8. ORGANISATION OF THE NERVOUS SYSTEM Links receptors & effectors to CNS : relays signals between CNS & rest of body HUMAN NERVOUS SYSTEM CENTRAL NERVOUS SYSTEM [CNS] PERIPHERAL NERVOUS SYSTEM [PNS] BRAIN SPINAL CORD CRANIAL NERVES [12 pairs] SPINAL NERVES [31 pairs]
9.
10.
11.
12. AN OVERVIEW OF THE FUNCTIONS OF THE NERVOUS SYSTEM Sensory receptors detect stimuli from int. & ext. environments & initiate nerve impulses carrying information to CNS CNS processes & integrates information by analysing & storing some of it, & then make decisions to initiate suitable responses Motor commands from CNS transmitted to effectors [muscles or glands] to carry out responses 1 3 2
13. THE HUMAN BRAIN HUMAN BRAIN HYPOTHALAMUS THALAMUS MEDULLA OBLONGATA CEREBELLUM CEREBRUM
14. THE HUMAN BRAIN SKULL MEDULLA OBLONGATA CEREBELLUM CEREBRUM VERTEBRA SPINAL CORD PITUITARY GLAND THALAMUS HYPOTHALAMUS
17. Medulla oblongata Pons Brainstem Cerebellum Cerebrum Thalamus Hypothalamus STRUCTURE OF THE BRAIN
18.
19.
20.
21.
22.
23. THE SPINAL CORD AND ITS MAIN FUNCTIONS INTERNEURONE DORSAL ROOT DORSAL ROOT GANGLION AFFERENT NEURONE RECEPTOR EFFECTOR EFFERENT NEURONE CENTRAL CANAL GREY MATTER [ contains cell bodies] SPINAL NERVE WHITE MATTER {contains myelin-coated axons] VENTRAL ROOT CROSS SECTION OF THE SPINAL CORD
24. Spinal cord in cross section showing the position of the vertebral column
25. CROSS-SECTION OF THE SPINAL CORD CENTRAL CANAL DORSAL ROOT GANGLION WHITE MATTER GREY MATTER VENTRAL ROOT OF SPINAL NERVE SPINAL NERVE DORSAL ROOT 0F SPINAL NERVE
26.
27. The spinal nerves emerge from the spinal cord through two short branches or roots. (a) The dorsal root contains the axons of the afferent neurones which conduct nerve impulses from the sensory receptors to the spinal cord. (b) The cell bodies of the afferent neurones are clustered in the dorsal root ganglion (c) The ventral root contains the axons of the efferent neurones which conduct nerve impulses away from the spinal cord to the effectors. (d) The dorsal and ventral roots join to form a spinal nerve. FUNCTION : The spinal cord (a) processes certain types of sensory information and sends out responses via the efferent neurones. (b) contains neurones that convey signals to and from the brain, (c) contains the neural pathway for reflexes
35. The transmission pathway of information Reception of stimuli by receptors Response by the effectors From the CNS to the effectors Integration & interpretation by the central nervous system From receptors to the central nervous system 1 5 4 3 2
36. Afferent neurone Efferent neurone Interneurone 1 5 4 3 2 6 Receptors in the ear Muscles in the arm Receptors in the ear pick up the ringing of the doorbell. The nerve impulses pass from the afferent neurones to the interneurones in the brain The receptors trigger nerve impulses in the afferent neurones. From the interneurones, nerve impulses are transmitted to the efferent neurones and then to the muscles The brain interprets the nerve impulses from many interneurones that the doorbell is ringing. The brain also decides that the door should be opened The muscles in the arm carry out the response and open the door 1 2 3 4 5 6 The transmission pathway of information
37. The transmission of nerve impulses along the three types of neurones Synaptic terminal dendrites axon dendrite Cell body receptor in skin axon myelin sheath Synaptic terminal on muscle fibre Cell body Cell body axon myelin sheath Efferent neurone synaptic terminal Afferent neurone Interneurone
38. DIFFERENCE BETWEEN STRUCTURE OF AFFERENT NEURONE & EFFERENT NEURONE Ends with effector Begins with receptor Cell body at the end of the neurone Cell body at the side of the neurone [not at the end] Short dendrite, long axon Long dendrite, short axon EFFERENT NEURONE AFFERENT NEURONE
44. Axon Synaptic cleft mitochondria Presynaptic membrane Postsynaptic membrane [plasma membrane of the cell body or dendrite of a neighbouring neurone] Receptor Dendrite Synaptic vesicle Synaptic terminal Direction of transmission of nerves impulses TRANSMISSION OF CHEMICAL SIGNALS ACROSS THE SYNAPSE When an electrical impulse reaches the presynaptic membrane, it triggers the synaptic vesicles to release neurotransmitters into the synaptic cleft The neurotransmitters diffuse across the synaptic cleft and bind to specific proteins or receptors which are attached to the postsynaptic membrane The binding of the neurotransmitters to the receptors leads to the generation of new electrical signal
45.
46.
47. VOLUNTARY ACTION & INVOLUNTARY ACTION TYPES OF NERVOUS ACTIONS VOLUNTARY ACTION INVOLUNTARY ACTION Involves skeletal muscles [eg raising your hand to answer a question] Involves skeletal muscles [eg knee jerk] Involves smooth muscles, cardiac muscles or glands [eg normal blood pressure]
48.
49. RECEPTOR EFFECTOR SENSORY (AFFERENT) NEURONE MOTOR (EFFERENT) NEURONE I NTERNEURONE STIMULUS RESPONSE CEREBRUM THE PATHWAY OF TRANSMISSION OF INFORMATION IN VOLUNTARY ACTION
50.
51.
52. A reflex arc involving 3 types of neurones and the spinal cord NB: brain not involved Afferent neurone 4.Efferent neurone
53. Grey The knee-jerk ---------A reflex arc involving 2 types of neurones and the spinal cord 1 2 3 4 afferent efferent
54. The rubber hammer hits a tendon that connects the quadriceps muscle in the thigh to a bone in the lower leg As the rubber hammer strikes the knee, the force stretches the quadriceps muscles and stimulates the stretch receptors in the muscles, triggering nerve impulses Afferent neurones transmit the information to the efferent neurones in the spinal cord The efferent neurones transmit this information to the quadriceps muscle, and the muscle contracts, jerking the leg forward The knee-jerk ---------A reflex arc involving 2 types of neurones and the spinal cord 1 2 3 4
