The divisions of the nervous system Flashcards
Nervous system
consists of the central nervous system and the peripheral nervous system
- specialised network of cells in the human body and is our primary internal communication system.
Nervous system main functions
- to collect, process and respond to information in the environment
- to co-ordinate the working of different organs and cells in the body
Central nervous system
consists of the brain and the spinal cord and is the origin if all complex commands and decisions
- brains outer layer, cerebral cortex, highly developed and distinguishes higher mental functions - 2 hemispheres
- spinal cord is extension of brain -> reflex actions
Peripheral nervous system
sends information to the CNS from the outside world, and transmits messages from the CNS to muscles and glands in the body
- Autonomic nervous system - governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
- Somatic nervous system - controls muscle movement and receives information from sensory receptors
Endocrine system
instructs glands to release hormones directly into the bloodstream.
- acts slower than nervous system but has widespread and powerful effects
Glands
an organ in the body that synthesises substances such as hormones
- various glands in the body, such as thyroid gland, produces hormones.
Hormones
chemical substances that circulate in the bloodstream and only affect target organs. They are produced in large quantities but disappear quickly. Their effects are very powerful
- e.g. the thyroid gland produces the hormone thyroxine
Main glands of the endocrine system
- Pituitary gland (in the brain) - ‘master gland’ = controls the release of hormones from all the other endocrine glands in the body
- Hypothalamus
- Thyroid
- Adrenal
- Pancreas
- Ovaries (female)
- Testes (male)
Fight of flight definition
the way an animal responds when stressed. The body becomes physiologically aroused in readiness ti fight and aggressor or flee
Endocrine and ANS working together: Fight or Flight
When stressor is perceived the hypothalamus triggers activity in the sympathetic branch of the autonomic nervous system.
- ANS changes from normal resting state (parasympathetic state) ti the physiologically aroused, sympathetic state.
- stress hormone; adrenaline is released from adrenal medulla into bloodstream
- adrenaline triggers physiological changes needed for fight of flight
- once threat has passed, parasympathetic nervous system returns to its resting state.
Sympathetic state
- increases heart rate
- increases breathing rate
- dilates pupils
- inhibits digestion
- inhibits saliva production
- contracts rectum
Parasympathetic state
- decreases heart rate
- decreases breathing rate
- constricts pupils
- stimulates digestion
- stimulates saliva production
- relaxes rectum
