Tissues Flashcards
What are glial cells and what is their function?
Glial cells are accessory cells to the neurones and provide support and insulation.
Examples: oligodendrocytes, astrocytes, schwann cells
Which are the three components of the cytoskeleton?
Microtubules, Microfilaments and Intermediate filaments
Name two main differences between the Smooth and Rough Endoplasmic reticulum
SER: No ribosomes on surface and network is tubular rather than the flattened stacks in the RER.
Name x3 functions of the Smooth Endoplasmic Reticulum
Lipid metabolism, detoxification and Ca2+ storage
Where are microtubules found?
Microtubules are found in spindle fibres, the cilia and flagellae
Where are microfilaments found?
Microfilaments are used in contraction of muscle e.g. actin filament
Where are intermediate filaments found?
In the epithelia e.g. cytokeratin and muscle cells e.g. desmin.
What is the function of intermediate filaments?
Adds mechanical strength
Name the five cell types
Epithelial tissue, connective tissue, haemopoeitic tissue, neuronal and contractile tissue
What are the two types of cell-cell junctions?
Maculae adherens or Zonulae adherens
What is the Zonula Occludens?
Tight junctions on membrane which blocks the paracellular pathway. Tight junctions separate the apical and basolateral membranes.
What is Zonula Adherens?
A junction which controls other junctions and is made up of cadherins and cytoskeleton.
What is a desmosome?
Also known as macula adherens, it is linked to the intermediate filament and provides mechanical strength.
What is the diameter of a microtubule?
20nm
What is the diameter of an intermediate filament?
10-15nm
Define ECM
The extracellular matrix is a network of macromolecules including proteoglycans, glycoproteins and collagen
What can a mutation in Fibrillin 1 cause?
Marfan’s syndrome
What can a mutation in the a2 chain of Laminin 2 cause?
Muscular dystrophy/ Epidermolysis Bullosa
Too much extracellular matrix is seen in which conditions?
Lung fibrosis, kidney fibrosis
Where does osmotic pressure push fluid?
Osmotic pressures pushes fluid out to the blood and lymph
What causes Oedema?
An excess of interstitial fluid caused by hydrostatic > osmotic pressure
OR a decrease in osmotic pressure e.g. hypoproteinaemia
What is the total body weight of water in men compared with women?
Men = 60%, women = 50%
What are the three components of extracellular fluid?
Blood, Interstitial fluid and transcellular fluid
What does an increase in oncotic pressure cause?
An increase in oncotic pressure causes interstitial fluid to move into circulation.
What are the two factors that determine interstitial fluid movement?
- Hydrostatic and oncotic pressure
2. Endothelial permeability
What can cause an increase in hydrostatic pressure?
Heart failure
What can cause a decrease in osmotic pressure?
Loss of protein through Nephrotic syndrome, Inflammation,
What are the three features of virchow’s triad?
Hypercoagulability, Endothelial dysfunction, Statins
Name the clinical triad of signs in Abdominal aortic aneurysm
Back pain, hypotension and pulsatile mass
What are the five types of shock
Cardiogenic, neurological, septic, anaphylactic and hypovolaemic
What is the most important complication of thrombosis
Pulmonary Embolism
What are two clinical features of sepsis
High respiratory rate and tachycardia
What are thrombi made up of?
Fibrin, platelets and red blood cells (if red)
Name x5 risk factors for Deep Vein Thrombosis
Immobility, contraceptive pill, increased age, obesity, pregnancy
What is the difference between red and white infarcts?
Red infarcts occur as a result of venous occlusions and occur in organs with dual circulation.
Give x3 causes of an M.I.
Coronary artery occlusion, coronary artery vasospasm or emboli e.g. in AF.
Define haemorrhage
Extravasation of blood due to vessel rupture
What is the thickness of a usual tissue section?
Less than 5um
How would nuclei appear under a microscope when stained?
A darker purple colour when stained
What is simple epithelia?
When cells are lined up adjacently directly attached to the basal lamina.
What is a primary role for columnar cells?
Absorption
What are the names of the mucus secreting cells in columnar epithelium?
Goblet cells
Apical side of structure faces which surface?
The lumen
Which side of the structure are the microvilli?
The apical side.
What does polarisation mean in a cell?
To have two surfaces with different properties
What is the name of the epithelium lining the small intestine?
Simple Columnar (absorptive) epithelia
What is a crypt?
Simple tubular glands in the intestine.
What is mesentery?
Thin layer of tissue which attaches intestine to the rest of the body
What is the difference between a columnar and squamous cell?
Columnar = taller than they are wide, squamous = wider than they are tall
What is endothelium?
The epithelial layer lining blood vessels
What is the name given to epithelia which consists of multiple layers?
Stratified
Why would the body need stratified squamous epithelia?
For protection; if cells closer to the lumen are damaged, the cells underneath can still maintain function.
What is the function of the goblet cell?
To produce mucus which prevents the oesophagus from drying out.
What is the function of cilia?
To move mucus back to the mouth to prevent it from accumulating
What is the name of the cells which are approximately equal in height and width?
Cuboidal cells
What is the structure of stem cells?
‘Simple’; attached to basal lamina
What is the opposite of a ‘simple’ cell structure?
Stratified
Why must cholesterol be transported in vesicles?
It is very insoluble.
Name x3 post-translational modifications to the ER
Glycosylation, folding, addition of disulphide bonds.
Name x1 disease where there is an error in the post-translational modifications but the protein cannot leave the ER as its exit is blocked.
Cystic Fibrosis where there is misfolding.
What is the name of the molecule which pinches the clathrin-coated vesicle from the membrane?
Dynamin
Which is the entry face of the GA (coming from the ER)?
Cis face
Which is the protective type of epithelia?
Stratified squamous epithelium
Where can we find keratinising epithelium and non keratinising epithelium?
Keratinising = skin Non-keratinising = oesophagus
Where are psuedostratified epithelium found?
The lungs and bronchi
Which is the ‘wet’ epithelia?
Non-keratinising epithelia
Why is polarity of the epithelium important?
Helps in transport and secretion - directs chemicals to the right compartment.
Is the mechanism of the Islet’s of Langerhans releasing hormones into the blood exocrine or endocrine?
Exocrine.
What causes callus?
Cell proliferation overrides cell loss
What does the basal lamina separate?
The epithelial tissue and connective tissue
What condition can be caused be a loss of ECM?
Osteoarthritis
Which protein is affected in Marfan’s syndrome?
Fibrillin
Which protein is affected in Alport syndrome?
Type IV Collagen
Which protein is affected in Osteogenesis Imperfecta?
Type I Collagen
What is the issue with low Vitamin C?
Vitamin C is needed for hydroxylation of collagen which makes collagen stronger.
Vitamin C deficiency can lead to what?
Scurvy
Name x2 diseases associated with Laminin mutations
Muscular dystrophy and Epidermolysis Bullosa
What is the structural change in muscular dystrophy?
Absence of alpha 2 chain in Laminin structure.
Name x2 purposes of Proteoglycans.
GAGs within the proteoglycan structure hydrate joint. GAGs are also negatively charged and so attract cations such as Na+ and hence water, which help to absorb shock.
Give x3 features of hyaluronan
Simple carbohydrate chain. No sulphates, but is carboxylated. No core protein.
Name x3 main intracellular cations/anions
K+, H+, HPO3-
Which cell provides myelin for PNS axons?
Schwann cells
Which cell provides myelin for CNS axons?
The oligodendrocyte.
Name two differences between oligodendrocytes and schwann cells
Oligodendrocytes provide myelin for the CNS whereas Schwann cells provide myelin for the PNS. Oligodendrocytes can provide myelin for many axons whereas schwann cells can only provide myelin for one axon each.
Name x1 example of endocrine signalling
Secretion of glucagon into the blood from alpha cells of the islet of langerhans of the pancreas to the liver
Name x1 example of paracrine signalling
Release of insulin from beta cells of the islet of langerhans of pancreas on glucagon.
Name an example of autocrine signalling
When a T cell is activated the release of IL-2 and presentation of IL-2 on its surface. IL-2 released binds to IL-2 on surface.
List one example of intercellular signalling and one example of intracellular signalling
Intercellular: Pancreas to liver to control glucose levels
Intracellular: Interaction between alpha and beta cells of the islet of langerhans.
What are the four types of receptors which can be involved in cell signalling?
Inotropic receptors, G protein coupled receptors, enzyme linked receptors and intracellular receptors
What type of receptor is B1 receptor?
GPCR
How does B1 receptor signalling in the heart work?
The ligand - adrenaline, binds to the Gs portion of the B1 receptor = stimulates adenylyl cyclase = converts ATP to cAMP = activates protein kinase A.
How many transmembranes does the GPCR have?
x7
What does binding to the Gs subunit cause?
Stimulation of adenylyl cyclase which converts ATP to cAMP which activates PKA.
What is an example of a Gs mechanism?
B1 receptors in the heart
What is an example of a Gi mechanism?
M2 receptors in the heart
What does binding to the Gq subunit cause?
Stimulation of Phospholipase C which converts PIP2 to IP3 and DAG. IP3 causes increase in Ca2+ release. DAG ACTIVATES PKC.
What is an example of the Gq mechanism?
Angiotensin receptor in vasoconstriction
Which is the slowest signalling mechanism?
Intracellular signalling
Give some differences between benign and malignant tumours
Malignant: MIDG - Metastasis, invasion of local tissue, differentiation, growth patterns
Define heterotopia
Normal tissue found where it is not normally found.
Define hamartoma
Localised, benign tissue overgrowth.
Define neoplasm
Autonomous overgrowth of tissue which has escaped the cell’s normal restrictions.
Name x5 ways through which cancers may spread
Lymphatic, haematogenous, perineural, locally through connective tissue, transcoelomic (through body cavities)
Define teratoma
Cancers derived from germ cells.
What is the difference between a germ cell and a somatic cell
A germ cell contains only half the number of chromosomes from an individual whereas a somatic cell contains a diploid number.
Define atrophy
Shrinking in cell size
Define metaplasia
The REVERSIBLE change when one cell is replaced with another.
What mechanism occurs in Barrett’s oesophagus and how does this mechanism work?
Metaplasia: Stratified cells turn to columnar cells.
Name x2 differences between apoptosis and necrosis
Apoptosis does not involve inflammation whereas necrosis does. Apoptosis requires ATP whereas necrosis does not.
Name the layers of the epidermis in descending order.
Stratum corneum, stratum granulosum, stratum spinosum, stratum basale.
In which layer of the skin are langerhan cells found?
Stratum spinosum
Eczema arises from defects in which cell layer?
Stratum corneum
In which layer of the epidermis are melanocytes and keratinocytes found?
Stratum basale
What is the name of the gene mutation found in eczema?
Filaggrin mutation
Where are ribosomes made?
In the nucleolus. The nucleolus is made up of proteins and rRNA. Many rRNA as each ribosome requires x1 rRNA.
Where is hyaluronan synthesised?
In the plasma membrane.
Is hyaluronan sulphated?
NO. Only contains OH- and COOH-
Is hyaluronan a proteoglycan or a glycoprotein?
Neither; does not contain a core protein. It is a GAG.
Chondroitin sulphate, heparan sulphate, keratan sulphate and dermatan sulphate are all examples of what?
GAGs. (Glycosaminoglycans).
Why is tonicity a better measure than osmolarity?
Tonicity measures solute + membrane permeability. Osmolarity does not consider membrane permeability.
Name x3 hydrophobic molecules which can freely diffuse through the lipid membrane.
O2, CO2, and N2.
How are proteins transported out of the capillary?
Exocytosis.
How are Na+ and K+ transported in and out of the capillary?
Through small pores. No channels in the capillary wall.
What is the job of the lymphatic circulation?
To return interstitial fluid to the blood circulation.
Which are the two dendritic cells within the epidermis?
Melanocytes and Langerhans cells.
Most epithelial cancers metastasise through which route?
Lymphatic system.
What does ‘grade’ define in cancer?
How differentiated the tumour is.
