Topic 2- Notes Flashcards
trachea, bronchi, bronchioles, alveoli
Do they have cartilage?
Trachea - c-shaped rings to keep airway open
Bronchi - irregular blocks
Bronchioles/alveoli - none
do trachea, bronchi, bronchioles and alveoli have ciliated epithelium?
Trachea, bronchi, bronchioles yes
Alveoli - they have simple squamous epithelium
Do trachea, bronchi, bronchioles and alveoli have mucous glands?
Trachea - goblet cells secrete mucus
Bronchi - fewer goblet cells
Bronchioles - none
alveoli - none
do trachea, bronchi, bronchioles and alveoli have elastic fibres?
Trachea - few
Bronchi, bronchioles, alveoli - yes
Do trachea, bronchi, bronchioles and alveoli have smooth muscle?
alveoli - no
the rest - yes
Do trachea, bronchi, bronchioles and alveoli have macrophages?
All - yes
How is diffusion aided in the alveoli?
Large SA
thin squamous epithelium .
surrounded by blood capillaries
What are epithelium?
- A tissue
- Found on outer surface of many animals and the surfaces of organs cavities and tubes
- Can be squamous (flattened and v thin or columnar (extended in height)
Epithelium function
Move mucus (and other trapped dust/microbes) up and out of lungs to throat, here it is swallowed.
Microorganisms destroyed by acid in stomach.
Goblet cells in ciliated epithelium, trachea and bronchi produce mucus which traps inhaled particles
2 problems caused by the sticky mucus produced by CF patients
1) Increase chances of lung infections: bacteria collect in mucus - too sticky for cilia to move therefore mucus builds in airways - stickier. Harder for white blood cells to fight - weakened.
2) Decrease in gas exchange efficiency: sticky mucus builds in bronchioles preventing ventilation to alveoli below: reducing no. working alevoli can lead to damage , elasticity, lungs
Fill in the gaps:
The actual respiratory surface is on the A inside the lungs. An average adult has about 600 mil alveoli, giving a total SA about 100m2, so the A is huge. The walls. the alveoli are composed. a single layer. flattened B cells, as are the walls. the capillaries, so gases need to C through just 2 thin cells. D diffuses from alveoli cells into the alveoli so that they’re always moist. E dissolves in this water before diffusing through the cells into the blood, where it’s taken up by F in the red blood cells. the water also contains a soapy G (a mixture of H molecules) with I its surface tension and stops the alveoli J. The alveoli also contain phagocyte cells to kill any K that’ve not been trapped by the L.
A - alveoli B - epithelial C - diffuse D - water E - oxygen F - haemoglobin G - surfactant H - phospholipid I - reduces J - collapsing K - bacteria L - mucus
What is fick’s law?
rate. diffusion SA x difference in conc/thickness. the gas exchange surface
What 3 properties of gas exchange surfaces is the rate.diffusion dependent on?
SA - rate.diffusion is directly ? to the SA. As SA increases, rate.diffusion increases.
Conc.gradient - rate.diffusion is directly ? to the diiffernce in conc.across the gas exchange surface. Great conc.gradient leads to faster the diffusion.
Thickness of the gas exchange surface - rate.diffusion is inversely ? to the thickness of the gas exchange surface. The thicker the surface the slower the diffusion.
What are proteins?
What are some of their biological roles?
Proteins are a group of large/complex polymer molecules made up of long chains of amino acids.
Biological roles:
Structural: They’re the main component of body tissues e.g. muscle, sin, ligaments and hair.
Catalytic: All enzymes are proteins, catalyzing many biochemical reactions.
Signalling: Many hormone and receptors are proteins.
Immunological: All antibodies are proteins. Immunological means related to the immune system.
A protein consists of 1 or more polypeptide chain folded into a highly specific 3D shape.
Describe the primary structure of a protein
The order of amino acids joined together by peptide bonds in a polypeptide.
There are 20 different kinds of amino acid, and thus a vast no. combinations are possible
Tertiary structure
The precise shape formed by folding of the secondary structure - due to interactions mainly between R groups.
eg.
i) ionic bonds
ii) disulfide bridges between S-S of cysteines
iii) hydrophobic interactions (i.e. non-polar amino acids face inwards)
iv) hydrogen bonds
Quartenary structure
the linking of a no. of 3) folded polypeptide chains e.g. haemoglobin = 2 identical beta chains and 2 identical alpha chains.
More than one tertiary structure
What are conjugated proteins?
Proteins containing non-protein material e.g. each alph and beta chain has a heme (iron containing) group at the centre of the chain. The non-protein part is called the prosthetic group.
the Davson -Danielli model (held up to the 1970s)
a) Description
b) evidence for
c) evidence against?
a) consists of: a lipid bilayer where 2 layers of polar lipid molecules are arranged with the hydrophilic heads outwards. A layer of protein covering the surfaces of the membrane. lipids aren’t free 2 move.
3 layers - protein, lipid sandwich.
b) evidence from electron micrographs. Dark outer layers thought to be proteins and lighter areas thought to be lipids.
c) Doesn’t allow hydrophilic phosphate heads to be in contact with water.
Experiments to figure out where the proteins went on a model:
a) increase ionic strength.solutions/adding detergent/
peripheral proteins:
- loosely attached to outside surface of membrane
- some could be dissociated by low ionic strength
integral proteins:
- fully embedded within the phospholipids membrane
- some needed more action/adding detergent in order to dissociate
b) analysis of amino acid content of proteins?
some proteins have polar, hydrophilic amino acids at end of proteins with a non-polar hydrophobic amino acid in the middle.
c) Freeze fracture and scanning EM (electron microscopy) studies?
Sample is frozen- cut/split- showing outer and inner layers - inner coated in heavy metal.
3D images from EM scanning
found mosaic-like structure (lipid tails)
bumps = integral proteins
d) Use. lectins which bind to polysaccharides previously labelled with ferritin?
- the lectins only bound to outer surface.
- Therefore membranes are asymmetric - not like the Davson Danielli model
e) Fusion. mouse and human cells to create hybrids?
Label same proteins in mouse with GFP (green fluorescent protein) and some proteins in human with RFP (red fluorescent protein)
Fill in the gaps:
Membranes are composed of A, B and C arranged in a D structure. The E form a thin, flexible sheet, while the proteins “float” in the F sheet like icebergs, and the carbohydrates extend out from the proteins.
The G are arranged in a layer 2 molecules thick, a H with their polar, hydrophilic I heads facing J and their non-polar hydrophobic K tails facing each other in the middle of the bilayer. This hydrophobic bilayer acts as a barrier to all but the smallest molecules, isolating the 2 sides of the membrane.
Different kinds of membranes can contain phospholipids with different L affecting the M and N of the membrane.
A) proteins H) bilayer
B) Lipids I) phosphate
C) carbohydrate J) outwards
D) phospholipid bilayer K) fatty acid
E) phospholipids L) fatty acids
F) phospholipid M) strength
G) phospholipids N) flexibility
Animal cell membranes also contain another vital lipid, what is it, and what is its role?
Cholesterol:
Maintains the fluidity of the membrane by affecting movement of the phospholipids
What is
a) exocytosis
b) endocytosis?
a) Used for bulk transport of substances OUT of the cell. Vesides fuse with the cell surface membrane, releasing their contents.
b) used for bulk transport of substances INTO the cell. Vesicles are created from the cell surface membrane, bringing their contents into the cell.
Summary of membrane transport:
method Uses energy Uses proteins specific Simple diffusion Facilitated diffusion Osmosis Active Transport Vesicles
Uses Uses Specific energy proteins No No No No Yes No No No No Yes Yes Yes No No No (it's the protein that makes it specific)
True or False
a) The neurotransmitter acetylcholine can activate a muscle cell and cause it to contract, even though the acetylcholine molecule never enters the cell because the acetylcholine receptor protein spans the plasma membrane.
b) Cholesterol molecules act to attach to carbohydrates.
c) The plasma membrane of animals contains carbohydrates on the side of the membrane facing away from the cell
a) True
b) False - alter the fluidity of the membrane
c) True
True or False?
a) Lipids form a barrier to the movement materials across the membrane.
b) The interior of the phospholipid bilayer is Aqueous
c) All proteins are anchored within the membrane
d) the amino acid side chains in the region of the protein that crosses the membrane are likely to be charged.
a) True
b) False - hydrophobic
c) False - many proteins can move around the bilayer
d) False - hydrophobic
Describe:
a) Proteins that span the membrane
b) Proteins on the inside surface of cell membranes
c) Proteins on the outer surface of cell membranes
a) They’re usually involved in transporting substances across the membrane.
b) they’re often attached to the cytoskeleton and are involved in maintaining the cell’s shape/in cell motility. They may also be enzymes, catalysing reactions in the cytoplasm.
c) they can often act as receptors by having a specific binding site where hormones/other chemicals can bind. This binding then triggers other events in the cell. They may also be involved in cell signalling and cell recognition/they may be enzymes, e.g. maltase in the small intestine (more in digestion)
where are the carbohydrates found in a cell membrane? (glycocalyx)
- On the outside surface of all eukanyotic cell membranes and are attached to the membrane proteins/sometimes to the phospholipids.
- They’re short polysacchaarides composed of a variety of different monosaccharides, and form a cell coat of glycocalyx outside the cell membrane.
- The glycocalyx is involved in protection and cell recognition and antigens such as the ABO antigens on blood cells are usually cell-surface glycoproteins.
Where are proteins found in a cell membrane and what’s their structure?
They usually span from 1 side of the bilayer to the other (channel proteins), can also sit on one of the surfaces. Can slide around the membrane very quickly and collide with each other, but can never flip from one side to the other.
The proteins have hydrophilic amino acids in contact with the H2O on the outside of membranes and hydrophobic amino acids in contact with the fatty chains inside the membrane.
Proteins comprise about 50% of the mass of membranes and are responsible for most of the membranes properties.
What is osmosis? Define: a) isotonic solution? b) hypertonic solution? c) hypotonic solution/
Osmosis is the net movement of water molecules from a solution of low conc. solute (high water conc.) to a solution of higher solute conc. (lower water conc) through a partially permeable membrane. a) equally concentrated b) higher osmotic pressure lower water potential which = high solute conc c) opposite to b) overall movement of water (arrow down): arrow down: hypo arrow both ways: iso arrow up: hyper
What is diffusion?
What can diffuse through a lipid bilayer?
The movement of molecules or ions from a region of high conc. to a region of low conc. by relatively slow random movements of molecules - until equilibrium.
Small uncharged particles, O2, CO2, non-polar and hydrophobic particles can diffuse through a lipid bilayer.
Diffusion across a membrane doesn’t require energy, it’s passive
Cell membranes are impermeable to most substances: Why is this important and what does it allow?
This property allows materials to be concentrated inside cells, materials to be excluded from cells or materials to be simply separated from the outside environment.
This compartmentalisation is essential for life, as it enables reactions to take place that would otherwise be impossible. Eukaryotic cells can also compartmentalisation materials inside organelles.
Obviously materials need to be able to enter and leave cells, and there are several methods by which substances can move across a cell membrane..
Globular and Fibrous Proteins
What are globular proteins?
- 3D
- Highly folded and compact spherical shape
- Tertiary structure easily disrupted
- Soluble-hydrophilic side groups on outer surface of the protein
- Precise shape needed for molecular interactions
- e.g. haemoglobin, antibodies, enzymes (protease), hormones (e.g. insulin)
- regular repetitive sequences of amino acids
- highly specific
- Always identical between 2 e.g. of the same protein
- metabolic functions.
What are fibrous proteins?
- composed of many polypeptide chains, chains are long and held together (often by H bonds)
- several polypeptide chains can be cross linked - stable
- usually insoluble
- they’re important for structural strength
- e.g. keratin in hair, callogen in skin and bone
- irregular amino acid sequences
- sequences may vary
- long parallel strands
- length of chain may vary
- support and structural functions
What does anabolic and catabolic reactions mean?
Anabolic reactions: building up
Catabolic reactions: building down
What is mucus like in non-CF sufferers /production?
Cells that line airways produce mucus.
Water content of mucus continuously regulated to maintain constant viscosity, the mucus.
Must be runny enough to move by cilia, not too runny so it floods airways.
Regulation - water content maintained by transport. sodium ions and chloride ions across epithelial cells.
Water follows ions by osmosis.
Organisms affected by CF:
Airways
Clogging and infection of bronchial passages impede breathing. The infections progressively destroy the lungs. Lung disease accounts for most deaths from CF.
Liver:
Plugging of small bile ducts impedes digestion and disrupts liver function in perhaps 5% of patients.
Pancreas
Occlusion of ducts prevents the pancreas from delivering critical digestive enzymes to the bowel in 65% of patients. Diabetes can results as well.
Small intestine
Obstruction of the gut by thick stool (constipation, faeces), necessitates surgery in about 10% of newborns.
Reproductive tract
Females have less chance of becoming pregnant - mucus plugs develop in the cervix - stops sperm reaching the eggs. males with CF usually the vas deferens (sperm ducts) meaning sperm can’t leave the testes/vas deferens can become partially blocked by a thick sticky mucus layer. Fewer sperm present in each ejaculation.
Skin
Sweat glands are exocrine gland, initially secrete into their lumen a solution of salt and water that’s isotonic to the blood. n an individual without CF, CFTR and ENaC proteins allow respiration of sodium chloride from the sweat as it moves up the duct towards the skin. The sweat that’s released on to the skin and evaporates if therefore hypotonic. (measurement of chloride in sweat is a mainstay of diagnosis)
Enzymes: write a definition for each:
biological catalyst
Enzymes are biological catalysts; they are protein carriers that speed up chemical reactions in living organisms. Different chemical reactions within cells are catalysed by specific enzymes. Without these enzymes, the reactions would take place very slowly at the temperature inside cells.
Activation energy
Before a chemical reaction can take place, bonds must be broken. This requires energy. This activation energy is normally provided by heating the substances involved in the reaction. Enzymes reduce the activation energy for a reaction, so reactions in living organisms can take place at relatively low temperatures.
