Primary Tissue Types Flashcards
What is a tissue ?
Group of specialised cells with distinct function
What are examples of simple multicellular organisms ?
Hydra and sponges
What are the advantages of cells grouping into tissues ?
- Division of labor and coordinated function for tissues
- Possibility for larger organisms
- Support and motility
- Exploitation of resources (not available to single cells)
What are the steps of differentiation ?
Each cell has genome of 1st cell of embryo –> selective expression and gene silencing (through DNA methylation) yields 100s of difference cell types
What is the role of differentiation programmes ?
To determine levels and pattern of protein expression (determines cell function)
What is asymmetric division ?
Process by which cell gives rises to 2 daughter cells with different contents. Some differentiate (New set of genes/proteins expressed to produce cells with distinct functions) whilst some remain stem cells.
How is gene expression regulated ?
By transcription factors
What are the types of stem cells?
Pluripotent- in early embryo
Tissue specific- in tissue
What are organs ?
Many tissues grouped together
What are the 4 basic body tissues ?
Epithelia, CT, muscle, neural tissue
What are the functions of epithelia ?
Absorption Secretion Transport Selective barrier + Protective barrier Strength and support
Why may burning be dangerous ?
Loss of skin barrier function –> Loss of fluid and possible infection
What are possible surface modifications for epithelia ?
Vili, microvili and cili
What is the role of tight junctions ?
Sealing
What is the role of desmosomes ?
Strengthening cell links
What is the role of adherens junctions ?
Linking movement proteins for movement
What is the role of gap junction ?
Connecting cytosol of adjacent cells
What does the BM of epithelia contain ?
Proteins linking to surface of epithelial cells and
Filamentous proteins providing strength
What is the CNS made up of ?
Brain and spinal chord
What is the PNS made up of ?
“Nerves and ganglia outside brain and spinal chord”
What is the neuron theory ?
Theory that neurons are seperate entities
What are neurons ?
Excitable nerve cells which convey information as action potential
What is the base and the apex of a neuron ?
Base is dendrites. Apex is axons.
Which of dendrites and Axons direct the impulse towards the cell and which away from the cell ?
Dendrites- Towards cell
Axon- Away from cell
What is an internode ?
Portion of Axon between 2 nodes of Ranvier. Covered with myelin sheath
What is a major advantage of myelination ?
Allows for quicker rate of action potential since they are jumping between nodes of Ranvier through saltatory conduction
Where does secretion occur ?
At the Axon end bulb, into the synapse.
What is the difference between PNS myelination and CNS myelination ?
In the PNS, one shwann cell builds one internode.
In the CNS, one oligodendrocyte builds a number of interonodes
What is the function of glial cells ?
Supporting the neurons
What are the glial cells of the PNS ?
Shwann cells (responsible for myelination) Satellite cells (support cells in ganglia)
What are the glial cells of the CNS ?
Oligodendrocytes (responsible for myelination)
Astrocytes
Microglia
Ependyma (lining cells of CNS cavities)
What is the shape and function of astrocytes?
Star shaped
Function includes metabolic and mechanical support, also found in CNS scar tissue
What is the origin and function of microgial cells?
Their origin is hematopoietic stem cells.
They have a function in phagocytosis and antigen presentation
What is the distinctive structural features of all muscle ?
Contain contractile filaments composed of actin and myosin.
What are the three types of muscles ? Are they voluntary ? Are they striated ?
Skeletal (voluntary, striated) BUT reflexes are involuntary
Cardiac (involuntary, striated)
Smooth (involuntary, unstriated)
What is the structure of each kind of muscle ?
Skeletal muscle - Draw it
Cardiac muscle - Structural linkages of myocytes (myocytes found in all three) via intercalated discs
Smooth muscle - Cells are spindle shaped. No striking array of myosin and actin
What is the main feature of connective tissue ?
Mix of cells and ECM
What are the different kinds of fibrocollaginous tissue ? Give examples for each. Which collagen is used in each ?
Loose (around epithelia/organs) Type 1 collagen
Dense (tendons, ligaments) Type 1 collagen
Reticular (liver, lymph nodes) Type III collagen
What are the types of cells found in fibrocollaginous tissue ?
Fibroblasts
Macrophages (phagocytose and present antibodies to stimulate immune cells)
Mast cells
Plasma cells (mature B cells) (synthesise antibodies)
Stem cells
Blood cells
Adipocytes (specialised in storage of fat)
What is the function of cartilage ?
Bring flexibility, smooth joint movement and strength
Is cartilage vascular ?
NO
Is bone vascular ?
YES
Are proteoglycans present in bone ECM ?
Yes
What types of adipose tissue exist ? What are the functions of each
White fat (white adipose tissue), energy storage, insulation and protection, producing adipokines Brown fat (brown adipose tissue), heat production
Which cells are adipocytes derived from ?
Mesenchymal stem cells
What are adipokines ?
Cytokines which send signals to regulate nutritional balance and other systems. E.g leptin
How does brown fat make heat ?
By uncoupling oxidative phosphorylation in mitochondria. Hence, has multiple mitochondria (and multiple globules of fat)
Where is brown fat located ?
In the upper trunk region.
