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12.1 The Brain
Today’s Learning Objectives:
Identify the cerebrum, cerebellum and medulla. Identify the hypothalamus and pituitary gland. State the function of the cerebrum, cerebellum and medulla. State the function of the pituitary gland. State the function of the hypothalamus. Be able to interpret information about brain injuries.
CerebrumControls conscious
decision, personality, memory and creativity.
CerebellumControls balance and coordinates muscle
movement
MedullaConnects brain to spinal cord. Controls breathing
rate and heart beat.
Hypothalamus and PituitaryHypothalamus is a monitoring centre (e.g. water balance, temperature). The pituitary gland releases regulating hormones (e.g ADH).
12.2 Sensing and Responding
Today’s Learning Objectives:
Identify the brain spinal, cord and peripheral nerves. Name the main parts of the central nervous system (CNS). Describe the passage of nerves through the nervous system. Describe the role of the CNS. State the direction in which nerve impulses travel along sensory and motor nerves. Identify the motor and sensory strips of the cerebrum
The Nervous System
Brain, spinal cord and nerve fibres
communicating with sense organs,
muscles, glands and internal organs
Central nervous System (CNS):
Brain and spinal cord, protected by skull and vertebrae.
Peripheral Nervous System:
Nerves that spread to every part of the body and connect with sense receptors, skin, muscle and internal organs.
12.3 Cells of the Nervous System
Today’s Learning Objectives:
State the general name given to nerve cells. State the function of a sensory neurone. State the function of relay neurones. Explain why the fibres of a relay neurone are usually highly branched. State the function of a motor neurone.
Neurons
The nervous system consists of 100 billion nerve cells (neurons).
80% of these are found in the brain.
Information is passed from neurone to neurone by electrochemical impulses.
Neurons come in various shapes and sizes but have a similar overall structure.
Sensory neuronsCarry information from sense organs to CNS.
Motor neuronsCarry information from CNS to muscles and glands.
Relay neuronsConnect neurones. Receive info from sensory neurones and transmit to motor neurones.
Sensory neuronsCarry information from sense organs to CNS.
Receptor
Sensory fibre
Axonfibre
Cell body with
nucleus
Impulses to CNS
Relay neuronsConnect neurones. Receive information from sensory neurones and transmit to motor neurones.
Impulses from
sensory neurone
Impulses to other
neurones
Cell body with nucleus
Main relay fibre
Motor neuronsCarry information from CNS to muscles and glands.
Effector:Muscle
or gland
Cell body with nucleus
Axon fibre
Impulses from CNS
In the spinal cord a neuron may have an axon of 2-3 feet long (tip of spine to big toe).
In the brain it may only be one thousandth of an inch long.
A bundle of elongated axons from hundreds/ thousands of neurons forms a nerve.
Nerves spread to every part of the body and connect with sense receptors, skin, muscle and internal organs.
This is collectively called the Peripheral Nervous System (PNS).
12.4 Nervous System in Action
Today’s Learning Objectives:
Describe how a stimulus affects the nervous system. Describe the role of receptors. Name the five main sense organs and the stimuli they detect. Describe the role of effectors. State the role of the CNS in conscious responses. Dive the function of sensory and motor nerves. State what is meant by a response and describe some examples. Describe the flow of information in the nervous system.
Sense Organs
Light information
Chemicals in air
Chemicals in food
Sound information
Temperature, pressure, touch and pain.
Flow of Information
Receptors
CNS
Effectors
Receptor cells in your nose detect a pungent smell.
The brain processes this as unpleasant (possibly dangerous). You choose to move.
Muscles in you legs move you away from the smell.
12.5 Reflex Responses
Today’s Learning Objectives:
State what is meant by a reflex response. Give some examples of reflex responses and explain their specific values. Describe what a reflex arc is. Describe what a synapse is and explain their value. Describe the direction of flow of nerve impulses in a reflex arc.
Reflex Responses
• Usually occurs in response to a dangerous stimulus requiring a rapid response.
• The reflex response results in a quick reaction without the information being processed by the brain.
• The necessary speed of the reflex reaction protects the body by preventing or minimising danger.
Reflex Arc Animation
12.6 Control of Body Temperature
Today’s Learning Objectives:
Describe the location and temperature of the body core and shell. State the location of the temperature monitoring centre in the body. Name the receptor cells of the hypothalamus. Describe how the hypothalamus functions when temperature change is detected. Describe responses of the skin to a decrease and increase in body temperature. State the response of skeletal muscles to a decrease in body temperature.
