Cells, tissues & organs Flashcards Preview

ESA 1 - Body Logistics > Cells, tissues & organs > Flashcards

Flashcards in Cells, tissues & organs Deck (32)
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1
Q

Give examples of cells that exist independently.

A

Spermatozoa
Ova
Blood cells

2
Q

What is tissue?

A

Collection of cells woven together.

3
Q

What are the 4 basic types of tissue?

A

Epithelial
Muscle
Nerve
(General) Connective

4
Q

What are the 6 types of specialised connective tissue?

A
Adipose
Lymphatic
Blood
Haemopoietic 
Cartilage
Bone
5
Q

What are organs and how many do we have in total?

A
  • Association of at least 2 types of tissue.

- 78

6
Q

What are systems and how many do we have?

A
  • A group of tissues and organs working together to complete a task.
  • 11
7
Q

Name the 11 body systems.

A
  1. Integumentory
  2. Cardiovascular
  3. Respiratory
  4. Digestive
  5. Reproductive
  6. Urinary
  7. Skeletal
  8. Endocrine
  9. Nervous
  10. Muscular
    11.
8
Q

How can we separate cells from tissues/organs?

A

Using:

  • collagenase
  • microdissection

Cells are then cultured in Petri dishes/flasks and grown in an incubator.

9
Q

Why is it difficult to culture individual cells?

A

Need to:

  • provide nutrients
  • control pH, temperature and oxygen
  • prevent bacterial contamination
10
Q

What are the cons of cultured cells (despite being a valuable research tool)?

A
  1. Behave and look different to the same cells in tissues.
  2. Demonstrate contact inhibition.
  3. Have a limited lifespan (senescence).
11
Q

What are the 4 main types of junctions mediating cell-cell adhesion (lateral domain)?

A
  1. Tight junctions
  2. Desmosomes
  3. Gap junctions
  4. Adherens junctions
12
Q

What are tight junctions and what is their function?

A
  • Fusion of plasmalemma of neighbouring cells.
  • Functions:
    ~ Seal: prevents movement of molecules between 2 cells.
    ~ Selective barrier for products
  • Location: intestinal epithelium
13
Q

What are desmosomes and what is their function/location?

A
  • Proteins that connect intermediate filaments of neighbouring cells.
  • Function: firmly adhere and strengthen the bond between cells.
  • Location: between epithelial cells that need to withstand physical stress (e.g. Skin). Found just under/next to tight junctions.
14
Q

What are adherens junctions?

A

Proteins that connect actin filament bundles in neighbouring cells.

15
Q

What are gap junctions and what is their function?

A
  • Connexon proteins form small channels that allow ions and small molecules to migrate between cells.
  • Functions: cell-cell communication and coordination (allow passage of small water-soluble molecules).
16
Q

What is cell attachment to the basement membrane mediated by?

A
  1. Hemidesmosomes

2. Focal adhesions

17
Q

What are hemidesmosomes and where are they found?

A
  • Anchor intermediate filaments in cells to the basement membrane.
  • Found in tissues subject to abrasion, e.g. Skin, oral cavity.
18
Q

What are focal adhesions and in what process are they important ?

A
  • Anchor intracellular actin filaments to the basement membrane.
  • Play a prominent tole in cell movement such as migration of epithelial cells in wound repair.
19
Q

What are the 2 main functions of integrins?

A

Transmembrane proteins that?
1. Attach the cell cytoskeleton to the ECM (sense whether adhesion has occurred).
2. Signal transduction from the ECM to the cell.
Also involved in a wide range of other biological activities, inc. immune patrolling and cell migration.

20
Q

What causes necrosis?

A

Physical disruption to the cell through injury, bacterial toxins or nutritional deprivation.

21
Q

Describe 3 characteristics of cell death by necrosis.

A

Cell loses functional control:
~ osmotic pressure causes organelle swelling
~ chromatin clumps
~ cell bursts

22
Q

What is the outcome of necrosis?

A

Cytotoxic cellular components spill out from the membrane - tissue damage and inflammation.

23
Q

What causes apoptosis?

A

Most eukaryotic cells are genetically programmed for cell death - molecular signals continually inhibit or promote this process.

  • Process initiated through a chain of enzymatic reactions leading to bcl-2 deactivation.
24
Q

Which protein plays an important role in apoptosis inhibition?

A

Bcl-2 on the outer mitochondrial membrane

25
Q

Describe the process of apoptosis.

A

Catabolic processes being throughout the cell.

  • Enzymes digest cytosolic components and fragment the nuclear DNA.
  • Caspases (specialised cysteine proteases) target proteins in the nuclear lamina and cytoskeleton.
26
Q

What is the outcome of apoptosis?

A

The cell is ‘re-packaged’ for safe removal.

  • Chromatin condenses, cell shrinks and fragments into small membrane-bound apoptotic bodies.
  • Compacted cell is phagocytosed by adjoining cells.
27
Q

Which cell types are static (do not renew)?

A

CNS
Cardiac
Skeletal muscle

28
Q

Which cells display stable renewal rates?

A

Fibroblasts
Endothelium
Smooth muscle cells

29
Q

Which cell types display high renewal rates?

A

Blood
Skin epithelium
Gut epithelium

30
Q

Is there a relationship between cell renewal rate and propensity to develop cancer?

A
  • Renewing cell lineages are at high risk for accumulating mutations.
  • 90% of adult-onset cancers arise as carcinomas in epithelial tissues (skin and intestine - renew throughout life).
  • Rare childhood cancers concentrate in tissues that undergo cell division early in life followed by relative cellular quiescence.
31
Q

What are the different domains of epithelial cells?

A

Apical
Basal
Lateral

32
Q

How can the apical domain of epithelial cells be specialised?

A
  • Microvilli: cytoplasmic processes that extend from the cell surface. E.g. Intestine and kidney tubule.
  • Stereovilli: particularly long microvili limited to epididymis and sensory hair cells of ear.
  • Cilia: motile cytoplasmic processes that can beat in synchrony with a rapid forward movement - the effective stroke, and a slower return recovery stroke. E.g. Tracheobronchial tree and oviducts.