The nervous system, and the endocrine system

what is the nervous system

a network of specialised communication cells based on electrical and chemical signals allowing messages to pass between the brain and the rest of the body

what are the two main functions of the nervous system

- to collect, process, and respond to information in the environment

- to coordinate the work of different organs and cells in the body

what does the nervous system allow the brain to do

regulate the bodies physiological functions and controls behaviour

what is the nervous system divided into

- central nervous system CNS

- peripheral nervous system PNS

what does the CNS consist of

- the brain

- the spinal cord

what is the spinal cord?

extension of the brain, passing messages to and from it, connecting to the PNS and responsible for reflexes (automatic actions)

what is the CNS protected by

- the brain is enclosed by 3 layers of meninges and encased by the skull

- the spinal cord runs through a column of vertebrae

- the brain and spinal cord are submerged in cerebrospinal fluid

what are the 3 main parts of the brain

- brain stem

- cerebellum

- cerebral cortex

what is the brain stem

the primitive region of the brain, responsible for physiological functions and automatic behaviours (swallowing, breathing)

what is the cerebellum

is attached to the back of the brain stem, controls and coordinates movements

what is the cerebral cortex also called

grey matter

what is the cerebral cortex

3mm thick layers of tissue containing billions of nerve cells, connected other brain parts via a layer of nerve fibres

what are nerve fibres also called

white matter

what percent of the cerebral cortex makes up the brain

40%

what does the cerebral cortex look like

wrinkled in apperance with bulges, grooves, and fissures between hemispheres and lobes

what are bulges called

gyri

what are grooves called

sulci

what do fissures and grooves do

expand the surface area of the cortex

what is the cortex subdivided into

lobes

name the lobes of the brain

- frontal lobe

- temporal lobe

- parietal lobe

- occipital lobe

what are the functions of the frontal lobe

- problem solving, speech production, personality, judgement

what are the functions of the temporal lobe

- understanding language, memory, hearing

what are the functions of the parietal lobe

- sense of touch, taste, and smell

- body orientation, reading, writing

what are the functions of the occipital lobe

- vision, colour perception

what are hemispheres connected by

thick bundle of nerves also called the corpus callosum

how many hemispheres are there and what are they called

2 - left hemisphere and right hemisphere

what are the functions of the left hemisphere

- language (Broca's and Wernicke's areas), logic and analytical thinking, mathematics, controls right side of the body

what are the functions of the right hemisphere

- spatial awareness, facial recognition, emotion processing, controls left side of the body

what is the peripheral nervous system PNS

not attached to spinal cord, sends info to CNS from outside world, transmitting messages from CNS to muscles and bodily glands

what is the PNS made up of

- automatic nervous system (ANS)

- somatic nervous system (SNS)

what makes up the ANS

- sympathetic nervous system

- parasympathetic nervous system

what is the ANS responsible for

vital functions (breathing, heart rate, digestion, arousal, stress)

what does the sympathetic nervous system do

mobilise the body fir action

what does the parasympathetic nervous system do

return the body to its resting state

what is the somatic nervous system responsible for

muscle movement and sensory perception

what does the endocrine system consist of

glands which produce hormones that get secreted into the bloodstream and can affect any cell in the body which contains relevant receptors

what do most hormones affect

organs and gets activated by the nervous system, slow-acting but powerful

what is the most important endocrine gland

the pituitary gland

what is the stress response an example of

the nervous and endocrine systems working together

what happens when an environmental stressor is detected

the hypothalamus activates the SNS turning to two stress response pathways

what are the two stress response pathways

- SAM = short-term (acute) stress

- HPA axis = prolonged (chronic) stress

what changes happen in the body in response to stress

- increased cholesterol and fatty acids in blood for energy production systems,

- increased BP,

- localised inflammation (redness, swelling, heat, pain),

- increased production of blood sugar for energy,

- decreased protein synthesis and intestinal movement and immune/allergic response systems,

- increased metabolism and faster heartbeat and faster respiration

- faster blood clotting

- increased stomach acids

what happens when the SAM pathway is activated

- sympathetic branch of the ANS is activated by the stressor

- causes adrenal medulla to release adrenaline

- adrenaline creates changes in the body (decreasing in digestion, increasing sweating, increased pulse and BP)

- resources conserved and body is prepared to fight or flee

what happens when the HPA axis is activated

- hypothalamus stimulates the pituitary gland

- pituitary gland secrets adrenocorticotropic hormone (ACTH)

- ACTH stimulates the adrenal glands to produce the hormone cortisol

- cortisol enables body to maintain steady supplies of blood sugar

- adequate and steady glucose levels help person to cope with prolonged stressor and helps body return to normal

- response takes about 20 minutes