•There are various type of the receptor cells. They are classified according to their sensitivity to different physical stimuli.
•For example chemical receptors only are stimulated by chemical stimuli.
•Photoreceptors are stimulated by light
•Mechanoreceptor by mechanical stimuli
•Baroreceptor by pressure
•Mechanical receptors are two type: phasic receptor (Paccini corpuscle), tonic mechanoreceptor (Strech receptor on the wall of urinary blood).
•Phasic receptor generate action potential only at the begining of stimuli, but tonic receptor is stimulated continously in the presence of stimuli.
•Photoreceptor found in the retina of eye.
•Baroreceptor found in the wall of blood vessel, they are free nerve ending
•Pain receptor is also free nerve ending and are stimulated chemical mediators relased from damaged cell.
•Chemoreceptors are found in tongue, olfactory nasal region.
•Receptors are localized in certain region of the body. Every receptor can be stimulated by the stimuli applied to region that they are localized.
•Information from around of the body are coded to the central nerveous system by the frequency of action potential.
•Olfactory stimuli is coded by the action potential frequency, since all receptor cell in olfactory region have more than one receptor molecule for different oder stimulant.
Intensity of pressure is also coded by action potential frequency
Receptor or Sensory Cell
Anatomy of Vertebrate Nervous Systhem
•Nervous system of animals examined in two region
•Peripheral nervous system; sensory neurons, afferent and efferent nerves and ganglia
•Central Nervous system; Spinal cord and brain
•Somatic afferents and efferents innervate somatic organs that are voluntarily controlled.
•Autonomic afferents and efferents innervate autonomic organs such as heart and digestive channal.
•Cranial nerves innervate usually the muscle and gland of head. They originate from brain stem
•Sensory or receptor cells are stimulated by physical stimuli and localized in various sensory region of the body.
•Environmental information is only recieved by receptor cell or sometimes free afferent nerve endings
Peripheral nervous sytem
•Peripheral nervous sytem comprise peripheral nerves; afferent and efferent, recepors or sensory cell, and autonomic ganglia.
•Afferent nerves carry impulses from sensory cell to the spinal cord or brain.
•Efferent nerves carry impulses from spinal cord or brain to the effector organs (Muscle etc.).
•There are two kind of afferent nerves; somatic, visceral.
•Afferent nerves enter into the cord dorsally, efferent nerves leave the cord ventrally.
•There are two kind of afferent and efferent system.
peripheral nervous system.
Neuron structure
Neurons all have same basic structure, a cell body with a number of dendrites and one long axon
Nerve Tissue and Nerve cells in Animals
•Nervous systhem is composed of various cells having different function.
•Neuron is basic cell type.
•Other cells are; astrocyte, microglial cells, oligodendrocytes, shwann cells, ependimal cells
•Neurons have two extension: long one is called as axon, short one dentrites.
•Neurons can be classified acording to type of extension: Unipolar, bipolar, Multipolar.
•The majority of invertebrates interneurons and motorneurons are unipolar.
•Astrocytes provide connection between capillaries and neurons.
•Oligodendrocyte make myelin sheeth
•Microglia are phagocytic, motile cells that engulf and destroy cellular debris and microbes.
•Glial Cells are three type: Astrocyte, oligodentrocyte, microglia.
•In the peripheral nervous system, myelin is formed by Schwann cells.
•Each Schwann cell associates with only one axon, when forming a myelinated internode.
Vertebrate Nervous System
•The organization of the vertebrate nervous system is different from invertebrates.
•Vertebrates have a well-organized hollow dorsal nervous system.
•The central nervous sytem inclued a brain and spinal cord.
•The peripheral nervous sytem comprise peripheral nerves extending from spinal cord and peripheral ganglia
Nervous System Generally Informations
Nervous sytem of human body; tasting, smelling, seeing, hearing, thinking, dreaming, breathing, heart beating, moving, running, sleeping, laughing, singing, remembering, feeling pain or pleasure, painting, writing all of these activites are depend on nervous system of our body.
you couldn't do any of these things without your central and peripheral nervous system.
so what is the nervous system?
answer : composed of your brain, your spinal cord, and an enormous network of nerves.
it's the control center for your entire body.
The brain uses information it receives from your nerves to coordinate all of your action,reaction
