Nervous System Overview

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Questions and Answers

What is the primary function of dendrites in a neurone?

Form myelin sheaths around axons

Receive information and pass it to the cell body (correct)

Transmit nerve impulses away from the cell body

Support and protect the neurone structure

Which type of neuroglial cell is primarily responsible for forming the blood-brain barrier?

Oligodendrocytes

Neurotransmitters

Microglia

Astrocytes (correct)

Which of the following substances can quickly cross the blood-brain barrier?

Inorganic ions

Large molecules

Glucose (correct)

Amino acids

What role do synaptic vesicles play in neurotransmission?

Store and release neurotransmitters Signup and view all the answers

What differentiates neuroglial cells from neurones?

Neuroglial cells do not transmit impulses Signup and view all the answers

Which neurotransmitter is commonly involved in synaptic transmission?

Acetylcholine Signup and view all the answers

Which statement correctly describes the structure of dendrites?

They have the same structure as axons but are shorter Signup and view all the answers

What is the role of microglia in the central nervous system?

To act as phagocytes during inflammation Signup and view all the answers

What are the two main divisions of the nervous system?

Central and Peripheral Nervous Systems Signup and view all the answers

Which type of cell provides myelin insulation to axons in the peripheral nervous system?

Schwann Cells Signup and view all the answers

Which feature of a neurone conducts electrical impulses away from the cell body?

Axon Signup and view all the answers

What is the function of the Nodes of Ranvier?

To assist in the rapid transmission of action potentials Signup and view all the answers

Which neurons are primarily involved in involuntary functions of the body?

Autonomic Neurons Signup and view all the answers

Which component of nervous tissue is responsible for providing support and insulation?

Neuroglial/Glial Cells Signup and view all the answers

Which statement accurately describes the difference between the nervous system and the endocrine system?

The nervous system works with the endocrine system to maintain homeostasis. Signup and view all the answers

What is a key characteristic of the myelin sheath?

It consists of high phospholipid content. Signup and view all the answers

What type of nerve impulse is characterized by traveling towards the brain and central nervous system?

Afferent (sensory) Signup and view all the answers

What is the function of synaptic knobs in neural transmission?

Store neurotransmitters Signup and view all the answers

How do local anesthetics impede nerve transmission?

By blocking sodium channels Signup and view all the answers

What happens to excessive nerve impulses in conditions like neuralgia?

They induce pain sensations Signup and view all the answers

What is the role of neurotransmitters after their release into the synaptic cleft?

They diffuse across to post-synaptic receptors Signup and view all the answers

What is the consequence of herpes simplex virus reactivation related to trigeminal neuralgia?

It emerges on skin surfaces as cold sores Signup and view all the answers

What occurs during synaptic transmission when an action potential reaches the synaptic knob?

Neurotransmitters are released by exocytosis Signup and view all the answers

Which statement best describes the structure of a synapse?

It is the point where a nerve impulse jumps from one nerve to another Signup and view all the answers

What is the primary function of the thalamus in the brain?

Processing sensory information in a basic form Signup and view all the answers

Which area of the brain is responsible for higher mental activities such as reasoning and problem-solving?

Cerebrum Signup and view all the answers

What role does the hypothalamus play in the nervous system?

Controls hormone output and autonomic functions Signup and view all the answers

Which structure separates the two hemispheres of the cerebrum?

Corpus callosum Signup and view all the answers

What is a notable feature of the cerebral cortex?

It is highly wrinkled to increase surface area. Signup and view all the answers

How does cerebrospinal fluid primarily benefit the central nervous system?

It acts as a shock absorber and provides cushioning. Signup and view all the answers

What function do nuclei in the midbrain serve?

Relaying nerve signals between the brain and spinal cord Signup and view all the answers

Which structure is primarily responsible for the basic perception of sensory information?

Thalamus Signup and view all the answers

What is one of the key roles of the Pons in the nervous system?

Forms a bridge between cerebral hemispheres Signup and view all the answers

Which of the following accurately describes the function of cerebrospinal fluid (CSF)?

Protects the brain by reducing its weight Signup and view all the answers

What does the medulla oblongata control?

Cardiovascular and respiratory functions Signup and view all the answers

How does cerebrospinal fluid contribute to waste management in the brain?

It takes potentially harmful metabolites away from the brain Signup and view all the answers

What is the approximate length of the spinal cord?

45cms Signup and view all the answers

What function does the cerebrospinal fluid serve as an endocrine medium?

Carries hormones to brain regions Signup and view all the answers

What effect does the buoyancy of cerebrospinal fluid have on the brain?

Reduces pressure at the base of the brain Signup and view all the answers

Which of the following best describes the location and protection of the spinal cord?

It is surrounded by cerebrospinal fluid and meninges in the vertebral canal. Signup and view all the answers

Study Notes

Nervous System

The nervous system detects and responds to internal and external changes.
Works with the endocrine system to control body functions and maintain homeostasis.
Nervous system responses are immediate, while endocrine responses are slower and more prolonged.

Divisions of the Nervous System

Central Nervous System (CNS): Brain & spinal cord
Peripheral Nervous System (PNS): All other nerves

Peripheral Nervous System Subdivisions

Sensory Division: Carries sensory information from the body to the CNS.
Motor Division: Carries motor commands from the CNS to the body.
- Somatic Nervous System: Controls voluntary movements.
- Autonomic Nervous System: Controls involuntary actions.
  - Sympathetic Nervous System: "Fight or flight" response.
  - Parasympathetic Nervous System: "Rest and digest" response.

Nervous Tissue Cells

Neurones: Specialized cells responsible for transmitting nerve impulses.
Schwann Cells: Form myelin sheath around axons in the peripheral nervous system.
Neuroglial/Glial cells: Support network of non-excitable cells in the CNS.

Neurones

Cell Body: Contains the nucleus and other organelles.
Axon: Long, slender extension that conducts impulses away from the cell body.
- Can be over 1 meter long.
- Large axons and those in the PNS are surrounded by a myelin sheath.
Schwann Cells: Form layers around axons, providing myelin insulation.
Nodes of Ranvier: Exposed areas between Schwann cells, facilitating rapid transmission of action potentials.
Dendrites: Branching extensions that receive information from other neurones.
- Shorter than axons.
- Have dense chemical ion channels for impulse transmission.
- Form synapses with other dendrites or terminate in sensory receptors.
Synaptic End Bulb: Specialized structure at the end of the axon, responsible for communication with other neurones.

Properties of Neurons

Irritability: Ability to initiate nerve impulses in response to stimuli.
Conductivity: Ability to transmit an impulse.

Neuroglial Cells

Support and maintain neurones in the CNS.
Continue to replicate throughout life.
Three types:
- Microglia: Phagocytic cells that remove cellular debris.
- Astrocytes: Star-shaped cells that provide structural support and regulate the environment around neurones.
- Oligodendrocytes: Form myelin sheaths around axons in the CNS.

Blood-Brain Barrier

Protective barrier that regulates what substances can enter the brain.
Allows passage of oxygen, carbon dioxide, glucose, and lipid-soluble substances.
Restricts passage of large molecules, many drugs, inorganic ions, and amino acids.

Synaptic End Bulbs

Contain synaptic vesicles, sacs that store neurotransmitters.
Release neurotransmitters into the synaptic cleft, allowing communication between neurones.

Synapse

Communication point between two neurones or a neurone and an effector.
Includes:
- Pre-synaptic neurone: Neurone sending the signal.
- Pre-synaptic knob: End of the pre-synaptic neurone.
- Neurotransmitters: Chemical messengers, e.g., acetylcholine, noradrenaline.
- Calcium: Plays a role in neurotransmitter release.
- Mitochondria: Provide energy for the synapse.
- Neurotransmitter receptors: On the post-synaptic membrane.
- Post-synaptic knob: End of the post-synaptic neurone.
- Post-synaptic neurone: Neurone receiving the signal.

Nerve Impulses

Nerve impulses are initiated by sensory nerve endings or by the passage of an impulse from another nerve.
A nerve impulse traveling towards the brain and CNS is afferent (sensory).
A nerve impulse traveling away from the brain and CNS is efferent (motor).
Nerve impulses (action potential) travel down the neuron.
Synapses are the points where nerve impulses jump from one nerve to another.
There are approximately 1000 trillion synapses in the human brain.
Synaptic knobs contain synaptic vesicles that store neurotransmitters.
The journey of a neurotransmitter begins with its synthesis by nerve cell bodies, followed by active transport along the axons, storage in synaptic vesicles, and release by exocytosis in response to the action potential.
Neurotransmitters diffuse across the synaptic cleft and act on specific receptor sites on the postsynaptic membrane.
The action of neurotransmitters is short-lived and they are inactivated by enzymes or taken back into the synaptic knob after action.
Local anesthetics block nerve transmission to pain centers in the central nervous system by binding to and inhibiting the sodium channel in the cell membrane of nerve cells.
The action of local anesthetics obstructs the movement of nerve impulses near the site of injection but does not affect awareness or sense perception in other areas.
Excessive nerve impulses can result in neuralgia, with trigeminal neuralgia being the most common type.
The herpes simplex virus lies dormant in the trigeminal ganglion and when re-activated it travels down the trigeminal nerve, emerging on the lip and causing a cold sore.

Central Nervous System

The brain weighs approximately 1.4 kg.
It is located within the cranial cavity.
The brain is comprised of the cerebrum, thalamus, hypothalamus, midbrain, pons, medulla oblongata, and cerebellum.

Cerebrum

The cerebrum is the largest part of the brain.
It has three main functional areas:
- Mental activities: memory, intelligence, problem solving, reflection, judgement, thinking, reasoning, initiative, inhibition, moral sense of responsibility and learning
- Sensory perception: perception of pain, temperature and touch
- Initiation and control of voluntary muscle contraction
The cerebral cortex has wrinkles, which increase its surface area and neuron density, enhancing brain efficiency.
A deep furrow divides the cerebrum into two halves known as the left and right hemispheres.
The corpus callosum connects the two hemispheres via bundles of axons.

Thalamus

The thalamus is a small structure.
Sensory receptors in the skin and viscera send information about touch, pain and temperature to the thalamus.
Input from special sense organs also travels to the thalamus.
The thalamus is involved in basic perception, arousal and the processing of some emotions and complex reflexes.

Hypothalamus

The hypothalamus is located within the cerebrum and attached to the pituitary gland.
It controls hormone release from the pituitary gland.
The hypothalamus controls effectors of the autonomic nervous system.
The hypothalamus is responsible for: - Emotional reactions - Hunger and thirst - Body temperature - Biological clocks

Midbrain

The midbrain comprises nuclei and nerve fibres that connect the cerebrum to the lower parts of the brain and spinal cord.
The midbrain nuclei act as relay stations for ascending and descending nerve fibres.
It plays a key role in auditory and visual reflexes.

Pons

The pons contains nerve fibres bridging the two hemispheres of the cerebrum.
It processes information from several cranial nerves.

Medulla Oblongata

The medulla oblongata is continuous with the spinal cord.
It controls effectors such as: - Cardiovascular centre - Respiratory centre
It also controls reflex centres responsible for: - Coughing - Vomiting - Sneezing - Swallowing

Spinal Cord

The spinal cord is an elongated, almost cylindrical part of the CNS.
Nerves carrying impulses from the brain to various organs and tissues descend through it.
It starts in the medulla oblongata and descends through the spinal column.
The spinal cord is suspended in the vertebral canal.
It is surrounded by meninges and cerebrospinal fluid.
The spinal cord is approximately the thickness of a little finger and about 45 cm long.

Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a clear colorless liquid that:
- Occupies the subarachnoid space in the brain.
- Acts as a "cushion" or buffer for the cortex.
- Is renewed four times a day.
- Contains proteins, glucose and lymphocytes.

Functions of Cerebrospinal Fluid

Protection: CSF protects the brain by 'buffering' it, reducing the impact of blows to the head.
Buoyancy: CSF immersion reduces the net weight of the brain from 1400g to about 50g, lowering pressure at the base of the brain.
Excretion of waste products: CSF flow from the CSF to the blood removes potentially harmful metabolites, drugs, and other substances from the brain.
Endocrine Medium: CSF acts as a transport medium for hormones to reach remote areas of the brain where they may act.

Peripheral Nervous System

The peripheral nervous system (PNS) is comprised of nerves that connect the CNS to the rest of the body.
It carries sensory information from the body to the CNS and motor commands from the CNS to muscles and glands.

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Description

Explore the essential functions and divisions of the nervous system in this quiz. Covering aspects such as the central and peripheral nervous systems, as well as the roles of sensory and motor divisions, this quiz will test your understanding of how the nervous system works in harmony with the endocrine system. Get ready to dive into the fascinating world of nervous tissue cells and neural communication.