15
Anatomy (Subject) / Anatomy IV (Lesson)
Advertisement
- Structure Nervous system 1. Central nervous system (CNS) - Brain and spinal cord 2. Peripheral nervous system (PNS) a) Cranial nerves: 12 pairs arise from the brain b) Spinal nerves: 31 pairs arise from the spinal cord
- SNS and ANS 1. Somatic nervous system - voluntary movements --> skeletal muscles 2. Anatomous nervous system - bodily function (digestion, breathing), unvoluntary --> parasymphatic and symphatic part
- Sorts of Neurons (3) 1. Multipolar neuron - 1 axon, multiple dendrites --> common 2. Bipolar neuron - 2 processes (1 dendrite and 1 axon) --> hearing, sight, smell 3. Pseudounipolar - one short process, 1 axon, 1 dendrite
- Reflex arc (Structure) Receptor (stimulus) --> Sensory neuron (afferent) --> Integration centre (synapse, sometimes interneuron) --> Motor neuron (efferent) --> Effector (neuromuscular junction of muscle)
- Rami (2) 1. Dorsal rami - only supply a small area of skin and muscle of the back of the body segmentally 2. Ventral rami - supply the trunk segmentally and the limbs as plexuses
- Dermatomes + Myotomes 1. Dermatome - area of skin innervated by a single spinal nerve 2. Myotome - portion of muscle innervated by a single spinal nerve
- Elements of nervous tissue 1. Neurons (perikaryon, dendrites, axon) 2. Support cells (CNS - neuroglia; PNS - Schwann cells and satellite cells)
- Neurons Structure 1. Cell body/soma/perikaryon - large central nucleous with nucleolus; Nissl bodies, mitochondria, vesicles, microtubules & neurofilaments, Golgi apparatus 2. Cell processes - dendrites and axon
- Def. Synapse "Communication between two neurons or between neurons and effector cells"
- Neuroglia (4) + morphology + function 1. Astrocyte - stellate cells with multiple processes - processes envelop blood vessels and axons and regulate the neuronal microenvironment; repair; enforcement of blood-brain barrier 2. Oligodendrocyte - small round cells with multiple processes - processes envelop segments of multiple axons and myelinate them 3. Microglial cell - smal oval cells with elongated nuclei and few processes - defence cells (phagocytosis) 4. Ependymal cell - simple cuboidal cells with cilia and microvilli lining the ventricles of the brain and spinal cord - synthesise, secrete and absorb CSF and propel the CSF within the CNS
- Advertisement
- Support cells (PNS) 1. Schwann cells - synthesise myelin by wrapping around axon forming myelin sheaths
- Characteristics Myelin - insulates the axon and thus increases the conduction velocity
- Demyelination and consequences - neurodegenerative autoimmune diseases demyelinise the axon (MS, Guillain-Barre syndrom,..) - loss/difficulties in vision, odd sensation, weakness, cognitive disruption, loss of dexterity and coordination
- Microanatomical structure of the CNS 1. Grey matter - perikarya, dendrites, neuroglia, prox. unmyelinated axons 2. White matter - myelinated axons, neuroglia
- Microanatomical structure PNS 1. Peripheral nerves - outside the brain and spinal cord - Spinal nerves (Epineurium) --> Fascicles (Perineurium) --> Nerve fibres (Endoneurium) 2. Ganglia - collection of cell bodies outside the CNS (e.g. dorsal root ganglion) 3. Nerve endings a) Free nerve endings - lose myelin sheath (next to epidermal cells in skin) b) Encapsulated - Pacinian corpuscle and Meissner's corpuscle (both in skin) c) Muscle spindle - skeletal muscle