Grade 12 lesson 6 the brain and its functions

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The Brain & its functions

Chapter 29.4

+Learning Objectives

To be able to: Explain the functions of the different parts of the brain

Cerebrum, Cerebral cortex, Cerebellum, Brain stem, Reflex arc, Somatic nervous system, Autonomic nervous system, Sympathetic nervous system, Parasympathetic nervous system

Keywords:

+The Brain Made up of three main

structures: Cerebrum – interprets

signals from your body & forms responses (emotions, pain, hunger, etc.)

Cerebellum – coordinates your movements.

Brainstem – connects the brain to the spinal cord and controls most basic activities for life (breathing, heartbeat, etc.)

+Lobes of the BrainThe cerebral cortex is the outer layer of the cerebrum and is part of the brain responsible for intelligence, language, memory and consciousness.

It interprets information from your sensory organs and generates responses.

+The Cerebral Cortex

+The Cerebellum The cerebellum is the part

of the brain that coordinates your movements

It helps maintain your posture and balance, adjusting automatically to help you move smoothly

It is located BELOW the large part of the brain

+The Brain Stem

Has 3 major parts: midbrain pons medulla oblangata

What are their functions?

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The Spinal Cord

Rope-like bundle of neurons Connects brain to nerves found

throughout the body All signals that go to or from the

brain passes through the spinal cord

The Stimulus-Response ModelThe basic pathway for a nerve impulse is described by the stimulus-response model

A receptor converts a stimulus into a nerve impulse, which is transmitted by a sensory neuron to the CNS (spinal cord)Relay neurons within the CNS will transmit this signal to a control centre (usually the brain), where the information is processedMotor neurons will transmit a resultant nerve impulse from the CNS to an effector organ (a muscle or gland), eliciting an appropriate response

+Voluntary and Involuntary ResponsesVoluntary responses are things that you can control, for example picking up a pen, kicking a ball.

Your brain sends an impulse down the spinal cord which then passes an impulse to your motor neurones to complete the action.

+Voluntary and Involuntary Responses

Involuntary responses are things you can’t control.

These are how you react to pain, your eyes dilating and contracting, your heart beating etc.

+ReflexA reflex is a rapid and involuntary response to a stimulus and results from an even simpler pathway called a 'reflex arc'

Reflex actions do not involve the brain in the decision making process - instead sensory information is relayed directly to motor pathways within the spineThis results in a reaction without conscious thought, which may be important in survival situations when quick reactions are necessary to avoid permanent damage or pain

+ The Reflex Arc

PNS CNS

+The Reflex ArcCopy and complete:

When you stand on a pin, the pain sensor sends an electrical impulse along the sensory neuron. This is passed across a synapse as a chemical and processed in the CNS in a relay neuron. It is passed across another synapse and through the motor neuron as an electrical impulse. This causes the muscle to move. It is an involuntary response.

CNS motor synapse electrical involuntary

sensor

+The Reflex ArcCopy and complete:

When you stand on a pin, the pain sensor sends and electrical impulse along the sensory neuron. This is passed across a synapse as a chemical and processed in the CNS in a relay neuron. It is passed across another synapse and through the motor neuron as an electrical impulse. This causes the muscle to move. It is an involuntary response.

CNS motor synapse electrical involuntary

sensor

+ Nervous System

CNS PNS

Somatic nervous system(voluntary)

Autonomic nervous system(involuntary)

Sympathetic nervous system

(action & stress,fight or flight)

Parasympathetic nervous system

(calm & relaxation)

+Nervous system

What is the role of the somatic nervous system? Give an example.

What is the role of the autonomic nervous system? Give an example.

What is the difference between the sympathetic and parasympathetic nervous systems?