Cell Tissue Flashcards
How is loose connective tissue composed?
Many cells, high content of ground substance, sparse collagen fibres
Describe the structure of a proteoglycan.
A core protein with many side-chain sugars, of which many are glycoaminoglycans
How are glycoaminoglycans charged? What affect does this charge have?
Glycoaminoglycans (GAGs) are negatively charged - this attracts positively charged Na+ ions, drawing with it water
Describe the 2 segments that make up elastin.
A hydrophobic region, which provides the molecules elasticity - an alanine-lysine residue rich region, responsible for cross-linkage of the elastin molecules to make a fibre
What is the basement membrane?
The underlying layer of tissue to which the epithlial cells are anchored - this separates the epithelia from surrounding connective tissue and keeps cells in their proper compartments
What is the role of integrin?
Integrins attach the cell cytoskeleton to the extracellular matrix
How is paracrine secretion different to autocrine secretion?
Paracrine secretion acts on cells locally (ie adjacent cells) while auto crime secretion involves the cell acting on itself
What is endocrine secretion?
Endocrine secretion involves secretion of molecules/hormones into circulation via the blood stream
What process involved the eukaryotic uptake of a prokaryote now known as mitochondria?
Endosymbiosis
What is controlled cell death; apoptosis or necrosis?
Apoptosis
What are the 4 main types of tissue?
Epithelial
Muscle
Nerve
Connective
What type of bond attaches GAGs to the core proteoglycan protein?
Covalent
What are keratan sulphate and chondroitin sulphate?
Sulphated GAGs
How is the ground substance different to the extracellular matrix?
The ground substance is a mixture of proteoglycan and water - the extracellular matrix contains further molecules such as collagen fibrils and extracellular proteins etc
How is dense connective tissue composed?
Few cells, many collagen fibres, low amount of ground substance
What substance does loose connective tissue resemble? What surfaces is loose connective tissue mostly associated with, and how does it impact these surfaces upon infection?
Lost connective tissue resembles a viscous gel - it is mainly associated with the epithelia, and can swell considerably when they become infected
What is the dermis? What is the epidermis?
The dermis is the skin - the epidermis is the outer-most layer of the skin
We know that dense connective tissue has a high abundance of collagen fibres. How does the orientation of these fibres differ in regular and irregular tissue?
In regular tissue, college bundles are all positioned parallel to on another in the same direction - in irregular tissue, collagen fibres are arranged in bundles which are orientated in various different directions
Is the dermis regarded as a regular or irregular dense connective tissue?
Irregular dense connective tissue
How does the differing structure of regular and irregular dense connective tissue affect its function?
Regular dense connective tissue is designed to withstand pressure in just one direction (as in a joint/ligament) while irregular dense connective tissue is designed to withstand pressure in multiple directions (as in the skin)
What is a ligament? Describe its tissue.
A ligament joins bone to bone - it consists of regular dense connective tissue (densely-packed collagen bundles), seperated by loose connective tissue
What 2 substances do fibroblast secrete? What is their activity mainly associated with?
Fibroblasts secrete procollagen and ground substance - they are associated with wound healing, specifically with closing the wound and the formation of scar tissue
Why aren’t mast cells located in the CNS?
The histamine they secrete increases vessel wall permeability and so induces oedema, which is damaging
List 2 granules that a mast cell might secrete. What are their effects?
Mast cells secrete:
- histamine - increases the vascular cell wall permeability
- heparin - an anticoagulant
What vitamin is associated with collagen synthesis? What disease is associated with a lack of this vitamin?
Vitamin C, a deficiency in which can cause scurvy
What is a desmosome?
A structure that attaches a cell to an adjacent cell
What is the difference between a gap junction and a tight junction? Where do they reside?
Both reside on the lateral domain of the cell - gap junctions allow movement of ions throughout a cell, while tight junctions prevent molecules from moving through the intercellular space
What is a hemidesmosome?
Specialised anchoring cells that anchor the epithelia to the basement membrane
State what structures desmosomes, hemidesmosomes, and integrins anchor an epithelial cell to.
Desmosome - attach adjacent cells to one another
Hemidesmosome - anchor cells to the basement membrane
Integrin - anchor the cell to the extracellular matrix (collagen)
Is there a relationship between a cell types renewal rate and its propensity to develop cancer?
Yes
What is the difference between endocytosis and exocytosis?
Exocytosis is the movement of particles out of a cell and endocytosis is the movement of particles into a cell
List 2 organelles found in eukaryotic cells which are found in prokaryotic cells.
Nucleus
Mitochondria
What is the name of an epithelial cell that has no free surface?
Epithelioid
Name 1 unique glycoaminoglycan?
Hyaluronic acid
What process does the composition of loose connective tissue aid?
Diffusion
Briefly, what mechanism results in the release of granules from a mast cell?
The mast cell becomes coated in IgE - these them form cross-links with allergens, resulting in the release of the mast cell contents
What is the most common protein in the human body?
Collagen
What type(s) of cartilage contain type II collagen?
Hyaline and elastic cartilage
Describe the structure of collagen. What amino acid is particularly key in this formation?
Collagen is a triple helix of alpha chains - glycine allows the 3 alpha helical chains to pack tightly together as it is the smallest amino acid
What disorder does abnormal type I collagen result in?
Osteogenesis Imperfecta
What type of collagen is reticulin (reticular fibres) composed of?
Type III collagen
What is the elastin in elastic fibres surrounded by?
Fibrillin
Suggest a disease caused by abnormal elastic fibres. What part of the elastic fibre is abnormal?
A mutation in the gene coding for the reticulin surrounding elastin may lead to a disorder called Marfan’s Syndrome
What kind of symptoms might you expect from an individual suffering from Marfan’s Syndrome?
Individuals with Marfan’s syndrome are abnormally tall, exhibit arachnodactyly, have frequent joint dislocation, and are at severe risk or an aortic rupture
Is the majority of adipose tissue in the human body white or brown fat?
White fat
What is the maim role of white fat?
As a reserve source of fuel, though they also have a role in shock absorption and insulation
What is the main role of brown fat?
Brown fat is primarily a heat generator
Why is brown fat brown?
Due to a high number of mitochondria, which underlie respiratory capacity to generate heat
What type of collagen is the major contributor to Fibrillin?
Type III collagen
