Lecture 3 - Tissue Basics: Structure and Histology Flashcards
Cellular differentiation
Cells differentiate into cell types by expressing different combinations of proteins
Cellular polarization
Asymmetry in molecular composition or structure between two sides
Ex. The ends of a neuron is different
Organ
Two or more types of tissue working together to perform specific functions
Tissue
A group of similar cells (and their products) working together to perform specific functions
4 main types of tissue and where can they be found?
- Epithelial tissue - covers exposed surfaces. Lines internal passageways/chambers and forms secretory glands
- Connective tissue - fills internal space and provides structural support. Stores energy
- Muscle tissue - contracts to produce movement. It includes skeletal muscle, cardiac muscle, and smooth muscle
- Nervous tissue - conducts electrical impulses and carries information
4 functions of epithelial tissue
- Provide physical protection
- Control permeability
- Provide sensation
- Produce specialize secretions
Epithelium
A sheet of connected epithelial cells attached to a basement membrane
3 basic features epithelial cells share
- They form glands
- They show polarization - they all have an apical surface and a basolateral surface
- Cells within an epithelium are bound to each other in multiple different ways - intercell junctions
Leaky tight junctions
Allow paracellular transport of water and solutes
Tight tight junctions
Do not allow paracellular transport
Simple epithelia and what are the different types?
A single layer of cells with every cell in direct contact with the basement membrane
Squamous - flat and sheet-like
Cuboidal - cube-like
Columnar - column-like - they are taller than they are wide
Stratified epithelia
Contains two or more layers of cells. The shapes are the same as simple epithelia, just layered
Pseudo-stratified
Closely packed cells that appear to be arranged in layers because they’re different sizes, but there’s actually just one layer of cells
4 functions of connective tissue
- Establish a structural framework for the body
- Transport fluids and dissolved material
- Protect organs, tissue (interconnect them too) and body from invading microorganisms
- Store energy, especially in the form of triglycerides
2 categories of connective tissue proper. Give examples in these categories
- Loose: areolar tissue, adipose tissue, and reticular tissue
- Dense: dense regular, dense irregular, elastic
Fluid connective tissue examples
Blood and lymph
2 categories of supporting connective tissues. Give examples in these categories
- Cartilage: hyaline cartilage, elastic cartilage, fibrocartilage
- Bone
Cells types found in loose connective tissue and their functions
Fibroblasts - secrete proteins of the extracellular matrix
Fibrocytes - mature fibroblasts. They maintain the proteins of the extracellular matrix
Mesenchymal cells - stem cells that can divide to replace damaged cells (fibroblasts)
Example of dense connective tissue proper
Tendons
Wandering cells
Can move into or through tissue depending on physiological demands
2 types of fibres found in connective tissue proper
- Collagen fibres - high tensile strength. Not stretchy
- Elastin fibres - elastic
Tissue membrane
A layer of epithelial tissue + underlying layer(s) of connective tissue. They cover body surfaces (inside and out)
Fasciae
Layers of connective tissue that surround organs, providing physical support. Not directly connected to an epithelium
Process of epithelial and connective tissue healing after damage
The epithelium undergoes rapid proliferation, which forms blood clots
Most connective tissue undergoes increased rates of matrix secretion. A scar forms when a dense web of collagen fibres is secreted at the injury site
