dot point 1 Flashcards
The Human Nervous System
The nervous system receives information, processes information and coordinates a response to that information
Central Nervous System
CNS comprises the brain and the spinal cord
Its role is to send and receive messages to and from the PNS, process it and to activate appropriate responses.
Brain
‘Control centre’ for the body, is responsible for everything we think, feel and do
A complex organ that coordinates mental processes and behaviour and regulates bodily activity
Processes sensory information
Coordinates a response to that information
Spinal Cord
Long, thin bundle of nerves that extends from the base of the brain to the lower back.
Function: to enable neural communication between the brain and the rest of the body
Receives sensory information from PNS and sends up to the brain through afferent tracts, which transmits sensory (afferent) messages. (up the spinal cord)
Receives motor information from the brain and sends it down to various parts of the body using the PNS through efferent tracts, which transmits motor (efferent) messages. (down the spinal cord)
Peripheral Nervous System
Made up of the entire network of nerves outside the CNS
Comprised of muscles, organs and glands (MOG)
Carries sensory information from sensory organs to the CNS
Carries motor information from the CNS
Divided into 2 branches; the somatic and autonomic nervous systems
Somatic Nervous System
Initiates skeletal movement
Controls voluntary (conscious) movement
Carries sensory (afferent) information from sensory receptor sites (skin, muscles, joints and tendons) and carries along sensory neural pathways to the CNS.
Carries motor (efferent) information from the CNS along motor neural pathways to skeletal muscles to control voluntary movements.
Connected to SENSORY receptors and SKELETAL muscles {SSS}
Autonomic Nervous System
Controls involuntary movement and functioning
Connects CNS to internal organs and glands
Regulates activity of visceral muscles, organs and glands
Self-regulation of MOG without conscious control (involuntarily)
Responsible for keeping our internal functioning at a stable level, homeostasis, and preparing our bodies to deal with threatening situations (FFF)
Sympathetic
Increases activity of internal muscles, organ and glands
Increases arousal
Prepare the body for action
Confront or flee a stressful/ threatening situation, fight-flight-freeze response
Activated by a stressor or fear stimulus and enhances survival by providing an immediate response
Releases hormones such as adrenaline, from the adrenal glands
Parasympathetic
Decreases activity
Calms the body after action
Dominates the sympathetic nervous system most of the time
Helps to maintain the internal body environment in a steady, balanced state of normal functioning, homeostasis
Counterbalances the activity of the SNS
Takes longer to return the body to its normal state as it has to remove hormones from the bloodstream
Rest and digest
The Neuron
A neuron is a nerve cell that receives and transmits neural information.
The nervous system is composed of billions of neurons arranged in neural pathways along which neural messages are transmitted.
Motor neurons (efferent)
transmit neural messages about motor movement from the CNS to the PNS
Sensory neurons (afferent)
Transmit neural messages about bodily sensations from the PNS to the CNS
Interneurons
Transfer neural messages between sensory neurons and motor neurons. The CNS, including the brain and spinal cord, is made up of interneurons.
Conscious responses
Conscious responses
A conscious response to a sensory stimulus is a reaction that involves awareness to external and internal stimuli.
Controlled by the somatic nervous system
Involves purposeful, voluntary and intentional reactions
Happens after you have paid attention to the stimulus
E.g. if the sun is shining, yo might put on sunglasses, walking, putting on a jumper (Somatic NS)
Unconscious responses
An unconscious response to a sensory stimulus is a reaction that does not involve awareness
Controlled by the autonomic nervous system
It is involuntary, unintentional, automatic and we cannot ordinarily control its occurrence
Regulated by the ANS, unconsciously regulating the functioning of your heart, digesting your food
The Spinal Reflex - ‘the reflex arc’
A spinal reflex is an unconscious and automatically occurring response to certain stimuli without any involvement of the brain (initiated by interneurons in the spinal cord)
A motor response has occurred before the brain processes a conscious perception of pain
The spinal reflex is an adaptive response, this allows for a faster reaction time in potentially harmful situations (lessen damage/injury)
E.g. if you touch something hot, you will pull your hand away immediately, without sensory information actually travelling all the way to the brain.
The Spinal reflex steps summarised
- Receptor site (skin) receives sensory stimuli
- Sensory neurons transmit the message along afferent pathways to the spinal cord
- Interneurons in the spinal cord relay the messages to motor neurons
- Motor neurons transmit the message along the efferent pathways to hand muscles causing a withdrawal reflex
- Whilst the spinal reflex occurs, sensory neurons also carry the neural message further up the spinal cord to the brain
- The brain then consciously perceives/interprets the sensory information as pain (WHY? = adaptive / for survival purposes so you can learn from it)
