Bio 004 lecture exam 1 pt 2 Muscle Tissue and Microanatomy

Major Tissue Types in the Body

Epithelial Tissue, Connective Tissue, Nervous Tissue, Muscle Tissue

Epithelial Tissue

Location: Wide Distribution, Body surfaces, Lines hollow organs & body cavities, Ducts, Forms glands
Function(s): Allow the internal environment to
interact with the external environment.

Connective Tissue

Location: Wide Distribution, Exceptions (confined rather than widely distributed): Bone, Blood & Cartilage
Function(s): General protection and support;
varies per tissue type
1. Binds organs together
2. Stores energy reserves
3. Provides immunity

Nervous Tissue

Location: Wide Distribution
function:
1. Detects changes in
conditions (inside and outside of body)
2. General electrical signals
3. Activation of muscle contraction and secretion from gland

Muscle Tissue

Location: Muscles, GI tract, Blood Vessels
Function:
1. Specialized cells for contraction/generation of
force
2. Provides heat/warmth

Cells Based on Movement/Lack of Movement

Cells that are anchored: most cells
Cells that migrate: Cells during growth and development
Phagocytic cells (monocytes, neutrophils, macrophages)

Biopsy

Definition: Removal of living tissue for microscopic examination
Purpose: For ruling out a diagnosis of cancer; unexplained infections, inflammation
Procedure:
1. Removal of both normal tissue and diseased tissue to compare
2. If tissue is removed with a needle=called "needle biopsy"
3. Preserved, stained (highlighted) to examine special properties
4. Can be done under anesthesia so a surgeon can perform surgery immediately

5 types of cell junctions

tight junctions, adherens junctions, desmosomes, hemidesmosomes, gap junctions

Tight Junctions

Definition: web-like strands of transmembrane proteins, fuse together on the outer sources of the adjacent plasma membrane to seal passageways
Role: Barrier
Function: 1) Inhibits passage of substances
between cells 2) Prevents contents of these organs from leaking into the blood or surrounding tissue
Location: 1) common in the epidermis (outermost layer of the
skin) 2) Cardiac muscles cells
Major Protein: Claudins

Adherens Junctions

Definition: cell-to-cell anchor inside the plasma membrane proteins and to microfilaments of the cytoskeleton
Role: stability
Function: Help epithelial surfaces resist separation during contractile activities
Location: epithelial cells that line the stomach, intestines, urinary bladder
Major Protein: Cadherin Proteins

Desmosomes

Definition:
1) Cell-to-cell anchor contains plaques and cadherins, similar to adherens junctions
2) attach cells to one another.
3) attach to intermediate filaments of the cytoskeleton
Role: Stability
Function:
1) Prevents epidermal cells from separating under tension
2) Prevents cardiac muscle cells from pulling apart during contraction
Location:
1) common in the epidermis (outermost layer of the skin)
2) Cardiac muscles cells
Major Protein: Cadherin proteins

Hemidesmosomes

Definition: cell-to-membrane anchor; half resemble desmosomes, anchor cells to the basement membrane; Integrins are transmembrane proteins in desmosomes [bind to the extracellular matrix]
Role: anchor
Function:
1) Prevents epidermal cells from separating
under tension
2) Prevents cardiac muscle cells from pulling apart during the contraction of the heart,
Location: epidermis/skin and heart muscle
Major Protein: Integrins
Outside attachment: to intermediate filaments made of the protein keratin
Inside attachment: attach to the protein laminin (found in the BM)

Gap Junctions

Definition: cell-to-cell junction that allows small particles and ions to flow between the two cells, but restricts larger molecules
Role: Communication
Function:
1) Allows for the transfer of nutrients and wastes
between cells in avascular tissues
2) Allows for communication of cells in a tissue
3) Allow nerve impulses to spread rapidly through cells
Location:
1) Lens, cornea
2) Embryonic Cells during growth/division
3) Neurons
4) Cardiac tissue
5) GI tract
6) Uterus
Major Protein: Connexins (for fluid-filled tunnels that connect neighboring cells.)

Functional Types of Cell Junctions

Occluding Junctions, Anchoring Junctions, Communicating
Junctions

Occluding Junctions

Function:
1) Seals cells together in the epithelium
2) Molecules cannot pass from one side to the other
Specific Junctions: Tight Junctions

Anchoring Junctions

Function:
1) Mechanically attach cells to their neighbors & ECM (extracellular matrix)
Actin-Filament Attachment site
Specific Junctions: Adherens junctions (cell to cell)
Intermediate filament site
Specific Junctions: Desmosomes (cell to cell) and Hemidesmosones (cell to matrix)

Communicating Junctions

Function:
1) Mediates passage of chemical or electrical signals from one cell to the other
Specific Junctions: Gap Junctions and Chemical Synapses

Epithelial (Epithelial vs Connective Tissue)

1) MATRIX/CELLS: Tightly packed (less matrix/more cells;
2) BV: No blood vessels;
3) LOCATION: Almost always forms surface layers; not covered by another tissue
EXCEPTION: the epithelial lining of blood vessels has blood constantly passing over the epithelium

CT (Epithelial vs Connective Tissue)

1) MATRIX/CELLS: Large extracellular matrix, less cells
2) BV: Significant network of blood vessels
3) LOCATION: Covered by other tissue; not open
to the surface

What does CT and Epithelial have in common?

1) Epithelial tissue lacks blood vessels and forms surfaces
2 Found immediately adjacent to BV rich in connective tissue
3 Purpose: Allows for oxygen/carbon dioxide/nutrient exchange critical for survival and function.

What are the major functions of epithelium?

Selective Barrier: Limits/aids transfer of substances in and out of the body
Secretory Surface: Releases products produced by cells onto the free surface
Protective Surface: Resists abrasive influences of the environment

Apical Surface

The surface that faces the outside of the body; the lumen. AKA: The free surface.
Structures: cilia; microvilli

Lateral Surface

The lateral region between two epithelial cells.
Structures: Cell junctions (Tight, adherens, gap
junctions and desmosomes)

Basal Surface

Resists abrasive influences of the environment
Structures: Hemidesmosomes

Basement Membrane

Location: The surface just under the epithelial
cell; at the basal surface.
Composition: Two layers
Top-layer (closest to the epithelium at the basal layer)=Basal lamina; Associated proteins: Laminin; collagen
Bottom-layer (closest to the connective tissue )=reticular lamina Associated proteins: collagen

Functions of the Basement Membrane

1) Place of attachment and support of
overlying epithelial tissue
2) Forms a surface along which epithelial
cells migrate during growth or wound
healing
3) Restrict passage of larger molecules
between epithelium and connective tissue
4) Participates infiltration within the kidneys

Nerve & Blood Supply of Epithelial Tissue

Epithelial Tissue
1) Has its own nerve supply
2) NO blood vessel supply
How does epithelial tissue undergo nutrient exchange?
- It relies on the blood supply from adjacent connective tissue, via the process of DIFFUSION

Epithelial Tissues consists of:

Simple, Stratified, Squamous, Cuboidal, Columnar, Pseudostratified, Transitional

Simple

One layer
Functions: diffusion, osmosis, filtration, secretion, absorption
"Secretion"=the production and release of substances such as mucous, sweat, enzymes
"absorption"= intake of fluids or other substances such as digested food from the intestinal tract

Stratified

More than one layer
Function: protection of underlying tissues in locations of wear and tear.

Squamous

Flat Cells: (longer than they are tall); nuclei is flat like pancake
Function: rapid passage of substances

Cuboidal

Cubed-shaped cells; as tall as they are wide. May have microvilli at the apical surface; nuclei will be round and in the center; may contain goblet cells
Function: Secretion/absorption

Columnar

Column-shaped; taller than they are wide; apical surfaces may have microvilli or cilia; nuclei will be taller than it is wide; may
contain goblet cells. Function: protect underlying structures

Pseudostratified

One layer, but appears to be multiple layers being that the nuclei are all at different locations in the cell

Transitional

Switches between stratified squamous and stratified cuboidal;
depends on whether the bladder is empty or full.

Definition of Exocrine Glands

Glands that open up/secrete into a lumen or onto the surface or the body.

Structural Classification of Exocrine Glands

consist of: Unicellular Glands and Multicellular Glands

Unicellular Glands

Single-cell glands
Example: goblet cells=unicellular glands which secrete mucus onto the surface of the body or into a lumen

Multicellular Glands

Multicellular glands: (majority) composed of many cells that form a distinct microscopic structure
examples: sudoriferous glands, sebaceous glands (oil), salivary
glands
Multicellular glands are categorized by two criteria:
1) Branched or unbranched ducts
2) Shape of the secretory proteins of the gland

Multicellular Glands consists of:

Simple gland: gland that does not branch
Compound gland: gland that branches
Tubular glands: glands with tubular secretory parts
Acinar glands: glands with rounded secretory parts

Functional Classification of Exocrine Glands

Merocrine Glands, Apocrine Glands, Holocrine Glands

Merocrine Glands

Released from the cell in secretory vesicles via exocytosis.
MOST glands are merocrine.
Ex: salivary glands/pancreas

Apocrine Glands

Accumulate secretory product at the apical surface of secreting cell; the portion that pinches off and secretes.
The cell repairs itself and is able to repeat this.
Ex: secretion of milk fats in the mammary glands

Holocrine Glands

Accumulates a secretory product in the cytosol. As the secretory cell matures it ruptures and becomes the
secretory product. This product contains a large amount of lipids from the plasma membrane.
Ex: sebaceous gland of the skim (Memory: HOL=WHOLE CELLS are secreted)

Functions of Connective Tissue

• Binds together, supports, and strengthens body tissues
• Protects and insulates internal organs
• Compartmentalizes structures (skeletal muscle)
• Serves as major transport system within the body
(blood is a fluid connective tissue)
• Primary location of stored energy reserves (adipose)
• Main source of immune responses

Basic Elements of Connective Tissue

consists of Extracellular Matrix and Cells

Extracellular Matrix (ECM)

consists of protein fibers and ground substance

Protein Fibers (collagen, reticular, elastic)

•Secreted by CT cells
•Account for the functional properties of the tissue
•Control the surrounding watery environment via specific proteoglycan molecules

Ground substance

Watery substance that suspends the
proteins and the cells.

Cells

Macrophages: phagocytes
Fibroblasts: Secrete the matrix/proteins
Lymphocytes: White Blood Cell
Fat cell: Energy storage
Mast Cell: Immune cell/secretes histamine
Neutrophil: White blood cell

Ground Substance

Definition: material between the cells and the protein fibers
Structure: fluid, semifluid, gelatinous or calcified
Composition: water, organic molecules (chondroitin sulfate,
glucosamine)
Functions:
1. Supports and binds cells
2. Supplies water and provides a medium for exchanged substances/nutrients between blood and cells
2. Active role in tissue development and metabolism

Collagen Fibers

Very strong; resists tension (pulling forces)
Properties: vary per tissue Cartilage vs. boneà surrounded by more water molecules than bone; cushioning effect Occur in parallel bundles (adds tensile strength)
Protein: collaged [most abundant protein in
the body (25%)]
Location: most types of CT (especially, bone, tendon and cartilage)

Reticular Fibers

Protein: collagen
Arrangement: fine bundles with glycoprotein covering
Locations:
1. Walls of BV
2. Network around cells in several tissues (areolar, adipose, nervous, smooth muscle tissue)
Produced by: fibroblasts
Characteristics: thinner than collagen; branching networks
Functions:
1. Support/strength
2. Forms the stroma of many soft organs
3. Helps form the basement membrane

Elastic Fibers

Smaller in diameter than collagen fibers; strong
Branch and join to form a fibrous network in
CT
Composition:
1. Protein: elastin (surrounded by)
2. Glycoprotein: fibrillin (tensile strength and stability)
Elasticity (can stretch up to 150% of relaxed
length; can revert back to original shape after
being stretched)
Location: skin, BV, lung tissue

What is the difference between "blasts" and "cytes"?

Blasts are Immature cells and Cytes are Mature cells

General Features of Connective Tissue

Location: Does not usually occur on body surfaces/Below epithelium
Vascularity: highly vascular (Exception: cartilage/blood=avascular; tendons=little blood supply)
Innervation: Supplied with nerves (Exception: Blood/cartilage=no nerves)

Types of Embryonic Tissue

Embryonic Mesenchyme and Mucus Connective Tissue (aka.
Wharton's Jelly)

Embryonic Mesenchyme

Location: Primarily in embryo; under the skin and along
developing bones; some in adult connective tissue occurring
along the blood vessels
When: Fertilization through 2nd month of pregnancy
Significance: Forms into other connective tissue
Characteristics: Irregularly shaped cells, embedded in a
semifluid-like ground substance; delicate reticular fibers

Mucus Connective Tissue (aka.
Wharton's Jelly)

Location: Umbilical Cord of the fetus
Significance: Support
Characteristics: Widely scattered fibroblasts embedded in a viscous, jelly-like substance; contains fine collagen fibers

Fibroblasts

Large flat cells with branching processes. Usually the most
numerous cell. Type will vary depending on the tissue type.
Location: all the general connective tissues
Function: migrate through the connective tissues, secreting
the fibers and certain substances of the ground substance of
the ECM.

Connective Tissue-Macrophages

Definition: A type of WBC, developed from monocytes. They have an irregular shape with short branching projections.
Function: engulf bacteria and cellular debris by phagocytosis

Types of Macrophages

Fixed Macrophages and Wandering Macrophages

Fixed Macrophages (reside in particular tissue)

Examples: alveolar macrophages (reside in
lungs); splenic macrophages reside in the spleen; Kuppfer Cells (liver)

Wandering Macrophages

Have the ability to wander throughout tissue and
gather at sites of infection and inflammation to carry on phagocytosis.

Mast Cells

Location: abundant along blood vessels that supply connective tissue
Function:
1. Produce histamine which causes small blood vessels to dilate in response to inflammatory response, reacting to injury or infection.
2. Bind to, ingest and kill bacteria

Plasma Cells

Small cells that develop from WBC are known
as B lymphocyte
Location: many places; most in connective tissue, especially GI and respiratory tract, salivary glands, lymph nodes, spleen, red
marrow.
Function: Secrete antibodies, proteins that
attach foreign substances in the body

Adipocytes

"Fat cells" are connective tissue cells
that store triglycerides (fats).
Location: deep to the skin & around
organs (heart & kidneys)
Function: storage of triglycerides

Leukocytes consists of

Neutrophils: gather at sites of bacterial infection
Eosinophils: migrate to sites of parasitic invasion and allergic
responses
Lymphocytes: Viral Infections
Monocytes: Blood phagocyte
Basophils: allergic response

Leukocytes

Definition: White Blood Cells
Location: not found in significant numbers in connective tissue,
but will migrate from the blood into connective tissue under certain conditions.
Function: protection from invasion of disease-causing organisms

Erythrocytes

Red Blood Cells: Carries oxygen to tissues

Thrombocytes

Platelets: for blood clotting

Simple Squamous Epithelium

Definition: 1 layer of flat cells
Location: Alveoli of the lungs, Bowman's capsule (kidneys)
Function: Diffusion/Filtration

Simple Cuboidal Epithelium

Definition: 1 layer of cube-shaped cells
Location: renal tubules; ducts
Function: secretion/absorption
Characteristics: very round/plump nucleus and by equal amounts of cytoplasm in the spaces between the nucleus and the plasma membrane on all sides.

Simple Columnar Epithelium

Definition: 1 layer of column-shaped cells
Location: bronchi, uterine tubes, uterus (ciliated); digestive tract, bladder (nonciliated)
Function: Secretion mucus, enzymes; absorption
Characteristics: nuclei are either oval or round; generally line up in a row. Taller than they are wide.

Simple Columnar Epithelium consists of

Non-Ciliated Simple Columnar and Ciliated Simple Columnar

Stratified Squamous Epithelium

Definition: multiple layers of squamous (flat) cells
Location: vagina, esophagus, mouth (non-keratinized); skin (keratinized)
Function: protection
Characteristics: flat nuclei; lipid/waxy material if the skin (keratin)

Stratified Squamous Epithelium consists of

Non-Keratinized Stratified Squamous and Keratinized Stratified Squamous

Stratified Cuboidal Epithelium

Definition: multiple layers of cuboidal cells
Location: ducts/glands
Function: secretion/absorption
Characteristics: round plump nuclei; equal amounts of cytoplasm

Stratified Columnar Epithelium

Definition: multiple layers of columnar
Location: pharynx, male urethra, some glands
Function: secretion/absorption
Characteristics: taller than wide nuclei

Pseudostratified Ciliated Columnar Epithelium

Definition: one layer of columnar cells, that appear to be multiple layers; nuclei are distributed throughout the cell at different levels
Location: Trachea/Upper respiratory tract
Function: Protection; movement of debris/microorganisms out of the respiratory tract.
Characteristics: one layer of columnar cells, that appear to be multiple layers; nuclei are distributed throughout the cell at different levels; contains goblet cells (for secretion of mucus) and cilia (hair-like structures at the surface).

Transitional Epithelium

Definition: Cells change shape depending on the stress on the tissue. The cells change between a cuboidal shape and a more flattened, squamous shape.
Location: Bladder; ureters
Function: Accommodates stress
Characteristics: Located in the apical surface of epithelium; transitional cells more
rounded or dome-shaped.

Areolar Connective Tissue

Location: widely distributed; in/around nearly every body structure. (aka: packing material); subcutaneous layer, just under the skin, papillary regions of the dermis of the skin (superficial); lamina propria of mucus membranes, around blood vessels, nerves and body organs
Function: strength, elasticity, support
Characteristics: random distribution of fibers (reticular, collagen, elastic); contains several types of cells (fibroblasts, macrophages, plasma cells, adipocytes, mast cells, a few WBC) embedded in a semi-fluid ground substance (hyaluronic acid, chondroitin sulfate, dermatan sulfate, keratin sulfate)

Adipose Connective Tissue

Cells derived from fibroblasts (aka. Adipocytes), are
specialized for the storage of triglycerides as a large
central droplet. Cells fill up with a liquid droplet and
push the cytoplasm to the periphery. Weight gain will
allow adipose tissue to increase and new blood
vessels to form.
Location: it will be found locations around areolar
tissue; the subcutaneous layer deep to the skin,
around the heart and kidneys, yellow bone marrow,
padding around joints, behind the eyeball in the eye
socket
Function: reduces heat loss through the skin; energy
production/reserve, supports and protects organs. In
newborns, the BAT generates heat to maintain proper
body temperature.

Reticular Connective Tissue

Fine, interlacing network of reticular fibers (thin form of collagen) and reticular cells
Location: Stroma (supporting framework) of liver, spleen, lymph nodes, red bone marrow, reticular lamina of the basement membrane, around blood vessels and muscles
Function: forms the stroma of organs; binds smooth muscle tissue cells, filters

Dense Regular Connective Tissue

Characteristics: shiny white extracellular matrix; mainly collagen fibers, regularly arranged in bundles with fibroblasts in rows between them.
Location: forms tendons (attach muscle to bone); forms ligaments (attaches bone to bone) and aponeuroses (sheet-like tendons that attach muscle to muscle or muscle to bone)
Function: Strong attachment between various structures; tissue structure withstands pulling (tension) along a long axis of fibers

Dense Irregular Connective Tissue

Characteristics: Collagen fibers; irregularly arranged; a few fibroblasts present; occurs in sheets
Location: occurs in sheets-fasciae (tissue beneath skin and around muscles and organs), reticular(deeper) region of dermis of skin, fibrous pericardium of the heart, periosteum of bone and cartilage, joint capsules, membrane capsules around various organs (kidneys, liver, testes, lymph nodes) also in heart valves
Function: provides tensile (pulling) strength in many directions

Elastic Connective Tissue

Characteristics: predominantly elastic fibers with fibroblasts in between them; unstained tissue is yellow
Location: lung tissue, walls of elastic arteries, trachea, bronchial tubes, true vocal
cords, suspensory ligaments of the penis, some ligaments of vertebrate
Function: allows stretching of various organs; strong ad can recoil to original shape after stretching. Elasticity is important to normal functioning of this tissue (recoil in exhalation) and elastic arteries (recoil between heart beats to help maintain blood flow)

Hyaline Cartilage

Characteristics: glassy, gel-ground substance and appears in the body as a bluish-white shiny substance
Location: most abundant cartilage in the body; at the ends of long bones, anterior ends of ribs, nose, parts of larynx, trachea, bronchi, bronchial tubes, embryonic and fetal skeleton
Function: provides smooth surface for movement at joints, flexibility and support; weakest type of cartilage; can be fractured

Elastic Cartilage

Characteristics: chondrocytes are threadlike network of elastic fibers within extracellular matrix, perichondrium present
Location: lid on top of larynx (epiglottis), part of the external ear (auricle), auditory (Eustachian tubes)
Function: Provides strength and elasticity; maintains shape of certain structures

Fibrocartilage

Characteristics: inflexible and tough; mostly collagen (Type I) fibers and a little Type II; dense whitish, fibrous tissues
Location: Intervertebral discs; pubic symphysis joint
Function: strength/support

Bone Tissue

Location: both compact and spongy bone tissue make up various parts of the bones of the body (compact bone=outside; spongy bone=inside)
Function: support, protection, storage, houses blood-forming tissues; serves as levers that act with muscle tissue to enable movement

Types of Bone Tissue

Compact bone: osteons (Haversian systems) containing lamellae, lacunae, osteocytes, canaliculi and central canals
Spongy bone: thin column of trabeculae, spaces between
trabeculae, filled with red bone marrow

Nervous Tissue

Location: Nervous System
Function: exhibits sensitivity to various types of stimuli; converts stimuli into nerve impulses
(action potentials); nerve impulses to other neurons,
muscle fibers or glands.

Two Principle Types of Cells

Neurons: (nerve cells sensitive to stimuli) [convert stimuli into electrical signals called action potentials]
Neuroglia: (supporting cells)

Skeletal Tissue

Characteristics: long, cylindrical striated fibers
Location: usually attached to bones by tendons
Function: motion, posture, heat production, protection

Cardiac Tissue

Characteristics: branched, striated fibers; usually only one centrally located nucleus, occasionally two.
Location: heart wall
Function: pumps blood to the entire body

Smooth Muscle Tissue

Characteristics: involuntary contraction; non-striated-"smooth"; small spindle-shaped fiber; tapered at each end. One centrally located nucleus.
Location: iris of eyes; walls of hollow internal structures, such as blood vessels, airways to lungs, stomach, intestines, gall bladder, urinary bladder and uterus
Function: Motion (constriction of BV and airways, propulsion of food through the GI tract, contraction of urinary bladder and gall bladder).