Biology A1 - cells, tissues and organs Flashcards
(65 cards)
what is cell differentiation
the development of cells with specialised structure and function from unspecialised precursor cells
what is amoeba
a type of unicellular organism
lives in fresh water and moves by ameboid movement
inhibit top layer of decaying organic material on the bottom of ponds
what are the different categories of tissues
epithelium
connective
muscle
nerve
what is tissue
group of cells with a common structure and function
what is epithelial tissue
a tissue that covers the outside of the body or lines an organ or cavity within the body
what are the types of epithelial tissue and where are they found
1) simple squamous epithelium - lines alveoli in lungs
2) cuboidal epithelium - kidney tubules
3) simple columnar epithelium - lines digestive tract
4) stratified squamous epithelium - skin
5) pseudostratified columnar epithelium - lines trachea
what two sides do polar epithelia have
basal side = closely interacting with other cells
apical side = side exposed to the lumen
what are occluding junctions in epithelial tissue
multiprotein complexes that seal neighbouring cells together to prevent the leakage of water and solutes
eg. tight junctions, anchoring junctions
what are communicating junctions in epithelial tissue
gap junctions - allow molecules to pass through from one cell to another
how are cells in epithelial tissue arranged
tightly packed together
what is epithelial tissue important for
secretion and absorption
what are goblet cells
found within epithelial tissue
specialized epithelial cells that secrete mucus and play a key role in maintaining the body’s mucosal barrier
how are cells arranged in connective tissue
sparsely distributed within an extracellular matrix that may be solid, jelly like or even liquid
connective tissue often contains a web of protein fibres, what are the different types
collagen - strong, non elastic
elastic - made of elastin
reticular - thin and highly branched, reticular fibres serve to join connective tissue to adjacent tissues
what are the different types of connective tissue
loose connective tissue
fibrous connective tissue
bone
adipose tissue
cartilage
blood
what are the different types of muscle tissue
smooth muscle
cardiac muscle
skeletal muscle
what is an intercalated disk
a specialized structure in the heart that connects cardiac muscle cells together, allowing for electrical and mechanical communication between cells
what is a sarcomere
the basic unit of muscle fibre
made of protein filaments
repeated units that make up myofibrils that are bundles of fibres that make up muscle tissue
describe cardiac muscle
location: heart
structure: straited
control: involuntary
power: high
describe skeletal muscle
location: limbs
structure: straited
control: voluntary
power: high
describe smooth muscle
location: gut, blood vessels
structure: non- straited
control: involuntary
power: low
what does it mean if muscle tissue has a straited structure
a muscle that has a striped appearance
what two types of protein filaments make up sarcomeres (muscle tissue)
actin - thin filament
myosin - thick filament
describe the process of muscle contraction (sliding filament model)
results from interactions between actin and myosin filaments
1) The myosin heads, which are energized by ATP, bind to the exposed active sites on the actin filaments, forming cross-bridges
2) Myosin heads pull actin filaments toward the centre of the sarcomere, using energy from ATP.
3) As actin slides over myosin, without changing lengths, leading to muscle contraction
4) New ATP causes myosin to detach from actin, and the cycle repeats as long as calcium and ATP are available.