Histology

Question 1

what is the plasmalemma

Answer 1

membrane that separates the cytoplasm from the outside environment

Question 2

what is the plasmalemma composed of?

Answer 2

it is a bimolecular slyer of amphipathic phospholipid molecules with their hydrophilic heads at the outer and inner surfaces and their hydrophobic fatty acid chains facing towards the middle of the two layers

Question 3

what is embedded in the plasmalemma

Answer 3

integral and peripheral proteins (ie receptors/channels/transporters/enzymes/cell attachment proteins

Question 4

what is the plasmalemma able to do for the cell

Answer 4

exocytose and endocytose material from the cell

Question 5

what does it mean when the cell membrane is said to be FLUID

Answer 5

can change shape easily, proteins can diffuse laterally in the cell membrane but many are anchored

Question 6

selectively permeable?

Answer 6

permeable to water/oxygen/hydrophobic molecules/charge ions

Question 7

plasmalemma building block composition

Answer 7

polar/hydrophilic head

non-polar hydrophobic fatty-acid chain

Question 8

what are inclusions

Answer 8

series of small lipid bubbles/ components synthesised by the cell itself

Question 9

what are the 3 main classes of filamentous cytosolic proteins in the cytoskeleton

Answer 9

1. microfilaments
2. intermediate filaments
3. microtubules

Question 10

how are several functions of the cell maintained?

Answer 10

by a set of filamentous cytosolic proteins

Question 11

what are the features of microfilaments

Answer 11

composed of the protein actin - polymerise into long proteins
7nm diameter
dynamic ie can depolymerise/polymerise

Question 12

what are the features of intermediate filament?

Answer 12

composed of 6 main proteins (which vary in cell types)
bind intercellular embalmment together and to the plasmalemma
provide good structural integrity
10-15nm

Question 13

what are intermediate filament used in clinically?

Answer 13

pathology to identify tutor origins

eg glial cells can make a glioma which is a tumour in the CNS

Question 14

what are microtubules composed of?

Answer 14

hollow tubules composed of two tublin proteins

made of subunits alfa and beta tublin subunits

Question 15

what are the features of microtubules?

Answer 15

can assemble and disassemble
originate from a special organising centre called the centrosome
they include stabilising proteins (ie microtubule-associated proteins MAPs)
participate in creating the spindle in cell division

Question 16

what is the function of the filamentous cytosolic proteins in the cytoskeleton

Answer 16

Attach to the membrane and to each other to form a dynamic 3-dimensional internal scaffolding in the cell - the cytoskeleton.

Question 17

what are microfilaments composed of?

Answer 17

Actin

Question 18

Why are intermediate filaments used clinically?

Answer 18

Diagnostic. To identify tumour origins.

i.e. neurofilaments should only be in nerve cells. cytokeratins should only be in epithelial cells.

Question 19

Where to microtubules originate from?

Answer 19

centrosome

Question 20

what protein stabilise microtubules

Answer 20

MAPs microtubule associated proteins

Question 21

What proteins allows movement of organelle cargo along microtubules? What direction do they move in?

Answer 21

Kinesin: ATPase moves towards cell periphery Dynein: ATPase moves towards cell centre
Particularly important in cells with long processes e.g. neurons.

Question 22

Which cellular strcutures and processes to microtubules have an important role in?

Answer 22

Mitosis, cillia, flagella

Question 23

Micotubules originate from the centrosome. What is this formed of?

Answer 23

Contain a core pair of organelles called centrioles which are composed of mainly specialised modified microtubules segments.

Question 24

what is the nucleus enclosed in?

and what is this composed of?

Answer 24

nuclear envelope

composed of an inner and outer nuclear membrane with nuclear pores providing continuity with the cytoplasm

Question 25

What is the area between the double envelope of the nucleus called? What is this continuous with?

Answer 25

perinuclear cistern | continuous with the cistern of the rough endoplasmic reticulum

Question 26

The outer nuclear membrane is studded with what? | What is this continuous with?

Answer 26

Ribsosomes. Continuous with the RER.

Question 27

What is the function of the nucleus?

Answer 27

The nucleus contains chromosomes and is the location of RNA synthesis. mRNA and tRNA are transcribed in the nucleus

Question 28

where is rRNA transcribed

Answer 28

nucleolus

Question 29

what is the nucleolus

Answer 29

a 1-3um diameter dense are within the nucleus

Question 30

What are the two forms chromatin can take in the nucleus?

Answer 30

euchromatin | heterochromatin

Question 31

what is the euchromatin (light)

Answer 31

DNA that is dispersed and is actively undergoing transcription

Question 32

what is heterochromatin (dark)

Answer 32

dense and compact DNA that is highly condensed and not undergoing transcription

Question 33

what is the nucleus surrounded by

Answer 33

double nuclear membrane

Question 34

Where are ribosomes fromed? What are they made of? | What is export of ribosomes dependent on?

Answer 34

Formed in the nucleolus. Composed of rRNA (small and large subunit) and protein. The nuclear pore complex in the nuclear envelope.

Question 35

What is the function of ribosomes?

Answer 35

The site of protein sythesis (translation).

Question 36

what is the ER continuous with?

Answer 36

perinuclear cistern

Question 37

function of RER

Answer 37

protein synthesis and the initiation of glycoprotein

Question 38

function of SER

Answer 38

site of the synthesis/detoxification of lipids/cholesterol

Question 39

function of Golgi

Answer 39

modification and packaging of secretions

Question 40

function of nucleus

Answer 40

contains genetic code

Question 41

function of mitochondria

Answer 41

powerhouse of cell, produce ATP energy via oxidative phosphorylation

Question 42

composition of mitochondria

Answer 42

inner and outer membrane, inner is folded to form cristae

Question 43

name the 3 types of intercellular junctions

Answer 43

occluding, anchoring, communicating

Question 44

another name for occluding junction

Answer 44

zonula occludens or tight junctions

Question 45

functions of occluding junction

Answer 45

link cells to form diffusion barrier | appear as a focal region of close apposition between adjacent cell membranes

Question 46

functions of anchoring junctions

Answer 46

provide mechanical strength | link submemnrane actin bundles of adjacent cells

Question 47

other 2 types of anchoring junctions

Answer 47

1. adherent junction/zonula adherents | 2. desmosomes/macula adherens ie anchoring

Question 48

describe zonula adherents

Answer 48

mechanical strength, – link submembrane actin bundles of adjacent cells Cadherin molecules bind to each other in extracellular space and to actin of cytoskeleton

Question 49

describe desmosomes/macula adherens

Answer 49

link submembrane intermediate filaments of adjacent cells

Question 50

function of communicating junction

Answer 50

1. movement of molecules between cells 2. allow selective diffusion of molecules between adjacent cells 3. termed as gap junctions 4. each junction is circular patch studded with pores(produced by connexion proteins)

Question 51

what is a junctional complex

Answer 51

close association of several types of junctions found in certain epithelial tissues

Question 52

what is endocytosis

Answer 52

membrane invaginate, fuses and newly made endocytotic vesicle buds into cell

Question 53

what is exocytosis

Answer 53

works in reverse of endocytosis

Question 54

phagocytosis

Answer 54

bacteria bind to cell surface, cell engulfs it to form phagosome, binds with lysosome containing digestive enzymes

Question 55

name the two main stains

Answer 55

H&E stain haematoxylin - purple/ basic eosin - pink/ acidic

Question 56

what are the 4 basic tissue types

Answer 56

1. epithelium 2. connective tissue 3. muscle 4. nervous

Question 57

describe epithelium tissue

Answer 57

cover surfaces of body, line hollow organs, form glands all have a basal lamina non-vascular polarised - apical and basal sides differ

Question 58

what are the functions of epithelia

Answer 58

``` mechanical barrier chemical barrier absorption secretion containment locomotion ```

Question 59

name the 3 shapes cells can be

Answer 59

squamous - flattened cuboidal - cube columnar - tall and thin

Question 60

name the 3 classifications of layers

Answer 60

simple - one layer stratified - two or more layers pseudostratified - tissue appears to have multiple layers

Question 61

cell surface, tissue surface specialisations

Answer 61

prominent microvilli cilia keratinised

Question 62

what specialised cell types are present in the epithelium

Answer 62

goblet cells

Question 63

glandular epithelia two classes

Answer 63

endocrine | exocrine

Question 64

where does the endocrine glands secrete

Answer 64

product secreted towards basal end of cell - distributed by vascular system - ductless glands

Question 65

exocrine?

Answer 65

product secreted towards apical end of cell - ducted glands

Question 66

define connective tissue

Answer 66

forms framework of body, dynamics role in development, growth and homeostasis of tissues and energy store

Question 67

what does glandular epithelia produce

Answer 67

secretory products eg sweat/milk/oil

Question 68

what 2 places are secretory products secreted?

Answer 68

endocrine glands and exocrine glands

Question 69

describe function of endocrine glands

Answer 69

into the body, towards the basal lamina