Coordination and Response Explain the role of the nervous and hormonal systems in coordinating the activities of the body. Describe the structure and function of the eye. Describe the role played by the brain and spinal cord in a reflex action. Explain how the blood glucose level is regulated by insulin and glucagon. Learning Outcomes

Coordination and Response Response is visible, but the stimulus is not. Sometimes response is automatic and involuntary, or at other times, under the control of the mind. A single stimulus may bring about responses from different parts of the body. Some responses must be coordinated.

Coordination and Response For quick co-ordination of the various parts of the body and regulate bodily functions MAIN PARTS The central nervous system comprises of the brain and spinal cord. The peripheral nervous system comprises of all the nerves and receptors. The Nervous System: Why needed?

Coordination and Response Components of a Co-ordinated Behaviour stimulus receptor CNS EFFECTOR (muscles & glands RESPONSE A change in external Environment eg. sound, Smell, pain Structure which contains sensory nerve cells. Coverts stimulus into electrical signals called impulse Receive information and co-ordinate behaviour, eg. Brain & Spinal cord Structures that react upon receiving impulse from receptor behaviour

Coordination and Response Organs, Tissues, Cells of the nervous system Organs: Brain, spinal cord Tissues: nerves Cells: nerve cell or neurone

Coordination and Response The brain – divided into forebrain, midbrain and hindbrain. The Central Nervous System (CNS) 9.1 The Nervous System

Coordination and Response The nerve –e–each nerve is made of several bundles of nerve fibres laced with blood vessels, insulating tissue and other supporting tissue. The Peripheral Nervous System (PNS)

Coordination and Response Sensory/receptor neurones – carry impulses from receptors to the central nervous system. Relay/intermediate neurones – carry information within the CNS, interconnect with the other neurones. Motor/effector neurones – transmit impulses from the central nervous system to effectors, eg. muscles or glands for some kind of action. Types of Neurones 9.1 The Nervous System

Coordination and Response Drawings of neurones

Coordination and Response In the neurones –I–Impulses flow only in one direction. The Impulse 9.1 The Nervous System

Coordination and Response SPINAL CORD structure

Coordination and Response A cylindrical mass of nervous tissue, extending from the posterior of the brain stem. Protected by the vertebral column (back bones) Spinal nerves are attached at intervals along the spinal cord.

Coordination and Response A stimulus results in the movement of ions across the neuron membrane. This changes the normal distribution of ions. Neighboring regions of the membrane are stimulated. A small gap called synapse exists either between one neuron and the next, or between a neuron and a muscle or gland. Transmission of Impulses 9.1 The Nervous System

Coordination and Response Nerve impulses which reach the end are converted into neurotransmitters into the synapse. Neurotransmitters diffuse across the synapse into the next dendrite Neurotransmitters trigger an impulse in the dendrite of the following neuron. Transmission of Impulses 9.1 The Nervous System

Coordination and Response The simplest reflex arc, in humans, involves only two neurons. The Simple Reflex Arc 9.1 The Nervous System

Coordination and Response Other reflex actions like the withdrawal reflex usually involve at least three neurons: – The sensory neuron leading from the receptor to the spinal cord; – The relay neuron inside the spinal cord; and – The motor neuron leading from the spinal cord to the effector muscle. The Simple Reflex Arc 9.1 The Nervous System

Coordination and Response VOLUNTARY & REFLEX ACTIONS

Coordination and Response REFLEX ACTIONS An immediate response to a specific stimulus without conscious control (not controlled by the brain) Eg. blinking, knee jerk, yawning, sudden withdrawal of hand on touching hot objects, pupil reflex 2 types:Spinal reflex actions are controlled by the spinal cord Cranial reflex is not controlled by the brain but takes place in the brain and usually occur in the head region.

Coordination and Response Unlearned reflexes help the body make rapid adjustments to stimuli without having to think first about what to do. These help to protect the body.

Coordination and Response A Simple REFLEX ACTION

Coordination and Response REFLEX PATHWAY

Coordination and Response Sequence of events that occur when the hand touches a hot object The heat on the object stimulates the nerve endings (receptor) in the skin Impulses are produced. The impulses travel along the sensory neurone to the spinal cord In the spinal cord the impulses are transmitted first across a synapse to the intermediate or relay neurone, and then across another synapse to the motor neurone Motor impulses leave the spinal cord along the motor neurone to the effector The effector is the biceps muscles which then contracts. The response is a sudden withdrawal of the hand.

Coordination and Response VOLUNTARY ACTIONS Actions under the control of the will. The impulse is initiated in the brain. The impulse travels along the relay neurone in the spinal cord to the appropriate motor neurone, and then to appropriate muscles. Eg. You wish to pull your hand away when someone touches it.

Coordination and Response REFLEX ACTION VS VOLUNTARY ACTION In-born behaviourLearned behaviour Very rapid responseRapid or slow response Brain or spinal cord involved Always Forebrain involved Response to a stimulus Initiated from the brain under conscious control Effectors are muscles or glands Effectors are muscles only