Download - A&P2 Cell Tissue
CELLS & TISSUE
Cells
1600’s: Robert Hooke The Cell Theory
All living things are made up of cells The cell is the basic unit of structure & function of
all living things All cells come from pre-existing cells
Review of Cells
C, O, H, N Interstitial fluid
Made from blood All exchgs bt cells &
blood made thru this fluid
Nucleus Plasma membrane Cytoplasm
Review cont:
Cytosol Mitochondrion Ribosome ER
Smooth rough
Golgi apparatus Lysosome Secretory vesicles Cytoskeleton Centrioles Cilia flagella
Cell Diversity
Connect body parts Fibroblast
Elongated Lies along the cable-like
fibers that it secretes Has lots of RER & GA to
make & secrete protein bldg blocks of these fibers
Erthrocyte (RBC) Carries O2
Concave disc=↑ SA Streamlined = flows easily So much O-carrying
pigment is packed in that all other organelles have been removed to make room
Cells that:
Covers & lines organs Epithelial cells
Hexagonal Pack together well Many intermediat
filaments wc resist tearing when rubbed/pulled
Move organs & body parts Skeletal muscle &
smooth muscle cells Elongated Filled w/ contractile
filaments Shorten Move bones Change size of organs
Cells that:
Store nutrients Fat cells Large & round From lg lipid droplet in
cytoplasm Fight disease
Macrophage (phagocytic cell) Long pseudopods sent out
to infection Has many lysosomes wc
digest infectious microorgs
Cells that:
Gather info & controls body functions Nerve cell
Very long Receives & transmits to other
parts of body Covered w/ lg plasma membr Many rER to make parts of
membr
Are for reproduction Oocyte (f)
Lgst cell Has many copies of all organells
to distribute to daughter cells Sperm (m)
Long, streamlined for “swimming”
Flagellum to propel
Cells that:
Body Tissues Epithelial Tissue
(epithelium) lining, covering &
glandular tissue Glandular epithelium forms
glands Lining & covering epith
covers all free body surfaces Contains versatile cells
intestine
Can form outer layer of skin Almost all subs that
body give/receives must go thru epith
Can dip in to line cavities Functions:
Protection Absoption Filtration Secretion
kidney
Special Characteristics Fit close together, forming sheets Bound together at many pts by
cell junctions (desmosomes & tight junctions)
Has an apical surface (unattached) Slick, smooth, microvilli, cilia
Has a basement membr (lower surface) Secreted by both epithel cells &
connective tissue cells next to it Avascular (lack own blood
supply) Depends on diffusion from
capillaries for nutrients & O2
Easily self regenerates
Classification of Epithelium 2 names First: = number of cell
layers it has Simple epith= one layer Stratified epith=more
than one cell layer Second = describe the
shape of its cells Squamous = flat Cuboidal = cube Columnar = columns
Stratified epith named for apical surface
Simple Epithelia
Thin layer ≠ protection =absorption, secretion, filtration Simple Squamous
Rests on basement layer Air sacs Walls of capillaries
Simple Cuboidal Rests on basement layer In glands and ducts Salivary glands, pancreas, walls of
kidney tubules, surface of ovaries Simple Columnar
Tall Goblet cells
Product lubricating mucus
Entire length of digestive tract (stomach to anus)
Line body cavities open to body exterior = mucosae/mucus membranes
Pseudostratified columnar Rests on basement membr
BUT: some cells shorter than others Nuclei at diff heights False impression that it is stratified
Absorption/secretion Ciliated variety =
lines resp tract Goblet cells traps
dust/debris
Stratified Epithelia More durable = protection
Stratified Squamous Most common strat epith Apical = squamous Basement memb = cub or
col Subject to abuse/friction
Esophagus, mouth, outer skin
Stratified Cuboidal Usually just 2 layers At least apical cells cub
Stratified Columnar Apical cells col Basal cells vary in size
& shape
Both fairly rare Mainly in ducts of lg
glands
Transitional Epithelium Highly modified
stratified squamous epith
Forms lining of only few organs
Urinary bladder, ureters & parts of urethra
Subject to considerable stretching
Basal layer cub or col Apical cells vary
Not Stretched = membr many layered, surface cells rounded/domed
Stretched = (w/urine) epith thins, surface cells flatten & become squamous-like
Allows cells to slip past ea other & chg shape (=transition)
Glandular Epithelium Gland=make & secrete a specific product = secretion 2 Major Types of Glands
Endocrine glands Lose connection to surface (duct) =
ductless All hormones Secretions diffuse directly into blood
vessels Thyroid, adrenals & pituitary
Exocrine Glands Have ducts where
secretion occurs to surface
Sweat & oil glands, liver & pancreas
Both internal & external
Connective Tissue
Connects body parts Everywhere, most
abundant & distributed tissue
Protecting, supporting & binding together other body tissues
Characteristics
Variations in blood supply Most well vascularized
Tendons & ligaments = poor blood supply
Cartilages = avascular = slow to heal
Would you rather break a bone or tear a ligament?
Extracellular Matrix made of many diff types of cells & varying amts of nonliving
substance outside the cells = extracellular matrix
Extracellular Matrix Made by CT then secreted to outside 2 main elements
Structureless ground substance fibers
Ground substance = mostly water plus adhesion proteins (“glue”) and lg charged polysaccharide molecule (will trap water as they intertwine)
Matrix can be very fluid, gel-like, firm, rock hard
Fibers = various types & amts Include: collagen = white, hi tensile strength Elastic = yellow Reticular = fine collagen fibers wc form internal “skeleton”
of soft organs (spleen)
Due to the extracellular matrix, connective tissue is able to form soft packaging
tissue around organs bear weight w/stand stretching w/stand abuse/abrasion
w/c other tissues couldn’t
Variations of connective tissue
One extreme to another Fat tissue = many cells, matrix
is soft Bone & cartilage = few cells,
very hard matrix (strong)
Types of Connective Tissue
Bone (osseous) = bone cells in lacunae (pits) surrounded by very hard matrix matrix contains Ca salts & lg amts of collagen fibers Excellent protection & support
Cartilage =less hard, more flexible only in a few places most common = hyaline cartilage (glassy)
Many collagen fibers in rubbery matrix Forms supporting structures
Larynx Ribs to breastbone Ends of bones at joints
Fetus = mostly hyaline, replaced by bone by birth
Fibrocartilage Highly
compressible Disks bt vertebrae
Elastic cartilage ear
Dense Connective Tissue Main matrix element = collagen fibers (in rows
w/fibroblasts) Forms strong rope-like structures
Tendons (m2b) Ligaments (b2b)
More elastic/stretchy
Lower layer of skin (dermis) = in sheets
Loose CT Softer More cells, fewer fibers (except blood) Areolar tissue
Soft/cobwebby Cushions/protects organs ‘glue’ wc holds organs in their positions Fluid matrix w/all types of fibers Appears to be empty space A resevoir of water & salts for all other cells to get nutrients and dispose of
“wastes”
Adipose tissue Reticular CT
Adipose tissue Fat Mostly oil… pushes
nucleus to one side Beneath skin Insulates/protects Kidneys surrounded Cushions eye in socket For fuel if needed Reticular CT
Interwoven reticular fibers Limited sites: stroma to
support free blood cells in lymph nodes, spleen, bone marrow
Loose connective tissue types Reticular connective tissue
Delicate network of interwoven fibers Forms stroma (internal supporting network) of lymphoid organs
Lymph nodes Spleen Bone marrow
Blood (vascular tissue) Blood cells surrounded by fluid matrix called blood plasma Fibers are visible during clotting Functions as the transport vehicle for materials
Muscle Tissue Function is to produce movement Three types
Skeletal muscle Cardiac muscle Smooth muscle
Muscle Tissue Types
Skeletal muscle Under voluntary control Contracts to pull on bones or skin Produces gross body movements or facial expressions Characteristics of skeletal muscle cells
Striated Multinucleate (more than one nucleus) Long, cylindrical
Cardiac muscle Under involuntary control Found only in the heart Function is to pump blood Characteristics of cardiac muscle cells
Cells are attached to other cardiac muscle cells at intercalated disks Striated One nucleus per cell
Smooth muscle Under involuntary muscle Found in walls of hollow organs such as stomach, uterus, and
blood vessels Characteristics of smooth muscle cells
No visible striations One nucleus per cell Spindle-shaped cells
Nervous Tissue
Composed of neurons and nerve support cells Function is to send impulses to other areas of the body
Irritability Conductivity
Tissue Repair (Wound Healing)
Regeneration Replacement of destroyed tissue by the same kind of cells
Fibrosis Repair by dense (fibrous) connective tissue (scar tissue)
Determination of method Type of tissue damaged Severity of the injury
Events in Tissue Repair
Capillaries become very permeable Introduce clotting proteins A clot walls off the injured area
Formation of granulation tissue Growth of new capillaries Rebuild collagen fibers
Regeneration of surface epithelium Scab detaches
Regeneration of Tissues
Tissues that regenerate easily Epithelial tissue (skin and mucous membranes) Fibrous connective tissues and bone
Tissues that regenerate poorly Skeletal muscle
Tissues that are replaced largely with scar tissue Cardiac muscle Nervous tissue within the brain and spinal cord
Developmental Aspects of Tissue
Epithelial tissue arises from all three primary germ layers Muscle and connective tissue arise from the mesoderm Nervous tissue arises from the ectoderm With old age, there is a decrease in mass and viability in
most tissues