Nerve Cell & Skin - Basic for Physiotherapy 1 - Lecture Notes PDF

Nerve cell & skin Prof. Dr. Marwa G.A. Hegazy Dr. Heba Afifi Basic for physiotherapy 1 (Tutorial 4)  Learning outcomes:  Describe the different types of neurons, including sensory, motor, and interneurons.  Identify the different types of...

Nerve cell & skin Prof. Dr. Marwa G.A. Hegazy Dr. Heba Afifi Basic for physiotherapy 1 (Tutorial 4)  Learning outcomes:  Describe the different types of neurons, including sensory, motor, and interneurons.  Identify the different types of glial cells, including astrocytes, oligodendrocytes, and microglia, and understand their roles in supporting and protecting neurons.  Understand the structure and function of the epidermis, and its role in protecting the body from external factors.  Understand the role of Langerhans cell in the epidermis, including their function in immune response. Basic for physiotherapy 1 (Lecture2)  Functions  Sensation – senses changes in the environment: internal and external  Integration – interprets the changes (stimulus)  Response – initiates a response through: muscle contraction or glandular secretion Cells of Nervous System Neurons or nerve cells Receive stimuli and transmit action potentials Organization Cell body or soma Dendrites: Input Axons: Output Neuroglia or glial cells Support and protect neurons: hold them in place; to supply nutrients to neurons; to insulate neurons electrically; to destroy pathogens and remove dead neuron. Nerve cell (Neuron) Structural and functional unit of the nervous system Basic for physiotherapy 1 (Lecture2)  Histological structure 1)Cell body -Nucleus : pale , large, spherical -Cytoplasm: ▪ rER and ribosomes (Nissil granules) ▪ G.A ▪ Mitochondria scattered ▪ No centrioles ▪ Microtubules &Neurofilaments Basic for physiotherapy 1 (Tutorial 4)  2)processes -Dendrites: Multiple, carry stimulus to neuron -Axon: Single, carry stimulus away from neuron Basic for physiotherapy 1 (Tutorial 5) 3) Myelin Sheath A white, multi layered, fatty covering for some nerve processes. Arranged in segments, separated by Nodes of Ranvier (enables salutatory conduction). Insulation of nerve process, Increased speed of conduction Neurilemma – outer layer of myelin sheath – essential for regeneration Basic for physiotherapy 1 (Lecture2)  Types of Neurons  Functional classification  Sensory or afferent: Action potentials toward CNS  Motor or efferent: Action potentials away from CNS  Interneurons or association neurons: within CNS from one neuron to another  Types of Neurons Structural Classification − Multipolar: many extensions from the cell body, common type − Bipolar: one axon and one dendrite, only found in eye, ear & nose − Unipolar (pseudounipolar) : have a short single process leaving the cell body − Anaxonic : no anatomical clues to determine axons from dendrites, functions unknown  Glial cells (Neuroglia) ❖10 times more abundant than neurons ❖Smaller than neurons ❖Surround the cell bodies and processes Basic for physiotherapy 1 (Tutorial 5)  Neuroglia of CNS  Astrocytes  Abundant, star-shaped cells  Regulate extracellular brain fluid composition  Promote tight junctions to form blood-brain barrier  Ependymal Cells  Line brain ventricles and spinal cord central canal  Help form choroid plexuses that secrete CSF  Neuroglia of CNS  Microglia  Spider-like macrophages  Dispose of debris  Oligodendrocytes  Form myelin sheaths if surround axon  Neuroglia of PNS  Schwann cells or neurolemmocytes  Wrap around portion of only one axon to form myelin sheath  Satellite cells  Surround neuron cell bodies in ganglia, provide support and nutrients  Skin ❖ A protective covering of the whole body ❖ Heaviest and largest organ Basic for physiotherapy 1 (Tutorial 5 )  Structure 1- Epidermis : keratinized stratified squamous epithelium 2- Dermis :thick C.T layer under epidermis Basic for physiotherapy 1 (Tutorial 5)  Epidermis ❖Stratum basale: single layer of columnar cells (mitotic figures) ❖stratum spinousm :4-8 layers of polyhedral cells &rounded nuclei ❖Stratum granulosum: 3-5 layers of flat cells &flat nuclei ❖Stratum lucidum: clear homogenous layer ❖Stratum corneum (Keratin): thick acidophilic layer (dead cells) Basic for physiotherapy 1 (Lecture2)  Langerhan’s cells ❖ Non keratinocytes ❖ Stellate shaped cells found between cells of stratum spinousm ❖ No melanin pigments, no keratin ❖ Skin immunity (antigen presenting cells ) Basic for physiotherapy 1 (Tutorial 5)  Types of skin Thick skin Thin skin Sites Palms and soles Rest of the body Tips &sides of fingers and toes Epidermis Thicker (thick keratin layer) Thinner (thin keratin layer) Appandeges hair present absent Sebaceous glands Arrector pili muscle Sweat gland More Less Basic for physiotherapy 1 (Tutorial 5) Basic for physiotherapy 1 (Tutorial 5 )  Keratinocytes Keratinocytes are the main cellular components of the epidermis. They release very little extracellular matrix so that the plasma membrane of adjoining keratinocytes are very close to one another. Basic for physiotherapy 1 (Lecture2)  Function of Keratinocytes The primary function of keratinocytes is the formation of a barrier against environmental damage by heat, UV radiation, dehydration, pathogenic bacteria, fungi, parasites, and viruses. Pathogens invading the upper layers of the epidermis can cause keratinocytes to produce proinflammatory mediators, particularly chemokines which attract monocytes, natural killer cells, T-lymphocytes, and dendritic cells to the site of pathogen invasion. Basic for physiotherapy 1 (Lecture2) Basic for physiotherapy 1 (Tutorial 5)  Mescher AL (2018): Junqueira’s basic Histology Text and Atlas 14th edition Basic for physiotherapy 1 (Tutorial)