Sesh 2: Cells And Tissue Types Flashcards
What are the 3 types of cell junction?
- Tight junctions
- Desmosomes
- Gap junctions
What is the main function of desmosomes?
To strengthen tight junctions between cells that need to resist stretching/twisting.
What type of proteins form channels at gap junctions?
Connexins/connexons
Tight junctions, desmosomes and gap junctions attach cells in the _________domain.
Lateral
How can cells be attached in the basal domain?
- Hemidesmosomes to basement membrane
- Focal adhesions to basement membrane
* Both involve the transmembrane glycoprotein integrin
What are the 2 functions of integrins?
- Attach cytoskeleton to ECM-mechanical
2. Signal transduction from ECM to cell-biochemical
Name 2 ways in which cultured cells behave differently to when in a living body.
- Contact inhibition
2. Limited lifespan- senescence
What are the 6 methods of cell communication?
- Direct-gap junctions
- Autocrine
- Paracrine
- Endocrine
- Synaptic
- Neurocrine-e.g. In adrenal medulla and pituitary gland
The cell bursts and dies in __________.
Necrosis.
Cells shrink and die in _________.
Apoptosis.
What is the relationship between cell renewal rate and cancer?
Higher cell renewal rate, higher risk for accumulating mutations, so higher cancer risk.
What are the 4 main types of tissue?
- Epithelial
- Muscle
- Nervous
- Connective(multiple specialised types)
What are the 6 main specialised types of connective tissue?
- Adipose
- Lymphatic
- Blood
- Haematopoietic
- Cartilage
- Bone
What are epithelioid cells?
Epithelial cells without a free surface/polarity. E.g. Islets of Langerhans, parenchyma of adrenal gland.
What domain of epithelial cells is often specialised?
Apical
What is normal plasma osmolality?
290 mOsmol/kg. Lower value=more dilute
What is the osmolality of normal saline?
300 mOsm/kg (150mmol/L Na+ and 150 mmol/L Cl-)- isotonic to plasma.
If you give a patient a colloid solution, the water should stay in what body compartment?
Intravascularly-protein is too big to leave blood.
Water moves to areas of ____ oncotic pressure.
High.
What is rabdomyelitis?
Damage to striated muscle causing necrosis, and potassium to leak into the blood, causing hyperkalaemia.
What are normal plasma concs of sodium and potassium?
- Na=140 mmol/L
2. K=5 mmol/L
What are the normal intracellular concs of Na and K?
- Na- 14 mmol/L
2. K- 160 mmol/L
What’s the normal range of blood pH?
7.35-7.45
What are normal plasma lactate levels?
<2nMol/L
Connective tissue can be broadly classified based on what 3 things?
- ECM-ground substance
- Fibres-protein
- Cells
Name 6 functions of connective tissue.
- Connecting
- Transporting
- Storing
- Protection/insulation
- Wound healing
- Defending
What are proteoglycans?
Core proteins with covalently bound glycosaminoglycans (GAGs) that make up connective tissue ground substance.
What is hyaluronic acid?
A unique GAG bound to proteoglycans by a link protein, found in cartilage ground substance.
What type of collagen is the most abundant?
Type I- around 90%
What is a disease of abnormal type I collagen?
Osteogenesis imperfecta
What is a disease of abnormal elastic fibres?
Marfan’s syndrome
Name key features of Marfan’s syndrome
- Arachnodactyly
- Very tall
- Frequent joint dislocation
What do mast cells release?
- Histamine
- Heparin
- Substances to attract neutrophils and eosinophils.
What is the main role of brown fat?
Non-shivering thermogenesis- especially important in babies.
What are the roles of white adipose tissue?
- Fuel reserve
- Insulation
- Shock absorption
Loose connective tissue mainly has a role in….?
Transport/diffusion of nutrients and waste products to/from epithelia.
Give examples of structures composed of dense regular connective tissue.
-Ligaments
-Tendons
-Aponeuroses
(All withstand unidirectional stress)
Give examples of where dense irregular connective tissue is found.
- Deep dermis
- Intestinal mucosa
What is osmolality?
A function of the concentration of particles in solution.
What is an abnormal plasma pH commonly due to?
Major organ dysfunction e.g. Lungs, kidney, liver. Shock- poor tissue perfusion–>hypoxia–>acidosis
What are the 2 main types of connective tissue proper?
Dense and loose.
What are glycosaminoglycans?
Long chain polysachharides that attract water to form a hydrated gel- allows CT to resist compression.
They are covalently bound to a core protein to form proteoglycans in the ground substance of connective tissue.
Where can loose connective tissue be found?
- Surrounding small blood vessels
- Associated with gland epithelium
- Superficial layer of dermis
- Colon submucosa
