AOS1

DP1: The nervous system

The Human Nervous System: the body’s entire network of specialised cells (neurons) that transmit signals between different parts of the body ****→ Messages are sent via neural pathways/tracts (circuits of interconnected neurons)

Stimulus a thing or an event that triggers a response/behaviour by evoking a specific functional reaction in an organ or tissue

Functions of the nervous system:

  1. Receive information

  2. Process information

  3. Coordinate a response to the information

Central Nervous System

The central nervous system: carries information to and from the PNS

→ Process information that is received from the body’s internal and external environments (stimulus) → Activate appropriate responses to the stimulus

The Brain

The brain: the organ responsible for controlling our thoughts, emotions and memories →Receives and analyses sensory information + responds by controlling bodily actions and functions.
→ Functions = activation of neural pathways (link different areas and structures together)

The Spinal Cord

The spinal cord: The long, thin bundle of nerve tissues that extends from the base of the brain to the lower back.
→Receive sensory information from the body (via PNS) → send messages to the brain for processing.
→Receive motor information from the brain → send to relevant parts of the body (control muscles, glands. organs) → appropriate actions can be taken.
→ Transmission of information → occurs through interconnected neurons that form nerve pathways.

Components of the spinal cord include:
o White matter: axons that are bundled together and run the length of the spinal cord. o Grey matter: mainly located near the centre of the spinal cord, made up of cell bodies, axons and dendrites.

Peripheral Nervous System

The peripheral nervous system: The entire network of nerves located outside of the central nervous system

→ Carries information from the body’s muscles, organs, glands (internal environment) and sensory organs (external environment) to the Central Nervous System → Carry information from the Central Nervous System to the body’s muscles, organs and glands

Receptors: groups of specialised cells that detect a change in the environment and produce electrical impulses in response. *Sense organs contain groups of receptors that respond to specific stimuli

Effectors: parts of the body (muscles and glands) that produce a response to a detected stimulus

Interaction between autonomic and sympathetic is vital to allow the body to adapt to dif situations and maintain a balance state of functioning

The Somatic Nervous System

The somatic nervous system: subdivision of the PNS respnsible for the voluntary movement associated with skeletal muscles

skeletal muscles: a muscle connected to bone that coordinates movement

Sensory/afferent neuron: a specialised nerve cell that transmits sensory information from sensory receptors to the CNS

Motor/efferent neuron: a specialised nerve cell that transmits signials from the CNS to muscles and glands

  • Sensory neurons = carry sensory information to the Central Nervous System

  • Motor neurons = carry motor information away from the Central Nervous System and to skeletal muscles.

Sensory Neural Pathway (afferent pathway):

  1. Sensory N receive information from sensory skin receptors

  2. Sensory N signals through an afferent sensory neural pathway to the CNS

Motor Neural Pathway (efferent pathway):

  1. Motor neurons carry motor information through efferent motor neural pathway from the CNS to enable voluntary/intentional bodily movement

The Autonomic Nervous System

The autonomic nervous system: the subdivision of the peripheral nervous system responsible for controlling involuntary responses → Connects CNS to the body’s visceral muscles = regulating activity + providing feedback to the brain e.g. digestion, blinking, breathing rate, heartbeat)

visceral muscle: smooth muscle controlled by the autonomic nervous system found in the walls of organs and structures including the digestive tract, blood vessels and respiratory airways

Sympathetic Nervous System: branch of the autonomic nervous system that activates the flight-or fight- or-freeze response – the body’s rapid involuntary response to stress

→Activates/increases activity of visceral M.O.G.= prepare body for vigorous activity/ deal with a stressful or threatening situation → Activates fight, flight or freeze response in times of high arousal or stress.
→ Release of hormones: activating various MOG e.g adrenaline

Flight-or-fight-or- freeze response: the bodies automatic psychological response to stress.threat which results in a person escaping the stressor, confronting the stressor or becoming immobile

Parasympathetic nervous system: a branch of the autonomic nervous system responsible for maintaining homeostasis and day to day function. → Regulate/maintain the internal body environment in a steady, balanced state of normal functioning in the absence of threat or stress (equilibrium) → Restore a state of calm once the need for the sympathetic nervous system activation has passed

Dominates the sympathetic nervous system most of the time in daily life + longer to return the body to its normal state/parasympathetic than sympathetic

→ Dilates pupil: allows more light in to see threat better → salivation: diverts resources →Relax bronchi - opens up airways → Increase heart rate: increase blood to skeletal muscles → Slows digestion: distribute resources to placed that need → Sweat: keeps the body cool →Increase adrenaline: gives you energy