Transcript Chapter 3 PowerPoint

Cells and Tissues
Chapter 3
Cells
Cells are the smallest living thing.
Membrane
Membranes
The cells connection to the outside world.
Absorption done through membrane.
Microvilli found in places where absorption
takes place.
Membrane Junctions
Where two cells come together.
Tight Junctions – keep things water tight.
Sm. Intestine
Desmosomes – Keeps cells together that
are constantly under mechanical stress.
Skin. Uses protein filaments to increase
stability
Gap Junctions – Allows for passing of
materials from adjacent cells.
Membrane Junctions
Tissues
Group of cells with similar structure and
function
Epithelium (covering), connective
(support), nervous (control), and muscle
(movement).
Nervous Tissue
Nervous Tissue helps to control the body
and pass signals from one organ to
another.
Muscle Tissues
Skeletal muscle – Connected to bones for
voluntary movement. Long striations
Cardiac muscle – tissues of the heart.
Striated like skeletal muscle, but shorter in
length.
Muscle tissues
Smooth muscle – no striations, found in
hollow organs. Stomach, intestines, etc.
Epithelial Tissue
Protection, absorption, filtration and
secretion
Characteristics
– Close together, make sheets
– Apical (free) surface
– Rests on basement membrane (bottom)
– Avascular – no blood vessels, depends on
diffusion for oxygen and food
– Regenerate quickly.
Epithelial tissue
Two types, simple (one layer) vs Stratified
(many layers)
Squamous – flat cells that fit together like
floor tiles, making a flat sheet. Lung and
esophogus tissue
Epithelial Tissue
Cuboidal – thicker then squamous
Columnar – elongated cells
Connective Tissues
Protects, supports, and binds tissues
together.
Characteristics
– Vascularized – most have good blood supply
– Extracellular Matrix – nonliving substances
outside of cells that help perform function
Cells make fibers that hold water, making
connective tissue very durable.
Types of Connective Tissue
Bone – cells surround by an extremely
hard matrix that contains calcium and
collagen.
Types of Connective Tissue
Cartilage – more flexible then bone (matrix
is softer). Mostly collagen, between bones
Types of Connective Tissue
Dense connective tissue – collagen with
fibroblasts. Tendons, ligaments, and
lower skin layers
Types of Connective Tissue
Loose Connective Tissue – softer with
fewer fibers
Areolar Tissue – most abundant, keeps
organs in place as well as stores water
and salts
Adipose tissue – areolar tissue that has
lipid containing cells in it.
Blood
Considered to be connective because it is
a cell (erythrocyte) surrounded by a matrix
(blood plasma).
Fibers in matrix are only visible during
clotting
Tissue Repair
Three levels
– Skin and mucus protect the body from the
outside environment.
– In case of injury, inflammation occurs to help
stop any further damage.
– Regeneration begins to fix broken or lost
tissue
Regeneration
Capillaries open - allows clotting materials
to exit blood stream and enter the wound.
Clotting agents seal the wound and stop
outside invaders from entering the body.
Granulation tissue forms – pink tissue,
mostly capillaries, that bring proteins to the
wound site for regeneration. Bleeds freely
(picking a scab before it is fully healed)
Regeneration
Surface epithelium regenerates –
granulation tissue gives way to brand new
epithelium tissue and scar tissue.
Skin and mucous membranes heal very
nicely, usually no scaring.
Muscle and nervous tissue heal poorly or
not at all.
Tissues over time
During childhood and adolescence the
body is growing and almost all tissues are
multiplying.
After adolescence, this changes.
Some tissues continue to reproduce
normally, skin, intestines etc
Some stops, but can start again. Liver
Some stops completely. heart
Aging
Aging caused by
– Toxins
– Radiation
– Genes (telomeres)
Skin loses elasticity and sags
Bones become porous and weaker
Muscles Atrophy due to lack of use
Neoplasm
Abnormal mass that grows when unneeded, aka
tumor.
Benign – grow in a capsule that does not allow
for cells to migrate, only dangerous if not
removed before it gets so large that it pushes on
important organs.
Malignant – not in a capsule, can Metastasis and
travel around the body. Grows into good tissue
causing functionality problems.