The Nervous System

28/09/23

Why do we have a brain?

-          Human brain is the command centre for the nervous system.

-          Enables thoughts, memory, movement and emotions.

-          Every interaction we have with world involves movement, that’s why some researchers say we have brain so we can move.

-          A theory that back this is the sea squirt. When they are small, they swim and move around. When they grow larger, they find a rock and stick to it. Once they’ve done this they absorb and ‘eat’ their own brain as they no longer require movement.

The Nervous System:

-          Made up of the brain, spinal cord and nerves.

-          Command centre of the body; controls thoughts, movement and automatic responses

-          Uses cells called neurons to send messages back and forth from the brain, through the spinal cord and to the nerves throughout the body.

The peripheral Nervous System:

-          Consists of the nerves that branch out from the brain and spinal cord.

-          Nerves form the communication network between the CNS and the body parts.

-          Subdivided into two different divisions: afferent and efferent neurons.

Afferent vs Efferent:

-          Afferent Neurons

§  Sensory neurons that carry nerve impulses from sensory stimuli towards the CNS and the brain.

-          Efferent Neurons

§  Motor neurons that transmit commands from the CNS to the muscles

-          The Efferent system can be split into 2 elements: Somatic Nervous System and Automatic Nervous System.

Somatic Nervous System –

-          Relays information from your senses to the CNS

-          Only has 1 nerve, goes from CNS to the muscle.

-          Obeys commands from the CNS and makes muscles contract and relax.

-          Voluntary control of the body movements via the use of skeletal muscles

Automatic Nervous System –

·       Main role is to regulate glands and organs without any effort from our conscious mind.

·       Regulates involuntary physiological processes.

·       Made up of two parts: sympathetic and parasympathetic.

·       The ANS regulates the internal organs to maintain homeostasis by balancing out these two systems that’s best for stability and survival.

Homeostasis: any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for it’s survival.

Sympathetic –

Ø  A network of nerves that helps your body activate it’s ‘fight or flight’ response.

Ø  This increases when you are stressed, in danger or physically active.

Parasympathetic –

Ø  Predominates in quiet ‘rest and digest’ conditions.

Ø  Main purpose is to conserve energy to be used later.

Ø  Regulates body functions such as digestion and urination.