Nervous System

Central nervous system

Brain and spinal cord - protected by bone

Peripheral nervous system (somatic)

Control of voluntary actions (movement of muscles)

Peripheral nervous system (autonomic)

Controls involuntary body functions (digestion, salivation, lacrimation (making tears, etc.)

Reflex Arc Order

Stimulus, Receptor, Control Centre, Effector, Response.

What is the stimulus?

A change in the internal or external environment that triggers a response

What is the receptor?

Specialised cells that detect change

What is the control centre?

Processes the signal from the receptor and sends a message to the effector about how to respond.

What is the effector?

The muscle or organ that is stimulated to contract, release a hormone, etc. (cause the response)

What is the response?

The body returning to a state of balance so that the receptors are no longer active.

What is the nervous system?

The body system consisting of the brain, spinal cord and peripheral nerves and receptors that communicate messages quickly within the body.

What is the somatic nervous system?

The part of the peripheral nervous system involved with voluntary control of body movements

What is the autonomic nervous system?

The part of the peripheral nervous system involved in involuntary physiological processes such as heart rate and digestion.

What does CNS stand for

Central nervous system

What does PNS stand for?

Peripheral nervous system

In the autonomic nervous system, what is sympathetic nervous system?

Flight, fight, freeze. Activates bodily functions responsible for preparing the body for action.

In the autonomic nervous system, what is parasympathetic nervous system?

Rest and digest. Maintains homeostasis. Conserves energy.

What is a synapse?

A synapse is a gap between neurons, the signal crosses using neurotransmitters and it ensure one-way transmission.

Key idea of nervous system?

Fast communicating system using electrical signals.

Neurons transmit neural information to, from and within the CNS. There are three types of neurons. What are they?

Sensory neurons, interneurons, motor neurons.

What is a sensory neuron?

A nerve cell that transmits messages from the sensory receptors to the central nervous system

What is a interneuron?

A nerve cell that transmits information within the brain and spinal cord (central nervous system)

What is a motor neuron?

A nerve cell that transmits messages from the central nervous system to effectors.

What does a sensory neuron DO?

Sensory neurons transmit neural information from sensory receptor sites in the PNS to the CNS. The sensory information being transmitted could be from any of your 5 senses

What does a interneuron DO?

Interneurons (also called relay neurons) transmit neural information within the spinal cord and brain. Interneurons connect the sensory and motor neurons and can only be found in the CNS.

What does the motor neurons DO?

Motor neurons transmit neural information from the CNS to the PNS. The purpose of this information is to initiate a response in an effector, which could be a muscle or gland.

What are neurotransmitters

The chemical messenger that is released from one neuron and travels across the synapse to bind to the next neuron.

What is the function of an Axon?

Transfers electrical impulses from the cell body to the synapse. Axons are called ‘nerves’ when they are grouped together in a bundle.

Function of axon terminal?

Found at the end of the axon and contain neurotransmitters that are held in vesicles. Neurotransmitters are released once an electrical impulse is received.

Function of cell body (soma)

Contains most of the cell’s organelles, including the nucleus.

Function of the Dendrite

Contains receptor sites that receive neurotransmitters from neighboring neurons.

Function of a Myelin Sheath

A fatty, insulating layer made of Schwann cells that covers the axon. It helps keep the electrical signals inside the cell, allowing faster transmission.

Function of a Nucleus

Control centre of the cell that contains it genetic material.

What is action potential?

The electrical impulse (message) that is transmitted along a neuron. An action potential is another name for the electrical or neural impulse that moves along a neuron. Once the action potential reaches the axon terminal, neurotransmitters pass the action potential on to the next neuron.

Role of Dopamine

Acts within the brain on pathways associated with motor functions (movement), and emotional arousal, and motivation.

Role of Acetylcholine

Transmits the message from the axon terminals of a motor neuron to a skeletal muscle.

Role of Serotonin

Produced in the intestine and central nervous system; regulates appetite, mood, memory and behavior.

Role of Glutamate

A neurotransmitter in the CNS, involved with memory and learning.

Dopamine; what can go wrong?

A lack of dopamine - producing cells in the brain can cause Parkinson’s disease, a neurological condition characterized by tremors, stiffness, and uncoordinated movements.

Acetylcholine; what can go wrong?

Curare is a plant-based toxin that was used by South American Indigenous peoples to paint the arrows of blow-darts. When shot at a victim, this toxin prevented acetylcholine from binding to the postsynaptic neuron, causing paralysis.

Serotonin; what can go wrong?

Some scientists theorise that low levels of serotonin are linked to depression

Glutamate; what can go wrong?

High glutamate levels are involved with depression, anxiety and symptoms typical of attention deficit hyperactivity disorder (ADHD), such as the inability to concentrate. Low levels of glutamate are linked to insomnia, lack of concentration and low energy levels.

What is a reflex action?

A reflex action is a fast, automatic response that protects the body from harm. A reflex action (also known as a reflex arc), involves a maximum of 3 neurons. At times the body must react quickly without waiting for instructions from the brain. During such instances, the spinal cord is mainly responsible for initiating a response.

Knee - jerk reflex

The tap of the hammer induces a slight stretch within the quadriceps muscle. Receptors in the muscle detect this stretch and send a message to the muscle. The knee-jerk reflex is unique because it is monosynaptic, meaning that no interneurons are involved. Instead, the sensory neuron transmits the message directly across a synapse to a motor neuron in the spinal cord. The motor neurons then conduct the impulse back to the quadriceps, causing the muscle contraction that triggers a kick.