Nervous System and Neurones

What is Psychology: It is based on three processes: Gathering factual information. Forming theories to explain this factual information. Testing these theories.

The Nervous System

Human Nervous System A communication system that controls all parts of your body. Made up of two parts: Central Nervous System (CNS) Made up of your brain and spinal cord Peripheral Nervous System (PNS) Made up of the nerves that send messages from the CNS to other parts of the body

Human Nervous System

Function of Parts of the Nervous System Central Nervous system (CNS) Transmits and receives messages to and from Peripheral Nervous System (PNS). The spinal cord runs from the base of the brain (brain stem), inside the bones of the spine (vertebrae) to the lower middle section of the spine.

Function of Parts of the Nervous System 2. Peripheral Nervous system (PNS) Communicate information from the body’s organs, glands and muscles to the CNS, via sensory neurons. Communicate information from the CNS to the body’s organs, glands and muscles, via motor neurons. The PNS has two subdivisions: the somatic nervous system and the autonomic nervous system.

Somatic Nervous System Carries messages between CNS and the body. Responsible for voluntary movement of skeletal muscles.

Somatic Nervous System Sensory organs include mouth, skin, ears, eyes, nose. These organs/ tissues have receptor cells which detect changes. The changes stimulate a message which is then sent to the brain for a response. Types of receptors: Mechanoreceptors Photoreceptors Thermoreceptors Chemoreceptors Pain receptors

Autonomic Nervous System Carries messages from the CNS to the internal muscles, organs and glands. Operates without voluntary control.

Autonomic Nervous System Responsible for: breathing, heart beat, sweating, pupil size, movement of food in your intestines. Two parts of the autonomic nervous system: Sympathetic Parasympathetic

Sympathetic Nervous System During times of danger or stress, the Sympathetic Nervous System is responsible for: Increases blood flow Releases adrenaline Stops other body functions such as digestion Opens the bronchioles in the lungs which increases the amount of air entering the lungs Increases heart rate Diverts blood away from the digestive system and to muscles.

Parasympathetic Nervous System During rest, the Parasympathetic Nervous System is responsible for: Reduces diameter of the bronchioles Slows down heart rate & blood flow Increases blood flow to the digestive tract

Activity Complete the following activities: Revision from Year 9 Body Coordination Functions of the nervous system

Nerve Cells (Neurones)

Neurones Trillions of neurones which carry electrical messages (nerve impulses) at very high speeds. Can only travel in one direction (don’t travel backwards). Two types of neurones: Motor neurones Sensory neurones

Structure of a neurone

Part Function Axon Carries information away from the cell body to their ends. These impulses are called action potentials – changes in electric charge of the axon. Cell body (Soma) Makes energy and protein for the cell. Contains the nucleus Dendrites Receives information from other neurones or sensory receptors. Myelin sheath Layer of fat to insulate the axon. Increase the speed of electrical conduction. Node of Ranvier Gaps between the myelin sheath. They are not covered by myelin which helps generate electrical activity. Synaptic terminal Connects one neurone to another. Secrete a chemical called a neurotransmitter.

Sensory neurone Motor neurone Also known as affectors or afferent neurons Also known as efferent neurons or effectors Receives information from external environment such as sense organs (skin) and inside the body (muscles and organs) Transmits messages from the brain to muscles, organs, glands. Sends a message to the brain via the spinal cord. Tells muscles to move, organs to secrete hormones.