Nervous system Reflex arc best way to start

Nervous system

Reflex arc – best way to start looking at nervous system

Nervous system This Photo by Unknown Author is licensed under CC BY-SA

Division of nervous system • Central nervous system – brain and spinal cord • Brain – non myelinated cells – looks grey hence grey matter. • Spinal cord – non-myelinated and myelinated • Peripheral nervous system – sensory and motor system – somatic nervous system and autonomic nervous system.

Somatic nervous system/Autonomic nervous system • Conduction of action potentials from CNS to effectors under voluntary controls ie kicking football • Rapid myelinated • Uses one single neurone • ANS – not voluntary, includes glands etc, at least two neurones. • Connected at small swellings called ganglia • Parasympathetic/sympathetic

Sympathetic nervous system • Prepares body for action • Leads out of CNS • Ganglia outside CNS • Short preganglia neurones • Long post ganglia neurons • Noradrenaline neurotransmitter • Increase heart rate, dilates pupils, increase ventilation, reduces digestive activity

Para sympathetic nervous system • Decreases body activity • Few neurones outside of CNS • Ganglia inside effector tissue • Long pre-ganglia neurones • Short post ganglia neurons • Acetylcholine neurotransmitter • decrease heart rate, constricts pupils, decreases ventilation, increases digestive activity

Sympathetic nervous system This Photo by Unknown Author is licensed under CC BY-SA-NC

Sensory nervous system

Brain • Found in skull • Top of spinal cord • Medulla oblongata – automatic responses • Cerebellum – co-ordinates movement and balance • Cerebral cortex – largest parts – higher thought processes. This Photo by Unknown Author is licensed under CC BY-SA

Cerebrum • Two central hemisphere – corpus callosum – outer layer of cells called cerebral cortex. • Conscious thought, actions, emotional responses, intelligence etc. • Sensory areas – action potential from sensory receptors • Association areas – compares sensory inputs with previous experience and judges an appropriate response. • Motor area – send action potential to muscle and glands. • Left hand sides control right hand side of body and vice versa.

Different areas of brain This Photo by Unknown Author is licensed under CC BY

Cerebellum • Half neurones in the brain • Balance and co-ordination • Sensory information – ie voluntary muscles • Body balance • Position of body when playing sports • Tension of muscles to use tools • Co-ordination contraction and relaxation of antagonistic skeletal muscles when walking and running.

Cerebellum This Photo by Unknown Author is licensed under CC BY-SA

Other key areas • Pituitary gland – anterior and posterior • Anterior – responds to releasing factors From hypothalamus – act on hypothalamus. Posterior – linked to hypothalamus via Neurosecretory cells. Example ADH. Hypothalamus - changes in body temp, and from skin receptors in skin. Osmoregulation – monitor water potential in blood

Hypothalamus and pituitary gland This Photo by Unknown Author is licensed under CC BY-SA-NC

Medulla oblongata • Controls non skeletal muscles – sends out action potentials though autonomic nervous system • Cardiac centre – controls heart rate • Vasomotor centre – regulates circulation and blood pressure • Respiratory centre controls breathing and depth of breathing. Uses negative feedback.

Medulla oblongata This Photo by Unknown Author is licensed under CC BY