Topic 2 Flashcards
How is air drawn to the lungs?
Air travels down the trachea due to low pressure in the lungs
- created by increase in volume of thorax
- as ribs move up
- and as diaphragm moves down
What happens when the diapragm muscles and those between the ribs relax?
- Volume of thorax decreases
- pressure rises
- air is forced out through the trachea
Describe the strcture of the trachea.
It’s divided into two bronchi which carry air to and from lungs
Describe the structure of the lungs.
- Tree-like system of tubes
- Ending in narrow tubes, bronchioles
- These are attached to tiny ballon-like alveoli
- sites of gas exchange
Where is mucus produced?
Produced continously from goblet cells in the walls of the airways
How is mucus removed?
Continously removed by the wave-like beating of cilia that cover epithelial cells lining the tubes of the gas exchange system
How does sticky mucus effect our health?
- Increases chance of lung infection
- Makes gas exchange less efficient
Where can epithelial cells be found?
- On the outer surface of many animals including mammals
- Line cavities and tubes within animals
- Cover surfaces of internal organs
What does the epithelium sit on?
The basement membrane
What is the basement membrane made up of?
Protein fibres in a jelly-like protein-carbohydrate matrix
What is the job of the basement membrane?
Anchors the epithelium onto the connective tissue below
Name the surfaces of the epithelium.
Surface that faces the basement membrane - basal membrane
Surface that faces away - apical membrane
What type of epithelium is in the walls of the alveoli and capillaries?
Squamous (pavement) epithelium
- Very thin, flattened cells
- Fit like paving
- Apical membrane faces lumen
What type of epithelium is in the small intestine?
Columnar epthelium
- Column-shaped cells
- extend out from basement membrane
- Free surface facing the lumen is covered in microvilli
- increase surface area for absorbtion
What type of epithelium is in the trachea, bronchi and bronchioles?
Ciliated epithelial cells
- Cilia on the apical surface
- Cilia beat in coordinated way to move substances along
- Appear stratified (composed of several layers) but actually each cell is in contact with basement membrane
- Appears stratified as some cells have nucleus at their base whereas others have them in their centre
- Therefore epithelium is known as pseudostratified
What are microorganisms that cause illness called?
Pathogens
How are pathogens killed?
Pathogens get trapped in mucus which is moved by the cilia into back of the mouth cavity
- Either coughed out or swalled, reducing risk of infection
- If swallowed the stomach acid kills most microorganisms
What effect does CF have on the mucus?
- Mucus is sticky so can’t move
- Production still continues
- layers of thickended mucus build up
- Low levels of oxygen in mucus
- due to oxygen diffusing slowly or epithilial cells use up more oxygen in CF patients
- harmful bacteria can thrive in anaerobic conditions
How do white blood cells make mucus even stickier?
White blood cells fight infections wihtin mucus but as they die they break down and release DNA that makes mucus even more sticky
How does oxygen croos the walls of the alveoli into the blood?
Diffusion
What’s special about the surface membrane’s in unicelluar organisms?
All of the surface area is the exchange surface.
How is a concentration gradient maintained?
Cells continously using the substances absorbed and producing waste
What are the main features of a gas exchange surface?
- Large surface area of alveoli
- Numerous capillaries around the alveoli
- Thin walls of alveoli and capillaries
What three properties is the rate of diffusion dependant on?
- Surface area
- directly proportional
- Concentration gradient
- directly proportional to the difference in concentration across the gas exchange surface
- Thickness of gas exchange surface
- inversely proportional
What is Fick’s law?
Why is there less water in mucus with people with CF?
Due to abnormal salt and water transportation across cell surface membranes
- Caused by a faulty transport protein channel in membrane
How many amino acids does a protein contain?
Between 50 and 200 amino acids
How many amino acids commonly occur in proteins?
20 different amino acids
- Plants can make all
- Animals can only make some (essiential amino acids)
What is the structure of an amino acid?
What is a peptide bond?
A bond that forms between two subunits of amino acids when they join in a condenastion reaction to form a dipeptide
What is the primary structure of a protein?
The sequence of amino acids in the polypeptide chain
What is the secondary structure of a protein?
Interactions between the amino acids in the polypeptide chain cause the chain to change shape into either α-helices or β-pleated sheets
Describe a α-helix
- extended spring
- hydrogen bonds form between the slightly negetive C=O of the carboxylic acid and the slightly postive -NH of the amine group of different amino acids
- stablises the shape
- sections of α-helix can be up to 35 amino acids long
Describe β-pleated sheets
- amino acid chains fold back on themsleves
- about 15 amino acids in length
- may link together with hydrogen bonds holding parallel chains in arrangement
- Hydrogen bonds are weeak but overall the H-bonds make the structure quite stable
What is the tertiary structure of a protein?
Polypeptide chains often bend and folds further to produce a precise 3D shape
- chemical bonds and hydrophobic interactions between R groups maintain the tertiary structure
What makes an R group polar?
When the sharing of electrons within it isn’t even
What makes R groups hydrophillic?
As they are polar they attract other polar molecules such as water.
What makes an R group hydrophobic?
If it isn’t polar.
- arranged so they face inside the protein, excluding water from the centre of the protein
How does a covalent disulphide bond form?
If two cysteine R groups are close to each a covalne disulphide bond will form as they contain a -SH side group.
Whats the strongest type of bond?
Disulphide and ionic bonds are stronger than hydrogen bonds.
However they are sensitive to changes in pH
What is a quaternary structure?
Proteins that have more than one polypeptide chains.
Single chain proteins stop at the tertiary level.
What is a conjugated protein?
Proteins that have another chemical group associated with their polypeptide chain(s).
What are the two distinct shapes of proteins?
Globular and Fibrous
Describe a globular protein.
- Polypeptide chain is folded into a compact spherical shape.
- Soluble due to hydrophillic side chains
- important in metabollic reactions
- 3D shape is crucial to their roles in binding to other substances
- Examples: enzymes, haemoglobin, myglobin
Describe a fibrous protein.
- Long chains
- Several polypeptide chains can be linked for additional strength
- Insoluble
- Important structural molecules
- Examples: Keratin, collagen
What is the phospholipid bilayer?
The surface membrane of epithelial cells are made up of tow layers of phospholipids
Why is the phosphate head hydrophillic?
The phosphate head is polar
- One end is slightly positive
- The rest is slightly negetive
Why is the fatty acid tail hydrophobic?
Its non-polar
How do phospholipids arrange themselves in water?
- Form spherical clusters called micelles or form a bilayer
- Hydrophillic tails point inwards
- A lipid bilayer will close on itself so no en are exposed with hydrocarbon chains
What are glycoproteins and glycolipids?
Glycoproteins- protein molecules with polysccharides attached.
Glycolipids - lipid molecules with polysccharides attached.
What makes the fluid mosaic model more fluid?
The greater the ratio of phospholipids that contain unsaturated fatty acids to those containing saturated fatty acids.
- The kinks in the hydrocarbon tails prevent them form packing closely together
- therefore more movement is possible
- Cholesterol sits between the phospholipids and maintains fluidity of membrane
What is the importance of glycolipids and glycoproteins?
Helps cell-to-cell recognition anf as receptors
How do molecules and ions move across membranes?
- Diffusion
- Osmosis
- Active transport
- Exocytosis
- Endocytosis
What is diffusion?
- Down a concentration gradient, form high to low until equilibrium is reached
- hydrophobic or small uncharged molecule
- through phospholipid bilayer
- passive, no energy required
What is facilitated diffusion?
- Dow a concentration gradient, form high to low until equilibrium is reached
- hydrophillic molecules or ions
- through channel proteins or via carrier proteins that change shape
- passive, no energy required
What is osmosis?
- type of osmosis involving movement of free water molecules
- from high concentrations to low until equilibrium is reached
- through phosphlipid bilayer
- passive, no energy required
What is active transport?
- Against a concentration gradient, from low to high
- through carrier proteins that change shape
- requires energy supplied by ATP
What is exocytosis?
- used for bulk transport of substances out of the cell
- vesuscles fusee with the cell surface membrane, releasing their contents
What is endocytosis?
- used for bulk transport of substances into the cell
- vesicles are created from the cell surface membrane, bringing their contents into the cell
What does viscosity mean?
‘stickiness’
