Chapter 4 Flashcards
Tissue
group of cells with a common embryonic origin in embryo + function together
Layers of Embryonic Germ
- OUTER : Ectoderm — Superficial layer of skin
- MIDDLE: Mesoderm — Mesothelium
- INNER: Endoderm — Endothelium
4 tissue types
Epithelial
Connective
Muscular
Nervous
Epithelial
- covers body surfaces, lines hollow organs / body cavities / ducts
- forms glands
Connective
- protects/supports body + organs.
- bind organs together, store energy reserves as fat,
- provide body with immunity.
Muscular
- Stretch + shorten
- Generates heat ; warms body
Nervous
- detects condition changes inside + outside body
- nerve action potentials/impulses; activate muscular contractions + glandular secretions.
Cell junctions
Points of contact between cells
5 junction types
Tight
Adherens
Desmosomes
Hemideamosomes
Gap
Tight junction
- Hold plasma membrane together
- Prevent harmful chemicals from passing between cells
- Cells of epithelial tissue ; lines stomach, intestines, bladder
Adherens Junctions
- Microfilaments bunch ‘adhesion belt’ create plaque inside plasma membrane
- cadherins — Transmembrane glycoproteins , joins cells
Desmosomes
- contain plaque in disc-like area
- Intermediate filaments (stronger than microfilaments) attach to disc-like area
- Held very tightly together
- Prevent cardiac muscles from separating in contraction
- Keratin — transmembrane protein
Hemidesomosomes
- 1/2 Desmosome — don’t link adjacent cells
- Links cell to protein on basement membrane (below epithelium)
- Only proteins — no cells
- Integrins— transmembrane protein
Gap junction
- Between 2 adjacent cells
- Plasma membranes separated by narrow intercellular gap
- Chemical/electrical communication between neighbours
- Force between proteins
- Small particles + fluid go through cells
- In cardiac muscle + nervous system (electrical communication)
- connexins — membrane proteins
Membranes
flat sheets of pliable tissue that cover or line a part of the body
Epithelial membranes
made of connective tissue + epithelium tissue
Mucous
lines body cavity ; opens directly to exterior
Serous
lines body cavity ; doesn’t open directly to exterior; covers organs in cavity
Cutaneous
lines outer skin; epidermis + dermis
Synovial membranes
only made of connective tissue — lines joints, secretes synovial fluid
Electrical excitability
ability to respond to stimuli by producing electrical signals; travel along plasma membrane due to specific voltage-gated channels
Excitable cells exhibiting electrical excitability
- Neurons
- Muscle fibers
Tissue repair
process that replaces worn out, damaged, or dead cells
Epithelial tissue repair
replaced by division of stem cells
Connective tissue repair
not all cells can repair
Muscle tissue repair
cells perform limited repair
Nervous tissue repair
some cells perform limited repair, others cannot
Fibrosis
formation of scar tissue
Younger bodies generally experience
• A better nutritional state
• A better blood supply to tissues
• A faster metabolic rate
Aging slows process of
Tissue repair
Aging results in
stiffening + loss of elasticity in tissues
Disorders of Epithelial tissues
specific to individual organs, such as ulcers in the stomach
Disorders of connective tissues
in nature, such as lupus
