Download Chapter 5 Notes Tissues

Chapter 5 Notes
Tissues
Levels of Organization:
Atoms-Molecules-Cells-Tissues-Organs-Organ Systems-Organisms
Tissues- group of cells performing specialized structural and functional roles.
4 Major types of Tissue In Humans:
1. Epithelial Tissue (7 types)
2. Connective Tissue (9 types)
3. Muscle Tissue (3 types)
4. Nervous Tissue
I. Epithelial Tissue
Characteristics:
- covers all body surfaces (inside and out) and major tissue of glands
- forms inner lining of body cavities
- lack of blood vessels but heal rapidly if injured
- tightly packed with little intracellular spaces
- functions as barriers to the outside, secretion, absorption, excretion, and
sensory reception.
A. Simple Squamous Epithelium
- single layer of thin, flattened cells (like floor tile)
- substances move easily through this tissue
ex. Lines air sacs of the lungs where oxygen and carbon dioxide are
exchanged.
- very thin so damages easily
B. Simple Cuboidal Epithelium
- single layer of cube-shaped cells
- covers ovaries and ducts of glands
C. Simple Columnar Epithelium
- single later of elongated cells (longer than they are wide)
- lining of uterus and digestive organs
- because they are elongated, tissue is thick and provides protection
- also secretes digestive fluids
Two types of columnar cells:
microvilli- extensions of the columnar cells to increase surface area for
absorption of nutrients.
goblet cells- flask shaped cells scattered among the columnar cells; secretes a
protective mucus.
D. Pseudostratified Columnar Epithelium
- appear to be stratified or layered but are NOT
- usually have cilia and goblet cells
-
lines the respiratory systems
ex. Mucus is sticky and traps particles of dust and microorganisms; the cilia
move particles upward and out of airway.
E. Stratified Squamous Epithelium
- many layers of cells
- thick layer
- cells reproduce in deep layers and push outward as they grow older
- outer layer of skin (epidermis) and lines mouth cavity, throat, vagina, and
anal canal.
F. Transitional Epithelium
- specialized to respond to increased tension
- forms lining of bladder and passage ways of the urinary system
- also forms a barrier to prevent the contents of the urinary tract from
diffusing out.
G. Glandular Epithelium
- specialized to produce and secrete substances
- occur commonly with columnar and cuboidal epithelia cells and one or more of
these cells constitute a gland.
Exocrine Glands- secrete products into ducts that open into an external or
internal surface
Ex. Salivary glands and mammary glands
Endocrine Glands- secrete into tissue fluid or blood
Ex. Thyroid and Parathyroid Glands
II. Connective Tissue
Characteristics:
- occurs throughout the body
- provides support, fills space, stores fat, produces blood cells, provides
protection against infections, and helps repair tissue damage.
- have a good blood supply and are able to reproduce easily
Major Cell Types:
Resident Cells- called this because they are usually
present in a relatively stable number.
Fibroblasts are included as a resident cell.
- most common type of resident cell
- large cell that is star-shaped
Mast Cells are also included as a resident cell.
- large cells that are spread out in connective tissue and located near blood
vessels
- has something to do with blood clotting and inflammation
Wandering Cells- appear temporarily in tissues in response to an injury
or infection.
Includes several types of white blood vessels.
Macrophages- can be a resident or wandering cell.
- as numerous as fibroblasts
- function is phagocytosis
Major Tissue Fibers:
Collagenous Fibers- thick and thread-like
- composed of collagen
- grouped in long, parallel bundles that are slightly elastic
- great tension strength – capable of resisting considerable pilling force.
Elastic
-
Fiberscomposed of elastin
branched and form complex networks
less strength than colleganous fibers but are very elastic.
stretch and resume their original lengths and shapes
Reticular Fibers- very thin
- composed of collagen
- highly branched and form supporting networks in a variety of tissues
- framework of lymphoid organs
A. Loose Connective Tissue
- forms delicate, thin membranes throughout the body
- binds the skin to the underlying organs
- contains fibroblasts, collagenous fiber, elastic fibers
- lies beneath epithelium where there are numerous blood vessels
B. Adipose
C. Fibrous
-
Tissue (fat)
specialized form of loose connective tissue
found beneath skin and in space between muscles
especially around kidneys, behind eyes, on surface of heart, and around
joints
function: protective cushion for joint and some organs
insulator beneath skin
stores energy in fat molecules
Connective Tissue
contains collagenous fibers and elastic fibers and fibroblasts
very strong, can withstand pulling forces and binds body parts together
Ex: tendons (bones to muscle) and ligaments (bones to bones)
poor blood supply so slow tissue repair
D. Cartilage
- supports parts, provides frameworks and attachments, protects
underlying tissues, and forms structural models for many developing bones
- intercellular material of cartilage is made of collagenous fibers
- chondrocytes- cartilage cells
- lack of direct blood supply and thus slow rate of cell reproduction and repair
3 kinds of cartilage:
1. Hyaline Cartilage – most common type
A. occurs on the end of bones in many joints, in soft parts of nose, and
rings of respiratory passage
B. also plays an important role in development of many bones
2.
-
Elastic Cartilage- more flexible
A. contains numerous elastic fibers
B. provides the framework for the external ears and parts of the larynx
3. Fibrocartilage- very tough tissue
A. contains many collagenous fibers
B. shock absorber for pressure; disks between vertebrae
E. Bone
-
most rigid of the connective tissues
hardness is due to the presence of mineral salts in the inner material
also contains collagen for flexible reinforcement
made of osteocyte cells
Function of bone: structure for body, protects vital organs, point of attachment for
muscles, forms blood cells
F. Blood
-
transporting a variety of substances between the body cells and helps
maintain homeostasis
blood plasma – fluid portion of blood
red blood cells
white blood cells
platelets
G. Reticuloendohelial Tissue
- cells are phagocytic – ingest food and destroy foreign particles
- important in fighting infections
- found in blood, lungs, brain, bone marrow, spleen, liver, and lymph nodes
- most common rreticuloendothelial cell is the macrophage
III.
Muscle Tissue
Characteristics:
- are contractile (cells can change shape by becoming shorter and thicker)
- basic cell is called muscle fibers
3 Types of Muscle Tissue:
1. Skeletal Muscle Tissue (voluntary muscle tissue)
- found in muscle that are usually attached to bones and can be controlled
by concscious effort.
2. Smooth Muscle Tissue (involuntary muscle tissue)
- lacks striations so called smooth and are shorter than skeletal
- found in the walls of hollow internal organs (stomach, bladder, uterus)
- cannot be stimulated by conscious effort
3. Cardiac Muscle Tissue
-occurs only in the heart
- striated and attached end to end
- controlled involuntarily
IV. Nervous Tissue
Characteristics:
- found in the brain, spinal cord, and peripheral nerves
- basic cell is called nerve cells or neurons
- sensitive to certain types of changes and send nerve impulses in response.