Primary Tissues Flashcards
Process of differentiation
- Expression of different gene subsets –> different protein expression
- Affects structure & function
Originator cell
Stem cell - first cell in the differentiation process
Define tissue
A group of specialised cells with a distinct function
Define organ
A group of specialised organs with a certain function
4 body tissues
- Epithelia
- Connective tissue
- Muscle
- Nervous tissue
Define epithelia
Covers and lines surfaces and body cavities - enclosing a sheltered environment
Define connective tissue
Fibrocollagenous tissue - consists of fibres, cells & extracellular matrix
Define muscle
Contractile tissue - contracts under voluntary or involuntary control
Define nervous tissue
Collects, processes and sends info through neuron network –> to create a response
Functions of epithelia x4
- Secretion
- Absorption
- Transport
- Protection
4 epithelial junctions & their function
- Tight junctions –> sealing
- Desmosomes –> strengthens cell links
- Gap junctions –> small molecules can pass between cells
- Adherens junctions –> connection linking actin
Burns
- what
- dangers
- Loss of skin barrier function
- Infection, fluid loss
Basement membrane
- features x2
- Proteins –> links to surface of epithelial cells
- Filamentous proteins –> strength
Neurons
- structure x3
- function
- elongated cells
- dendrites –> basal, collect info
- axon –> apical, single digital output
- secrete neurotransmitters by exocytosis
Myelination - in PNS
Schwann cells wrap around neurones to produce the fatty sheath
Myelination - in CNS
Oligodendrocytes (glial cells) produce the fatty sheath
4 types of glial cells
- Schwann cells
- Satellite cells
- Astrocytes
- Microglial cells
Astrocytes
- what
- function
- white vs grey matter
- Star-like fibular proteins
- Metabolic support –> attach to & maintain endothelium
- Grey = ‘blobby’, white = more strung out
Microglial cells
- what
- function
- Macrophage
- Engulfs pathogens, synapses, dead cells etc.
3 types of muscle
- Skeletal
- Cardiac
- Smooth
Skeletal muscle
Striated, multinucleate, coordinated contraction = mostly voluntary.
Fibres have peripheral nuclei
Cardiac muscle
Striated, coordinated contraction, involuntary, branched Junctions - e.g. intercalated discs Central nuclei (as wide as cell)
Smooth muscle
Non-striated, coordinated contraction, involuntary, spindle shaped –> hard to see cell boundaries
Not much cytoplasm
Central nuclei
Examples of connective tissue x4
- Cartilage
- Bone
- Teeth
- Adipose tissue
2 functions of fibrocartilagenous / fibrocollagenous tissue
Packing, support tissues e.g. around organs
3 types of fibrocartilaginous tissue
- Loose
- Dense
- Reticular
Structure - loose connective tissue x3
- Lots of cells
- Collagen
- Spaces occupied by proteoglycans
Structure - dense connective tissue x3 (& example)
- Packed
- Collagen
- Less spaces
- e.g. tendons
Structure - reticular connective tissue x2 (& example)
- Soft framework
- Support
- e.g. liver
Cells in fibrocartilaginous tissue (& their function) x4
- Fibroblasts –> make collagen
- Macrophages –> phagocytose
- Mast cells –> synthesise histamine
- Plasma cells –> synthesise antibodies
Cartilage
- function
- 3 types
- Flexibility, smooth joint movement
- Elastic, hyaline, fibrocartilage
Elastic cartilage
Flexible (as contains elastin)
Hyaline cartilage
- Low friction, durable
- Contains chondrocytes & lots of cytosol
Fibrocartilage
Strong (as contains collagen)
Adipose tissue - white fat
- structure
- function x2
- One lipid droplet occupies most of the cell
- Stores energy
- Releases leptin
Adipose tissue - brown fat
- structure
- function
- Contains multiple fat globules
- Generates heat (instead of ATP)
Dorsal horn cells
- what
- structure x2
- function
- Biggest neurons
- V long processes
- Satellite cells around edge
- Proprioception (detecting position in space)
Axons vs dendrites
- Axons contain less organelles
- Axons stay the same size –> dendrites decrease away from the cell
Axon hillock
- appearance in histology
- function
- Paler - as lacks Nissl substance
- Axon potential generation
Myelin & histology
- Rapid freezing used (not embedding) - as myelin is rich in membrane
Structure - fibroblasts x2
- Lots of rER (for secretion of fibrous proteins)
- At surface, processes = continuous w fibres
Structure - macrophages x1
Derived from monocytes = differentiated into phagocytes
Structure - mast cells x1
Contain granules (modified secretory lysosomes) –> contain histamine, heparin
Structure - plasma cells x3
- B cell lymphocytes
- Small round nucleus w a lot of cytoplasm
- Have differentiated to be antibody-secreting
Structure - adipose tissue x2
- Originate from fibroblast-like precursors
- Accumulate lipid droplets –> therefore, thin cytoplasm
