Unit 3: Behaviour, Populations and environment Chapter 26: Organisation of the nervous system 07/08/2015Mrs Smith Ch26 The Nervous Sysem 1 Higher Human Biology

Learning Intentions To examine the workings of the brain and the nervous system. Success Criteria 2.Define the terms; a.Central nervous system b.Peripheral nervous system c.Somatic nervous system d.Autonomic nervous system 07/08/2015 2Mrs Smith Ch26 The Nervous Sysem

The Nervous System Image source: The nervous system is a network of specialised cells that communicate information about an individual’s surroundings and itself. It processes this information and causes reactions in other parts of the body. 07/08/20153Mrs Smith Ch26 The Nervous Sysem

Summary: The Nervous System 07/08/20154Mrs Smith Ch26 The Nervous Sysem

CNS (central nervous system) PNS (peripheral nervous system) Structural Division: The Nervous System Based on the structure and location of the component parts, the nervous system can be divided as shown in the diagram. Brain Spinal Cord 07/08/20155Mrs Smith Ch26 The Nervous Sysem

Central Nervous System 07/08/20156 Mrs Smith Ch26 The Nervous Sysem Peripheral Nervous System Somatic – some involuntary reflex actions, mostly voluntary actions Autonomic - involuntary actions

Autonomic (involuntary - muscles) PNS (peripheral nervous system) Crainial nerves + spinal nerves) Somatic (mostly voluntary) Functional Division: The Nervous System Parasympathetic Sympathetic ANTAGONISTIC have opposite effects A further method of dividing up the nervous system is based on different functions performed by the two separate branches of the peripheral nervous system as shown in the diagram 07/08/20157Mrs Smith Ch26 The Nervous Sysem

The Somatic Nervous System The peripheral nervous system has 2 branches, called the somatic and the autonomic nervous systems. The somatic nervous system (including spinal nerves) controls the skeletal muscles. Most movements that it controls are voluntary but it also controls certain involuntary reflex actions (e.g. limb withdrawal). SENSORY NERVE C.N.S MOTOR NERVE Brain & Spinal cord - processes information. STIMULUS RESPONSE 07/08/20158Mrs Smith Ch26 The Nervous Sysem

The autonomic nervous system (ANS) controls involuntary responses to stimuli by the body, so there is no conscious control, but under exceptional some people can suppress certain autonomic responses intentionally. The Autonomic Nervous System The nerves start at the nerve cells in the brain, pass down the spinal cord then emerge at the appropriate organ. Autonomic nerves regulates the heart, blood vessels, bronchial tubes, alimentary canal & sweat glands. 07/08/20159Mrs Smith Ch26 The Nervous Sysem

Autonomic Nervous System 07/08/201510Mrs Smith Ch26 The Nervous Sysem

Antagonistic nature of the Autonomic Nervous System The sympathetic and parasympathetic systems which make up the autonomic nervous system are described as being antagonistic. i.e. They affect many of the same body structures but exert opposite effects on them. 07/08/2015Mrs Smith Ch26 The Nervous Sysem 11

Image source: Parasympathetic v Sympathetic HomeostasisResponse to stress ANTAGONISTIC have opposite effects Tries to maintain a stable internal environment ‘Flight or flight’ response Adrenal gland only connected to sympathetic nerves Calms the body down after stress Helps body conserve resources & store energy 07/08/201512Mrs Smith Ch26 The Nervous Sysem

Harmonious Balance The autonomic nervous system is concerned with maintaining a stable internal environment by playing a part in homeostasis. The sympathetic and parasympathetic nervous systems are constantly working in an opposite but equal manner (neither wins). 07/08/2015Mrs Smith Ch26 The Nervous Sysem 13

Fight or flight In response to a crisis the sympathetic system prepares the body for action and the expenditure of energy by Increasing heart rate and blood pressure. Diverting blood to skeletal muscle. Increasing perspiration. The hormone ADRENALINE helps to sustain this state till the emergency is over. 07/08/2015 Mrs Smith Ch26 The Nervous Sysem 14

Calming Down When the crisis is over, the parasympathetic system briefly takes over by; Returning heart rate and blood pressure to normal. Peristalsis in the digestive tract increases. Blood is diverted away from skeltal muscles and back to the intestine (allowing digestion to resume). THIS ALLOWS THE BODY TO STORE ENERGY AND CONSERVE RESOURCES. 07/08/2015Mrs Smith Ch26 The Nervous Sysem 15

Task: Torrance-TYK pg 215 Qu’s /08/201516Mrs Smith Ch26 The Nervous Sysem

Task: Torrance AYK pg215/216 Qu’s /08/201517Mrs Smith Ch26 The Nervous Sysem