cells, tissues and organs

Question 1

the cytoskeleton

Answer 1

Microfilaments (~7nm)
Intermediate filaments (10-15nm)
Microtubules (24nm)
Thick filaments (myosin)

Question 2

microfilaments (cytoskeleton)

Answer 2

• actin
  Forming contractile skeleton in cell, regulating cell shape and tactile activities (villous, movement or pinocytosis…etc).

Question 3

intermediate filaments (cytoskeleton)

Answer 3

• vimentin, cytokeratin
  Attaching organelles to each other and to the cell membrane. Useful in diagnosis as different ones are present in different tissue types e.g vimentin in fibroblasts, cytokeratin in epithelium

Question 4

microtubules

Answer 4

tubulins (a and b)
Functions:
Positioning of organelles and cell shape changes. Used for the centrioles in cell division, cilia formation

Question 5

cell surface specialisations

Answer 5

Extensions of the cell membrane and cytoskeleton:
Cilia (and flagellae): extensions of the microtubule cytoskeleton that actively move
Microvili (and stereocilia): extensions of the actin microfilament cytoskeleton, no active movement

Question 6

microvilli

Answer 6

Microvilli (& stereocillia) - actin core and increased surface area (no active movement)

Question 7

cilia and flagellae

Answer 7

Cilia and (flagellae) have a microtubule core with a specific structure
They actively move, their role is to move things along a surface.

Question 8

centrioles

Answer 8

Centrioles are cylindrical structures, found in animal cells groupings of microtubules arranged in a 9 (triplets) + 0 pattern (like MTOC). They help to organize the assembly of microtubules during cell division

Question 9

tight junctions

Answer 9

Barrier junctions (occluding) prevent the passage of substances between cells
Help maintain position of membrane proteins (polarity)

Question 10

adherens junctions

Answer 10

Structural junctions attach cells to each other and to the cytoskeleton: zonula adherens (actin) and desmosomes (intermediate fillaments)

Question 11

hemidesmosomes

Answer 11

Anchoring junctions – to attach epithelia to the basement membrane and hence to the tissues beneath e.g. skin
Made of integrins, laminin collagen

Question 12

gap junctions

Answer 12

For direct communication between adjacent cells
Allow passage of ions, amino acids, sugars, second messengers, metabolites
Permits co-ordinated cell activity (coordinates heart, muscle etc)
Made of connexins which assemble into connexons

Question 13

cells to systems

Answer 13

Cell = basic unit of living organism
Simple tissue = collection of similar cells
Compound tissue = mix of cells & ECM
Organ = Distinct group of (several) tissues
System = group of organs with distinct role

Question 14

tissues

Answer 14

cells are arranged into tissues.
A collection of similar cells +/- support cells
Where do they come from? The 3 embryonic primary germ layers
The 4 basic tissue types are: 
Epithelium
Connective tissue 
Muscle
Nerve

Question 15

ectoderm

Answer 15

Nervous tissue; lens; skin -
epidermis and derivatives;
linings of oral, nasal, vaginal
and anal cavities; pituitary
gland; adrenal medulla

Question 16

mesoderm

Answer 16

Muscle; connective tissue;
skin - dermis; blood vessels
and lymphatics; internal
reproductive organs;
kidneys and ureters;
adrenal cortex

Question 17

endoderm

Answer 17

Epithelium of pharynx,
auditory tubes, tonsils,
thyroid and parathyroid,
thymus, larynx, trachea, lungs,
digestive tract, bladder,
urethra and vagina; liver
and pancreas

Question 18

organs

Answer 18

Organs are composed of elements of some or all of the 4 main tissue types
Organs are distinct groups of (several) tissues, arranged to suit the function of the organ

Parenchyma: cells that perform the main function
Stroma: support cells including connective tissue, blood vessels, nerve