Tissues Flashcards
What is a tissue
Groups or layers of similar specialised cells with common function
What are organs
2 or more tissues combined
What do organs consist of
a. Parenchyma: the functional element
b. Stroma: supportive framework
Epithelial tissue definition
Forms outer layer of a body, lines alimentary canal and other hollow structures and makes up glands
Epithelial tissue functions
Secretion, barrier, absorption, protection, transcellular transport, sensing
Epithelial tissue characteristics
Have polarity: portion of the cell exposed to the lumen One or many sheets Highlight cellular Cell to cell contacts Avascular Nerve supply Cells resting on basement membrane
Basement membrane
Made of collagen fibres and glycoproteins
Sits on a bed of loose connective tissue
Anchors epithelium to loose connective tissue
Forms organised scaffold to provide structural support
Simple squamous epithelium
Fast absorption
Diffusion
Make thin membranes
Simple cuboidal epithelium
Absorb nutrients
Produce secretions
Nucleus very circular and central
Simple columnar epithelium
Absorb nutrients
Produce secretions
Nuclei elliptical
Simple epithelium
Simple = one layer thick
Stratified epithelium
Stratified = many stacked layers
Keratinised stratified squamous epithelium
Special features of epithelial tissue
Keratin:
Fibrous structural protein that protects epithelial cells from damage or stress
Extremely insoluble in water and organic solvents
Key structural material making up the outer layer of human skin
Keratin function
Adheres cells to each other
Forms a protective layer on the outside of the skin
Psuedostratified epithelium
Looks like several layers, but is one
Cells connect to the basement membrane
Muscle tissue types and general function
Smooth, skeletal, cardiac
Can contract, highly cellular, highly vascular, contains myofilaments
Skeletal muscle
Striations, nuclei near cell membrane, multiple nuclei per cell, voluntary contraction
Cardiac muscle
striations, intercalated discs, branched, involuntary contraction, uninucleated
Smooth muscle types
Often presents in two different planes
- inner layer of smooth muscle= circular in tranverse section
- outer layer of smooth muscle tissue = longitudinal cut
Smooth muscle function
Fusiform, nucleus central, involuntary contraction, lack striations
Connective tissue characteristics
Very variable type of tissue
Can be vascular or not
Extracellular matrix between cells
Extracellular matrix
Fibres embedded in ground substance
Ground substance mainly tissue fluid
Scaffold between cells
Biochemical support to the surrounding cells
Cell proliferation and differentiation: the two main stages
Immature: blast, undifferentiated, actively mitotic divisions, secretes fibres and ground substance
Mature cell type: cyst, mainly differentiated, less cell divisions
Chondroblast
secrete extracellular matrix in cartilage, differentiate into chondrocytes
Chondrocytes
Function mainly in diffusion of nutrients and other substances and in repair of matrix
Connective tissue functions
Support Protection Insulation Transport Storage
Connective tissue proper
Loose: areolar, adipose, reticular
Dense: regular, irregular
Cartilage
Type of connective
Hyaline
Elastic
Fibrocartilage
Bone
Type of connective
Spongy
Compact
Nervous tissue characteristics
Found in the nervous system: CNS - brain and spinal cord PNS = ganglia Important for communication and control Highly cellular
Neurons
Excitable cells that transmit electrical signals
Glial cells
Supporting cells:
Oligodendrocyte
Astrocyte
