Tissues of the Human BodyTissues: groups of cells closely associated that have a similar structure and perform a related function

HistologyThe study of tissues is

known as Histology.

People who study histology spend a lot of time looking in microscopes at the various body tissues.

4 Types of Tissues1. Epithelial

2. Connective

3. Muscular

4. Nervous

Most organs contain all 4 types

1. Epithelial TissueDescription: coverings (0ne side of epithelial

tissue is always exposed to the outside **which could still be inside the body**)

Location: lining and covering organs and body cavities, the secretory parts of organs and glands, the transport membranes of capillaries and alveolar sacs, and membranes which lubricate organs

Names: according to structure, number of layers, arrangement, and shape

1. Epithelial TissueFunctions

protection – epidermisabsorption – lining of intestinessecretion – ducts of glandsexcretion – epidermis and lining of kidney

capillariesfiltration – lining of kidney capillaries

Epithelial StructuresEpithelium: layers of cells that line the cavity and cover flat surfaces

Basement membrane: Basal Lamina (protein scaffolding) secreted by epithelial cellsReticular Lamina (crossed collagen fiber network) that support and anchor

the epithelium

Connective tissue: supports, connects, or separates different types of tissues

*No blood supply. Nutrients and gases through diffusion.

*Easily regenerates. Sheets of cells quickly regrow.

Microscopy

Here is an example of an epithelial tissue. Note that one side of the tissue is exposed to the outside and the tissue is connected by a basement membrane.

Epithelial tissueBasement membrane

Classes of Epithelia

Simple: just one layer or cell shape

Stratified: multiple layers and cell shapes

Shapes of EpitheliaTYPE CELL SHAPE PICTURE EXAMPLE

Squamous Squashed Endothelium (lines blood vessels)Mesothelium (serous lining of coelem)

Cuboidal Cubed Walls of glands

Columnar Columns*Cilia**Goblet Cells*

Lining of the gut tube; sometimes has cilia

Pseudo-stratified

Flat cells give rise to columns

With cilia in respiratory tubes to move mucous/particles out of lungs.

Transitional

Stretches from 6 to 3 cells thick

Lines urinary structures such as the bladder

Make a chart:Epithelium

TypeLocations in

BodyFunction in

Body

Simple Squamous Epithelium

Squamous cells are flat. From the side they look something like a fried egg.

Simple Cuboidal Epithelium

Secretory and absorptive tissue in glands as well as the liver and kidneys

Simple Columnar Epithelium

The secretory and absorptive lining of the Gastro-Intestinal tract

Stratified Squamous Epithelium

The epidermis of the body’s skin

Stratified Cuboidal Epithelium

Lines ducts

Found in the ducts of mammary glands, sweat glands, salivary glands, and the pancreas

Stratified Columnar Epithelium

Found in the vas deferens and pharynx.

Provides a thicker lining for some tubular structures in the body

Pseudostratified Columnar Epithelium

Located at trachea, bronchi, vas deferens

Help secrete mucus and used for absorption

Looks like it’s stratified, but it’s not.

The nuclei appear to be at different levels, however, there is really only one layer of cells.

TransitionalLooks like stratified

squamous but the cells are rounded at both the base of the tissue and the section exposed to the outside.

Found in the urinary bladder to allow it to expand and contract.

Glandular EpitheliumCan secrete substances into the bloodstream

(endocrine glands) or into ducts (exocrine glands).

Endocrine Glands

Secrete products into the bloodstream

Products are stored in secretory cells or in follicle surrounding secretory cells

Hormones travel to target organs to increase response

No ducts

Exocrine GlandsSecrete their products into a systems of ducts.

Classified by how substances are excreted.Merocrine: release fluid substances via exocytosis

(salivary and sweat glands)Apocrine: lose small portion of the cell body

(mammary and ceruminous glands)Holocrine: releases the entire cell (sebaceous glands)

Other Structures: Goblet Cells

Associated with columnar epithelium.

Secretes mucous.

Other Structures: CiliaAssociated with columnar cells.

Lines respiratory tract.

Works with goblet cells to move substances along the cells. Cilia

Can You Identify the Classes of Epithelium?

A B

C

D

EQuiz!!

2. Connective Tissue Description: support using fibers

Location: universal and most abundant tissue type in body

Functions: • Provide support and protection• Serve as frameworks• Fill spaces• Store fat• Underlies epithelium• Produce blood cells• Protect against infections• Help repair tissue damage

Always originates from mesenchyme (loosely organized undifferentiated mesodermal cells)

Have varying degrees of vascularity from cartilage (avascular) to bone (which has a rich blood supply)

Has non-living extracellular material/matrix (ground substance plus fibers) between its cells

Extracellular Matrix Functions:

medium to dissolve solutes transport site of chemical reaction

Fibers Collagen Reticular fibers Elastic

Ground substance Jelly-like material made of sugar-protein molecules (proteoglycans) Does not include include the fibers

Cells of Connective Tissues

Fibers of Connective Tissues

Connective Tissue Categories

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• Fibrous/Proper Connective Tissue (with semi-fluid ground substance):

• Loose/Areolar connective tissue• Adipose tissue• Reticular connective tissue• Dense (regular and irregular) connective tissue• Elastic connective tissue

• Supporting/Specialized Connective Tissue:• Cartilage• Bone• Blood

Connective Tissue Types

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• Loose Connective Tissue•Composition: fluid to gel-like matrix, fibroblasts, macrophages, collagen and elastic fibers•Location: beneath most epithelia, between muscles•Function: diffusion of nutrients; wrap and cushion organs

Connective Tissue Types• Adipose Tissue

• Composition: Adipocytes (fat cells) and reticular fibers

• Location: beneath skin (subcutaneous layer), behind eyeballs, around kidneys and heart

• Function: Cushions, protects, insulates, energy storage

Connective Tissue Types

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• Reticular Connective Tissue• Composition: collagen fibers, fibroblasts, lymphocytes• Function: supports internal lymphatic organ walls• Location: walls of liver, spleen, lymphatic organs

Connective Tissue Types• Dense Regular Connective Tissue

• Composition: packed collagen fibers, few fibroblasts

• Location: tendons, ligaments• Function: attachment, tensile strength**Poor blood supply (slow healing)

Connective Tissue Types

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• Dense Irregular Connective Tissue• Composition: primarily collagen fibers

randomly arranged• Location: dermis of skin, heart valves &

capsules of organs• Function: tensile strength

Connective Tissue Types• Elastic Connective Tissue

• Composition: elastic fibers, some collagenous fibers, fibroblasts

• Location: walls of large arteries, airways, heart

• Function: attachments between bones

Specialized Connective Tissue:Bone

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• Bone (Osseous Tissue)• Composition: Solid matrix, osteocytes in lacunae• Location: skeleton •Function: supports and protects, forms blood cells, attachment for muscles**Highly vascular= fast healing

Specialized Connective Tissue:

Cartilage

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• Cartilage• Composition: Rigid matrix; chondrocytes in lacunae; poor blood supply• Three (3) types:

• Hyaline Cartilage• Location: ends of bones, nose, respiratory

passages• Function: flexible support

• Elastic Cartilage• Location: external ear, larynx• Function: provide flexibility

• Fibrocartilage• Location: intervertebral discs, pads of knee

and pelvic girdle• Function: shock absorber

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Three (3) types of cartilage:

Hyaline Cartilage Elastic Cartilage

Fibrocartilage

Specialized Connective Tissue: Cartilage

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• Blood• Composition: fluid matrix called plasma; red blood cells; white blood cells; platelets• Location: throughout body in blood vessels; heart• Function: transports, defends (immune system), involved in clotting

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Specialized Connective Tissue: Blood

Epithelial Tissues Quiz Review

http://www.biologycorner.com/anatomy/histology/

3. Muscular Tissue

Function: movement

Types: Skeletal, Cardiac, Smooth

Location: throughout body

Cardiac MuscleStriated (bands perpendicular to length of cell)

Have a single, centrally located nucleus and the muscle fibers branch often

Where two cardiac muscle cells meet, they form intercalated discs containing gap junctions and desmosomes, which bridge the two cells

Cardiac cells are the only cells that pulsate in rhythm…slow contractions and does not tire easily

Can only function under aerobic respiration

Cardiac Muscle

Cardiac Muscle

Smooth MuscleConsists of cells with a single, centrally located nucleic

Cells are elongated/cylindrical with tapered ends and do not appear striated

Smooth muscle lines the walls of the blood vessels and certain organs such as the digestive and urogenital tracts, where it serves to advance the movement of substances

Called involuntary muscle because it is not under direct conscious control…slow and sustained contractions

Possess gap junctions

Mainly functions under aerobic respiration

Smooth Muscle

Smooth Muscle

Skeletal MuscleConsist of long, cylindrical cells that, under a microscope, appear

striated with bands perpendicular to the length of the cell

The many nuclei in each cell (multinucleated cells) are located near the outside along the plasma membrane, which is called the sarcolemma (muscle cell membrane)

Skeletal muscle is attached to bones and causes movements of the body

Because it is under conscious control, it is also called voluntary muscle…rapid contractions with great force and tire easily

No gap junctions present

Can function under aerobic and anaerobic respiration

Skeletal Muscle

Skeletal Muscle

REVIEW

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• General characteristics:• Muscle cells are elongated cells = muscle fibers• Contractile• Three (3) types:

• Skeletal muscle• Smooth muscle• Cardiac muscle

• Skeletal muscle• Attached to bones• Striated, multiple nuclei per cell• Voluntary movement of body

• Smooth muscle• Walls of hollow organs, skin, walls of blood vessels•Non-striated, cells tapered at end, one nucleus per cell•Involuntary movement

• Cardiac muscle • Heart wall• Striated, one nucleus per cell, branched ends with intercalated discs•Involuntary movement

Skeletal Muscle Coverings Endomysium: thin connective tissue covering muscle fiber

Perimysium: coarser fibrous membrane covering bundles of muscle fibers creating a fascicle (bundle of muscle fibers bound together by connective tissue)

Epimysium: tough fibrous connective tissue surrounding many fascicles; outer covering of entire skeletal muscle; blend into tendons or aponeurosis

Tendon: cord of dense fibrous tissue attaching a muscle to a bone

Aponeurosis: fibrous/membranous sheet connecting muscle and the part it moves

Fascia: layers of fibrous tissue covering and separating muscles

Skeletal Muscle Anatomy Myofilament bundles (actin and myosin) Myofibril bundles Muscle

fiber (cell)

Banding pattern: light and dark bands created by the arrangement of myofilaments (thick-myosin, thin-actin) in sarcomeres

Light (I) Bands: contain only actin filaments, parts of two adjacent sarcomeresHas a darker area in the middle, Z disc (midline interruption

between the connections of actin filaments

Dark (A) Bands: consists of actin and myosin; myosin filaments extend the entire length of A band; has a lighter central area, H zone (H zone has a central line called

M line (protein rods connecting myosin filaments))

Skeletal Muscle Anatomy

4. Nervous TissueFunction: control and communication

Location: brain, spinal cord, nerves

Cells are called neurons

Support cells are called glia

Anatomy of a Generalized Neuron

Cell body: metabolic center (contains typical cell organelles except centrioles—amiotic)

Axon: one per cell; process of neuron, conduct impulses away from the cell body

Dendrites: many per cell; extension of neuron; conduct impulses toward the cell body

Axon hillock: axon arises from this cone-like region of cell body

Axon terminals: 100s to 1000s of brances at terminal end of axon; contains vesicles of neurotransmitters

Collateral branch: branch off of an axon

Synaptic cleft (synapse): separation between axon terminal and next neuron

Myelin: covering of most long neurons; whitish, fatty substance; protects, insulates, and speeds up neural transmission

Anatomy of a Generalized Neuron

Nervous Tissue

Nervous Tissue

Central vs. Peripheral Nervous System

Central Nervous System Consists of: brain and spinal cord

Functions: integrating center (interpret incoming sensory information) and command center (issue instructions based on past experience and current conditions)

4 types of cells: Astrocytes: brace and anchor neurons to capillaries; control chemical

environment in brain by picking up excess ions and recapturing released neurotransmitters

Microglia: phagocytes that dispose of dead brain cells and bacteria Ependymal: help circulate cerebrospinal fluid that fills cavities and forms

protective cushion around CNS Oligodendrocytes: forms myelin sheath; protects and cushions nerves to

speed up nerve transmission speed; produces white matter of brain

Peripheral Nervous System

Consists of: nerves (cranial and spinal) and ganglia (group of nerve cell bodies)

Function: communication lines; linking all parts of the body

Functional Classifications:Sensory/Afferent Division: nerve fibers that carry impulses to

the CNS from receptors located throughout the bodyMotor/Efferent Division: nerve fibers that carry impulses from

the CNS to effector organs bringing about a motor response

2 types of cellsSchwann cells: myelinate axonsSatellite cells: protects and cushions cells of PNS neurons

Practice Tissue Identification

http://www.wisc-online.com/objects/index.asp?objID=AP1402

http://www.gwc.maricopa.edu/class/bio201/histoprc/prac1q.htm

http://teachers.olatheschools.com/~sschultzos/APHistology/EpithelialSlidesPracticeQuizA.pdf

http://spot.pcc.edu/anatomy/PDF/Q3_Tissues.pdf

http://bio.rutgers.edu/~gb102/lab_6/601am-epithelial.html