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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
34
• 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
37
• 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
41
• 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
43
• 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
44
• 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
45
Three (3) types of cartilage:
Hyaline Cartilage Elastic Cartilage
Fibrocartilage
Specialized Connective Tissue: Cartilage
46
• 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
(
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
59
• 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