biopsychology - the nervous system and the endocrine system

Question 1

the nervous system

Answer 1

• specialised network of cells in the human body, primary internal communication system
• based on electrical and chemical signals
• uses sensory neurons
• has two main functions
  1. to collect, process and respond to information in the environment
  2. to co-ordinate the working of different organs and cells in the body

Question 2

subsystem 1 - the central nervous system (CNS)

Answer 2

• brain is centre of all conscious awareness
• outer layer of brain (cerebral cortex) only 3mm thick and covers the brain in the same way orange peel covers an orange, only found in mammals
• brain is highly developed in humans, distinguishes our higher mental functions from those of other animals, only a few living creatures don’t have brains
• brain is divided into two hemispheres
• spinal cord is extension of brain, passes messages to and from the brain and connects nerves to PNS
• also responsible for reflex actions

Question 3

subsystem 2 - the peripheral nervous system (PNS)

Answer 3

• transmits messages via millions of neurons (nerve cells), to and from the CNS

subdivided by -

autonomic nervous system (ANS) - governs vital functions in body such as breathing, heart rate, digestion, sexual arousal and stress responses

somatic nervous system (SNS) - governs muscle movement and receives information from sensory receptors

Question 4

the endocrine system - glands and hormones

Answer 4

• endocrine system works alongside nervous system to control vital functions in the body, it acts slower but produces widespread and powerful effects
• glands such as thyroid glands (hormones regulate metabolic rate, growth and development) produce hormones which are secreted into the bloodstream and affect any cell that has a receptor for that hormone
• most hormones affect cells in more than one organ, leading to diverse and powerful responses
• main endocrine gland is the pituitary gland, located in the brain, which is often called the master gland because it controls hormone release from all other endocrine glands

Question 5

the endocrine system - endocrine and ANS working together (fight or flight), sympathetic and parasympathetic nervous systems

Answer 5

• will often work in parallel with each other during stressful situations
• when stressor is perceived, hypothalamus activates the pituitary gland which triggers activity in the sympathetic branch of the ANS
• ANS changes from normal resting state (parasympathetic state) to the physiologically aroused sympathetic state
• sympathetic and parasympathetic branches are antagonistic, they work in opposition to each other and when one is switched on the other is switched off, reciprocal inhibition
• amygdala processes everything that is happening

adrenaline - released from adrenal medulla into bloodstream, triggers physiological changes in the body (eg. raised heart rate, sweating, pupils dilate so you can pay more attention, inhibits saliva, more blood being circulated to prepare you to flight, taking in more oxygen, oxygen rich blood transported to muscles so they are ready) which creates the physiological arousal needed for fight or flight response

immediate and automatic - this all happens in an instant as the threat is detected, this is an acute and automatic response / reaction in the body

parasympathetic action - once the threat has passed, the PNS returns the body to its resting state, the parasympathetic branch works in opposition to the SNS, acts as a brake and reduces activities of body that were previously increased (rest and digest response)

HPA axis - hypothalamus sends signal to pituitary gland which tells adrenal glands to produce adrenaline