* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Spinal Cord/ Reflex Action mainly
Aging brain wikipedia , lookup
Metastability in the brain wikipedia , lookup
Mirror neuron wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Embodied language processing wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Endocannabinoid system wikipedia , lookup
Neural engineering wikipedia , lookup
Central pattern generator wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Single-unit recording wikipedia , lookup
End-plate potential wikipedia , lookup
Neuroregeneration wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Development of the nervous system wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Synaptic gating wikipedia , lookup
Biological neuron model wikipedia , lookup
Synaptogenesis wikipedia , lookup
Nervous system network models wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Neuroanatomy wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Human Responses 2 Nervous system Compared to Endocrine System (hormones) Spinal Cord Reflex action SYNPASE 2 Synapse—region where two neurons come into close contact. Synaptic cleft—the gap between two neurons, bridged by chemicals (neurotransmitters). SYNAPSE Neurotransmitter —chemical released across a synaptic cleft to carry a signal from one neuron to another e.g. acetylcholine 3 Sequence of events SYNAPSE 1. Impulse moves along neuron as ions move in/out of neuron 2. impulse arrives at synpatic knob 4 3. Neurotransmitter vesicles move to edge of syn.knob 4. Neurotransmitter chemical released 4 4. Neurotransmitter chemical crosses synaptic cleft by diffusion 5. Neurotransmitter chemical lands on receptors on next neuron 6. Impulse sent along next neuron 7. The neurotransmitter chemical is then inactivated by enzymes &reabsorbed by presynaptic neuron – makes new neurotranmitter chemical to clear receptor sites for next impulse SYNAPSE 5 LEARNING CHECK • Distinguish between synapse and synaptic cleft. • What are neurotransmitter chemicals? • What are neurotransmitter vesicles? • What would happen if there were no gaps between neurons? • What is the refractory period and why does it occur? 6 Spinal chord structure 7 31 pairs of Spinal nerves 8 Different view Bone 9 The spinal cord is well protected by the vertebrae, meninges (three membranes) and cerebrospinal fluid. Meninges not shown they are wrapped around here It transmits impulses to and from the brain and controls many reflex actions. This diagram not needed 10 A cross-section through the spinal cord shows a small central canal, filled with cerebrospinal fluid, surrounded by an area of grey matter, shaped somewhat like the letter H. Learn this diagram well 11 Grey matter contains cell bodies and dendrites (regions of a neuron that have no white myelin covering). Outside the grey matter, the spinal cord consists of white matter (containing mostly axons) – white due to myelin -fatty. 12 In humans, 31 pairs of spinal nerves branch off from the spinal cord. Each spinal nerve has a dorsal root and a ventral root. The dorsal root consists of nerve fibres carrying information into the spinal cord from the senses. The dorsal root ganglion is a swelling that consists of the cell bodies of the sensory neurons. hint – Dorsal / sensory/swelling 13 The ventral root consists of nerve fibres carrying information out from the spinal cord, to the muscles and glands. hint - Move out The cell bodies of the motor neurons are positioned within the grey matter of the cord. The spinal cord transmits impulses to and from the brain and controls many reflex actions. 14 Reflex action 15 Go to video clip OF REFLEX ACTION. 16 REFLEX ACTION --- The Reflex Arc A reflex action is a quick, automatic response to a particular stimulus. Interneuron 17 REFLEX ACTION --- The Reflex Arc Suppose you touch a hot flame….. Interneuron Pain Receptors detect the heat and send an impulse along the sensory neuron Which enters the dorsal root to the GREY matter of spinal 18 cord In the spinal cord, the sensory neuron synapses with the interneuron and this synapses with the motor neuron, An impulse is sent along the motor neuron, out the ventral root into muscles that respond by contracting and pulling your hand from the flame. Only now does the brain become aware of what has happened Interneuron 19 This response saves the body from injury. Interneuron The response is called a reflex action, as it does not involve conscious control, and is FAST predictable and automatic. Many of the activities of the body, such as breathing and keeping our balance, are regulated by reflex actions. 20 SUMMARY OF PATHWAY OF REFLEX ACTION. Pain receptor (skin) sensory neuron IN Through dorsal root and dorsal root ganglion TO Grey matter of spinal cord synpases with interneuron Synpases with motor neuron Impulse OUT via ventral root Muscle to carry out response (move hand or foot etc) Brain becomes aware of what has happened 21 Go to video clip OF REFLEX ACTION. 22 Nervous System Disorder Parkinson’s disease is a nervous system disorder, normally seen in older people, in which muscles become rigid and movement is slow and difficult, with persistent tremors [shaking]. It is caused by the brain reducing the normal amount of dopamine that it makes. There is at present no means of preventing it, but giving L-dopa (which the body changes into dopamine) can relieve the symptoms in many patients. 23 LEARNING CHECK • • • • • • • How is the spinal cord protected? Distinguish between grey and white matter. Distinguish between dorsal and ventral root What is meant by reflex action? Give some examples of reflex action> What is an interneuron? Distinguish between cell bodies and ganglions. • Give cause treatment symptoms of 24 parkinson’s disease Comparison of the endocrine and nervous systems - 1 Endocrine Cells involved Gland Message Chemical (Hormone) Carried by Blood Message sent to Cells throughout the body Received by Target organ 25 Comparison of the endocrine and nervous systems - 1 Endocrine Nervous Cells involved Gland Sense receptor Message Chemical (Hormone) Electrical(Impulse) Carried by Blood Nerve cell Message sent to Cells throughout the body A specific cell or tissue Received by Target organ Effector (muscle or 26 gland) Comparison of the endocrine and nervous systems -- 2 Endocrine Nervous Speed of transmission Usually slow Rapid Effects Can be widespread Localised usually Duration long-lasting (hours) Usually brief (seconds) 27 LEARNING CHECK • Co-ordination of an organism’s activities is carried out by what 2 body systems? • Distinguish between the CNS and PNS. • What is a neuron? • What is an impulse? • List the main differences between the endocrine and nervous systems. 28