Chapter 4 Review - Tissue Flashcards
Tissue
refers to a collection of several different cell types, along with their cell products, all coordinated together to perform a limited number of functions
Embryological Tissue
200 different cell types are embryological tissues: Ectoderm, Mesoderm & Endoderm.
Types of Tissue
Connective, Muscle, Epithelial, and Neural
Epithelial Tissue
which typically covers exposed surfaces, lines internal passageways or forms glands. Epithelial cells may be derived from each of the three embryologic germ layers.
Characteristics: Cellularity, Polarity, Attachments, Avascularity, Regeneration.
Cellularity
ET. Cells packed tightly together without much extracellular material.
Intercellular Cement
ET. is made from sticky proteoglycans containing glycosamine.
Cell Adhesion Molecules (CAM’s)
ET. are transmembraneous proteins that proceed through the cell membrane and can bind to CAM’s from other cells or to the basal lamina
Cell Junctions
ET. Tight Junctions, Gap Junctions, Desmosomes; specialized areas of bound or interlocking membranes
Tight Junctions
ET. band of transmembrane proteins which produce a waterproof barrier .
Gap Junctions
ET. allow substances such as ions to freely flow from one cell to another.
Desmosomes
ET. patches of plaques reinforced by intermediate filaments. They are found in areas subject to much mechanical stress
Polarity
ET. There is an apical portion on top and a base below (above loose CT).
Hemidesmosomes
ET. Attachments. Hemidesmosomes attach epithelia to basement membrane (from epithelia secretions from above- lamina lucida and lamina densa from CT secretions from below).
Avascularity
ET. Derive nutrients from absorption through basement membrane.
Regeneration
ET. often subject to mechanical stress, damage and cell loss. Stem cells (also known as geminative cells) are often located near the basement membrane.
Stem Cells
Geminative Cells. Located near the basement layer.
Functions of Epithelial Tissue
Physical protection, selective permeability, provide sensation, and specialized secretions.
Physical protection
ET. serves as lining or covering to serve as barrier.
Selective permeability
ET. substances must pass through cell membrane to enter.
Provide sensation
ET. Often possess sensory supply to alert the body as to both the internal and external environment. Neuroepithelia are highly specialized receptors for a particular sensory function (taste, smell, sight, equilibrium & hearing).
Specialized secretions
ET. All the glandular tissues of our body consist of epithelial tissue.
Neuroepithelia
are highly specialized receptors for a particular sensory function (taste, smell, sight, equilibrium & hearing).
Endocrine Glands
glands which secrete hormones out basal surface into interstitial fluids.
Exocrine Glands
glands in which secretions are from apical surface into ducts which exit the body. Exocrine excretions can be serous (liquidy) as with enzyme releasing glands &/or mucous to protect the GI tract.
Merocrine
Exocrine secretion. xocytosis (mucous glands of digestive tract) and is perhaps the most common exocrine gland.
Apocrine
Exocrine secretion. apical surface of cell is shed the along w/secretory vesicles and cytoplasm. The cell must then repair itself. Milk production in lactating breast cells and some sweat glands in the groin and armpit.
Halocrine
Exocrine secretion. glands become packed w/secretory vesicles and then burst, releasing all the contents and destroying the cell (sebaceous glands).
Classification of Epithelial Tissue
According to cell shape and presence of layers.
Simple Squamous
single layer of thin flat cells.
a. Respiration: lining lung alveoli for gas exchange.
b. Reduce friction: slippery surface of mesothelium and blood vessels.
Simple cuboidal
allows for secretion & absorption of renal tubules (altering filtrate)
Simple Columnar
seen in digestive tract providing enzymes, secretions & absorption.
Ciliated Simple Columnar
creating a fluid current in the uterine tube
Pseudostratified Ciliated Columnar
In Upper Respiratory Tract to remove debris
Transitional Epithelia
many layers of cells which change shape- Urinary bladder
Stratified Squamous
consists of layers of squamous cells, typical of linings which are exposed to mechanical stress such as the skin, mouth, rectum and vagina. Cells of these tissues are of ectodermal origin.
Stratified Cuboidal
layers of cuboidal cells, eg- ducts of sweat & mammary glands
Connective Tissue and it’s origin
establishes a structural framework for the body (binds together, supports & strengthens body tissues), it protects, insulates and compartmentalizes body structures. All CT is derived from embryologic mesoderm.
Connective Tissue characteristics
CT vary in consistency (liquid to bone), but all have specialized cells & a matrix (protein fibers and ground substance)
- Specialized Cells
- Ground Substance
- Protein Fibers
Specialized Cells
Vary according to CT type.
a. fibroblasts
b. macrophages
c. adipocytes
d. mesenchymal cells
e. melanocytes
f. mast cells
g. lymphocytes
h. microphages
Fibroblasts
in all CT. Secrete glycosaminoglycans & collagen
Macrophages
large scavengers that engulf & digest foreign bodies & damaged cells
Adipocytes
store lipid droplets
Mesenchymal Cells
mesodermal stem cells utilized for tissue repair
Melanocytes
synthesize & secrete melanin (color pigment)
Mast Cells
near blood vessels and release chemicals (histamine & heparin) promoting inflammation to help fight infectious agent
Lymphocytes
migrate through CT to destroy foreign substances and some become plasma cells and produce antibodies
Microphages
small phagocytic WBC’s drawn to sight of infection by chemotaxis
Ground Substance
CT. fills space between cells: It can be liquid, gel or solid
a. glycosaminoglycans (GAGs)
b. proteoglycans
c. chondroitin sulfate
d. fibronectin
Glycosaminoglycans (GAGs)
Viscous substance like Hyaluron
Proteoglycans
complex carbohydrates
Chondroitin Sulphate
main GAG of cartilage
Fibronectin
connects the ground substance to protein fibers
Protein Fibers
Fibroblasts secrete protein subunits which interact in matrix to become:
a. collagen fibers
b. reticular fibers
c. elastic fibers
Collagen Fibers
unbranched fibers wound together to provide tensile strength-most common
Reticular Fibers
single unbranched fiber forms stroma (like spider web)
Elastic Fibers
unbranched wavy fibers of elastin- stretch and recoil
Classification of CT
- Embryonic CT
- CT Proper
- Fluid CT
- Supportive CT
Embryonic CT
contains mesenchymal stem cells from which all other CT is formed.
a. mesenchymal CT
b. Whartons Jelly
Mesenchymal CT
embryonic ct. Mesenchymal cells w/fine reticular fibers- forms into adult CT
Whartons Jelly
embryonic ct. found in umbilical cord. Like mesenchymal, but also has fibroblasts.
CT Proper
found throughout body w/variable amount of cell, can be loose or dense.
- Loose CT: areolar, adipose, reticular
- Dense CT: dense regular, dense irregular, elastic CT
Loose CT
CT Proper. functions as packing material to cushion & stabilize organs.
a. areolar CT
b. Adipose
c. Reticular CT
Areolar CT
CT Proper: Loose CT.
Areolar CT has variety of cells and fibers, separates skin from deeper layers and has extensive blood and nerve supply. Fibroblast lay down reticular layer of basement membrane (for epithelial tissue).
Adipose
CT Proper. Loose CT.
consists mainly of adipocytes for cushioning & heat-loss barrier. White fat in adults, but brown fat in children w greater vascularization for energy.
Reticular CT
CT Proper. Loose CT.
serves as 3-D stroma to support parenchyma of organs such as liver, spleen, lymph nodes and bone marrow. Reticular fibers serve as a platform for macrophages.
Dense CT
CT Proper. packed w/collagen (collagenous tissue).
a. Dense Regular
b. Dense Irregular
c. Elastic CT
Dense Regular CT
CT Proper. Dense CT.
- fibers all aligned in one direction
a. tendons
b. ligaments
c. aponeurosis
Tendons
CT Proper. Dense Regular.
-connect muscle to bone.
Ligaments
CT Proper. Dense Regular.
- connect bone to bone.
Aponeurosis
CT Proper. Dense Regular.
- broad flat tendinous sheath
Dense Irregular.
CT Proper. Dense CT.
- interwoven fiber in all different directions
a. capsules
b. periosteum
c. perichondrium
Capsules
CT Proper. Dense Irregular.
- that surround organs or joints
Periosteum
CT Proper. Dense Irregular.
- that surround bone tissue (except at a joint)
Perichondrium
CT Proper. Dense Irregular.
- that surround cartilage
Elastic CT
dense array of fibers but majority are elastic (eg- Ligamentum Flavum of spinal column).
Fluid CT
both blood & lymph which have liquid matrix w/o insoluble fiber.
a. Blood
b. Lymph
Blood
Fluid CT
- has a matrix of Plasma (55% of blood) and cells called Formed Elements(45%).
Formed Elements
Fluid CT. Blood. 45%.
- RBCs/erythrocytes
- WBCs/leukocytes
- platelets/thrombocytes
Erythrocytes
Fluid CT. Blood. Formed Elements.
- most common cell and functions to carry O2.
- RBCs
Leukocytes
Fluid CT. Blood. Formed Elements.
- WBCs
- function as body defense system. Consists of neutrophils, lymphocytes, monocytes, eosinophils & basophils.
Thrombocytes
Fluid CT. Blood. Formed Elements.
- Platelets
- Are fragments of megakaryocytes of the bone marrow and function to provide enzymes for clotting
Lymph
Fluid CT.
- matrix like plasma, but less protein. Contains the majority of lymphocytes.
a. Specific Immune System: lymphocytes can respond to specific antigens
b. Return interstitial fluid back to the circulatory system.
Supportive CT.
Strong matrix with numerous fibers designed to support & protect. Can handle physical loads with permanent deformation.
a. cartilage
b. bone
Cartilage Characteristics
Supportive CT. Characteristics: a. Gel like matrix b. Chondrocytes c. Avascular and Aneural d. perichondrium e. growth
Gel like matrix
Found in cartilage.
- Chondroitin Sulfate is the main GAG
Chondrocytes
Main cell of cartilage, as chondroblast lays down cartilaginous matrix, these cells mature into chondrocytes trapped in spaces called lacunae.
Avascular/Aneural
Cartilage.
-nutrients & waste products must diffuse through matrix, so slow to heal.
Perichondrium
Cartilage.
- double layer
i. outer later of dense regular CT.
ii. inner cellular layer consists of chondroblast for growth and maintenance
Growth
Cartilage.
-typically growth occurs only during childhood development.
Interstitial growth or appositional growth
Interstitial Growth
chondrocytes divide increasing length of cartilage.
Appositional Growth
chondroblasts from inner layer of perichondrium divide increasing the width of cartilage. Cartilage widens if increased amounts of growth hormone after growth has halted.
Classification of Cartilage
- Hyaline Cartilage
- Elastic Cartilage
- Fibrocartilage
Hyaline Cartilage
- most common form of cartilage.
- Articular Cartilage
- Between ribs and sternum
- Maintaining patency of respiratory tract
Articular Cartilage
- covering opposing boney surfaces w/in moveable joints. Articular cartilage is not covered w/perichondrium.
Elastic Cartilage
mainly elastic fibers, seen in epiglottis & ear lobes.
Fibrocartilage
strongest cartilage of interwoven collagen fibers. Serves as padding (shock-absorption) of Intervertebral Discs,meniscus of knee joint & Pubic Symphysis.
Bone
Ossified (mineralized) matrix so offers rigidity for weight-bearing.
Bone Characteristics
a. boney matrix
b. osteocytes
c. periosteum
Osteoid Matrix
consists of collagen fibers (tensile strength & flexibility) & calcium salts (withstand deformation w/compression).
Osteocytes
- Osteoblasts lay down matrix and mature into osteocytes trapped w/in lacunae and communicate w/each other and blood supply through canaliculi.
- Osteocytes maintain blood supply and remain metabolically active throughout life.
- Can not divide like chondrocytes, so NO INTERSTITIAL GROWTH. Bones increase in length owing to cartilaginous growth plate
Periosteum
two layers:
- Outer fibrous layer of Dense Irregular CT
- Inner cellular layer: contains osteoblasts which can lay down osteoid matrix resulting in a widening of bone referred to as Appositional growth.
Membranes
consists of epithelium with underlying CT & serve to line or cover body surfaces
- Serous Membranes
- Cutaneous Membranes
- Synovial Membranes
- Mucous Membranes
Serous Membranes
- mesothelium includes visceral & parietal layers as Pleura, Pericardium & Peritoneum and consists of simple squamous on a thin layer of areolar CT. Epithelial layer secretes serous fluid to diminish friction between body surfaces.
Cutaneous Membranes
Skin.
- covers body surface consisting of stratified keratinized squamous offering a water-resistant barrier overlying areolar CT which is reinforced by a deeper layer of dense irregular CT.
Synovial Membranes
- entirely from CT, it does not have an exposed surface, but is found w/in moveable (synovial) joints and contains specialized CT cells called synoviocytes which secrete synovial fluid to bath & nourish hyaline cartilage covering the boney surface.
Mucous Membranes
- lines passageways that communicate with the external environment (eg- digestive, urinary, reproductive & respiratory tracts). Epithelium sits on areolar CT referred to as a Lamina Propria.
Fasciae
Connective tissue is wrapped around the body in a Framework referred to as fasciae which provides strength & stability, maintains organ position & serves as a route for blood and nerve supply.
Several fascial planes:
1. Superficial Fascia (Subcutaneous Layer)
2. Deep Fascia
3. Subserous Fascia
Superficial Fascia (Subcutaneous Layer)
between skin and underlying organs composed of areolar CT and adipose.
Deep Fascia
Strong fibrous dense CT serving as capsules, periosteum, perichondrium, tendons & ligaments.
Subserous Fascia
a layer of areolar CT between deep fascia and serous membranes which line the body cavities. Protects delicate serous tissue from muscular activity.
Muscle Tissue
are specialized tissue for contraction to provide tension or movement.
- Skeletal (striated or voluntary) Muscle
- Smooth (Visceral or involuntary)
- Cardiac
Skeletal (striated or voluntary) Muscle
- Muscle fibers are large, multinucleated cells in periphery
- Striations: due to pattern of cytoskeletal fibers actin & myosin
- Actin & Myosin bind and slide over one another to shorten the fiber.
- Collagen & elastin framework blend muscle fibers into tendons or aponeurosis.
- Amitotic: fiber cannot divide. Satellite cells may differentiate into muscle for repair.
Smooth (Visceral or involuntary)
- found in blood vessels and organs
- Small spindle shaped w/single central nuclei, exists in sheets.
- No Striations: actin and myosin do not exist in pattern, but still shorten muscle.
- Mitotically active: so readily regenerates and repairs.
Cardiac Muscle
-found in heart & is involuntary control but is striated.
- Cardiocytes
Striations: have repetitive arrangement of actin & Myosin
- Branching of fiber: in order to contact many other cardiocytes.
- Intercalated discs
i. Desmosomes & intercellular cement
ii. Gap Junctions
Cardiocytes
are cardiac muscle cells which have one nuclei
Intercalated Discs
are the attachments between cardiocytes which allow for nearly all the cardiocytes to contract in unison…described as a functional syncytium.
Desmosomes and intercellular cement
hold cells together at intercalated discs.
Gap Junctions
allow for spread of wave of depolarization through cells at disc.
Nervous Tissue
functions as messaging system by conducting electrical impulses.
a. Neurons
b. Neuroglia
Neurons
functional unit of neural tissue which conducts electrical impulses
a. cell body/soma
b. dendrites
c. axons
Soma
Cell body. Where neurotransmitters are manufactured so contain large nucleus & prominent nucleolus.
Dendrites
Branches emerging from cell body which receive information from receptors or other neurons.
Axons
One axon emerges from the cell body which functions to conduct information to other cells. Often referred to as nerve fibers.
Neuroglia
cells which physically & nutritionally support neurons. Protect neuronal environment & help with neuron growth & repair.
Tissue Regeneration/Repair
Tissue/Cell damage leads to increased levels of intracellular substances (K+ & prostaglandins) in the intracellular environment which leades to inflammation. Inflammation is followed by a process of regeneration.
Inflammatory Process
initiated by histamines dilating local capillaries and bringing in WBC’s. Non-Steroidal Anti-Inflammatories (NSAID’s) reverse inflammatory symptom:
a. Rubor
b. Calor
c. Tumor
d. Dolor
Rubor
redness from increased blood
Calor
heat from increased blood
Tumor
swelling from increased blood
Dolor
Pain from chemicals & pressure
Regeneration
replacing damaged tissue & breaching injury gap. All regeneration begins with fibroblasts laying down new collagen matrix (granulation tissue).
First Intention Healing
mitotically active tissue replaced damaged cells with like cells. Epithelial cells utilize granulation tissue as a healing platform on which to breach the gap.
Second Intention Healing
typically from amitotic tissues in which the injured gap is filled with granulation tissue & fibrosis (scarring) rendering the tissue less functional. Note: Nervous tissue and Cardiac & Skeletal Muscle tissue is amitotic and heals by fibrosis.
Aging
as cells die there is an incomplete regeneration resulting in tissue changes. Weaker matrix of CT and bones become osteoporotic. The immune system declines so more susceptible to invading pathogens & cancers.
