nervous system 🧠

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Questions and Answers

What is the primary function of the central nervous system (CNS)?

To make voluntary actions automatic

To facilitate sensory reception only

To transmit nerve impulses to effectors

To regulate bodily functions and activities (correct)

Which type of neuron is responsible for transmitting nerve impulses from the sense organs to the CNS?

Sensory neurone (correct)

Relay neurone

Interneuron

Motor neurone

What type of action is primarily controlled by the spinal cord?

Reflex actions (correct)

Voluntary actions

Involuntary actions

Cognitive actions

What role do synapses play in the nervous system?

Junctions where chemical signals are transmitted between neurones Signup and view all the answers

Which of the following accurately describes the structure of a motor neurone?

Has an irregular-shaped cell body and one long nerve fibre Signup and view all the answers

How is a nerve impulse transmitted across a synapse?

By chemicals released by the neurones Signup and view all the answers

In the context of nerve impulses, what do 'effectors' refer to?

Muscles or glands that perform actions Signup and view all the answers

What occurs when a stimulus is detected by the receptors?

Nerve impulses are generated and transmitted to the CNS Signup and view all the answers

What does the term 'involuntary actions' refer to in the context of the nervous system?

Automatic actions not controlled consciously Signup and view all the answers

What is the primary function of a motor neurone in reflex actions?

To convey nerve impulses from the spinal cord to the effector muscles. Signup and view all the answers

Which type of reflex action is controlled by the spinal cord?

Spinal reflex Signup and view all the answers

What does the reflex arc represent?

The route nerve impulses take from receptor to effector. Signup and view all the answers

In the case of touching a hot object, which neurones transmit signals to the spinal cord?

Sensory neurones Signup and view all the answers

What is a key difference between the nervous control and endocrine control systems?

Responses from endocrine control are generally longer lasting. Signup and view all the answers

Which example illustrates a cranial reflex?

Rapidly blinking when a foreign object approaches the eye. Signup and view all the answers

Which statement accurately describes the nature of responses in nervous control?

Responses can be either voluntary or involuntary and are usually quick. Signup and view all the answers

Study Notes

Sensitivity and Response

Sensitivity refers to the ability of organisms to react to stimuli in the environment.
A stimulus triggers a reaction known as a response.

Role of the Nervous System

The human nervous system regulates bodily functions and interactions with the environment.
Voluntary actions are consciously controlled; involuntary actions operate without conscious control (e.g., heartbeat, breathing).

Components of the Human Nervous System

Central Nervous System (CNS) includes the brain and spinal cord.
- The spinal cord mainly handles automatic reflex actions.
- The brain processes sensory information from touch, smell, and taste.
Peripheral Nervous System (PNS) comprises cranial and spinal nerves, as well as sensory organs.
- Sensory organs actuate nerve impulses in response to stimuli.

Neurones

Nervous tissue comprises nerve cells called neurons.
Each neuron consists of a cell body with a nucleus and nerve fibers (cytoplasmic strands).
- Sensory Neurone: Transmits impulses from sense organs to the CNS, featuring a circular cell body and a long nerve fiber.
- Relay Neurone: Relays impulses between sensory and motor neurons, typically located in the CNS with many short nerve fibers.
- Motor Neurone: Sends impulses from the CNS to effectors, characterized by an irregular-shaped cell body and a long nerve fiber.

Synapse

A synapse is the junction between two neurons.
Nerve impulse transmission across a synapse relies on chemicals, as impulses cannot cross directly.
Painkillers can block these synaptic spaces, preventing the transmission of nerve impulses.

Nerve Impulse Pathways in the Spinal Cord

Sensation: Involves sensory and relay neurons; the brain interprets nerve impulses for sensations (e.g., feeling temperature).
- Pathway: Receptor → Sensory Neurone → Relay Neurone → Brain.
Voluntary Action: Involves relay and motor neurons; initiated by conscious decision (e.g., raising a hand).
- Pathway: Brain → Relay Neurone in spinal cord → Motor Neurone → Effector (muscle).

Reflex Action

A reflex action is an automatic response to a stimulus without conscious thought.
Types of reflexes:
- Cranial Reflexes: Controlled by the brain (e.g., blinking).
- Spinal Reflexes: Governed by the spinal cord (e.g., withdrawing hand from heat).
Reflex Arc: The pathway for reflex actions, involving receptors, sensory neurons, relay neurons, motor neurons, and effectors.

Endocrine vs. Nervous Control

Similarities: Both systems transmit messages to target organs in response to stimuli.
Differences:
- Nervous control is localized; endocrine control can affect multiple organs via hormones.
- Nervous control elicits quick responses; endocrine responses are slower.
- Nervous responses can be voluntary, involuntary, short-lived; endocrine responses are usually involuntary and can be long-lived.