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Week 1 - Cells & Organelles > Histology > Flashcards

Histology Flashcards

1
Q

Define histology ?

A

Histology is the study of microscopic structures of biological tissues

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2
Q

Define a cell

A

Cell is the basic structural and functional unit of living organisms

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3
Q

List the two types of cells and describe a distinct feature of each

A
  • Prokaryotes = no nucleus such as bacteria
  • Eukaryotes = cytoplasm and nucleus - human cells
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4
Q

Describe the structure and function of the plasma membrane

A
  • physical barrier
  • selectively permeable
  • sensitive to the environment
  • provides cell with support
  • specialisations (cilia)
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5
Q

Describe structure and function of Nucleus

A
  • Double layer capsule which stores DNA
  • most cells contain 1
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6
Q

Describe the structure of cytoplasm and its continents

A
  • cytoskeleton - network of proteins which provides structure and support
  • cytosol - intracellular fluid
  • Organelles - ribosomes (makes proteins) , mitochondria, ER, Golgi apparatus
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7
Q

Define a tissue

A

Tissue group of similar cells which work together to carry out a common function

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8
Q

List the two types of tissue and describe their differences

A
  • Parenchyma = working tissue - carries out a specific function
  • Stroma = scaffold and nutrition
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9
Q

Define organ

A

Composed of several tissue types which all have a morphologically recognisable structure and performs specific sets of functions

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10
Q

List the 4 main types of tissues and their functions

A

Connective tissue = protects and supports , fat, blood and cartilage

Epithelia - covers/ lines body surfaces

Muscle - cells contract to generate force

Nervous - generate electrical signals in response to the environment

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11
Q

How are most cells within tissue jointed

A
  • through ECM material between the cells
  • Cell junctions which allows cells to be joined to other cells and remain the structure
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12
Q

Define metastasis

A

The spread of a disease producing agent from primary producing site to a distanced area of section of the body.

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13
Q

List the 4 stages of tissue processing for histology

A
  • fixation
  • embedding
  • sectioning
  • staining
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14
Q

Explain what happens at the fixation stage of tissue processing

A

Fixation
- freezing at - 80 degrees (dry ice or liquid nitrogen)
- preserves tissue which prevents further breakdown
- chemical fixation (aldehyde based) - binds proteins that harden tissue and prevents enzyme from breaking down tissue further p

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15
Q

Explain the process of the embedding stage of tissue processing

A

Embedding
- frozen sample is placed in paraffin wax which allows ease of sectioning
- water in tissue requires replacement of Zylin, with fat (lipids) removed

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16
Q

Explain the process of sectioning

A
  • tissue is split into smaller sections
  • thinner the slice the higher the resolution
  • allows more to be views in 2D
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17
Q

Explain the process of staining

A
  • better to see the tissue under microscope
  • ## wax is rehydrated and used as a stain
18
Q

Name the 2 most common stains & what they stain

A
  • Haematoxylin ( basic positively charged) and stains acidic structures (basophilic) purplish blue colour e.g. Nucleus
  • Eosin (acidic negatively charged) stains basic structures (acidophilic) red or pink e.g. cytoplasm
19
Q

What is PAS used to stain

A

PAS stains complex carbohydrates and glycogen

  • Tissue stained with is PAS positive
  • PAS stains the liver as lots of glycogen - magenta colour
  • Stains mucus, basement membrane and brush border of the intestine
20
Q

Define epithelial tissue

A
  • Covers and protects surfaces outside and inside the body
  • Cells are polarised and sit on the basement membrane
  • epithelia tissue is not vascularised
    -Lines internal cavities and blood vessels, respiratory, digestive and urinary or reproductive organs
  • Forms glandular structures
  • forms barriers
  • combines with nervous tissue - forms special senses (smell and hearing)
21
Q

List functions of epithelial tissue

A
  • prevents water retention - cells closely packed together
  • acts as a water barrier - abrasive skin has many layers
  • epithelial tissue found in glands which is discharged and released into blood
22
Q

What is the function of covering epithelia

A
  • covers and lines body surfaces, cavities and tubes
23
Q

What is the function of glandular epithelia

A
  • Secretory epithelia which forms glands
  • invagination of epithelia
  • contributes to glandular organs - salivary glands
24
Q

List of the two type of glands in glandular epithelia

A
  • Exocrine glands = retain continuity with surface (ducts)
  • Endocrine glands = lose contact with surface and secrete directly into the blood stream ( thyroid gland)
25
Q

List the number of layers the epithelial tissue has and how many layers in each

A
  • simple = single layer - absorption, secretion and fragile
  • stratified = 2 or more layers of cells - protection
  • Pseudo-stratified = one layer with a mixture of cell shapes
26
Q

List the shape of the cells and structure of each

A
  • squamous = flat
  • Cuboidal = cube
  • Columnar = tall, cylindrical
  • Transitional = readily changes shape - accommodates
27
Q

Describe the structure and function of simple squamous epithelia

A

Simple squamous;

  • single layer of flat hexagonal cells
  • Nuclei appear flat

Function
- Mainly diffusion, filtration, secretion and absorption
- small barrier against friction

28
Q

Where is simple squamous located

A
  • linking of blood vessels and heart
  • Alveoli
  • Lining of serous membranes of the body cavities
  • Lining of some kidney tubules
29
Q

Describe the structure and function of simple cuboidal epithelia

A

Simple cuboidal epithelia

Structures
- single layer of cube shaped cells
- some cells have microvilli

Function
- Diffusion
- Secretion
- Absorption

30
Q

List the location of simple cuboidal epithelia

A
  • kidney tubules
  • Glands and their ducts
  • lining of terminal bronchioles of the lungs
  • Surfaces of the ovaries
31
Q

Describe the structure and function of simple columnar epithelia

A

Simple columnar columnar structure
- single layer of tall narrow cells
- cells have cilia - bronchioles of lungs, auditory tubes, uterus
- cells have microvilli (intestines)

Function:

  • Movement of substances
  • absorption
  • secretion
  • more protection than flatter cells
32
Q

State the locations of simple columnar epithelia

A
  • glands and other ducts
  • bronchioles of the lungs
  • auditory tubes
    -uterus
  • uterine tubes
  • stomach
  • intestine
  • gallbladder
  • bile ducts
  • ventricles of brain
33
Q

Describe the structure and function of Stratified squamous epithelia

A

Structure

  • Multiple layer of cells which are cubed shaped in basal layer
  • cells flatter at the surface
  • Keratinised and non- keratinised

Function:

  • Protects against abrasion
  • Barrier against infection
  • reduces water loss from body
34
Q

State the location of stratified squamous epithelia

A
  • Keratinised (skin)
  • Non- Keratinised (mouth, throat, larynx, oesophagus, anus, vagina, inferior urethra and cornea)
35
Q

Describe another characteristic of Keratinised stratified epithelia on skin

A

Cytoplasm of cells at surface are replaced with protein keratin - dead cells

  • keratinised epithelium (extra top layer which provides moisture). This is a superficial layer of cells have keratin. Dead cells makes the skin thicker - soles of feet increased pressure & abrasion.
36
Q

Describe the structure and function of Pseudo-stratified Epithelia

A

Structure

-Single layer - some cells reach free surface
- Nuclei at different levels so appears stratified
- Almost always ciliated and associated with goblet cells - secrete mucus

Function

  • synthesise and Secrete mucus
  • moves mucus or liquid which has foreign particles over the surface
37
Q

State the location of Pseudo-stratified Epithelia

A

Lining of nasal cavity

Nasal sinuses

Auditory tubes

Pharynx

Trachea

Bronchi of lungs

38
Q

Describe the structure and function of transitional epithelia

A

Stretched structure - squamous and flattened

Not stretched - cuboidal and columnar

When stretched the number of layers decrease from 5/6 to 2/3 - cells shift over one another

Function:

  • Accommodate for fluctuation
  • fluid in organs and tubes - tolerate stretching and recoil without damage
  • protects against caustic affects of urine
39
Q

State the location of the transitional epithelia

A
  • Lining of urinary bladder
  • uterus
  • superior urethra
  • pelvis of the kidney

Structures where considerable expansion occurs

40
Q

What is the main function of connective tissue

A

It supports and protects

41
Q

Provide 2 examples of connective tissue

A

Blood vessels - brings nutrients and oxygen to other surrounding tissues and organs

Cartilage - provides protection as it covers the joints surfaces between bone

Week 1 - Cells & Organelles (5 decks)

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