Chapter 5 - Tissues Flashcards
In complex organisms, cells are organized into…?
Tissues
Tissue
group of similar cells with a common function
Histology
the study of Tissues
What are the 4 major types of Tissues in the body?
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
Epithelial tissue
- Cover organs and body surface
- Line cavities and hollow organs
- Make up glands
- Have a free surface on outside, and basement membrane on inside
- Lack blood vessels (avascular), and nutrients diffuse to epithelial
tissue from underlying connective tissue - Cells readily divide; injuries heal rapidly
- Cells are tightly packed
Cell Shapes
Squamous - flat
Cuboidal - cube-shaped
Columnar - tall
Cell Layers
simple (one layer of cells), stratified (2 or more layer of cells), or
pseudostratified (appears layered, but is not)
Simple squamous epithelium:
- Single layer of thin, flat cells
- Substances pass easily through air sacs (alveoli) and capillaries
- Thin and delicate, can be easily damaged
- Found in diffusion and filtration sites
- Makes up walls of air sacs (alveoli) and capillaries
- Lines blood and lymphatic vessels
Simple cuboidal epithelium:
- Single layer of cube-shaped cells
- Secretion and absorption
- Lines kidney tubules, thyroid follicles, ducts of some glands
- Covers ovaries
Simple columnar epithelium:
- Single layer of elongated cells
- Nuclei usually at same level, near basement membrane.
- Sometimes have microvilli, cilia, goblet cells (secrete mucus)
- Secretion and absorption
- Lines uterus, stomach, intestines
Pseudostratified columnar epithelium:
- Single layer, but appears layered
- Nuclei at 2 or more levels
- Cells vary in shape, but all reach basement membrane
- Often has cilia, goblet cells
- Protection from infection
- Lines respiratory passageways
Stratified squamous epithelium:
- Many cell layers; thick
- Protective layer
- Outermost cells are squamous, deeper cells are cuboidal
- New cells produced in deep layers, push older cell toward free
surface - Outer layer of skin, called the epidermis, is keratinized
- Lines oral cavity, vagina, anal canal
Stratified cuboidal epithelium:
- 2 to 3 layers of cube-shaped cells
- More protection than 1 layer
- Lines ducts of mammary, sweat, and salivary glands, and
pancreas
Stratified columnar epithelium:
- Several layers of cells
- Top layer of elongated cells
- Cube-shaped cells in deeper layers
- Lines part of male urethra, ducts of exocrine glands
Transitional epithelium(uroepithelium):
- Many cell layers
- Cube-shaped and elongated cells
- Changes shape and appearance with increased tension;
stretches - Forms barrier and lining that can expand
- Lines urinary bladder, ureters, and part of urethra
Glandular Epithelium:
Composed of cells that produce and
secrete substances into ducts or body fluids
What are the 2 types of Glands in the body?
Endocrine Glands
&
Exocrine Glands
Endocrine glands
secrete into tissue fluid or blood
Exocrine glands
secrete into ducts that open onto a surface
What are the 2 structural types of Exocrine Glands?
Unicellular
&
Multicellular
Unicellular
Composed of one cell, such as a goblet cell
(secretes mucus)
Multicellular
Composed of many cells; can be simple or
compound; examples: sweat and salivary glands
What are the 3 types of Glandular Secretion?
Merocrine Glands
&
Apocrine Glands
&
Holocrine Glands
Merocrine glands:
Secrete fluid products by exocytosis;
salivary and sweat glands, pancreas
Apocrine glands:
Lose small part of cell during secretion;
mammary and ceruminous glands
Holocrine glands:
Release entire cells filled with product;
sebaceous glands
General characteristics of connective tissues:
- Most abundant tissue type by weight
- Cells are farther apart than epithelial cells
- Contain abundant extracellular matrix between cells, consisting
of protein fibers and a ground substance - Consistency varies from fluid to solid
- Categories:
- Connective tissue proper
- Specialized connective tissues
- Most have good blood supply, so are well-nourished
Functions of connective tissues:
- Bind structures together
- Provide support and protection
- Serve as frameworks
- Fill spaces
- Store fat
- Produce blood cells
- Protect against infections
- Help repair tissue damage
Fibroblasts
- Most common fixed cell
- Large star-shaped cell
- Secrete fibers into extracellular matrix
Macrophages (Histiocytes):
- Usually attached to fibers, but can detach and wander
- Conduct phagocytosis
- Defend against infection
Mast Cells:
- Large cells, widely distributed
- Release heparin to prevent blood clotting
- Release histamine, which causes inflammatory response
Fibroblasts produce what 3 fiber types in connective tissue?
Collagen FIbers
Elastic (Yellow) Fibers
Reticular Fibers
Collagen Fibers
- Thick threads of collagen, the body’s main structural protein
- Great tensile strength and flexible, slightly elastic
- Found in ligaments and tendons
Elastic (Yellow) Fibers:
- Composed of elastin protein; branching
- Can stretch and return to original shape
- Not as strong as collagen fibers
- Found in vocal cords, respiratory air passages
Reticular Fibers:
- Thin, branching fibers of collagen
- Form delicate, supporting networks
- Found in spleen, liver
Connective Tissue Proper:
- Loose connective tissues:
- Fewer collagen fibers than dense tissues
- Types: Areolar, Adipose, Reticular
- Dense connective tissues:
- Contain abundant collagen fibers
- Types: Dense regular, Dense irregular, Elastic
Specialized connective tissues:
- Cartilage
- Bone
- Blood
Areolar connective tissue:
- Forms thin, delicate membranes
- Cells are mainly fibroblasts, in a gel-like ground substance
- Collagenous and elastic fibers
- In subcutaneous layer
- Beneath most epithelia, where it nourishes nearby epithelial cells
Adipose tissue (fat):
- Adipocytes store fat
- Push their nuclei to one side
- Crowd out other cell types
- Cushions and insulates
- Beneath skin (subcutaneous layer), behind eyeballs, around heart and
kidneys, in spaces between muscles
Reticular Connective Tissue:
- Composed of network of thin reticular fibers
- Supports walls of internal organs
- Walls of liver, spleen
Dense Regular Connective Tissue:
- Closely packed collagenous fibers
- Fine network of elastic fibers
- Most cells are fibroblasts
- Very strong, withstands pulling
- Binds body parts together
- Tendons, ligaments, dermis
- Poor blood supply; slow to heal
Dense Irregular Connective Tissue:
- Randomly organized, thick, interwoven collagenous fibers
- Can withstand tension exerted from different directions
- Dermis of skin
- Around skeletal muscles
Elastic Connective Tissue:
- Abundant yellow elastic fibers, and some collagenous fibers
- Fibroblasts
- Attachments between bones of spinal column
- Walls of hollow organs, such as large arteries, airways
- Parts of heart
- Elastic quality, stretches
Specialized Connective Tissues:
- Cartilage, bone and blood
- Have unique matrix with specialized cells
Cartilage
- A rigid, specialized connective tissue
- Support, framework, attachments
- Protection of underlying tissue
- Models for developing bone
- Matrix contains collagen in gel-like ground substance
- Chondrocytes (cartilage cells) in lacunae (chambers), surrounded by
matrix - Lacks blood supply; heals slowly
What are the 3 types of Cartilage?
Hyaline, Elastic, and Fibrocartilage
Hyaline cartilage:
- Most common type
- Fine collagen fibers in matrix
- Ends of bones in joints, nose, respiratory passages, embryonic
skeleton
Elastic cartilage:
- Flexible, due to elastic fibers in matrix
- External ear, larynx
Fibrocartilage
- Very tough, due to many collagen fibers
- Shock absorber
- Intervertebral discs, pads (menisci) of knee, and pelvic girdle
Bone (Osseous Tissue):
- Most rigid connective tissue
- Solid matrix, composed of mineral (Ca) salts and collagen
- Supports structures
- Protects vital structures
- Produces blood cells
- Stores and releases Ca, P
- Attachment sites for muscles
- Forms skeleton
- Contain osteocytes (bone cells) in lacunae
What are the 2 types of bone (Osseous Tissue)?
Compact and Spongy
Compact Bone:
- Osteoblasts deposit matrix in lamellae (layers)
- Lamellae occur in rings around central canals
- Osteocytes + matrix + central canal form cylindrical units called
osteons - Osteocytes send out processes into canaliculi, and share blood
supply
Osteons
- Osteons are cemented together to form compact bone
- Central canals contain blood vessels; bone is well-nourished, heals
more quickly than cartilage
Spongy Bone:
- Makes up interior part of bone
- Consists of bony plates containing osteocytes, with space between
them for marrow - Lighter in weight than compact bone
Blood
Formed elements (cells and fragments) suspended in fluid
matrix called plasma
Transports substances around body
3 Types of formed elements:
- Red blood cells transport gases
- White blood cells defend again infection
- Platelets help in blood clotting
What are Membranes?
Membranes are sheets of cells. Epithelial membranes are composed of
epithelial and connective tissue; cover body surfaces and line cavities
What are the 3 types of Epithelial membranes? CHECK THIS ONE IN THE POWERPOINT
Serous Membranes
Mucous Membranes
Cutaneous Membranes
Synovial Membranes
Serous membranes:
- Line body cavities that do not open to outside of body
- Inner linings of thorax and abdomen; covers organs
- Simple squamous epithelium + areolar connective tissue
- Secrete serous fluid for lubrication, reducing friction
Mucous membranes:
- Line cavities and tubes that open to the outside of body
- Lining of digestive, respiratory, urinary, and reproductive tracts
- Epithelium + areolar connective tissue
- Goblet cells secrete mucus
Cutaneous membranes:
- Covers body surface
- Commonly called skin
- Part of integumentary system
Synovial membranes:
- Different from epithelial membranes
- Composed entirely of connective tissue
- Line joint cavities
General Characteristics of Membranes:
- Excitable; respond to nervous stimulation
- Muscle cells are also called muscle fibers
- Contractile; can shorten and thicken
3 types of muscle tissue:
skeletal, cardiac, and smooth
Skeletal muscle tissue:
- Attached to bones
- Striated
- Voluntary
- Long, cylindrical, multinucleated cells
- Stimulated by nerve cells
Smooth muscle tissue:
- Non-striated
- Spindle-shaped fibers
- Walls of hollow organs and blood vessels
- Involuntary
Cardiac muscle tissue:
- Only in wall of heart
- Branching cells
- Involuntary
- Striated
- Intercalated discs, specialized intercellular junctions
Nervous tissues:
Found in brain, spinal cord, peripheral nerves
Neurons
- Main cells, which are specialized for communication, via
conduction of nerve impulses (sensory reception, motor
control) - Coordinate, integrate, and regulate body functions
- Composed of cell body (soma), dendrites, and an axon
Neuroglia
Cells that support and nourish neurons
