Chapter 11 (MH) 13 (N) MH: 364 N: 406 Homeostasis Maintenance of a constant internal environment The nervous system collects informa6on about external condi6ons in rela6on to the bodies internal state. MH: 367 N: 408 Nervous system organiza6on Central Nervous System Peripheral Nervous System Spinal Brain cord Somatic Autonomic MH: 367 N: 408 1
Nervous system organiza6on Somatic Autonomic Sensory Motor Sympathetic Parasympathetic MH: 367 N: 408 Cells of the nervous system MH: 368 N: 409 Cells of the nervous system Nerves Neurons and glial cells organized into 6ssue Neurons The basic structural and func6onal unit of the nervous system Glial cells Nourish the neurons, remove their wastes, and defend against infec6on MH: 368 N: 409 2
Cells of the nervous system MH: 368 N: 410 Cells of the nervous system MH: 369 N: 410 Cells of the nervous system Sensory receptor Modified neurons that convert a physical s6mulus to a nerve impulse Sensory neuron Transmits impulse to the CNS Interneuron Found in the CNS, processes incoming sensory informa6on, relays outgoing motor informa6on MH: 369 N: 410 3
Cells of the nervous system Motor neuron Transmits impulse from the CNS to effector cells (muscles and glands) Effector cell Converts nerve impulse to an ac6vity MH: 369 N: 410 Reflex arc MH: 369 N: 411 Reflex arc Uses fewer neurons for faster response 6me Does not depend on the sensory interpreta6on and response centres of the brain MH: 370 N: 412 4
The structure of a neuron MH: 372 N: 409 The nerve impulse Electrical nature confirmed on a squid s axon Different from electricity in a wire: Conduc6on is slower Poten6al difference atained by ion concentra6ons Impulse does not degrade MH: 373 N: 415 Res6ng membrane poten6al MH: 373 N: 415 5
Membrane poten6al Sodium ions on the outside gives the extracellular surface a posi6ve charge Compara6vely fewer potassium ions combined with chlorine ions and nega6vely charged proteins gives the cytoplasmic surface a nega6ve charge The separa6on of charges keeps the cell polarized The res6ng membrane poten6al is - 70 mv MH: 374 N: 416 Ac6on poten6al MH: 377 N: 417 Ac6on poten6al MH: 376 N: 417 6
Ac6on poten6al MH: 376 N: 417 Ac6on poten6al The poten6al reaches +35 mv causes the sodium ion gates to close and the potassium ion gates to open. Potassium ions diffuse out Repolariza6on Membrane poten6al changes back Refractory period A^er the ini6al depolariza6on, the membrane cannot be s6mulated again un6l normal res6ng poten6al is achieved MH: 376 N: 417 Ac6on poten6al Image reference: https://eapbiofield.wikispaces.com/file/view/0645.jpg MH: 376 N: 417 7
Nerve impulse MH: 378 N: 418 Nerve impulse During depolariza6on, sodium ions diffuse into and ALONG the axon Depolariza6on at a neighbouring node breaches the threshold causing another ac6on poten6al Saltatory conduc6on: When ac6on poten6als jump from one node to the next MH: 378 N: 418 The synapse MH: 379 N: 420 8
The synapse The 20 nm space (cle^) between the axon terminal of one neuron, and the dendrite of the next. NeurotransmiTers are released from the presynap6c membrane, diffuse across the synap6c cle^, and bind to protein receptors on the postsynap6c membrane. MH: 379 N: 420 The synapse Excitory neurotransmiters open sodium ion channels on the postsynap6c membrane propaga6ng the ac6on poten6al Inhibitory neurotransmiters open potassium ion channels to hyperpolarize the postsynap6c membrane The cell body integrates signals from mul6ple presynap6c neurons at once MH: 379 N: 420 Neuromuscular junc6on MH: 380 N: 420 9
Neurotoxins Image:http://www.morphographic.com/Sphere/Images/Fugu12a-pequena.jpg Image:http://zoltantakacs.com/zt/im/scan/reptiles/15823-120.jpg MH: 382 N: 421 Reuptake MH: 383 N: 422 NeurotransmiTers The fate of neurotransmiters: ATach to postsynap6c membrane receptors Destroyed by synap6c enzymes Acetylcholine excitory neurotransmiter for muscle contrac6on Cholinesterase synap6c enzyme that breaks down acetylcholine ATach to presynap6c receptors for reuptake Diffuse out of the synap6c cle^ MH: 383 N: 422 10
Endorphins Image:http://media1.break.com/dnet/media/2008/4/04apr19-oh-ouch.jpg Natural painkillers in brain synapses 382 The brain MH: 387 N: 426 The meninges MH: 388 N: 426 11
Blood-brain barrier Special capillaries with tightly fused cells Transport mechanisms permit diffusion of glucose and oxygen Lipid bilayer can allow in lipid-soluble chemicals MH: 388 N: 426 The cerebrum Myelinated axons (white mater) on the inside Unmyelinated axons (grey mater) on the outside (aka cerebral cortex) Fissured to increase surface area MH: 389 N: 427 The cerebrum MH: 389 N: 427 12
The cerebrum Corpus collosum the nerve tract that joins the two hemispheres. MH: 390 N: 428 The cerebrum MH: 390 N: 428 The cerebrum Occipital lobe receives and analyzes visual informa6on Temporal lobes visual and mainly auditory and processing Parietal lobes receives and processes sensory informa6on from the skin MH: 391 N: 428 13
The cerebrum http://www.parismarashi.com/ppm/wp-content/uploads/2007/10/sensory_homunculus.jpg 390 The cerebrum Occipital lobe receives and analyzes visual informa6on Temporal lobes visual and mainly auditory and processing Parietal lobes receives and processes sensory informa6on from the skin Frontal lobes associated with reasoning, language, memory, personality, voluntary motor func6on MH: 391 N: 428 14
Hindbrain Cerebellum controls limb movements, balance, muscle tone Pons relays informa6on between the cerebellum and the medulla oblongata Medulla oblongata controls involuntary muscle ac6on and coordina6ng centre of the autonomic nervous system MH: 391 N: 429 Midbrain Receives specific sensory informa6on and connects the hindbrain to the forebrain MH: 391 N: 429 Forebrain Thalamus relay sta6on direc6ng sensory informa6on to appropriate parts of the cerebrum Hypothalamus maintains the bulk of the body s internal equilibrium, and is the interface between the nervous and endocrine systems. MH: 391 N: 428 15
Peripheral nervous system Somatic Sensory Motor MH: 396 N: 433 Soma6c nervous system MH: 397 N: 434 Peripheral nervous system Somatic Autonomic Sensory Motor Sympathetic Parasympathetic MH: 397 N: 434 16
Autonomic nervous system Controls glandular secre6ons, the cardiac muscle and smooth muscles Controlled by the hypothalamus and medulla oblongata Comprises two opposing subsystems: sympathe6c and parasympathe6c MH: 397 N: 434 MH: 398 N: 434 Sympathe6c nervous system Ac6vated in the fight or flight response Excitory neurotransmiter released is norepinephrine S6mulates organs necessary for emergency situa6ons Decreases some organ s ac6vi6es during stressful situa6ons MH: 398 N: 435 17
Parasympathe6c Ac6vated when the body is calm and at rest ( rest and digest response) Acetylcholine s6mulates the organ responses S6mulates organs necessary to counter the sympathe6c nervous system MH: 398 N: 435 Key terms Homeostasis Nervous System Central Nervous System Neurons Glial Cells Nerves Reflex Arcs Dendrites Cell Body Axon Myelin Sheath Schwann Cells Membrane Potential Resting Membrane Potential Polarization Sodium/Potassium Exchange Pump Depolarization Nodes of Ranvier Action Potential Threshold Potential Repolarization Refractory Period Synapse Neuromuscular Junction Neurotransmitters Acetylcholine Cholinesterase MH: 366 N: 440 18