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Case 4:Histology, image, Connective Tissue of Skeletal Muscle
The…
Case 4:Histology
Histology of the Blood VesselDescribe the basic structures of a Blood Vessel
- Except for smallest vessels, arteries and veins have 3 distinct features:
- Tunica Interna (or Tunica Intima)
- It is the innermost layer, and it is in direct contact with blood.
- It is made of Endothelial cells
- Tunica Media
- Tunica media is the middle layer
- It is made up of Smooth Muscle and Elastic Fibres
- Tunica Externa ( or Tunica Adventitia)
- Tunica externa is the outermost layer
- It is adjacent to the surrounding tissues
- Tunica (Coat or Tunic) refers to a distinct layer of the wall of a hollow structure such as a blood vessel.
General Structure of Blood VesselsOutline the different general structure of blood vessels
- Artery
- Thick outer wall (Tunica externa)
- Thick inner layer of Muscle (Tunica Media)
- Thin Tunica interna
- Narrow Central tube (Small Lumen)
- Vein
- Thin outer wall (Tunica externa)
- Thin inner layer of Muscle (Tunica Media)
- Thin Tunica interna
- Wide Central Tube (Large Lumen) which is a Collapsed Lumen
- Capillary
- Capillary is made up of one wall and the wall is one cell thick
Describe the components of each layer of the Blood Vessels
- Tunica Intima (interna)
- Thin inner layer that is in direct contact with Blood
- Composed of:
- Flat Squamous Endothelial Cells which lie on a Basement Membrane
- Below the Basement membrane is usually a thin layer of Loose Connective Tissue called the Sub-endothelial layer
- Internal Elastic Lamina is a sheet of Elastic Fibres with the window like openings - Looks like Swiss Cheese
- Openings facilitate diffusion between Tunica Intima and Tunica Media
- It is well defined in Muscular arteries only and indistinct in Veins
- Tunica Media
- Usually composed of Concentric sheets of Smooth Muscle Cells in between Elastic and Collagen Fibres
- This allows for changes in Diameter
- In the Tunica media, Collagen binds the Tunica media to inner and outer layers
- External elastic Lamina separates the Tunica media to the Tunica externa
- It is prominent in arteries and is similar to the Internal Elastic Lamina
- Tunica Externa (Adventitia)
- Tunica extern is the outer layer:
- Tends to merge to surrounding connective tissue and anchors vessels to adjacent tissue
- It is a connective tissue sheath
- In Arteries it contains Collagen and Elastic Fibres
- In Veins is contains Elastic Fibres and Smooth Muscle cells
- It is the most prominent layer in the Veins
Compare the Histological Features between the 3 Tunica Layers of the Arteries and Veins
ArteriesOutline the Function of the Arteries in relation to their structure
- Arteries carry blood away from the heart to the tissues
- Tunica Media is the thickest layer with Elastic and Collagen fibres
- The functional properties of arteries are Elasticity and Contractility
- Elasticity is due to the elastic tissue in all Tunica Layers but mostly in the Tunica media
- Elasticity allows arteries to accept blood under great pressure from contraction of the ventricles and send it on through the system
- Prevents arteries from collapsing
- Contractility is due to the smooth muscles in the Tunica Media
- Contractility allows arteries to increase or decrease Lumen size
- Elastic aorta and arteries stretch during ventricular contraction
- Elastic aorta and arteries recoil during ventricular relaxation
Types of ArteriesList the types of Arteries
- Large/Elastic/ Conducting Arteries
- Aorta, Pulmonary Trunk and their branches
- Medium/Muscular/Distributing arteries
- Coronary artery and Radial artery
- Small Arteries/Arterioles
Describe the functions of the different types of Arteries
- Large/ Elastic/ Conducting Arteries
- Tunica Media is the thickest layer with Smooth Muscle interspersed with many Elastic Sheets/Lamella and Collage Fibres
- Tunica Intima is thick and contains Endothelium and Connective Tissue
- Tunica Externa is thin and contain Elastic and Collagen fibres and Vasa Vasorum
- Receive main blood output, therefore they need to withstand High Systolic Pressure (Distend) and maintain adequate pressure during Diastole and to continue pumping blood.
- Muscular/ Medium/Distributing Arteries
- Tunica Media is the thickest layer with Smooth Muscle interspersed Elastic and Collage Fibres
- Tunica Intima is thin with a Prominent Internal Elastic Lamina that is usually folded
- Tunica externa is thin with a prominent External Elastic Lamina
- Thicker than the Tunica externa of the Elastic arteries
- As we move away heart, the artery diameter decreases but the Total Diameter of ALL arteries increases therefore, pressure falls.
- As a result, Muscular arteries have more Smooth Muscle than Elastin this is to allow for them to Regulate pressure
- Arterioles
- Tunica Media is the thickest layer with 2-3 layers of Smooth Muscle
- Tunica intima is mostly only Endothelium
- Tunica externa is minimal
- Internal Elastic lamina is present BUT External Elastic lamina is absent
- The main function of Arterioles is to redistribute blood flow to capillaries and to alter blood pressure by altering Peripheral Resistance to blood flow
- Arterioles can change diameter very drastically therefore affecting blood pressure and blood flow
CapillariesDescribe the structure and function of Capillaries
- Capillaries are the functional unit of the Cardiovascular System for the exchange of Gases, Nutrients, and Wastes between blood and tissues
- Capillaries are very small
- However, they have a Large Total Diameter therefore, Low Pressure and Flow Rate
- Capillaries only have a Tunica Intima with the thinnest walls composed of Endothelial Cells and Basement Membrane
- Capillaries form a network in virtually all body tissues
Types of CapillariesList the types of capillaries
- Continuous capillary
- Fenestrated capillary
- Sinusoid capillary
Outline the Blood flow through the Capillaries
- Capillaries form an extensive capillary network throughout the tissues and are found near almost every cell in the body
- Capillaries are controlled by Smooth Muscle Segments called Metarterioles - preferred channel through a Capillary bed
- Precapillary Sphincter closes the capillary bed temporarily to redistribute blood flow and control blood flow through capillaries in pulses
VeinsOutline the Function of the Vein in relation to their structure
- The Veins have Thinner Walls and a Large Collapsed Lumen
- Three layers in the veins are much less obvious
- Tunica externa is the thickest layer with many Vasa Vasorum
- Tunica media is thin with Smooth Muscles and Collagen Fibres
- Tunica intima is thin BUT there is NO Internal Elastic Lamina
- Veins are a low pressure system and are responsible for returning blood from the Capillary network to the Heart
- Blood is propelled forward by the Contraction of Smooth Muscles in the Veins and external compression by Skeletal Muscles
- Valves are essential for one way flow of blood
- Compared to Arteries, Veins have thinner walls and a larger Diameter Lumen
Types of VeinsList the types of Veins
- Venules
- Medium/Small Veins
- Large Veins
- Superior and Inferior vena cava
Describe the functions of the different types of Veins
- Venules
- Venules are very small veins
- Muscular Venules have:
- Tunica intima is thin with Endothelial cells and Connective Tissue
- Tunica media thin with one or two layers of smooth muscle
- Tunica externa is thin and identifiable
- Venules are responsible for the exchange of gases, nutrients, waste products between tissues and blood
- Medium/ Small Veins
- Tunica externa (Tunica adventitia) is the thickest layer with bundles of Elastic and Collagen Fibres
- Tunica media is a thin layer of Smooth Muscle and Connective Tissue
- Tunica intima is thin with a thin Endothelium layer and little Connective tissue
- Medium-sized Veins have Valves that are formed by the folding of Tunica Intima
- Medium/Small veins are responsible for collecting blood from smaller venous vessels
- Large Veins
- Tunica intima is thin and better developed BUT does not have Valves
- The Internal Elastic lamina is present in the Tunica Intima
- Tunica media is thin with Smooth Muscle, Collagen and Elastic fibres
- Tunica externa (Tunica adventitia) is thick and contains Vasa Vasorum with bundles of Smooth Muscles fibres
- Large veins are responsible for collecting blood from medium-sized veins and return it to the heart
Venous ValvesExplain why venous valves are important
- Venous Pressure is often not great enough to return blood to the heart
- Blood pressure in the Vein is so low that is cannot oppose the Force of Gravity
- Therefore, Medium-sized Veins of limbs have Valves
- Valves are formed by the folds of the Tunica Intima that project from the vessel and point in the direction of the Blood Flow
Outline the function of the Venous Valves
- Valves permit flow in one direction only and any movement that distorts or compresses a vein will push blood towards the heart
- Valve failure results in Varicose Veins
Muscular System
- Skeletal Muscles
List the functions of the Skeletal Muscles
- Produce skeletal movement
- Maintain body temperature
- Store nutrient reserves
Describe the structure of Skeletal Muscles and Skeletal Muscle Fibres(Cells)
- Skeletal Muscles Fibres have striations due to the uniform arrangement of Myofibrils
- Skeletal Muscle fibres are Straight, Cylindrical, Parallel and Non-Branching
- Skeletal muscle fibres (cells) have Multiple, Peripheral Nuclei
- Skeletal Muscle fibres do NOT have Discs
- There is an Endomysium between the individual Skeletal Muscle Fibres
Describe Skeletal Muscles according to Location, Muscle Control, Function and Speed of Contraction
- Skeletal muscles are located or attached to bones or skin
- Skeletal Muscles control is Voluntary
- Skeletal Muscles have the Fastest speed of Contraction
What do we identify when looking at the Slide of Skeletal Muscles ?
- Endomysium
- Multiple, Peripheral Nuclei
- Striations
- Individual muscle fibres
- Cardiac Muscles
List the functions of Cardiac Muscles
- Cardiac Muscles are responsible for Heart Contraction
Describe the structure of Cardiac Muscles and Cardiac Muscle Cells (Cardiocytes) according to: Striation, Cells, Nucleus, Discs
- Cardiac Muscle Cells are Striated due to Myofilaments
- Cardiac Muscle Cells are Tapered Cylinders, Parallel and Branched
- Cardiocytes have a Single, sometimes 2 Central Nuclei
- Myocardial Cells are interconnected to form a continuous unit via Intercalated Discs
- Cardiac muscle cells branch and then fuse forming bridges
- Between the Cardiac Muscle Cells are spaced filled by capillaries and Connective Tissues
Describe Cardiac Muscles according to Location, Muscle Control, Function and Speed of Contraction
- Cardiac Muscles are located in the Heart Wall
- Cardiac Muscles control is Involuntary Control
- Cardiac muscles have an intermediate speed of contraction
What do we look for when looking at a Cardiac Muscle Cells Microscopy
- Striations due to Myofilaments
- Central Nucleus with Nucleoli
- Step-like Intercalated discs
- Smooth Muscles
List the functions of Smooth Muscles
- Smooth muscles are responsible for Visceral and Circulatory movement
Describe the Structure of Smooth Muscles and Smooth Muscle Cells according to: Striation, Cells, Nucleus, Discs
- Smooth muscles are NOT striated
- Myofilaments are not uniformly arranged
- Smooth muscles cells are Elongated, Spindle Shaped and Tapering
- Smooth Muscles cells have a One Central Nucleus
- Smooth Muscles cells do not have an Intercalated Disc
Describe the Smooth Muscles according to Location, Muscle Control, Function and Speed of Contraction
- Smooth muscles are located in Hollow Organs and are found as sheets or bundles in the Walls of the gut, Uterus, Blood Vessels
- Smooth muscle control is Involuntary control and can be stimulated by Nerves, Hormones, or Contract spontaneously
- Smooth muscles have the slowest speed of contraction
What do we look for when looking at the microscopy of a Smooth Muscle
- Longitudinal section: Elongated Spindle Shaped Cells with Tapered ends
- Large central Nucleus
- Absence of Striations
SkinList the Principles layers of the skin and give the function of each layerThe Skin is made up of the:
- Epidermis
- Dermis
- Hypodermis
- Between the Epidermis and Dermis is a Dermo-Epidermal Junction
- Epidermis is responsible for:
- Providing a waterproof barrier
- Providing a biological barrier to the external environment, preventing an penetration by irritants
- Dermis is responsible for:
- Providing support to the Epidermis
- Vascular Supply
- Thermoregulation
- It is Robusta and Flexible
- Hypodermis is responsible for:
- Providing the main structural support to the skin
- Insulation and Shock absorption due to the presence of Adipose Tissue, Sweat Glands, Connective Tissue and Large Blood Vessels
- Dermo-Epidermal Junction provides greater mechanical strength due to the folds
Epidermis
- Epidermis is a Keratinized Stratified Squamous Epithelium
List the layers of the Epidermis
- Epidermis is composed of 4 cell types:
- Keratinocytes
- Melanocytes
- Langerhans Cells
- Merkel Cells
- Epidermis is made up of Strata 5 layers
- The Strata layers are as follows from top to bottom:
- Stratum Corneum
- Stratum Lucidum
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale
Outline the differences between Thick and Thin Skin according Definition, Epidermis, Dermis, Hair Follicles, Apocrine Sweat glands, Sebaceous Gland
- Thick skin
- Thick skin covers the Palms of Hands, Fingers Tips and Soles of Feet
- Epidermis: Thick skin has 5 Strat layers including Stratum Lucidum layer is present
- Dermis: Thick skin has a Thin Dermis
- Apocrine Sweat Glands: Absent
- Thin skin
- Thin skin covers majority of the body
- Epidermis: Thin skin have 4 Strata layers excluding the Stratum Lucidum
- Hair Follicles: Hair follicles are present
- Apocrine Sweat Glands: Apocrine sweat glands are present and produce sweat
- Sebaceous glands: Sebaceous glands are present and produce Sebum
Sensory Receptors in The SkinList the types of Sensory Receptors
- Meissner Corpuscle
- Merkel Cell
- Ruffini Cylinder
- Pacinian Corpuscle
- Senses pressure and Vibration
Meissner's Corpuscle
- Outline Meissner's Corpuscle according to Structure, Location, Mechanism, Effective stimuli and Sensory function*
- Structure: Meissner's Corpuscle is an encapsulated tactile Mechanoreceptor with a Cylindrical/Pear Shape
- Meissner's Corpuscle has a zig-zag arrangement of Unmyelinated Terminal Afferent nerve fibres with supporting (Laminar) Cells thought to be Schwann Cells
- Location: Meissner's Corpuscle is located in the Dermal papilla below the Epidermis
- They are present in the fingers, foot, lips, tongue, glabrous and hairy skin.
- Mechanism:
- Meissner's Corpuscle are Fast Adapting and have a Small Receptive Filed
- Stimuli: Meissner's corpuscle are stimulated by Skin Motion
- Sensory Function: Motion detection and Grip Control
Pacinian CorpuscleOutline Pacinian Corpuscle according to Structure, Location, Mechanism, Effective stimuli and Sensory function
- Structure: Pacinian Corpuscle is a Mechanoreceptor/Pressure receptor
- It is Ovoid and resembles a cut onion
- Contains a Terminal Afferent Nerve fibres which loses its Myelin sheath after entering the Corpuscle and has Laminar cells
- Location: Pacinian Corpuscle is located in the Deep Dermis, Deep fascia or Hypodermis of Weight-bearing and sensitive areas
- Mechanism: Pacinian Corpuscle is Rapidly Adapting with a Large Receptive Field
- Effective Stimuli: Pacinian Corpuscle is stimulated by Vibration
- Sensory Function: is the perception of distant events through transmitted vibrations or tool use.
Glands
- Sebaceous Glands
Describe the Sebaceous Glands
- Most Sebaceous glands have ducts that lead into Hair Follicles, BUT others have ducts that open directly onto the skin surface
- Sebaceous Glands are present in all skin except the Palms and Soles
- Sebaceous glands are Numerous and Productive in the scalp and face
- The largest sebaceous glands are found on the Nose, Forehead and Upper Back
- Sebaceous glands are Hormonally responsive
- Sebaceous glands secrete secretions via Holocrine Secretions
- Sebaceous glands secrete Sebum
List the functions of Sebum
- Sebum is an oil that is responsible for:
- Skin lubrication, and keeps the skin moist and soft
- Preventing brittle hair
- Slightly acidic and kills bacteria
What do we look for when looking a Histology Slides of a Sebaceous Glands
- Basal layer (Mitotic)
- Sebum-filled Cells
- Excretory duct (Holocrine Secretion)
- Hair Canal
Sweat GlandsList the types of Sweat Glands
- Eccrine/Merocrine Sweat Glands
- Apocrine Sweat Glands
Outline Eccrine/Merocrine Seat Glands
- Eccrine Sweat glands are made up of Stratified Cuboidal Epithelial Cells with a small lumen
- Eccrine Sweat glands are numerous in the body except in the Lips, Some External Genital Areas and External Auditory canal
- Eccrine Sweat Glands open via Duct to Pore on the skin
- Eccrine sweat glands have a Secretory Portion and a Duct Portion
- Eccrine sweat glands secrete sweat via Merocrine secretion
Describe the Secretory and Duct portion of the Eccrine Sweat Glands
- Secretory Portion of the Eccrine Sweat glands is located in the Deep Dermis or Upper Hypodermis
- Myoepithelial cells are present
- Myoepithelial cells are Contractile Cells and assist with secretions
- Duct portion of Eccrine Sweat Glands is made up of a Stratified Cuboidal Epithelium without the Myoepithelial Cells
- Duct leaves the Secretory portion as a coiled duct and then becomes a straight duct
Outline the function of Eccrine Sweat Glands
- Eccrine sweat glands are responsible for secreting sweat (salt, water and metabolic wastes)
- Sweat is important for Thermoregulation and Excretion
What do you look for when looking at the Histology Slide of an Eccrine Sweat Gland ?
- Secretory Unit:
- Narrow Lumen
- Myoepithelial Cells
- Gland/Secretory Cells
- Basements Membrane
- Duct Portion:
- Excretory Ducts
- Capillaries
Apocrine Sweat GlandsOutline the Apocrine Sweat Glands
- Apocrine sweat glands are found mostly in the:
- Axillae
- Breast Areolae
- Genital areas
- External ear canal (Ceruminous glands)
- Apocrine sweat glands are larger than Merocrine Sweat glands
- Apocrine Sweat glands have a Secretory Portion and a Duct Portion
- Apocrine sweat glands secret Fatty Acids and Proteins through Merocrine secretion
Describe the Secretory and Duct Portion of the Apocrine Sweat Glands
- Secretory portion
- Secretory portion is made up of a Single row of Cuboidal Cells
- Secretory portion is located in the Deep Dermis or Upper Hypodermis
- Has a Lumen that is up to 10 times wider than that of a Eccrine sweat gland
- It is surrounded by a row of Myoepithelial cells (contractile cells), that assist secretion by contractions
- Duct portion
- Duct portions is made up of 2 layers of Cuboidal Cells, an Inner Cuticle BUT no Myoepithelial Cells
- Apocrine duct travels from the Secretory portion and empties into the Infundibulum (Upper part) of the Hair Follicle, above the entrance of the Sebaceous Gland Duct
Outline the function of Apocrine Sweat Glands
- Apocrine Sweat Glands secrete Fatty Acids and Proteins
- Begin secreting at puberty
- They are activated during Stress, Pain and Sexual arousal
- Controlled by nervous system and circulating hormones
What do you look for when looking at the Histology Slide of an Apocrine sweat gland
- Secretory portion
- Wide lumen
- Myopeithelial cells
- Single row of Cuboidal cells
- Duct Portion
- Absence of Myoepithelial cells
- 2 Rows of Cuboidal cells
- Inner cuticle
Nervous Tissue
- The function of the nervous receive stimuli (both outside and inside) and convert into a response
- Nervous System is divided into a:
- Central Nervous System
- CNS is made up of the Brain and Spinal cord and Neural parts of the eye.
- Peripheral Nervous System
- PNS is made of Peripheral Ganglia, Nerves and Nerve Endings connecting Ganglia with the CNS, Receptors and Effectors of the Body
Outline the Cells of the Nervous System
- The typical neuron produces and conducts electrical impulses
- There are 3 types of neurons:
- Sensory neuron
- Afferent nerve fibres, Conduct the impulse from the Periphery to CNS
- Motor neuron
- Efferent, Conduct the impulse from the CNS to the Periphery
- Interneuron
- Connects the Sensory neuron to the Motor Neuron
Structure of a Typical NeuronDescribe the structure of a typical Neuron
- Dendrites
- Dendrites are cytoplasmic extension
- They receive input
- Cell Body
- Cell body contains a Nucleus with a Nucleolus
- It is a Metabolic Centre which provides protein
- Main concentration of Organelles
- Axon
- Axon is a single cytoplasmic extension
- It conducts nerve impulses
Neuroglial CellsDefine Neuroglial Cells
- Neuroglial cells also called Supporting cells are Non-Neuronal Cells in that they maintain homeostasis, Form myelin and Provide support and protection for neurons
- Neuroglial cells are found in the connective tissue of the nervous tissue
- There are two main types of neuroglial cells in the PNS
- Schwann Cells: Forms myelin around the axon
- Satellite Cells: Support neuron cell bodies
- There are 4 main types of neuroglial cells in the CNS
- Oligodendrocytes: Forms myelin around the axon
- Microglial cells: Phagocytose foreign/degenerate material
- Astrocytes: Regulate the external environment and Provides structural support and nutrient
- Ependymal cells: Cells line the Cerebrospinal Fluid filled Ventricles in the Brain and the Central Canal of the Spinal Cord
- Ependymal produces Cerebrospinal Fluid (CSF) that cushions the Neurons
Types of NeuronsList and Describe the types of Neurons
- Sensory Neurons
- Sensory neurons are Unipolar
- Sensory neurons are activated by sensory input from the environment
- They have 1 Cells Body, 1 Axon which splits into 2 main branches
- Motor neurons
- Motor neurons are Multipolar and a part of the CNS
- They connect to muscles, glands and other organs
- Motor neurons transmit impulses from the Spinal cord to the Skeletal system and smooth muscles
- They have 1 Axon and several Dendrites
- Interneurons
- Interneurons are Bipolar
- They connect the Spinal Neurons and Sensory Neurons
- They can also communicate with each other
Nissl Granules
- Nissl granules are large granular bodies found in the cell body of the neurons.
- They are made of Rough Endoplasmic Reticulum with plenty of ribosomes
- Nissl granules play a role in Protein synthesis
The SynapseDefine the Synapse and its components
- Synapse is a junction between the Post-Synaptic neuron and Pre-Synaptic neuron
- Synapse can be Excitatory or Inhibitory
- Transmission in the Synapse can be Electrical or Chemical (Hormones)
- Synapse operates in a Unidirectional manner
The MyelinDefine and Describe Myelin
- Myelin is an insulating layer surrounding the axons.
- Myelin is made up of Proteins and Fatty substances
- Myelin allows electrical impulses to transmit quickly and efficiently along the nerve cells.
- Myelin is made by either Schwann Cells or Oligodendrocytes
Differentiate between the production of Myelin by the Schwann cells and Oligodendrocytes
- Schwann Cells
- Schwann cells myelinate the axons in the PNS
- When Schwann cells myelinate, their cell bodies actually wrap around the Axon
- Oligodendrocytes
- Oligodendrocytes myelinate the axons in the CNS
- When Oligodendrocytes myelinate, they secrete the myelin sheaths around the axons
Neurons can have Myelinated or Unmyelinated AxonsOutline the differences between Myelinated and Unmyelinated Axons
- Difference is the Speed of Conduction
- Myelinated axons have a faster conduction speed since the Myelin Sheath acts as an Insulator that helps propagate the electrical signals faster
- Most neurons in the PNS and CNS are myelinated because they require fast conduction speeds
- Unmyelinated axons are found in the PNS and CNS in nerves responsible for transmitting secondary pain
Spinal CordOutline the structure of the Spinal Cords
- The Spinal cord is made up of an Inner Grey Matter and an Outer White Matter
List the components of the Grey matter and White matter of the Spinal Cord
- Grey Matter:
- Is an area of Cell bodies, Dendrites and Unmyelinated Axons of Motor and interneurons
- Sensory neuron - Motor neuron connections occur in the grey matter
- Synapses occur in the grey matter
- White Matter:
- Contains Myelinated axons
- Has spinal tracts which ascend and descend the spinal cord
Spinal nerves: Dorsal Root GanglionDefine the Dorsal Root Ganglion and Spinal Ganglia
- Dorsal root ganglion (or Spinal Ganglion) is a cluster of neurons in a dorsal root of a spinal nerve
- Spinal ganglia contain cell bodies of a sensory neurons entering the cord at that region
What to look for when looking at the Spinal Ganglia or Dorsal Root ganglia Histology slide
- Cell Bodies of Unipolar neurons (Sensory neurons)
- Nucleus
- Axons/Nerve Fibres of Unipolar neurons
- Satellite Cells surrounding the cell bodies of Ganglion Cells
- Satellite cells are Neuroglial cells of the PNS
- They compose the thin cellular sheaths that surround the individual neurons in these ganglia
Peripheral nerveDefine a nerve
- A nerve is a collection of Axons linked together by connective tissue
Outline the Peripheral nerve
- Peripheral nerve is composed of:
- Axons that may be Myelinated or Unmyelinated
- Schwann cells which make Myelin
- Spindle shaped fibroblasts which produce Connective tissue
- Blood vessels
Connective Tissue of the Peripheral Nerve
- There are 3 types of connective tissue of the Peripheral Nerve:
- Endoneurium
- Endoneurium surrounds individual axons with their Schwann cells
- Perineurium
- perineurium surrounds groups of Axons to form a Fascicle
- Epineurium
- Epineurium is an outer sheath that binds the individual fascicles into a nerve
-
Connective Tissue of Skeletal Muscle
- The epimysium is the dense connective tissue that surrounds the entire muscle tissue.
- The perimysium is the connective tissue that surrounds each bundle of muscle fibers.
- The endomysium is the connective tissue that covers each single muscle fiber or myofiber or muscle cell.