1. Animal Responses

2. Introduction Responses in animals are generally more complex than in plants: – there are sensors or detectors – muscles for moving the animal – systems for controlling and coordinating activity and/or homeostatic mechanisms In animals, the nervous and endocrine systems control and coordinate the response.

4. Organisation of the Nervous System The ability to respond to stimuli is a fundamental characteristic of living organisms. The nervous system is specifically adapted for this and has three functions: – collect information about internal and external conditions – process and integrate the information – act upon the information, by producing a coordinated response or action

5. The nervous system can be divided into a number of different parts, depending upon the role or function. It can be divided into: – central nervous system (CNS) – peripheral nervous system (PNS) itself divided in to – sensory system – motor system

7. Receptors collect information about internal and external conditions. – The receptors and their sensory neurones make up the sensory system. Processing of the sensory information is carried out by the central nervous system (CNS). Information is transmitted to the effectors by the motor (effector) system. – motor system has two parts the autonomic nervous system which carries out involuntary actions the somatic system which carries out voluntary actions The sensory and effector neurones are the peripheral nervous system (PNS).

8. Nervous system Peripheral NSCentral NS BrainSpinal Cord MotorSensory AutonomicVoluntary (somatic) Sympathetic Parasympathetic

9. TASK: Complete the following table to summarise this information. Nervous system Central Nervous System (CNS)Peripheral Nervous System (PNS) Comprised of: Sensory systemMotor system Consists of: Voluntary or somatic systemAutonomic system

10. Nervous system Central Nervous System (CNS)Peripheral Nervous System (PNS) Comprised of: The brain and spinal cord. The central nervous system receives sensory information from the sensory system, processes it and then sends instructions via the motor system to the effectors. Comprised of: The nerves of the sensory and motor systems. The nerves of the PNS take sensory information from receptors to the central nervous system instructions from the central nervous system to the effectors (muscles and glands) Sensory system (PNS)Motor system (PNS) Consists of: Receptors and the sensory neurones that collect and transmit information. Consists of: The autonomic (involuntary) and voluntary (somatic) systems. Voluntary or Somatic systemAutonomic system Carries out voluntary actions like moving your arm Carries out the unconscious actions involved in maintaining internal conditions – breathing, circulation, etc.

11. Autonomic Nervous System The autonomic nervous system is: – self-regulating and controls internal conditions by homeostasis – uses the involuntary activities of smooth muscles and certain glands – also involved in the fight or flight response (see later) It is part of the peripheral nervous system It is sub-divided into the: – sympathetic nervous system – parasympathetic nervous systems

12. Both systems (sympathetic and parasympathetic) have motor neurones that connect the CNS to their effector organs. Each pathway has a: – pre-ganglionic neurone – post-ganglionic neurone 1.So unlike the somatic system at least 2 neurones connect to the effector rather than just one. 2.The ganglion is a swelling where the two meet

13. In the sympathetic system: – the ganglion is near the spinal cord short pre-ganglionic fibres long post-ganglionic fibres In the parasympathetic system – the ganglion is close to or in the effector long pre-ganglionic fibre short post-ganglionic fibre

14. The sympathetic and parasympathetic systems have opposing or antagonistic actions – one system causes a muscle to contract – other causes it to relax Generally – sympathetic system stimulates effectors – parasympathetic system inhibits them The balance between the two systems is what regulates the involuntary activities of glands and organs. Note: With training you can control some of the activities of the autonomic nervous system – e.g. control of bladder and anal sphincters (hopefully!)

15. Label the diagram and give a brief explanatory note, using the following: – Sympathetic system – Parasympathetic system – Short pre-ganglionic neurone – Long pre-ganglionic neurone – Ganglion near the CNS – Ganglion near effector – Short post-ganglionic neurone – Long post-ganglionic neurone – Many post-ganglionic fibres (widespread effects) – Few post-ganglionic fibres (localised effects) – Noradrenaline released – Acetyl choline released

16. Effector e.g. heart muscle of bronchioles muscle of iris anal and bladder sphincters hair erector muscles CNS

17. Short post-ganglionic fibre supplies the effector Ganglion close to or in the effector Sympathetic nervous systemParasympathetic nervous system Ganglion close to CNS Long post-ganglionic fibre supplies the effector Short pre-ganglionic fibres Effector e.g. heart muscle of bronchioles muscle of iris anal and bladder sphincters hair erector muscles CNS Long pre-ganglionic fibres Nerve endings release acetyl choline (ACh) which generally has an inhibitory effect Nerve endings release noradrenaline which generally has a stimulatory effect

18. Examine the diagram which summarises some of the key features of the autonomic nervous system (next slide) and then answer the questions. Q. What is the benefit of the opposing or antagonistic actions of the sympathetic and parasympathetic systems? Q. Why does sympathetic stimulation ‘mimic’ action of adrenaline and the fright response? You might like to consider specific examples, e.g. the effect on the heart/vascular system; respiratory system; digestive system and liver; and the eye. Q. How is the stimulatory effect of the sympathetic system reinforced by the adrenals?

20. Effect of stimulation by system Sympathetic system Stress or activity Parasympathetic system Sleep or relaxation Dilates pupilConstricts pupil Inhibits saliva flowStimulate saliva Dilates bronchiConstricts bronchi Increase heartbeatReduce heart rate Contract pyloric sphincter and inhibits digestion Relaxes pyloric sphincter and stimulate digestion Stimulates glucose production Stimulates digestive secretion Release adrenalineLess adrenaline Contract anal sphincterRelax anal sphincter Constriction of vessels to erectile tissue, i.e. reduce sexual arousal Dilation of vessels to erectile tissue, i.e. increase sexual arousal Inhibits bladder contraction and urination Contracts the bladder and brings about urination

21. Q. What is the benefit of the opposing or antagonistic actions of the sympathetic and parasympathetic systems? Action of one system opposes the other Brings a quicker end to an effect Improves control over the conditions

22. Q. Why does sympathetic stimulation ‘mimic’ action of adrenaline and the fright response? You might like to consider specific examples, e.g. the effect on the heart /vascular system; respiratory system; digestive system and liver; and the eye. Adrenaline is a hormone whilst noradrenaline is a neurotransmitter. – structure is almost identical – can fit into the same receptors... hence – stimulate cardiac output (heartbeat and stroke volume) – dilate bronchioles – inhibit digestion and stimulate production of glucose by liver – dilates pupils

23. Q. How is the stimulatory effect of the sympathetic system reinforced by the adrenals? When the sympathetic system is stimulated, the adrenals are also affected. – Adrenals release adrenaline which enters the blood stream. – Adrenaline is taken to organs where they have the same effect as sympathetic stimulation.