Tissues, Organs And Systems Flashcards
What holds cells together (4)
Cell adhesion molecules, extracellular matrix proteins (fibres), Internal/external scaffolding, close proximity
Connective tissue
Extracellular matrix plentiful, cells sparse(as full of fibres), matrix is rich in fibres (collagen) direct attachments between cells
Epithelial tissue
Cells tightly bound in sheets (epithelia), no extracellular matrix (just basal lamina underlying) cells attached via adhesions (lots of stress), strong intracellular protein filaments, junctions proteins
Features of connective tissue
Primary cell - mesenchymal stem cells: Interconvert between cell types, produces most of extracellular fibres.
What does mesenchymal stem cell do in culture
Quickly converts to mature fibroblast, allows cells to adhere to plastic/glass surfaces (fibroblasts divide faster than tissue)
Epithelial tissue function
Line cavities and free surfaces of body, tissue barriers, rest on basement membrane - attaches epithelial layer to other tissues
What is an organ
More than 1 type of tissue together
Epithelial adherence systems in lateral surface
Adherens, tight junctions, gap junctions, desmosome, cell adhesion molecules
Epithelial adherence system in basal surface
Focal adhesions, cell adhesion molecules, hemidesmosome, integrins, proteoglycans
Tight junctions
Very top, prevent movement of larger molcules to deeper tissue layers (bladder). In gut can open to allow paracellular transport of small molecules.
Adhesion junctions
1/3 from top, found in pairs, formed from actin, linked to E-cadherin proteins (form bridges). Transport barrier and stabilising factor
Desmosome
Strongest(found in tissues undergoing intense mechanical stress) , 1/2 way down, randomly distributed. Mechanical strength, prevent tissue destruction (only cell to cell in skin)
Gap junctions
Close to base, cardiac and smooth muscle. Allows wave of electrical impulse (contraction) and movement of small molecules
Hemi-desmosome
Basal surface, attach to extracellular matrix. Anchor epithelial cells to basal lamina (via integrins attached to cytokeratin inside cell)
Focal adhesions (basal)
Attach to basal lamina, uses actin and integrins, binds to fibronectin - then binds to collagen
Integrins
Alpha beta dimer, dimers come together (focal adhesion kinase) to form stronger bonds (skin/blastocyst attachment to endometrium)
Mucosal membrane
Lines moist and hollow internal organs of body, secretes mucus (thick), stop pathogens, lubricate, hydrate.
3 examples of mucosal membranes
GI tract, Respiratory tract, Urinary tract
Mucosal membrane layers
Epithelial, lamina propria, muscularis mucosae (submucosa, musclularis externa, serosa)
Oesophagus structure layers
Epithelium - stratified squamous (withstand abrasion). Submucosa - contains mucus secreting glands (goblet cells) Muscularis externa - two layers (circular and longitudinal) allows food to be moved via peristalsis
Stomach layers and structure
Epithelial mucosa - secretes acid, digestive enzymes, Rugae (folds increase SA). Muscularis externa - 3 layers (oblique, circular, longitudinal) allows mixing.
Jejunum
Simple columnar epithelium. Pilcae circulares - folds of mucosa projects into gut lumen
Large intestine
Crypts of lieberkuhn produce lots of mucus, surface epithelia absorb water and electrolytes
Overall GI tract function
Absorb substances, prevent pathogen ingress, move contents and expel water
How is the GI tract modified for its function
Folds of mucosa/ microvilli help substances be absorbed. Peristaltic actions from layers of muscularis externa allow for contents to be moved. Lamina propria connects to lymphatic system allowing prevention of pathogens.
Urinary tract structure - epithelial
Squamous epithelial in bowman capsule, cuboidal in ducts.
Where do muscle layers appear in urinary tract
Ureter and bladder - 2 layers (inner and longitudinal) allowing stability and control
Epithelium in ureter and bladder
Uroepithelium (transitional) - produce mucus(protection from acidic urine) with tight junctions to prevent leakage.
Bladder features
Fat acts as shop absorber, umbrella cells protect epithelium from acidic urine, transitional epithelium flatten when bladder is filled with urine.
Urethra
Similar to bladder, mucus glands produce lots of sticky mucus to protect ingress of pathogens from outside of body.
Urinary tract summary
Similar to GI tract - absorb nutrients, prevent pathogens (especially in lower), remove waste products
Respiratory function and parts
Gas transport and exchange. 2 parts: conducting (nasal to bronchioles) and respiratory(bronchioles to alveoli)
Trachea and primary bronchi mucosa
Epithelial - pseudo-stratified covered in cilia (moves debris and bacteria towards mouth). Lamina propria - thin. Muscularis Mucosae - no longitudinal
Submucosa trachea and primary bronchi
Collagen and elastin fibres (connective tissue layer) seromucous glands (watery mucus secretions that thicken during infection)
C shaped Hyaline cartilage
Two layers - perichondrium(collagen fibres), chrondrogenic (cartilage formed)
Cartilage feature
Cells can interconvert between chrondroblasts and chondrocytes to make hyalin and elastic cartilage
How is Resp tract different to GI and Urinary
No muscularis externa in respiratory
Secretions from Trachea and bronchi
From epithelial and submucosa - mucins (sticky mucus) serum proteins (lubricate) lysozyme (destroys bacteria) anti proteases (inactivate bacterial enzymes)
How is movement of debris aided in trachea
Mucociliary escalator - goblet cells and cilia. Thick basement membrane, lamina propria rich with immune cells, elastic fibres.
Secondary and tertiary bronchi
Similar to primary(pseudostratified, ciliated, seromucous glands) but cartilage is not full circles of rings. Instead crescent shaped to keep airway open
Alveolus structure
Flattened (squamous) specialised epithelial (endothelium), folds in basal lamina allow for expansion when air is drawn in. Connective tissue - Collagen and Elastin fibres allow recoil.
What is definition of tissue
Collection of cells adapted for specific function
4 types of tissue
Epithelial, connective(blood, cartilage, bone, fat), muscle, nerve
What is an organ
Two or more tissues combined to create a structural unit that has a particular function
3 cell types that are not part of organs
Ova, spermatozoa, corpuscles of blood
What cells are derived from ectoderm
In contract with environment - nerve cells, skin.
What cells derived from mesoderm
Muscle and connective tissue
What cells are derived from endoderm
Mucosae - GI tract, respiratory tract
