The nervous system and the endocrine system Pages 114-115 4.2.2 - Biopsychology Specification details The divisions of the nervous system: central and peripheral (somatic and autonomic). The function of the endocrine system: glands and hormones. The fight or flight response including the role of adrenaline.

The nervous system Biopsychologists assume that behaviour and experiences are caused by activity in the nervous system The nervous system is a specialised network of cells in the human body and is our primary internal communication system It has two main functions: To collect, process and respond to information in the environment To co-ordinate the working of different organs and cells

The major sub-divisions of the human nervous system Peripheral nervous system (PNS) Central nervous system (CNS) Autonomic nervous system Somatic nervous system Brain Spinal cord Sympathetic nervous system Parasympathetic nervous system Print this sheet for students to complete The major sub-divisions of the human nervous system

The major sub-divisions of the human nervous system Peripheral nervous system (PNS) Central nervous system (CNS) Autonomic nervous system Somatic nervous system Brain Spinal cord Sympathetic nervous system Parasympathetic nervous system The major sub-divisions of the human nervous system

The central nervous system (CNS) The CNS is made up of the brain and the spinal cord The brain is the centre of all conscious awareness. The brain’s outer layer, the cerebral cortex, is highly developed in humans The brain is divided in two hemispheres The spinal cord is an extension of the brain. It is responsible for reflex actions The CNS passes messages to and from the brain and connects nerves to the PNS

The peripheral nervous system (PNS) The PNS transmits messages via millions of neurons (nerve cells), to and from the central nervous system The PNS is further sub-divided into: the somatic nervous system (SNS) the autonomic nervous system (ANS)

The somatic nervous system This is the part of the PNS that is responsible for carrying sensory and motor information to and from the spinal cord

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

The two main divisions of the ANS The two main divisions of the autonomic nervous system are: The sympathetic nervous system The parasympathetic nervous system Their actions are mostly antagonistic - that is they usefully work in opposition to each other

The opposing actions of the sympathetic and the parasympathetic nervous system Organ Sympathetic nervous system Parasympathetic nervous system Gut Slows digestion Increases digestion Salivary glands Inhibits saliva production Increases saliva production Heart Increases heart rate Decreases heart rate Liver Stimulates glucose production Stimulates bile production Bladder Stimulates urination (relaxes the bladder) Inhibits urination (contracting bladder) Eye Dilates pupils Constricts pupils Lungs Dilates bronchi Constricts bronchi

Generally, maintains and conserves body energy and functions Generally prepares the body to expend energy for fight or flight

Fight or flight response Anxiety and fear are actually important for survival because they act as a mechanism to protect the body against stress and danger. The sympathetic nervous system controls what has been called the "Fight or Flight" phenomenon because of its control over the necessary bodily changes needed when we are faced with a situation where we may need to defend ourselves or escape. 

Imagine… You are walking down a dark street at night by yourself.  Suddenly you hear what you suspect are footsteps approaching you rapidly.  What happens?   Your sympathetic nervous system kicks in and in an instant, your body is prepares itself for either defence or escape.

Fight or flight? These changes enable the body to take action and protect itself in dangerous situations, either by running away or fighting – hence, the fight or flight response.

When the ‘threat’ has passed… Now imagine that the footsteps belong to a good friend who catches up to you and offers to walk you home.  You feel relief instantly, but your body takes longer to adjust.  In order to return everything to normal, the parasympathetic nervous system kicks in.  This system is slow acting, unlike its counterpart, and may take several minutes or even longer to get your body back to where it was before the scare.

These two subsystems are at work constantly shifting your body to more prepared states and more relaxed states.  Every time a potentially threatening experience occurs (e.g., someone slams on their breaks in front of you, you hear a noise in your house at night, you hear a loud bang, a stranger taps you on the shoulder unexpectedly), your body reacts. 

The constant shifting between these two systems keeps your body ready for your current situation.

The Endocrine System The endocrine system is in charge of body processes that happen slowly, such as cell growth. Faster processes like breathing and body movement are controlled by the nervous system. However, even though the nervous system and endocrine system are separate systems, they often work together to help the body function properly.

This controls the release of hormones from all other endocrine glands These release adrenalin directly into the bloodstream which prepares the body for fight or flight by constricting blood vessels in the stomach. This inhibits digestion and gives you that sick feeling as well as increasing your heart rate This facilitates the release of the female hormones – oestrogen and progesterone This facilitates the release of the male hormones – testosterone

Summary questions Using an example, explain what is meant by the fight or flight response If you hear a noise that makes you jump, your body immediately diverts blood away from your stomach to your muscles in order for you to stay and confront a potential attacker (fight), or run away (flight)

Summary questions Give two actions of the sympathetic nervous system and two actions of the parasympathetic nervous system Sympathetic nervous system – dilates pupils, inhibits saliva production, dilates bronchi, speeds up heart rate, inhibits digestion, stimulates glucose production, inhibits urination Parasympathetic nervous system – constricts pupils, stimulates saliva production, constricts bronchi, slows down heart rate, stimulates digestion, stimulates bile production, stimulates urination

Summary questions Billy is an A level student. He has been asked by his teacher to give a short presentation to the other psychology students in his class. Just before his presentation, Billy feels his mouth go dry and he starts to sweat. After the presentation has ended, Billy feels his breathing slow down and he begins to feel thirsty. Use your knowledge of the autonomic nervous system to explain Billy’s behaviour before and after the presentation.

Possible answer Billy feels stressed about giving a presentation to the class and this activates sympathetic responses in his autonomic nervous system. Blood is diverted to the muscles for energy and as a result, Billy sweats to allow heat energy to be lost from the surface of the skin. It is the body’s cooling mechanism. His salivary glands have inhibited saliva production making his mouth go dry. Once the presentation is over, Billy’s stress is no longer present and his parasympathetic nervous system is now acting to restore his bodily functions to a normal state; this is why his breathing is slowing down. He feels thirsty as his previously inhibited saliva production has dried his mouth out and now he is aware of this and this needs rectifying

Can you? Outline the role of the central nervous system (4 marks) Identify two divisions of the autonomic nervous system (2 marks) Identify the two components of the central nervous system (2 marks) Outline the role of the somatic nervous system (4 marks each) Outline the role of the autonomic nervous system (4 marks each) Using an example, outline the function of the endocrine system inn the human body (4 marks) Answer the ‘Check it’ questions on page 115

Ensure you have written up your class notes to include the following: Homework Ensure you have written up your class notes to include the following: The divisions of the nervous system including: central and peripheral (somatic and autonomic). The function of the endocrine system: glands and hormones. The fight or flight response including the role of adrenaline.