Week 1 Anatomy

Question 1

What can you visualise with an electron microscope?

Answer 1

Mitochondria, ribosomes, RER, SER, golgi, individual elements of the nucleus and secretory granules.

Question 2

What can you visualise with a light microscope?

Answer 2

Cell walls, vacuoles, cytoplasm, nucleus (grossly) and cell membrane.

Question 3

What are the 4 fundamental categories of tissues?

Answer 3

Nervous, muscle, epithelial and connective.

Question 4

What is parenchyma and what is stroma?

Answer 4

specialised tissue does the organs job. Stroma = supports parenchyma.

Question 5

Where do you find epithelial tissue, what are its functions and give examples briefly.

Answer 5

Covers exposed body surfaces, lines internal passage ways & chambers and forms glands. Lining vs glandular epithelium.
Functions = 
Protection
-Mechanical
-Chemical
-Radiation
-Pathogens (Immunological function)

Permeability
-Exchange of chemicals
(Depends on specialisation; transporters; functional polarity of cells)

Secretions
-Glandular epithelium – sweat, mucus, enzymes, immunological defences, other products delivered by ducts

Immunosurveillance

Examples: skin, surface of tongue, lining of bladder, multiple glands

Question 6

Where do you find connective tissue, what are its functions and examples.

Answer 6

Throughout body, often fills internal spaces, never exposed to outside environment.
Functions: provides structural support, transports of materials, stores energy reserves, defends against microorganisms, protects delicate organs, allows cell communication.
Examples: adipocytes, loose and dense connective tissue

Question 7

Where is muscle, functions and examples briefly.

Answer 7

Muscles surround the skeleton (skeletal), heart (cardiac) and walls of hollow organs (smooth). Functions include movement of bod, circulation of blood through CVS and movement of material along digestive tract. Examples include biceps, ventricles of heart, walls of blood vessels.

Question 8

Where is nervous tissue, functions and examples briefly.

Answer 8

98% of the brain and spinal cord (CNS) and in GIT (enteric NS).
Functions = carriers information from one part of the body to another through electrical impulses and support of neurons (neuroglia)
Examples: brain, spinal cord, Schwann cells, astrocytes, microglia.

Question 9

Where are oligodendrocytes found? And where are Schwann cells? What is the main difference between them

Answer 9

Oligodendrocytes - CNS
One oligodendro - multiple axons
Schwann cells - PNS
One Schwann - one axon

Question 10

Describe the different categories of epithelia giving typical anatomic locations and the functions of each. 1) lining/covering

Answer 10

Type of epithelia (categorised by shape of cells of outer layer):

covering/lining

-simple: squamous (thin),

cuboidal (cubed) and

columnar (taller than wide), elongated nucleus

• stratified (2 or more layers) - stratified keratinised squamous on epidermis and stratified non-keratinised squamous in mouth, oesophagus, vagina. Stratified cuboidal are rare; in secretory ducts of salivary and sweat glands
• transitional e.g. urinary tract, layer of dome like cells
• pseudostratified: although having disordered nuclei to suggest stratified, ONLY 1 CELL LAYER THICK

Question 11

Describe the different categories of epithelia giving typical anatomic locations and the functions of each. 2) Secretory/glandular

Answer 11

Function = secretory, glandular cells that lie in clusters, deep in the covering and lining epithelium. A gland may consist of one cells or a group of specialised epithelial that secrete substances into ducts or into the blood.
Exocrine = secrete products into ducts or tubes that empty at the surface of the covering/lining epithelium .e.g enzymes, sweat.
Endocrine = ductless, secrete into blood, secretions are always hormones, e.g. thyroid, adrenals.
Secretory cells may synthesise, store and secrete proteins e.g. pancreas, lipids or carbs/protein complexes e.g. salivary glands

Simple glands don’t have branched ducts compared to compound ducts that have 2 or more branches
Secretory portions are either tubular (straight down) or acinar (grape-like with small lumen).

Can have simple, branched or coiled tubular.
Simple or branched acinar.

Question 12

Describe exocrine glands

Answer 12

Organised as a continuous system of secretory portions and ducts Ducts can be simple (unbranched) or compound (branched)
Examples sweat, salivary, mammary
Exocrine = secrete products into ducts or tubes that empty at the surface of the covering/lining epithelium .e.g enzymes, sweat.

Question 13

What are unicellular glands?

Answer 13

E.g. goblet cells in upper respiratory tract

Question 14

What are 3 methods of secretion?

Answer 14

Merocrine = most common, exocytosis of membrane bound vesicles or secretory vesicles (can be serous enzymes or mucous mucin) e.g. pancreatic acinar

Apocrine = a portion of membrane containing secretion buds off, lipid drops in mammary glands

Holocrine = whole cell disintegrates as it terminally differentiates, filled with product, contents empty into lumen e.g. sebum in air follicles

Question 15

What is epithelial polarity?

Answer 15

Polarity refers to the uneven distribution of organelles and membrane proteins in different parts of the cell. Region facing connective tissue is called basal pole and opposite region known as apical pole facing the lumen.

Question 16

What are the main functions of intercellular junctions?

Answer 16

Intercellular communication, permits strong adhesion to both neighbouring cells and basement membrane
Maintain epithelial polarity: control arrangement of proteins and lipids within the plasma membrane and membrane associated intracellular protein that mediate polarised organisation of the cytoplasm.

Question 17

What are tight junctions (Zonular occudens)?

Answer 17

Function to occlude. Seal between adjacent cells. Junctions form a band encircling cell (zonula), located immediately beneath the luminal surface/closest to the apex.
Proteins include: occludins, claudins, ZO proteins
Cytoskeletal component is actin filaments
Function to seal between cells and separate apical and basolateral membrane domains.
Maintains polarity by keeping proteins on basolateral side there and apical on apical side. Structure–>function.
Doesn’t allow paracellular movement. Things must cross transcellularly.
Defects in occludins: defect in BBB–>neurological disorders
Stops back leak of ions/salt

Question 18

What are adherens junction (zonular adherens)?

Answer 18

An anchoring junction. On lateral surface, continuous band encircles cell immediately below tight junctions. Encircles below the ZO, it is an adherent junction, firmly anchoring the cell to its neighbour. Cell adhesion mediated by cadherins 9E-cad) which are TM glycoproteins which need Ca2+. Cadherins bind to catenin which is linked via actin binding proteins to actin. Links to cytoskeleton of adjacent cells to stengthen/stabilise junctions
E-cad lost in cancer–>metastasis

Question 19

What are desmosomes (macula adherens)?

Answer 19

A type of anchoring junction. Interact with IFs. Desmocollins and desmogleins. Coupling of IFs of adjacent cells. Pemphigus –>autoimmune–>cell cell attachment lost

Question 20

What are hemidesmos?

Answer 20

Basal surface links to basement membrane. Has integrins, linkes with IFs, anchors cytoskeleton to bm.. Integrin mutations–>epidermolysis bullosa

Question 21

What are focal adhesions?

Answer 21

A type of anchoring adhesion. Basal surface, integrins, linked by paxillin to FAK–>integrins bind to laminin–>signalling cascade–>cell motility, gene expression, cell adhesion changes
Role in oncogenes

Question 22

What are gap junctions?

Answer 22

Communicating junctions, on lateral surface, via connexins and connexons, transfer of small molecule and ions between cells.

Question 23

What are some apical surface specialisations of epithelial cells?

Answer 23

Microvilli, cilia, sterocilia (nothing to do with cilia)

Question 24

What are the key stains and their uses?

Answer 24

H&E and eosin - H stains DNA and other acidic structures blue. E stains other cytoplasmic components and collagen pink.
Trichromes i.e. Mallory - shows nuclei and cytoplasm and distinguish extracellular tissues better than H&E

Question 25

What do these microscopy terms mean in bright field microscopy:
Lenses and condenser
Objective
Eyepiece
Resolving power

Answer 25

Lenses and condenser = collects and focuses light, illuminating object.
Objective = enlarges and projects image of object into eyepiece of lens
Eyepiece = provide further magnification and focuses light onto the retina
Resolving power = smallest distance between two particles at which they can be seen as different objects.
Max resolving power is about 2micrometers.

Question 26

What is fluorescence microscopy?

Answer 26

Tissue sample irradiated with UV, and emission is in visible spectrum. Strong UV light source and filters to filter out different wavelengths. Dye can be used to distinguish RNA and DNA, as well as adding Abs.

Question 27

What is the process of preparing an epithelium specimen for microscopy?

Answer 27

Fixation = prevent tissue degradation and decay.
Embedding = imparts rigidity to tissue, facilitating sectioning my microtome.
Much thinner samples needed for TEM than bright field. Staining the sample differentiates cell components (basic and acidic stains select for different organelles). Magnification = enlarges sample, resolving power define the distance.