BIO 214 UWEC Lecture C5

50 trillion

How many cells are in the human body?

histology

Microscopic anatomy-study of tissues and how they are arranged

Tissue

a group of similar cells working together to perform a specific role in an organ

Matrix

Extracellular material

Fibrous proteins, ground substance

The matrix is composed of

ectoderm, mesoderm, endoderm

3 primary germ layers

Ectoderm

(Outer) gives rise to epidermis and nervous system

Endoderm

(Inner) give rise to mucus membrane lining digestive and respiratory tracts.

Mesoderm

(Middle) becomes gelatinous tissue called mesenchyme, bone, blood, muscle

longitudinal section

Tissue cut on its long axis

cross section

tissue cut perpendicular to long axis of organ

Oblique section

Tissue cut at angle between cross and longitudinal sections

epithelia

sheets of closely adhering cells, one or more cells thick

avascular

no blood vessels

protection, absorption, filtration, secretion, sense stimuli

functions of epithelial tissue

basement membrane

layer between an epithelium and underlying connective tissue

basal surface

surface of epithelial cell facing the basement membrane

apical surface

surface of epithelial cell that faces away from the basement membrane

simple epithelium

single layer of cells

stratified epithelium

several layers of cells

alveoli, glomeruli, endothelium, and serosa

location of simple squamous epithelium

goblet cells

wineglass-shaped mucus-secreting cells in simple columnar and pseudostratified epithelia

lining of GI tract, uterus, kidney, uterine tubes

location of simple columnar epithelium

liver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules

location of simple cuboidal epithelium

respiratory tract and portions of male urethra

location of pseudostratified epithelium

stratified squamous

most widespread epithelium in the body

desquamation/exfoliation

when cells flake off and die

keratinized

found on skin surface, abrasion resistant

locations: epidermis, palms, soles

nonkeratinized

lacks surface layer of dead cells

locations: tongue, oral mucosa, esophagus, vagina

cell junctions

connections between two cells

tight junctions

linkage between two adjacent cells by transmembrane cell-adhesion proteins

Gap (communicating) junctions

formed by ring-like connexons

glands

cell or organ that secretes substances for use elsewhere in the body or releases them for elimination from the body

secretion

product useful to the body

endocrine glands

have no ducts; secrete hormones directly into blood

exocrine glands

maintain their contact with surface of epithelium by way of a duct

capsule

connective tissue covering of exocrine gland

stroma

connective tissue framework of the gland

parenchyma

cells that preform the task of synthesis and secretion

serous glands

- Produce thin, watery secretions
- Perspiration, milk, tears, digestive juices

mucous glands

Produce glycoprotein, mucin, which absorbs water to form mucus

mixed glands

Contain both serous and mucous cell types and produce a mixture of the two types of secretions

Apocrine

lipid droplet covered by membrane and cytoplasm buds from cell surface

merocrine

(used by eccrine glands) uses vesicles that release their secretion by exocytosis

holocrine secretion

cells accumulate a product until they disintegrate

The cutaneous membrane (skin)

largest membrane in the body

Mucous membrane (mucosa)

lines passages that open to the external environment (example: digestive tract)

serous membrane (serosa)

Simple squamous epithelium resting on a layer of areolar tissue
Produces serous fluid that arises from blood
Covers organs and lines walls of body cavities
Endothelium lines blood vessels and heart
Mesothelium lines body cavities (pericardium, peritoneum, and pleura)

Hyperplasia

cell multiplication

hypertrophy

enlargement of preexisting cells

Neoplasia

development of a tumor

blood

the only tissue type that is a liquid at room temperature

Differentiation

development of more specialized form and function by unspecialized tissue
Example: embryonic mesenchyme becoming cartilage and bone

Metaplasia

Changing from one type of mature tissue to another
Simple cuboidal tissue of vagina before puberty changes to stratified squamous after puberty
Pseudostratified columnar epithelium of bronchi of smokers to stratified squamous epithelium

stem cells

undifferentiated cells that are not yet performing any specialized function
Have potential to differentiate into one or more types of mature functional cells

developmental plasticity

ability of a stem cell to give rise to a diversity of mature cell types

totipotent

have potential to develop into any type of fully differentiated human cell including accessory organs of pregnancy

Pluripotent

can develop into any type of cell in the embryo (but not accessory organs of pregnancy)
Source—cells of inner cell mass of embryo (blastocyst)

Multipotent

Adult stem cells—undifferentiated cells found in mature organs

Some are ________________________ —able to develop into two or more cell lines (example: bone marrow stem cells)

Some are unipotent—produce only one cell type (example: cells giving rise to sperm)

induced pluripotent stem cells

Start as a multipotent stem cell, reprogrammed to mimic a pluripotent stem cell.

Regeneration

replacement of dead or damaged cells by the same type of cell as before Examples: repair of minor skin or liver injuries

Fibrosis

replacement of damaged cells with scar tissue
Scar holds organs together, but does not restore function
Examples: repair of severe cuts and burns, scarring of lungs in tuberculosis

Histamine

first stage of skin healing: Mast cells and damaged cells release__________

blood vessels

second stage of skin healing: Histamine dilates_________ and makes capillaries more permeable

antibodies, clotting protiens

third stage of skin healing: Blood plasma seeps into the wound carrying______

blood clot forms

4th stage Knits edges of cut together
Inhibits spread of pathogens

phagocytize

5th stage Macrophages _______ and digest tissue debris

capillaries

6th stage: New ______ sprout from nearby vessels

granulation tissue

7th stage: Deeper portions of clot become infiltrated by capillaries and fibroblasts
Transform into soft mass called__________ ________
Macrophages remove the blood clot
Fibroblasts deposit new collagen
Begins 3-4 days after injury and lasts up to 2 weeks

atrophy

shrinkage of a tissue through loss in cell size or number

neorosis

pathological tissue death due to trauma, toxins, or infections

infraction

sudden death of tissue when blood supply is cut off

gangrene

tissue necrosis due to insufficient blood supply (usually involves infection)

Apoptosis

programmed cell death

less space

Connective tissue—a diverse, abundant type of tissue in which cells occupy _______________than matrix

functions of connective tissue

connecting organs, support, physical protection, immune protection, movement, storage, heat production, transport

tendons and ligaments

Connecting organs: this function of connective tissue occurs where?

bones and cartilage

support: this function of connective tissue occurs where?

cranium, ribs, sternum

physical protection: this function of connective tissue occurs where?

white blood cells attack foreign invaders

immune protection: this function of connective tissue occurs where?

bones provide lever system

Movement: this function of connective tissue occurs where?

fat, calcium, phosphorus

storage: this function of connective tissue occurs where?

metabolism of brown fat in infants

heat production: this function of connective tissue occurs where?

blood

transport: this function of connective tissue occurs where?

Fibroblasts

fibrous connective tissue cell: produce fibers and ground substance of matrix

Macrophages

fibrous connective tissue cell: phagocytize foreign material and activate immune system when they sense foreign matter (antigens)

Leukocytes

fibrous connective tissue cell: white blood cells
Neutrophils attack bacteria
Lymphocytes react against bacteria, toxins, and other foreign agents

plasma cells

fibrous connective tissue cell: synthesize antibodies (proteins)
Arise from lymphocytes

mast cells

fibrous connective tissue cell: often found alongside blood vessels
Secrete heparin to inhibit clotting
Secrete histamine to dilate blood vessels

Adipocytes

fibrous connective tissue cell: store triglycerides (fat molecules)

collagenous fibers

Fibers of fibrous connective tissue: Collagen is most abundant of the body's proteins—25%
Tough, flexible, and stretch-resisant
Tendons, ligaments, and deep layer of the skin are mostly collagen
Less visible in matrix of cartilage and bone

reticular fibers

Fibers of fibrous connective tissue: Thin collagen fibers coated with glycoprotein
Form framework of spleen and lymph nodes

elastic fibers

Fibers of fibrous connective tissue::
Thinner than collagenous fibers
Branch and rejoin each other
Made of protein called elastin
Allows stretch and recoil

Glycosaminoglycans

Ground substance of fibrous connective tissue
Usually has a gelatinous to rubbery consistency

random

Fibers run in ______________ directions

Mostly collagenous, but elastic and reticular also present

areolar tissue

Nearly every epithelium rests on a layer of ____________

reticular tissue

Mesh of reticular fibers and fibroblasts
Forms supportive stroma (framework) for lymphatic organs
Found in lymph nodes, spleen, thymus, and bone marrow

parallel, muscles

Dense regular connective tissue

Densely packed, ______________ collagen fibers

Compressed fibroblast nuclei

Elastic tissue forms wavy sheets in some locations

Tendons attach ______________ to bones and ligaments hold bones together

unpredictable

Dense irregular connective tissue

Densely packed, randomly arranged, collagen fibers and few visible cells

Withstands ______________ ______________ stresses

Locations: deeper layer of skin; capsules around organs

adipose

______________ tissue (fat)—tissue in which adipocytes are the dominant cell type