المحاضرة الرابعة فسيو (بعد التعديل)

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Questions and Answers

What is the main function of the cell body (soma) in a neuron?

Control the activity of the whole neuron (correct)

Connect with muscle or glands

Conduct impulses towards the cell body

Receive information from axon

Which cranial nerve is responsible for taste sensation?

C X - Vagus nerve

C III - Oculomotor nerve

C XII - Hypoglossal nerve

C IX - Glossopharyngeal nerve (correct)

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

Afferent neuron (correct)

Interneuron

Efferent neuron

Motor neuron

Which of the following cranial nerves is purely motor?

C VI - Abducens nerve Signup and view all the answers

What junction is formed when an axon terminates at a muscle?

Neuro-muscular junction Signup and view all the answers

Which component of the reflex pathway is responsible for processing the information received?

Center in the CNS Signup and view all the answers

From where does the sympathetic nervous system originate?

Lumbar and thoracic segments of spinal cord Signup and view all the answers

What is the role of interneurons in the nervous system?

Act as a link between neurons Signup and view all the answers

What is the function of the accessory nerve (C XI)?

Motor to muscles of the back of neck Signup and view all the answers

Which segment of the spinal cord is associated with the parasympathetic nervous system?

Sacral segments S2, S3, S4 Signup and view all the answers

What type of neuron is responsible for carrying impulses from the CNS to effector organs?

Efferent (motor) neuron Signup and view all the answers

What is a reflex arc primarily responsible for?

Carrying out involuntary responses to stimuli Signup and view all the answers

How many percent of nerve cells are interneurons in the nervous system?

99% Signup and view all the answers

How many pairs of spinal nerves are there in the human body?

31 pairs Signup and view all the answers

Which part of the nervous system is involved in voluntary control?

Somatic Nervous System Signup and view all the answers

Which cranial nerve is responsible for the sense of smell?

Olfactory nerve Signup and view all the answers

What is the total number of pairs of cranial nerves in humans?

12 pairs Signup and view all the answers

Which cranial nerve controls eye movement?

Abducent nerve Signup and view all the answers

Which component is part of the brainstem?

Midbrain Signup and view all the answers

Which of the following cranial nerves are involved in the parasympathetic nervous system?

Cranial nerves III, VII, IX, X Signup and view all the answers

What is the origin of the sympathetic nervous system at the spinal level?

Thoracic and upper lumbar segments Signup and view all the answers

What characterizes all spinal nerves in terms of function?

They are mixed nerves Signup and view all the answers

Which cranial nerves are identified as purely motor?

Cranial nerves III, IV, VI Signup and view all the answers

Which statement best describes the role of afferent neurons in the nervous system?

They carry impulses from the environment to the central nervous system. Signup and view all the answers

What is the primary function of the interneurons located within the central nervous system?

To connect various neurons and facilitate communication. Signup and view all the answers

In reflex pathway, which component is responsible for reacting to a stimulus?

Effectors (muscles or glands) Signup and view all the answers

Which part of a neuron conducts impulses away from the cell body?

Axon Signup and view all the answers

Which type of junction is formed between an axon and another neuron?

Neuro-neural junction Signup and view all the answers

How many segments compose the spinal cord?

31 segments Signup and view all the answers

Which of the following best defines a reflex arc?

A pathway that integrates sensory input and produces an involuntary response. Signup and view all the answers

Which of the following statements about axons is false?

Axons are short and branched processes. Signup and view all the answers

What constitutes the primary anatomical unit of the nervous system?

Neuron Signup and view all the answers

What division of the nervous system is responsible for involuntary control?

Autonomic Nervous System Signup and view all the answers

Which cranial nerve is responsible for controlling the eye's moving ability?

Oculomotor nerve Signup and view all the answers

Which part of the spinal cord has the fewest associated pairs of spinal nerves?

Coccygeal segment Signup and view all the answers

Which nervous system component connects to glands and cardiac muscles?

Autonomic Nervous System Signup and view all the answers

Which structure is NOT part of the brainstem?

Cerebellum Signup and view all the answers

Study Notes

The Nervous System

The nervous system controls body functions by receiving information, integrating it, and determining a response.

Structure and Components of a Neuron

Neuron is the structural unit of the nervous system.
Cell body (soma) controls the activity of the whole neuron.
Cell processes are responsible for transmitting information.
- Dendrites are multiple, short processes that receive impulses and conduct them towards the cell body.
- Axon is a single, long process that conducts impulses away from the cell body.
Axon Termination connects to:
- Muscle (neuro-muscular junction)
- Gland (neuro-epithelial junction)
- Another neuron (neuro-neural junction)

Types of Neurons

Afferent (sensory) neuron: Carries impulses from receptors to the central nervous system (CNS).
Efferent (motor) neuron: Carries impulses from the CNS to effector organs.
Interneuron (associative neuron):
- Located inside the CNS.
- Acts as a link between neurons.
- Constitutes 99% of nerve cells.

Reflexes and the Reflex Arc

Reflex: An involuntary programmed response to a stimulus.
Reflex arc: The functional unit of the nervous system responsible for reflexes.
Components of the reflex arc:
- Receptors receive stimuli.
- Afferent (sensory) neuron transmits information to the CNS.
- Center in the CNS integrates the information.
- Efferent (motor) neuron transmits information to effector organs.
- Effectors (muscles or glands) carry out the response.

Central Nervous System

The CNS is protected by bones: skull and vertebral column.

Components of the CNS

Brain:
- Cerebrum:
  - Cerebral cortex: The outer layer responsible for higher cognitive functions.
  - Subcortical centers:
    - Thalamus: Relay station for sensory information.
    - Hypothalamus: Regulates homeostasis and many vital functions.
    - Basal ganglia: Controls movement and coordination.
- Brain stem:
  - Midbrain: Connects the forebrain to the hindbrain.
  - Pons: Involved in sleep, breathing, and other functions.
  - Medulla: Controls vital functions like breathing, heart rate, and blood pressure.
- Cerebellum: Coordinates movement and balance.
Spinal Cord:
- 31 segments, each giving rise to a pair of spinal nerves.
- Segments:
  - 8 Cervical
  - 12 Thoracic
  - 5 Lumbar
  - 5 Sacral
  - 1 Coccygeal

Peripheral Nervous System

Connects the CNS to other tissues via nerves.

Anatomical Classification of the Peripheral Nervous System

Cranial nerves: 12 pairs connected to the brain
Spinal nerves: 31 pairs connected to the spinal cord.

Physiological Classification of the Peripheral Nervous System

Somatic nervous system:
- Voluntary control.
- Connects to skeletal muscles, skin, tendons, bones, and joints.
Autonomic nervous system:
- Involuntary control.
- Connects to smooth muscles, cardiac muscles, and glands.

Cranial Nerves

12 pairs connected to the brain.
They can be sensory, motor or mixed.
I (Olfactory): Smell.
II (Optic): Vision.
III (Oculomotor): Moving the eyeball.
IV (Trochlear): Moving the eyeball.
V (Trigeminal): Sensory to face, motor for mastication muscles.
VI (Abducent): Motor to eye muscles.
VII (Facial): Motor to muscles of the face.
VIII (Auditory): Hearing and equilibrium.
IX (Glossopharyngeal): Taste sensation, secretory to salivary glands.
X (Vagus): Sensory and motor to muscles of thoracic and abdominal viscera.
XI (Accessory): Motor to muscles of the back of the neck.
XII (Hypoglossal): Motor to muscles of the tongue.

Spinal Nerves

31 pairs connected to the spinal cord.
Roots:
- Dorsal root: Sensory fibers.
- Ventral root: Motor fibers.
All spinal nerves are mixed nerves (sensory and motor).

Autonomic Nervous System

Two divisions:
- Sympathetic: Fight or flight response.
- Parasympathetic: Rest and digest response.

Origin of the Autonomic Nervous System

Sympathetic nervous system:
- Thoracic and upper 3 lumbar segments of the spinal cord.
Parasympathetic nervous system:
- Cranial part: 3, 7, 9 and 10 cranial nerves.
- Sacral part: S2, S3, S4 (pelvic nerve).

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