Presentation on theme: "The Human Nervous System"— Presentation transcript:
1The Human Nervous System A simple reflex arc is the simplest response to a stimuli. There whole arc only involves 3 sections of a nerve pathway. The the response is automatic and very rapid, the reason that it is so fast is because the information does not have to travel or be processed by the brain. The three neurons which normally make up the pathway are(1) sensory neuron(2) relay neuron(3) motor neuronThis is how it worksStimulus sensor coordinator effector responseTouch pain receptor CNS muscle movement
2ANS The 2 DivisionssympatheticparasympatheticPupil dilation tear production not affectedPupil constricts tear production stimulatedHeart rate increaseHeart rate decreaseBronchi dilateBronchi constrictGastric+pancreatic activity inhibitedGastric+pancreatic activity stimulatedGlycogen converted into glucoseGlucose converted into glycogenRelease of adrenaline+noradrenalineRelease of adrenaline+noradrenaline ceasePeristalsis inhibitedPeristalsis stimulatedBladder relaxesBladder constrictsThe roles of the sympathetic and parasympathetic nervous system are opposing. Generally the sympathetic nervous system has a stimulatory affect and prepare the body for action while the parasympathetic system returns the body functions to normal.
3The autonomic nervous system and the pupil To operate well in different light conditions the eye must be able to control the amount of light entering the eye it does this by changing the diameter of the pupil. The changes in the size of the pupil are brought about by a reflex arc so it involves no conscious thought. The light receptors in the retina detect the intensity of the light (sensor). E.g too weak or too strong this information is then sent to the brain via the optic nerve(Sensory Neuron). Then impulses from the brain are transmitted to the iris muscles by the nerve fibres.
4Emptying of the bladder The human bladder can hold up to 800 cm3 of urine but what happens when its full? Stretch receptors in the bladder wall send a impulse to the CNS alerting it to the urgency the rely neuron send an impulse to the motor neuron which sends an impulse to the sphincter muscles to relax and we urinate. But not always as we humans have learnt hoe to control our sphincter muscles (potty training) so we can go when and where convenient.