Chapter 4 Flashcards
Histology
Study of tissues
Epithelial Tissue
Tight packed sheets of cells
Connective Tissues
Bind, support, protect and allows for transportation;
Muscle Tissue
Generating force by contracting ;
Nervous Tissue
Cells capable of generating, sending, receiving messages, and cells that support this activity
Extracellular Matrix
ECM;
Liquid surrounding cells of a tissue;
Two components: ground substance & protein fibers
Functions:
Tensile-stretches (PULL)
Compressive forces (PUSH)
(A) Ground substance
Consists of ECF;
Includes water, nutrients, ions and macromolecules
Glycoaminoglycan (GAGs)
Example- Chondroitin sulfate and Hyaluronic acid
Functions:
Draw water out of cells & blood vessels by [Osmosis]
Trap water in ECM and Resist comprehension/compression
Proteoglycans
Bound to a protein core;
Functions:
Resistant to compression
Barrier to diffusion from invading microorganisms
Cell-adhesion molecules (CAMs)
[Glyco]proteins;
GLYCO=GLUCOSE
Functions:
Adhere cell to cell- holds everything in place;
Bind to cell surface proteins
Maintain normal tissue structure- keep its shape;
(B) Protein Fibers
Long molecules;
Rope like structure;
Tensile strength;
3 types:
Collagen
Elastic
Reticular
Collagen Fiber
Resistant to tension & pressure
Elastic Fiber
[Yellow Fibers]
Protein elastin;
Stretch; Once stretched fibers [return] to resting [length] elasticity
Reticular Fiber
Short collagen fibers; Form mesh work
Weblike structure;
Functions:
Supports cells
Traps foreign cells (3D network)
Cell Junction
Cells bind to one another;
3 types:
Tight junctions
Desmosomes
Gap junctions
Tight Junctions
[Occluding Junctions]
Impermeable to big molecules
Function:
Holds cells together;
Forms a seal around perimeter (outside) cell; Once Locked
Allows for some leakage
Example:
Found between cells in blood vessels; [Preventing] blood from [Exiting] vessels
Desmosomes
Functions: Link proteins; [Allows] materials to [Pass] through [Between Cells] Increase strength Structural reinforcement
Located:
In tissues subjected to [Mechanical Stress]- pulling,
Such as [Epithelia of Skin]
Gap Junctions
Small pores;
Functions:
[Allow] small [Substances] to [Flow freely];
Communicate with Electrical Signals
Example- cardiac muscle cells
Epithelial Tissues
On [Every Internal & External] body surface;
Line organs;
Functions:
Protection from [Mechanical] & [Thermal] Injury
Forms [Barriers]; Protect against Immune Defenses
Forms glands such as [Hormones & Oils]
Transport in other tissues-Selectively Permeable;
Sensation-Change in Internal & External environment (Taste Buds)
Components of Epithelial Tissue
Tight packed cells;
Tight packed Junctions & Desmosomes
Functions:
Make sheets of cells [Impermeable & Resistant] to [Stress & Injury];
Avascular Tissue:
[Lacks blood vessels]- Must obtain Oxygen through [Diffusion]
ECM=Basement Membrane;
Two Components:
Basal lamina
Reticular lamina
Basal Lamina
Collagen fibers & Ground substance; [Epithelial Cells]
Reticular Lamina
*[Connective Cells] *
Reticular fibers
[Together] Basal Lamina and Reticular Lamina do what ?
The layers [GLUE] or [ANCHOR];
Form a [BARRIER]
What [TWO] components [CLASSIFY] Epithelial Tissue?
( a ) Number & ( b ) Shape;
(A) 1. Simple Epithelia [Single Layer]
2. Stratified Epithelia [2+ Layers]
(B) 1. Squamous Cells [FLAT]
2. Cuboidal Cells [SHORT] 3. Columnar Cells [TALL, ELONGATED]
Covering & Lining of Epithelia
Inner & Outer surfaces;
[Simple Epithelia] :
One layer thick for Diffusion
[Stratified Epithelia]
More than one layer for [Protection & High Stress]
[MICROVILI] - Increase Surface Area
[CILIA] - Moving Substances
4 Types of Simple Epithelia
- Simple Squamous:
Very thin layer;
Functions:
Diffusion of substances - oxygen, carbon dioxide, fluids, and ions
Located: Air sacs, kidney tubules, and blood vessel lining
4 types of Simple Epithelia
- Simple Cuboidal:
Single layer with large nucleus
Located: Tubules [tubes], respiratory passages, ducts of glands, and thyroid gland
4 types of Simple Epithelia
- Simple Columnar:
Rectangle shaped- Single layer;
Nuclei on Bottom, Microvili on Top (increase surface area)
Or Cilia (propels substance)
Located:
In small intestine, uterine tubes, and respiratory tract
Pseudostratified Columnar
[Appears] to be [Layered], but it is [Simple] due to [Different Nuclei Heights]
Located:
Respiratory tract & Nasal cavity; [Ciliated]
Transportation across Epithelia
- Paracellular: [Para=Between]
Little leakage [Between Cells] due to tight junctions - Transcellular : [Trans=Cross]
Substance enters by crossing the membrane, then diffusing across cytosol, and then exiting cell through plasma membrane
Keratinized Stratified Squamous
Filled with [Keratin]-> making cells tough and resistant to friction;
Located:
Outer layer of skin
Nonkeratinized Stratified Squamous
Retains [Nuclei]; (alive)
Regions where mechanical stress is there to [Keep Moist]
Located:
Mouth, throat, esophagus, anus, and vagina
Stratified Cuboidal
Rare;
Located:
Sweat gland ducts
Stratified Columnar
Rare;
Located:
Male urethra, cornea of eye, and salivary glands
Transitional Epithelium
[Only] found in Urinary system
Location:
Kidney, uterus, urinary bladder, and urethra
Gland
Structure that synthesizes & secretes a product;
*Products are released by two systems:
Endocrine
Exocrine
Endocrine Gland
Secretes their products (hormones) directly in bloodstream without ducts:
- [Ductless or No Ducts]*
- Can have an [Effect] on distant cells
Exocrine Gland
- Multicellular *
- Release product on surfaces on the [External] surface;
- [Line] hollow organ that opens to outside of body
Local Effects:
Glands vary in Complexity
Glandular Epithelia:
Goblet Cell
[Common Gland]
[UNI] cellular gland; [UNI=ONE]
Secretes [Mucus]
Located:
Digestive & Respiratory tract
Glandular Epithelia
Duct structure:
- Simple
- Compound
- Simple:
Don’t branch; - Compound:
Branch;
[Classify as Shape]
- Tubular: Long; Straight
- Acinar: Spherical
- Tubuloacinar: Tube & Acinar shaped
Two methods for [Secreting] products :
Classifying
- Merocrine Secretion:
(Molecules) - Majority of exocrine glands
- Release by exocytosis
Example-
Saliva & Sweat
Holocrine Secretion
(Whole):
- Skin to create Sebum [Oil]
- Only release when cell ruptures & dies
Connective Tissue
-Divides into 2 groups
-Differs in cell types & ECM components :
Connective tissue proper & Specialized connective tissue
Functions:
-Connecting & Binding
(Anchor tissue layers in organs and linking them together)
-Support
(Bone & Cartilage support body’s weight)
-Protection
(Bone tissues protect Internal organs; Cartilage & fat provide absorption)
-Transport
(Blood is fluid connective tissue; Main [Transport] in body)
Connective Tissue Proper
Widely distributed in body;
Connect tissues & Organs;
Components of Internal architecture of some organs;
Cells:
(Resident Cells)
-Inhabit the tissue permanently;
-Migrant cells migrate
Fibroblasts
(Common Resident Cell)
Functions:
- Mature cells with properties of Immune “Blast” cells;
- Make protein fibers & ground substance;
- Continually produce collagen proteins
Adipocytes
- (Fat cells)*
- In many different connective tissues;
- Cytoplasm filled with (Single) Lipid Inclusion
Mast Cells
- (Largest Resident Cell)*
- Immune system cells filled with [Granules]—> cytosolic inclusions of [Histamine]—> inflammatory mediators
- Release mediators [Degranulate] when stimulated, causing [Inflammation]—> protective response
Phagocytes
- (Immune System Cells)*
- Ingest foreign substances, microorganisms, & dead/damaged cells by [Phagocytosis];
- Includes [Macrophages]-> resident/migrant cells & [Neutrophils]-> migrant cells
Other Immune System Cells
-Migrate In & Out of connective tissues depending on body’s needs
4 types of Connective Tissue Proper:
(A) Loose Connective
(B) Dense Connective
(C) Reticular
(D) Adipose
(A) Loose Connective Tissue
[Areolar Tissue]
-Mostly ground substance;
-Contains [all] 3 types of [Protein Fibers, Fibroblasts, & Adipocytes ( suspends in ground substance)]
-Contains & Supports blood vessels [Vital] to Avascular Epithelial Tissues;
(Houses Immune System cells)
Located:
- Beneath epithelium of skin
- In membranes lining body cavities
- Within walls of hollow organs
(B) Dense Connective Tissue
Mostly Protein Fibers; 3 Classes: - Dense Irregular - Dense Regular - Dense Regular Elastic
Dense Irregular Tissue
[Disorganized Collagen Bundles]
- Strong; Resists Tension in [All 3 movement planes]
- In High Tension areas, [Dermis]-> deep to skin and surrounds organs & joints
Dense Regular
- Organized in Parallel Collagen bundles;
- In Tendons & Ligaments;
- Subject to tension in [1 Plane Movement]
Dense Regular Elastic
-Parallel-oriented elastic fibers with random oriented collagen fibers;
-In walls of organs that [MUST] stretch to function;
(Large blood vessels & Ligaments)
(C) Reticular Tissue
(Mostly Fibers, produced by Fibroblasts)
- Forms networks that support small structures;
(Blood & Lymphatic vessels)
-In lymph nodes & Splean;
(Forms [Weblike] nets that [Trap] old cells
-Forms part of basement membrane; Supports all Epithelia & Internal Structure of [Liver & Bone Marrow]
(D) Adipose Tissue
[Fat Tissue]
- Fat storing adipocytes, surrounding fibroblasts, and ECM;
- Can increase in size
Functions:
- Fat storage [Energy Reserve]
- Insulation [Retains Warmth]
- Shock absorption & protection
2 Types of Adipose Tissue:
- White adipose tissue:
- Fat tissue;
- Adipocytes with [1] large lipid inclusion in cytosol
- Deep to skin [Subcutaneous] fat
Located:
Abdomen, breasts, hips, buttocks, and thighs
[Visceral Fat] -> surrounds heart & abdominal organs
2 Types of Adipose Tissue:
- Brown Adipose Tissue:
- Brown appearance [Due To] numerous mitochondria in [Cytoplasm & Blood supply;
- Contains multiple lipid inclusions
- Readily converted to energy to produce heat
Obesity
Excess adipose tissue;
2 Forms:
- Hypertrophic
- Hypercellular
Hypertrophic
- Accumulates fatty acids;
- Increase size up to 4
- Number of Adipocytes remains unchanged
Hypercellular
- Severe;
- Number of Adipocytes Increases;
- Obesity development in Infancy/early childhood
- Adult Adipocytes lack ability to divide to form new cells
What do both Hypertrophic & Hypercellular have in common?
Both increase risk of health problems
3 Types of Specialized Connective Tissues:
Cartilage, Bone Tissue, & Blood
1) Cartilage
- Avascular;
- Absorbs shock and Resists tension, Compression and Shearing forces;
- ECM consists of Collagen and Elastic Fibers, Proteoglycans, & Glycosaminoglycans
Located:
In Joints between bones, ear, nose, & segments of respiratory tract
2 Cell Types :
[Cartilage]
- Chondroblasts [Immature Cells];
- Divide by Mitosis - Surround themselves in [Lacunae]—> small cavities in ECM to become Inactive [Chondrocytes]
3 Classes of Cartilage:
[Divided by ECM Composition]
1st class:
- Hyaline Cartilage [Most Abundant]
- Gives tissue glossy bluish-gray appearance;
- On ends of bones in joints [ Articular Cartilage ] —> (Linking Sternum to Ribs, Framing sections of Respiratory Tract, & In Nose)
- Most of Fetal Skeleton, replaced with Bone during development
3 Classes of Cartilage:
[Divided by ECM Composition]
2nd Class:
Fibrocartilage:
- Filled with bundles of Collagen Fibers; Little room for Ground Substance.
- Fills ECM with Collagen & Elastic Fibers;
- Tissue has tensile strength with some elasticity;
Located:
- Resides in Tissue;
- In between Bones of Fibrous Joints;
3 Classes of Cartilage:
[Divided by ECM Composition]
3rd Class:
Elastic Cartilage: [ Elastic Fibers in ECM ]
- Allows tissue to vibrate
- [External Ear] -> detection of sound in air;
- [Larynx] -> assists with production of sound;
3 Types of Specialized Connective Tissues:
2) Bone Tissue :
- 65% of ECM is Inorganic Calcium Phosphate Crystals, which makes [Bone Hard];
- Dynamic Tissue:
[Remodeling]
Occurs in stress regions;
- Compression increases osteoclast activity & bone resorption
Osteoblasts
- Bone builders; Outer surface of Bones
- Associated with [Periostenum];
- Carries out bone deposition process;
Osteocytes
[Mature Cells= Inactive]
- Osteoblasts that surround themselves with ECM in Lacunae;
- Make & Secrete substances for bone maintenance \
Osteoclasts
- Large, multinucleated bone destroyers;
- Carry out bone resorption process;
- Secretes hydrogen ions & enzymes that break down Inorganic and Organic ECM
3 Types of Specialized Connective Tissues:
3) Blood:
- ECM is fluid;
Plasma Proteins
Small with different functions;
[ Transport of Substances & Blood Clotting ]
Erythrocytes
- [Red Blood Cells]*
- Bind to & Transports oxygen throughout body
Leukocytes
- [Unite Blood Cells]*
- Function in Immunity
Platelates
- [ Cell Fragments ]*
- Blood Clotting
Muscle Tissue
For Contraction;
* Chemical energy of ATP [Into] Mechanical energy of movement *
Walking, breathing, heart beating result from Muscle Contraction
[Main Component] :
- Muscle Cell (Myocyte), which responds to electrical or chemical stimulation
2 Forms of Muscle Cells:
[Based off of {Myofilaments} -> protein bundles; In cytoplasm]
- Striated
- Smooth
Striated Muscle Cells
Arranged in light & dark regions;
[Appear striped under a microscope]
Smooth Muscle Cells
Arranged in Irregular bundles;
Endomysium
- Small amount of ECM that surrounds Muscle Tissue;
- Helps hold Muscle Cells together in Tissue
3 Types of Muscle Tissue:
- (a) Skeletal
- (b) Cardiac
- (c) Smooth
*Both [Skeletal & Cardiac] are STRIATED *
(A) Skeletal Muscle Tissue
- Contraction produces body movement;
- [Must Be] stimulated by nervous system to contract; [Voluntary]
- Skeletal Cells [Muscle Fibers] are long;
- Forms by fusion of embryonic myoblasts, resulting in cells with more than one nucleus [Muiltinucleate]
(B) Cardiac Muscle Tissue
[ Only In Heart]
- Composed of Cardiac Muscle Cells; Striated
- Involuntary; Brain has [NO] control over contraction
- Cells are short, Branched;
- [Intercalated Disc]-> dark line separating individual muscle cells; Contains gap junctions & tight junctions
( Not In: Skeletal Muscle )
- Allows heart to contract as a Unit;
(C) Smooth Muscle Tissue
- Consists of Smooth Muscle cells;
- Involuntary contractions;
- In walls of nearly [ALL] hollow organs, blood vessels, eyes, skin, and ducts of certain glands;
- Flattened cells with [1] located Ovoid Nucleus;
- [In Most] the plasma membrane of neighboring cells are linked by Gap Junctions
Nervous Tissue
- Makes up the majority of Brain, Spinal Cord, and Nerves;
Two Main Types:
- Neurons
- Neurological Cells
Neurons
- Sends and Receives messages;
Neurological Cells
- Performs different functions and Supports neuron activities
[Excitable] Neurons
- Once mature, it is no longer divides by [Mitosis]
3 Main Components :
- Cell body
- Solitary Axon
- Dendrites
Cell body [Soma]
- Biosynthetic center of Neuron;
Located:
In Nucleus & Most Organelles
Solitary Axon
- Extends from one end of Soma;
- Responsible for moving Nerve Impulses from Soma to [ Target Cell ]-> another neuron, muscle cell, or gland
Dendrites
- Another extension protruding from Soma;
- Short with multiple branches
- Receive Impulses from Axons or Neighboring Neurons
- Delivers Impulses to Soma
Neurological Cells
Group of smaller cells;
* Able to divide by Mitosis *
Functions:
- Anchor neurons & Blood vessels in place;
- Monitor composition of ECF
- Speeds up nerve impulse rate
- Circulates fluid surrounding the Brain & Spinal Cord
Organ
Two or more Tissues;
Example : Skeletal Muscle
2 Main Tissues of an Organ
- Skeletal Muscle
2. Dense Irregular Collagenous Connective Tissue
Skeletal Muscle
Allows for Contraction
Collagenous Connective Tissue
Surrounding Connective Tissue binding the Muscle Cells together & supporting them so contraction of the whole organ produces again
Trachea
- More Complex Organ *
- Hollow; Provides a passageway through which air passes on the way In & Out of lungs
- Each tissue layer serves a role in overall function;
Example: Conducting Air
Membrane
- Thin sheet of one or more tissues;
- Lines body surface or the cavity :
[Most] consist of superficial epithelial layer resting on the connective tissue layer;
Functions:
Anchors joints in place, serves as barriers, function in Immunity, & secretes various substances
True Membrane
Serous and Synovial Membranes;
Example:
Serous or Serosae;
- Lines pericardial, peritoneal, and pleural cavities
- Consists of [Mesothelium]-> thin layer of squamous epithelium;
- Associated with basement membrane, and layer of the connective tissue;
2 layers that fold over themselves:
- Outer Parietal layer lines the body wall
- Inner Visceral layer covers organ within the body cavity
Membrane-like Structure
Nucleus and Cutaneous
Synovial Membranes
- Line cavities surrounding joints ( knee or shoulder )
- Two connective tissue layers [without] layer of epithelial cells
[OUTER LAYER] :
Composed of loose & dense irregular connective tissue
[INNER LAYER] :
( Synoviocytes ) -> modified fibroblasts;
- Secrete [Synovial fluid];
- Watery fluid
Function:
Lubricate the Joint
Mucus Membrane
[Mucosac]
- Lines all passages opening to outside of the body:
Respiratory passages, mouth, nasal cavity, digestive tract, and male & female reproductive tracts;
- Layer of Epithelium and Basement Membrane (Connective Tissue, called Lamina Propria); Can be Smooth Muscle
- Contains glands with [Goblet Cells]
- Provides and Secretes mucus
- Serves several functions; For protection
Cutaneous Membrane
[Skin]
Largest organ of the body;
Consists of -
- Outer layer of [Keratinized Stratified Squamous Epithelium]-> epidermis;
- Tough, consistent protective surface;
Dermis
- Layer of Loose Connective Tissue beneath epidermis, along with a deep layer of dense irregular connective tissue;
- Home to many blood vessels; Providing means for oxygen & nutrients to ( Diffuse ) into Avascular epidermis
Friction Rub
- Resulting in Grating sound; Can be heard with a stethoscope
- Serous fluid secreted for lubrication becoming inadequate to reduce friction; Layers rub together as organs contract and expand;
Can cause chest pain
Tissue Repair
- Wound healing;
- Dead or damaged cells are removed and then replaced with new cells or tissues;
- Fills gap for maintenance of Homeostasis
Tissue Repair Process
- Certain Tissues can Regenerate; 2. Damaged cells are replaced with cells of the same type; 3. When the process if finished, tissues return to normal function level; 4. Other tissues are [NOT] capable of full regeneration; 5. Fibroblasts fills gap left from Injury by [Fibrosis];
Fibrous Functions:
- Fibroblasts divide by Mitosis; Produces collagen to fill the gap
- End result of Fibrosis is Scar Tissue
Capacity for Tissue Repair
Dependent on cells ability to undergo mitosis:
- Epithelial undergo regeneration: Skin & Digestive tract lining are subject to stress; Must bare mechanism for replacing dead, damaged, or worn out cells. New cells are derived from [Stem Cells]-> Immature cells capable of Mitosis
- Other Epithelial Tissues (Liver & Blood vessels) : Mature cells in the area of injury are capable of replacing that damaged cell by dividing
Connective Tissue Regeneration
- Connective Tissue Proper, Bone & Blood regenerate through division of resident immature cells;
- Cartilage is an (exception); Heals by Fibrosis
Smooth Muscle Regeneration
- Retains ability to undergo Mitosis; Healed by regeneration
- Mature Skeletal Muscle Fibers and Cardiac Muscle Cells have lost their ability to divide by Mitosis; Meaning it can’t regenerate
Satellite Cells:
Can divide and mature into skeletal muscle cells;
Cardiac Muscle Tissue, has [NO] satellite cells that results in injuries healed by Fibrosis
Nervous Tissue undergoing Fibrosis
- Neurons lost ability to divide by mitosis and replace the dead or damaged neurons with scar tissue;
- Neurological cells retain ability to divide by mitosis and also replace the damaged neuron with scar tissue;
- Axons of Neurons outside the brain and spinal cord can regenerate
