The human nervous system

what are the two features of the human nervous system

• Central nervous system (CNS)

• Peripheral nervous system (PNS)

what are the two features of the central nervous system

• brain

• spinal cord

what is the function'/ features of the brain

• centre of all conscious awareness

• cerebral correct is highly developed in humans

• the brain is divided into two hemispheres and four regions

what is the function'/ features of the spinal chord

• extension of the brain

• responsible for reflex actions such as pulling your hand away from a hot plate 

• passess messages

what are the two features of the peripheral nervous system

• autonomic nervous system

• somatic nervous system

features of autonomic nervous system

• involuntary

• governs vital functions in body such as breathing, heart rate, digestion, sexual arousal and stress response

• involved in homeostasis

• split into the sympathetic and parasympathetic

features of somatic nervous system

• voluntary

• controls muscle movement and receives information from sensory receptors 

• connects brain with the environment

steps for fight or flight

1. situation is appraised and perceived as stressful

2. the hypothalamus is alerted. It recognises the stress as acute so it activates the sympathetic branch of ANS

3. this stimulates the adrenal medulla which is part of the adrenal gland (located just above Kidneys)

4. the adrenal medulla secretes the hormone adrenaline and indirectly the neurotransmitter noradrenaline into the blood stream

5. this prepares the body for fight or flight which causes a number of physiological changes.

changes that happen in the body when sympathetic division of the ANS is activated?

• increased heart rate

• pupils dialate

• sweating increases

• dry mouth

• flushed face or pale skin

• racing thoughts

why do you experience increases heart rate

pump oxygen to muscles if you need to run away

why do you experience pupils dilating

lets in more light to enhance peripheral vision

why do you experience sweating more

cools body temperature down

why do you experience dry mouth

flood flow directed away from the digestive system

why do you experience racing thoughts

quicker thinking - evaluate danger and make rapid decisions

what do the changes facilitate (fight or flight)

• allow more oxygen to the muscles to allow them to work better

• allows more oxygen to the brain to allow quicker thinking and problem solving

what does the parasympathetic branch of the nervous system do?

• antagonistic to the synpathetic system and acts as a brake response

• serves to return the body back to it’s normal resting state

what does the sympathetic branch of ANS do?

• increases bodily activites

• releases noradrenaline

• activates in stress response

what does the parasympathetic branch of ANS do?

• decreases bodily activites

• release of acetylchloin

• activates in rest