

During a reflex action, which component acts by carrying impulses away from the CNS to the effector?

Motor neuron Signup and view all the answers

What role do astrocytes play in the nervous system?

They support neurons and maintain a proper chemical environment Signup and view all the answers

Which part of the brain is described as the largest and divided into two hemispheres?

Cerebrum Signup and view all the answers

Which type of neuron carries impulses from receptors to the central nervous system?

Sensory Neurons Signup and view all the answers

What do you call a bundle of nerve axons located within the central nervous system?

Nerve Tract Signup and view all the answers

What connects the spinal cord to the peripheral nervous system?

Spinal nerves Signup and view all the answers

Which type of neuron carries impulses from the central nervous system to muscles and glands?

Efferent Neurons Signup and view all the answers

What structure is responsible for the movement of cerebrospinal fluid within the central nervous system?

Ependyma Signup and view all the answers

Which of the following is NOT a characteristic of neuroglia in the central nervous system?

Conduct electrical impulses Signup and view all the answers

Which cranial nerves are responsible for senses other than motor functions?

I, II, VIII Signup and view all the answers

What is the primary function of the cerebellum?

Coordination of voluntary muscles Signup and view all the answers

Which of the following cranial nerves contains only motor fibers?

Trochlear Signup and view all the answers

What role does the Reticular Activating System play?

Maintains consciousness levels Signup and view all the answers

Which cranial nerve is involved in the sense of taste from the anterior two-thirds of the tongue?

Facial Signup and view all the answers

What is one of the functions of the medulla oblongata?

Regulation of heart rate Signup and view all the answers

Which component of the brain stem is primarily responsible for reflex actions like sneezing and coughing?

Medulla oblongata Signup and view all the answers

Which part of the cerebellum is referred to as the 'vernix'?

Middle portion Signup and view all the answers

What is hydrocephalus primarily characterized by?

Abnormal increase in the amount of CSF within the ventricles Signup and view all the answers

What is the primary function of the cerebral cortex?

To analyze and interpret incoming impulses Signup and view all the answers

Which structure serves as a bridge between the left and right hemispheres of the brain?

Corpus callosum Signup and view all the answers

What type of matter connects the lobes of the cerebrum to one another?

White matter Signup and view all the answers

Which of the following describes the central sulcus?

Lies between the frontal and parietal lobes Signup and view all the answers

What is the role of the basal ganglia?

To initiate and regulate voluntary movements Signup and view all the answers

How does the folding of the cerebral cortex benefit its function?

Allows more neurons to be present in the cortex Signup and view all the answers

What can happen to an adult with hydrocephalus due to an increase in intracranial pressure?

Severe headache, drowsiness, and vomiting Signup and view all the answers

Study Notes

Nervous System Study Guide 7

The nervous system detects changes, feels sensations, organizes and stores information, and initiates responses to these changes.

Functions of the Nervous System

Detects changes and feels sensations.
Organizes and stores information.
Initiates responses to changes.

Division of the Nervous System

Central Nervous System (CNS): Brain and Spinal cord
Peripheral Nervous System (PNS): Cranial Nerves & Spinal Nerves.

Nerve Tissue

Neurons: the functional units of the nervous system.
- Cell body: Contains the nucleus and other organelles; regulates neuron function.
- Nerve cell processes (extensions):
  - Dendrites: Carry impulses toward the cell body.
  - Axon: Carries impulses away from the cell body.

Structure of a Neuron

Diagram of a neuron with labels for cell body, dendrites, axon, axon hillock, myelin sheath, node of Ranvier, and synaptic end bulbs.

Neuron

Myelin Sheath: Multilayered lipid and protein covering formed by Schwann cells (PNS) and oligodendrocytes (CNS), surrounding axons of many peripheral and CNS neurons. Allows rapid conduction of impulses.
Nodes of Ranvier: Spaces between individual Schwann cells or segments of the myelin sheath.

Saltatory Conduction

Diagram illustrating the process of saltatory conduction. This rapid transmission of nerve impulses occurs along myelinated axons.

Neuroglia (Glial Cells)

Non-neuronal cells of the CNS.
- Oligodendrocytes: Produce the myelin sheath to electrically insulate axons of CNS neurons.
- Microglia: Capable of movement and phagocytosis of pathogens and damaged tissue.
- Astrocytes: Support neurons, help maintain proper chemical environment, and form the blood-brain barrier.
- Ependyma: Line the ventricles and central canal of the spinal cord. Involved in cerebrospinal fluid (CSF) circulation.

White & Gray Matter

White matter: Nerve tissue within the CNS, primarily myelinated axons of neurons.
Gray matter: Nerve tissue within the CNS, primarily cell bodies of neurons.

Types of Neurons

Sensory (afferent) neurons: Carry impulses from receptors to the CNS.
Motor (efferent) neurons: Carry impulses from the CNS to muscles and glands (effectors).

Nerve

A bundle of neuronal axons and/or dendrites and associated connective tissues located outside the CNS.
- Sensory nerve: Made only of sensory neurons.
- Motor nerve: Made only of motor neurons.
- Mixed nerve: Contains both sensory and motor neurons.

Nerve Tract

A bundle of nerve axons within the CNS; often referred to as white matter.
- Ascending tract (sensory): Carries sensory information towards the brain.
- Descending tract (motor): Carries motor information away from the brain.

Ascending & Descending Pathways

Diagrams illustrating ascending (sensory) and descending (motor) pathways.

Nerve Impulse (Nerve Action Potential)

Self-propagating wave of electrical current carrying information along a nerve.
Stimulus: Any change in the internal or external environment that excites a sensory receptor, neuron, or muscle fiber.

State or Events (Action Potential)

Polarization: Neuron is not carrying an electrical impulse. Neuron membrane has a positive charge outside and a negative charge inside.
Depolarization: Generated by a stimulus. Entry of Na+ ions and reversal of charges on either side of the membrane.
Propagation: Rapid transmission of a nerve impulse from one node of Ranvier (in a myelinated neuron) to the next; characteristic of myelinated neurons.
Repolarization: Immediately follows depolarization. Exit of K+ ions and restoring of the (+) charge on the outside and (-) charge on the inside of the membrane. Sodium and potassium pumps return Na+ and K+ ions to their original sides.

Synapse

Point of junction for transmission of nerve impulses; the space between an axon of one neuron and dendrites or cell body of another neuron.
Neurotransmitters: Chemicals released by an axon that enable a nerve impulse to cross a synaptic junction. (Examples: acetylcholine, norepinephrine, dopamine, and GABA)

Spinal Cord

Encloses within the vertebral canal; extends from foramen magnum to the intervertebral disc between the first and second lumbar vertebrae.
Contains:
- Gray matter: Primarily cell bodies of motor neurons and interneurons.
- White matter: Primarily myelinated axons of neurons.
- Central canal: Contains cerebrospinal fluid (CSF).

Functions of the Spinal Cord

Conducts sensory impulses through ascending tracts to the brain.
Conducts motor impulses through descending tracts to motor neurons that supply muscles or glands.
Reflex activities: Simple, rapid, and automatic responses involving few neurons. (Reflex arcs).

Spinal Nerves

31 pairs connected to the spinal cord.
Cauda equina: Lumbar and sacral nerves that extend below the end of the spinal cord.
Posterior (dorsal) root: Contains sensory neurons carrying impulses into the spinal cord.
- Posterior (dorsal) root ganglion: Contains the cell bodies of sensory neurons outside the CNS.
Anterior (ventral) root: Contains motor neurons carrying impulses from the spinal cord to muscles and glands.
All spinal nerves are mixed nerves.

Distribution of Spinal Nerves

Plexus: Networks of nerves distributing branches to various body parts.
- Cervical plexus: Supplies motor and sensory impulses to neck and back of the head. Phrenic nerve arises.
- Brachial plexus: Supplies nerves to shoulder, arm, forearm, wrist, and hand.
- Lumbosacral plexus: Supplies nerves to lower extremities. Sciatic nerve is the largest branch.

Reflex Arc

Diagram illustrating pain receptors stimulating a reflex arc; a pathway connecting receptor and effector in the nervous system..

Brain

Part of the central nervous system located within the cranial cavity.
- Main parts of the brain:
  - Cerebrum
  - Diencephalon
  - Brainstem
  - Cerebellum

Main Parts of the Brain

1. Cerebrum: Largest part of the brain, divided into right and left hemispheres by the longitudinal fissure.
2. Diencephalon: Located between the cerebral hemispheres and the brainstem, includes thalamus, hypothalamus, and pineal gland.
- Thalamus: Main relay center for sensory impulses.
- Hypothalamus: Controls the ANS; produces hormones ADH and oxytocin.
- Pineal gland: Secretes melatonin.
3. Brainstem: Connects cerebrum and diencephalon to spinal cord. Includes midbrain, pons, and medulla oblongata.
- Midbrain: Upper portion of the brain stem.
- Pons: Connects the midbrain with the medulla; regulates breathing together with the medulla oblongata.
- Medulla Oblongata: Connects the brain to the spinal cord, regulates respiration, heart rate, and blood vessel diameter; also contains reflex centers for coughing, sneezing, swallowing, and vomiting.
4. Cerebellum: Located below the back part of the cerebral hemisphere, connected to the brain stem by pons. Coordinates voluntary muscle movements and aids in balance and muscle tone..

Covering of the Brain and Spinal Cord: Meninges

Dura mater: Thickest and toughest membrane, lines the skull and vertebral canal.
Arachnoid mater: Middle membrane, loosely attached to pia mater.
Pia mater: Thin, innermost membrane containing many blood vessels.

Subarachnoid Space

Space between arachnoid and pia mater containing CSF (cerebrospinal fluid).
- CSF functions:
  - Supports neural tissue.
  - Cushions the CNS.
  - Carries nutrients and removes waste products from cells.

Ventricles

Spaces within the brain that produce and circulate CSF.
- Choroid plexus: Network of capillaries in each ventricle, filters blood plasma to form CSF.

Four Ventricles

Lateral ventricles: Largest ventricles in the cerebral hemispheres.
Interventricular foramen: opening connecting lateral ventricles to 3rd ventricle.
Third ventricle: Surrounded by the diencephalon.
Cerebral aqueduct: Tunnel through midbrain allowing CSF flow from the 3rd to 4th ventricle.
Fourth ventricle: Located at back of the pons and connects with central canal of the spinal cord.
- CSF circulation: CSF flows throughout system, eventually reabsorbed into the blood plasma through arachnoid granulations in the meninges.

Pathway of CSF Flow

Diagram illustrating CSF flow from the brain ventricles to venous sinuses..
Foramina of Luschka and Magendie: Openings that connect the ventricle system to the subarachnoid space.

Hydrocephalus

Abnormal increase in CSF within brain ventricles.
Causes: blockages in CSF outflow or problems with reabsorption
Symptoms: Possible head enlargement in babies. Symptoms vary by age; could involve increased intracranial pressure, causing headache, vomiting, or drowsiness.
Surgical management: VP shunt or VA shunt diverting CSF to another part of the body.

Surgical Management

VP shunt or VA shunt are procedures for hydrocephalus; medical devices redirect the flow of cerebrospinal fluid (CSF).

Cerebrum

Cerebral Cortex: Gray matter on the surface of cerebral hemisphere composed of cell bodies. Receives and analyzes impulses.
Internal white matter: Composed of myelinated axons. Connects lobes, other parts of cerebrum, and brain.
Cerebral Cortex Folding: Folded into gyri (elevated parts) and sulci/fissures (grooves). The folding increases the surface area and number of neurons.
**Important Sulci:**Central sulcus; Lateral sulcus; Longitudinal fissure.
Corpus Callosum: Band of nerve fibers connecting left and right hemispheres. Used for communication across hemispheres.
Basal Ganglia: Masses of gray matter deep within the cerebrum. Control subconscious muscle movements (e.g. automatic arm movements)
Limbic System: Part of the cerebrum concerned with aspects of emotion and behavior and memory storage and retrieval.
Lobes of Cerebral Hemispheres:
- Frontal Lobe: Contains the Motor Area & Broca's area, controls voluntary movements and involved in speech.
- Parietal Lobe: Contains the Sensory Area; responsible for processing sensations from touch, temp, and pain; interprets sensory information.
- Temporal Lobe: Contains Auditory Area for receiving and interpreting auditory information. Contains Olfactory Area; responsible for sense of smell
- Occipital Lobe: Contains the Visual Area, for receiving and interpreting visual information.

Important Sulcus

Central sulcus: Separates frontal and parietal lobes.
Lateral sulcus: Separates temporal lobe from frontal and parietal lobes.

Cranial Nerves

12 pairs of nerves emerging from brain stem and other parts of the brain.
- Some contain only sensory fibers (CN I, II, and VIII)
- Others have mostly motor fibers (CNIII, IV, VI, XI and XII)
- Others are mixed nerves (CN V, VII, IX, and X) and contain both.
Specific Cranial nerve functions (tables in the original text).

Autonomic Nervous System (ANS)

Portion of PNS controlling involuntary functions.
- Visceral motor neurons stimulating smooth muscle, cardiac muscle, and glands.
- Two-neuron pathway in ganglia:
  - Preganglionic neurons: from CNS to ganglia
  - Postganglionic neurons: from ganglia to effectors
Two Divisions:
- Sympathetic: (Thoracolumbar division) dominant in stressful situations.
  - Prepares body for physical demands
  - Nerve fibers originating in the thoracic and lumbar regions of the spinal cord -> reach sympathetic ganglia and synapse with the second set of neurons -> these then extend to glands and involuntary muscles using norepinephrine.
- Parasympathetic: (Craniosacral division) dominant in relaxed situations.
  - Promotes normal functioning
  - Cell bodies located in the brain stem and sacral part of spinal cord-> axons extending to parasympathetic ganglia generally located close to the target organs themselves -> The postganglionic neurons of this pathway release acetylcholine.

Effects of the Sympathetic and Parasympathetic Nervous System

Table showing how these systems operate on specific organs to regulate many functions (e.g. iris, heart, lungs, glands, digestive system, etc).

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