COORDINATION AND RESPONS

1. COORDINATION AND RESPONS

2. Coordination : coordination is the way in which receptors detect stimuli, and then nerve impulses are sent to the effectors to respons . coordination is carried out through the activities of nervous system and the endocrine system

3. nervous coordination is brought about by transmission of nerve impulses between receptors and effectors through nerve fibres endocrine coordination is brought about by hormones secreted from endocrine glands

4. nervous system of humans consists of central nervous system(CNS) and peripheral nervous system • CNS includes brain and spinal cord and the peripheral nervous system includes cranial nerves and spinal nerves

5. spinal cord brain Central Nervous System • includes brain and spinal cord in higher animal

7. Structure of Neurones • neurones make up nervous system in human • each neurone has a cell body and nerve fibres • cell body is a mass of cytoplasm with nucleus inside and it is called ganglion • nerve fibres are cytoplasmic processes of neurones and there are two types, one is dendron and the other is axon

8. skull vertebral column Protection of Central Nervous System • brain is enclosed in cranium of skull while spinal cord is enclosed in vertebral column • CNS is also enveloped in three layers of meninges and between the inner two layers is a cavity filled with cerebrospinal fluid

9. dendron transmits nerve impulses towards cell body while axon transmits nerve impulses away from cell body • nerve fibres may be protected by a fatty layer which serves as an insulator to prevent the spread of nerve impulses and help to speed up the rate of transmission

10. Peripherel nervous system

12. Types of Neurones • there are three types of neurones: afferent neurone, efferent neurone and inter neurone

13. cytoplasm direction of nerve impulses dendron nucleus cell membrane axon nucleus of cell which makes the myelin sheath Efferent neuron

14. - afferent neurone: transmits nerve impulses from central nervous system to effectors.

15. - afferent neurone: transmits nerve impulses from receptor to the central nervous system

16. Did you know? The human brain contains approximately 100 billion neurons Neurons are the longest and oldest cells in the body!

17. - inter neurone: connects the afferent neurone to the efferent neurone and also the neurones in the central nervous system

24. neurone nerve fibre Nerve • bundles of nerve fibres • usually myelinated and surrounded by a sheath of white connective tissue nerve

28. impulses do not jump from one fibre to another because of the presence of fatty substance in nerve • in sensory nerves, there may be ganglia where the cell bodies are situated • nerve fibres found inside the central nervous system do not have insulating fatty layers

29. neurone

30. Nerve Impulses Transmitted in Nerve Fibre • stimulation of the receptors may initiate nerve impulses and this follows “All-Or-None” principle

31. ALL impulses are alike regardless of the site from which they are fired off • impulses travel very quickly in one direction from dendron to axon of the same neurone

32. Nerve Impulses Transmitted across the Synapse • neurons are not in direct contact with each other. A small gap called synapse exist between two neurons • impulses need to jump across the synapse as to travel from one end of axon to dendron of another neuron

38. Synapses

39. synapse • ending of axon secretes a chemical which diffuses into synapse and stimulates the next neurone to pass on the impulse

40. presence of synapse enables nerve impulses to travel only from axon of one neuron to dendron of another neuron • it also allows higher level of nervous coordination as one neuron can be linked with a number of other neurons

41. Functions of Cerebrospinal Fluid • act as a cushion for absorbing external shock • nourish neurones inside as it enables diffusion of oxygen and food to the nerve cells • it also filled up cavity called ventricle in brain and in the central canal of spinal cord • it also helps in preventing collapse of CNS

42. Brain

43. External view of the brain

44. cerebrum medulla oblongata cerebellum Parts of Brain brain is divided into three main parts: cerebrum, cerebellum and medulla oblongata

45. Brain--Cerebrum • lies in the front part of brain and divided into two cerebral hemispheres connected by nerve fibres • surface of cerebrum is highly folded to increase area for coordination • centre of thinking, memory, reasoning, imagination, learning and voluntary actions

46. motor area association area sensory area • divided into three functional areas - sensory areas: receive impulses from receptors - motor areas: send out impulses to effectors - association area: correlates impulses from different receptors and assists in producing appropriate responses

47. Brain--Cerebellum • lies below the back part of cerebrum • centre for muscular coordination and involved in control of body balance • damage of cerebellum will lead to a loss of ability to maintain balance

48. Brainstem • Connects the brain and spinal cord • Includes medulla oblongata and pons

50. Brain--Medulla Oblongata • lies at the floor of cerebellum • reflex centre for controlling involuntary actions such as breathing, heartbeat, swallowing, coughing, sneezing and salivation • damage of medulla oblongata may lead to death