Control Mechanism

  • Created by: livvvd26
  • Created on: 18-05-18 11:14

Body Systems

Nervous System

  • Key role in regulation the other body systems to maintain homeostasis - If homeostasis fails this sytem is the first to be severly affected and damaged

Cardiovascular System

  • Distribution of nutrient and oxygen to other systems - is to transporting waste prdocuts away from tissues

Respiratory System

  • Supplies oxygen to and removes waste carbon dioxide from systems
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Function of the systems


Respiratory System:

  • get oxygen into the body cells and remove carbon dioxide 
    • Gas transport
    • External transport
    • Internal transport

Cardiovascular System:

  • Taking oxygen from the lung to the body tissue and taking waste carbon dioxide from the body tissue to the lungs
  • Transport nutrients from intestines to body tissue
  • Chemical communication - transporting hormones from endocrine glands around the body
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Function of the systems 2

Nervous System:

Somatic Nervous System

  • Include parts from both the central and peripheral nervous system whohc deals with sensation, perception and other cognitive processes. It sends nerve impulses to move muscles to produce voluntary behaviour

Autonomic Nervous System

  • Includes from both central and peripheral nervous systems which deal with involuntary repsonses and control body systems that operate automatically 
  • ANS is controlled by the hypothalamus.. in the brain

Function so the ANS is to monitor and adjust body systems to cope with demands on the body

Two divisions - Sympathetic and Parasympathetic

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Autonomic Nervous System


Prepares the body for action e.g. increasing heart rate, ventilation, dilating vessels and suppressing digestion


Restores and maintains normal body conditions e.g. slows down respiration, heart rate and increases digestion

  • ANS will adjust breathing , heart rates, blood pressure, digestion, sweating and body systems
  • ANS operates in conjuction with the endocrine systems
  • ANS to maintain the homeostasos with various body systems
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  • The maintenance and control of the internal environment 
  • It controls:
    • Temperature
    • Blood sugra
    • Water
    • Carbon Dioxide

It works by using the endocrine and nervous system

Homeostasis mechanisms use the principle of NEGATIVE FEEDBACK (reduce increased activity and increase reduced activity to stabilise a system)

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The control of the body temperature 37c

Body temperature is constantly monitored by the hypothalamus

  • It detects temperature of blood - if low it triggers the sympathetic reaction that reduces blood flow to skin surface . Reduce sweat loss
  • It recieves impulses along nerves from the temperature receptors in the skin as well as from receptors inside the body
  • ANS triggers muscle contractions - shivering 
  • If the body temperagre changes the hypothalamus sends out a respone to correct the change
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Nerve Signals

  • Receptors pick up a stimulus and send out a signal
  • The signal travels along nerves to the hypothalamus
  • The hypothalamus sends back a response telling the skin what to do
  • Signals are very fast
  • Travelling along axons and passing across dendrites from one nerve to another
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Negative Feedback

  • The control of body temperature is an example of negative feedback
  • As a charge in the body happens in one direction, mechanisms in the body work to make it change in the opposite direction
  • This keeps conditions under control at the right level
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Regulating body temperature

Below 37:

  • Muscles contract and relax producing heat
  • Shivering
  • Pale skin as blood vessels constrict and become deeper in the skin to maintain/ conserve heat (vasoconstriction)
  • Hair may stand on its end to trap a layer of air above the skin, to insulate and maintain heat

Above 37:

  • Skin flushes (red) blood vessels expand and move closer to the surface to release heat (vasodilation) (radiation)
  • Sweat forms on the skin to evaporate and cool the body down
  • Hair stays flat to the skin surface 
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Heart Rate

  • Its never constant and varies to meet demands on the body
    • Electrical impusles from the heart muscle causes your heart to beat (contract)
    • This electrical signal begins in the sinoatrial node (SA), located at the top of the heart (right atrium)
    • The SA node is called the natural pacemaker
    • The SA node is automatically produces impulses, these then trigger contractions of the chambers of the heart
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Hormones and the Heart

  • Sympathetic division (ANS) raise heart rate in response to increase in demand from body 
  • By stimulating the adrenal glands to release adrenaline
  • Adrenaline is a hormone released at moments of great anger or excitement or exercising
  • Adrenaline can increase the rate of the heart by stimulating the sinoartrial node (SA)
  • Parasympathetic division of ANS slows and maintains the heart beat - nerves release neurotransmitter - acetylcholine 

Respiratory Rate:

  • The respiratory centre of the brain is in the medulla oblongata at the bottom of the brain
  • The respiratory centre recieves controlling signals of neural, chemical and hormonal nature
  • It controls the rate and depth of repsiratory movements of the diaphragm and other respiratory muscles

People with respiratory/cardiovascular disorder tend to avoid exercise and body systems can no longer maintain high levels of ventilation and cardiac output so they feel 'short of breath'

Hypertension can occur when voluntary behaviour overrules the autonomic control of breathing and intentionally take a series of rapid breaths supplying more oxygen than the body requires

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Respiratory Rate

Describe how respiratory rate is controlled:

Levels of oxygen and carbon dioxide in the blood controlled by homeostatic mechanisms A/W • Controlled by areas of the brain/ medulla of the brain stem • respiratory centre in the brain • detects the level of carbon dioxide in the blood flowing through it • high levels of carbon dioxide go with low levels of oxygen and vice versa • if carbon dioxide levels rise, negative feedback mechanisms operate to reduce it • sympathetic division of Autonomic nervous system (ANS) controls respiration • bronchi dilate • allows a faster airflow in and out of the lungs • tidal volume increase A/W a larger proportion of the air in the lungs is inspired and expired at each breath • ventilation rate increases • sympathetic increase in the activity of cardiovascular system • produces an increase in the transport rate of gases (oxygen and carbon dioxide) to and from tissues • respiratory centre in brain detects levels of carbon dioxide return to normal • parasympathetic division of ANS reduces ventilation and circulation back to the normal level • voluntary behaviour can affect gas levels • people with respiratory and/or cardiovascular disorders tend to avoid exercise and body systems can no longer maintain high levels of ventilation and cardiac output so they feel “short of breath” • hyperventilation can occur when voluntary behaviour overrules the autonomic control of breathing and intentionally take a series of rapid breaths supplying more oxygen than the body needs.

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