Unit 3: Behaviour, Populations and environment

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

2. Learning Intentions Success Criteria To examine the workings of the brain and the nervous system. • Define the terms; • Central nervous system • Peripheral nervous system • Somatic nervous system • Autonomic nervous system Mrs Smith Ch26 The Nervous Sysem

3. The Nervous System 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. Mrs Smith Ch26 The Nervous Sysem Image source: www.drstandley.com

4. Summary: The Nervous System Mrs Smith Ch26 The Nervous Sysem

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

6. Central Nervous System Peripheral Nervous System • Somatic – some involuntary reflex actions, mostly voluntary actions • Autonomic - involuntary actions Mrs Smith Ch26 The Nervous Sysem

7. ANTAGONISTIC have opposite effects Functional Division: The Nervous System PNS (peripheral nervous system) Crainial nerves + spinal nerves) Autonomic (involuntary - muscles) Somatic (mostly voluntary) 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 Parasympathetic Sympathetic Mrs Smith Ch26 The Nervous Sysem

8. SENSORY NERVE MOTOR NERVE Brain & Spinal cord -processes information. 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). C.N.S STIMULUS RESPONSE Mrs Smith Ch26 The Nervous Sysem

9. The Autonomic Nervous System 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. Autonomic nerves regulates the heart, blood vessels, bronchial tubes, alimentary canal & sweat glands. The nerves start at the nerve cells in the brain, pass down the spinal cord then emerge at the appropriate organ. Mrs Smith Ch26 The Nervous Sysem

10. Autonomic Nervous System Mrs Smith Ch26 The Nervous Sysem

11. 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. Mrs Smith Ch26 The Nervous Sysem

12. Adrenal gland only connected to sympathetic nerves Image source: www.biocomtech.com Parasympathetic v Sympathetic ANTAGONISTIC have opposite effects Homeostasis Response to stress • Tries to maintain a stable internal environment • ‘Flight or flight’ response • Calms the body down after stress • Helps body conserve resources & store energy Mrs Smith Ch26 The Nervous Sysem

13. 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). Mrs Smith Ch26 The Nervous Sysem

14. 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. Mrs Smith Ch26 The Nervous Sysem

15. 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. Mrs Smith Ch26 The Nervous Sysem

16. Task: Torrance-TYK pg 215 Qu’s 1-4 Mrs Smith Ch26 The Nervous Sysem

17. Task: Torrance AYK pg215/216 Qu’s 1-4 Mrs Smith Ch26 The Nervous Sysem