Nervous System

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Questions and Answers

What is the primary role of the myelin sheath in the peripheral nervous system?

To conduct electrical impulses towards the cell body

To facilitate the generation of action potentials

To store neurotransmitters at synaptic ends

To provide insulation to axons (correct)

Which component of a neuron is responsible for conducting electrical impulses away from the cell body?

Synaptic end bulb

Axon (correct)

Cell body

Dendrites

What is the function of the Nodes of Ranvier in myelinated neurons?

To facilitate rapid transmission of action potentials (correct)

To increase the length of the axon

To absorb neurotransmitters released at synapses

To support the structural integrity of the axon

Which division of the peripheral nervous system is responsible for involuntary actions?

Autonomic nervous system Signup and view all the answers

Which of the following functions does the nervous system NOT perform?

Secreting hormones for long-term responses Signup and view all the answers

What type of cells primarily provide myelin insulation to axons in the peripheral nervous system?

Schwann Cells Signup and view all the answers

Which part of the nervous system is composed of the brain and spinal cord?

Central nervous system Signup and view all the answers

What is the primary function of neuroglial or glial cells in the nervous system?

Supporting and protecting neurons Signup and view all the answers

What is the function of dendrites in neurones?

To receive information and pass it to the cell body. Signup and view all the answers

Which property of neurones allows them to react to stimuli?

Irritability Signup and view all the answers

Which type of glial cell is primarily involved in inflammation and cell destruction?

Microglia Signup and view all the answers

What is the main role of oligodendrocytes in the central nervous system?

They form and maintain myelin sheaths. Signup and view all the answers

What substances can easily cross the blood-brain barrier?

Glucose and oxygen Signup and view all the answers

What structure contains the neurotransmitter receptors in a synapse?

Post-synaptic neurone Signup and view all the answers

What is the primary function of synaptic end bulbs?

To conduct impulses between neurones. Signup and view all the answers

Which of the following substances does NOT typically cross the blood-brain barrier efficiently?

Large molecules Signup and view all the answers

Study Notes

Nervous System

Detects and responds to changes inside and outside the body.
Works with the endocrine system to control body function and maintain homeostasis.
Nervous system stimulation provides an immediate response while endocrine activity is slower and more prolonged.

Central Nervous System (CNS)

Brain and spinal cord.

Peripheral Nervous System (PNS)

All other nerves.
Sensory division.
Motor division (voluntary - somatic nervous system and involuntary-autonomic nervous system)
- Autonomic nervous system:
  - Sympathetic - fight or flight.
  - Parasympathetic - rest and digest.

Nervous Tissue

Composed of neurons, Schwann cells, and neuroglial/glial cells.

Neurons

Nerve cells responsible for transmitting information throughout the body.
Key features:
- Cell body.
- Axon.
- Schwann cells.
- Nodes of Ranvier.
- Dendrites.
- Synaptic end bulb.

Cell Body

Contains the nucleus and other organelles.

Axons

Communication route between the cell body and axon terminals.
Conducts electrical impulses away from the neuron's cell body.
Longer than dendrites (can be over 1 meter long).
Larger axons and those of the peripheral nervous system are surrounded by a myelin sheath.

Schwann Cells

Wrap around axons in layers.
Mainly provide myelin insulation to axons in the peripheral nervous system.
Myelin sheath: high phospholipid content offers electrical insulation.

Nodes of Ranvier

Exposed areas between Schwann cells.
Assist rapid transmission of action potentials in myelinated neurons.

Dendrites

Extensions of the cell body providing a large surface area to receive information to pass to the cell body.
Shorter than axons.
Plasma has dense chemical ion channels for impulse transmission.
Form synapses with other dendrites or terminate in specialized sensory receptors, e.g., skin.

Properties of Neurons

Irritability - Ability to initiate nerve impulses in response to stimuli from inside or outside the body.
Conductivity - Ability to transmit an impulse.
Neuroglial Cells: Support network in the central nervous system formed by three types of non-excitable glial (glue-like) cells:
- Microglia: Mainly found in the area of blood vessels. Become phagocytic during inflammation and cell destruction.
- Astrocytes: Form the main supporting tissues of the CNS. Star-shaped with branching processes. Found in large numbers adjacent to blood vessels.
- Oligodendrocytes: Smaller than astrocytes. Clustered around the neuron cell wall and along the length of myelinated nerve fibers in the CNS. Form and maintain myelin, similar to Schwann cells in the peripheral nervous system.

Blood-Brain Barrier

Selective barrier protecting the brain from toxic substances and chemical variations in the blood, e.g., after a meal.
Oxygen, carbon dioxide, glucose, and lipid-soluble substances (alcohol) cross the barrier quickly.
Large molecules, drugs, inorganic ions, and amino acids pass more slowly.

Synaptic End Bulbs

Important for nerve impulse conduction from one neuron to another or from a neuron to an effector.
Contain enclosed sacs called synaptic vesicles.
Synaptic vesicles store neurotransmitters.

Synapse

Junction between two neurons or between a neuron and an effector cell.
Composed of:
- Pre-synaptic neuron.
- Pre-synaptic knob.
- Neurotransmitters - acetylcholine/noradrenaline.
- Calcium.
- Mitochondria.
- Neurotransmitter receptors.
- Post-synaptic knob.
- Post-synaptic neuron.