what are tissues? what is the study of tissues?
Tissue = a group of similar cells with a common function.
The study of tissues = Histology
what are the four major tissue types in the body?
Epithelial tissue
Connective tissue
Muscle tissue
Nervous tissue
what are tissues made up of?
extracellular material AKA the matrix
what do tissues differ in?
Cell size
* Cell shape
* Amount and type of material between cells
* Function
what is the function of epithelial tissue, its location and its distinguishing features?
Functions
Protection
Secretion
Absorption
Excretion
Location
Covers bodies surface
Lines internal organs (formed by sheets)
Forms glands
Distinguishing features
No blood vessels
Cells tightly packed
Rapid division
what is the function of connective tissue, its location and its distinguishing features?
Function:
Provide structural and functional support such as binding and supporting
Protect and fill spaces
Stores fat
Produces blood cells
Location:
Widely distributed
Distinguishing features
usually Good for blood supply
Cells farther apart
Large extracellular matrix
what is the function of muscle tissue, its location and its distinguishing features?
Muscle tissue
Function
Movement
Location
Attached to bones
Walls of hollow organs
Heart
Distinguishing features
Can contract
what is the function of nervous tissue, its location and its distinguishing features?
Function:
Conduct impulses
Regulation
Integration
Sensory reception
Location:
Brain
Spinal cord
Nerves
(dorsal body cavity!)
Distinguishing features
Cells communicate electrically
what makes tissues differ? how does homestasis relate to this?
Tissues differ in the amount and kind of fluid
material between the cells
Homeostasis is The relative constancy of the
internal fluid environment
so basically Tissues differ in the amount and composition of extracellular matrix between their cells, and the matrix helps maintain homeostasis by supporting nutrient exchange and cell signaling.
what is known as “the bodies glue”? why, whats its function and composition like?
the matrix aka the extracellular matrix is known as the bodies glue.
Matrix = material between the cells.
Composition:
Jelly like
Mostly water
Interlocking protein fibers (collagen, elastin, etc)
Function:
1. Provides environment for maintaining homeostasis
2. Provides ions and nutrients support
3. Acts as a scaffold so it organizes and anchors cells
4. Relays chemical signals which control cell division, differentiation, repair, and tissue repair
true or false: connective tissue has a large amount of a matrix and so does epithelial tissue
FALSE! connective tissue does have a large amount of a matrix, but epithelial tissue DOES NOT since there is very little amount of matrix causing the cells to be very tightly packed, providing protection and allowing it to function.
explain why epithelial tissue have very little extracellular matrix
less matrix = more tightly packed cells which allows for protection, absorption, secretion, and forming barriers, and to act as a seal or lining.
what are fibroblasts?
Fibroblasts are the cells found in connective tissues ECM and can produce collagen and other fibers. They play an important part in maintaining the ECM that surrounds them.
how does cancer relate to the ECM and the fibroblasts found there?
Can convert fibroblasts (the cell in connective tissue) → myofibroblasts (which can have the same characteristics of cancer cells) and This promotes migration, allowing cancer spreading aka metastasis
also loosens fibroblast connections, allowing migration of converted fibroblasts and thus spreading cancer
how does liver fibrosis occur?
Liver fibrosis happens when there is excess collagen deposition in the extracellular matrix (ECM). The ECM increases beyond its normal amount (around 3% of the organ), which thickens and stiffens the tissue. This can interfere with normal blood flow through the liver, especially if inflammation continues for a long period of time, and may eventually lead to cirrhosis.
how does heart failure and arthersclerosis relate to the ecm
Excess collagen can stiffen the heart, blocking blood flow too
what two things does epithelial tissue include?
Epithelium
Glands (exocrine and endocrine)
what are general characteristics of epithelial tissue? (again… a little more here) 🙄
Covers organs and body surfaces
Lines cavities and hollow organs
Forms glands
Has polarity
Avascular (no blood vessels)
Tightly packed cells
Rapid regeneration
what holds epithelial tissue closely packed togehter?
Cell Junctions
- Desmosomes along lateral surfaces
- Cells tightly packed
- Provide structural integrity
are epithelial cells polar or nonpolar? what is its characteristics of their structure
Epithelial cells are polar.
They have an apical surface which faces free space (lumen/exterior)
- This may contain microvilli and cillia
They also have a basal surface which is attached to the basement membrane
- This is attached to the protein layer the basal lamina
what are the two main classificaitons of epithelial tissue and describe each
- Cell shape
Squamous
Cuboidal
Columnar
Transitional - Arrangement (layers)
Simple (one layer)
Stratified (multiple layers)
describe the cell shapes of epithelial cells (hint, four of them, briefly describe them)
Squamous
Flat
Scale like
Cuboidal
Cube shaped
Columnar
Taller than wide
Transitional
Very in shape and can stretch
describe what simple squamous epithelium is like (structure, function, locaiton, some characteristics)
Simple (one layer) squamous (flat, scale like) epithelium
Structure:
- single layer, thin, flat cells
Function:
- diffusion and filtration (hence being found in air sacs, capillaries, and blood/lympth vessels)
Location:
- makes up walls of air sacs (alveoli) and capillaries. also lines blood and lympatic vessles.
Characteristics:
- thin and delicate, easily damaged!
describe waht simple cuboidal epithelium is like (structure, function, location)
Structure:
- Single layer, cube shaped cells
Function:
- secretion and absorption
Location:
- Lines kidney tubules, thyroid follicles, ducts of some glands. also Covers ovaries
