Topic 1 - Lifestyle, Health and Risk Flashcards
Diffusion
the net movement of particles from an area of high concentration to an area of low concentration
Closed Circulatory Systems
- blood is fully enclosed within blood vessels at all times
- ensures a higher pressure than open systems
Single Circulatory Systems
- deoxygenated blood enters atrium + pumped towards the gill capillaries by the ventricle
- blood is oxygenated at gill capillaries
- oxygenated blood moves towards tissues
- deoxygenated blood returns to atrium
Double Circulatory Systems (3-chambered)
- deoxy blood enters right atrium
- oxy blood enters left atrium
- both enter ventricle (partial mixing)
- blood is pumped separately to gill capillaries (gain oxygen) and systemic capillaries (supply oxygen)
Mammalian Circulatory System (4-chambered)
- double circulatory system
- deoxygenated blood enters right atrium via vena cava
- blood travels from the right atrium to the right ventricle, passing through the tricuspid valve
- blood exits the heart via the pulmonary artery, becoming oxygenated in the lungs
- blood leaves via the pulmonary vein to the left atrium
- blood passes through the mitral valve to reach the left ventricle.
- leaves the heart via the aorta
Peripheral resistance
the impediment of the flow of blood due to friction caused by contact between blood and the walls of blood vessels
Contents of plasma (what plasma is made up of)
- glucose
- oxygen
- CO2
- ions
- proteins (enzymes, hormones, antibodies)
- urea
- amino acid
Structure of water
- oxygen is negatively charged
- hydrogen atoms are positively charged
- this makes water dipolar
Hydrogen bonding in water
- dipole nature of water means weak attraction between water molecules through hydrogen bonds
- allows for cohesion of water molecules
- H bonds form between other molecules and water
Water as a solvent for ionic substances
ionic substances can dissolve due to dipole nature of water
Water as a solvent for polar substances
- amino acids + glucose can also dissolve in water
- -OH and -NH2 groups become surrounded by water and go into solution
Water as a thermal regulator
- temp of substances go up with speed
- due to hydrogen bonding (prevents KE increase), temp. of water remains stable despite surrounding temp. changes
- therefore, water has a very high specific heat capacity
Freezing properties of water
- when temp. is low enough, hydrogen bonding properties result in a lattice structure
- ice is less dense than water
- ice reflects light energy
- ice also acts as thermal insulation, which allows water below to remain liquid and habitable
Cardiac cycle
all of the events that take place in one beating of the heart
How the cardiac cycle is controlled
Myogenically - the electrical impulses are initiated by the heart muscle cells (myocytes) themselves and there is no need for an external stimulus (e.g. from a neuron)
Cohesion/adhesion of water
polar nature of H2O
- allows for enough surface tension for insect habitat
- allows water to be cohesive and adhesive - can move upwards through plant stems, acting as a transport medium in plants (xylem/phloem)
Diastole
- Blood from the body enters the right atrium and blood from the lungs enters the left atrium (relaxation)
- atrial pressure > ventricular pressure, resulting in AV valves opening
- blood trickles into ventricles
Atrial systole
- the two atria contract, forcing blood through the AV valves into the ventricles
- atrial pressure > ventricular pressure
- AV valves remain open
Ventricular systole
- the ventricles contract, increasing pressure and causing AV valves to close
- blood is forced into the aorta and pulmonary arteries, opening semilunar valves
- ventricular pressure > atrial pressure
- ventricular pressure > aortic pressure
CVD
any condition that interferes with the heart or blood vessels
Atherosclerosis
the disease process that leads to CHD and CVD
a thickening of artery walls caused by a buildup of fatty plaques (atheroma) on the inside walls
Thrombosis
blockage by a blood clot
Positive feedback
the enhancing or amplification of an effect by its own influence on the process which gives rise to it
Why blood clots form in arteries
more likely to form when blood vessel walls are damaged/when blood flows very slowly
How blood clots form in arteries
- platelets come into contact with damaged vessel wall
- they change from discs to spheres with long, thin projections
- their cell surfaces change, causing them to stick to exposed collagen in the wall and each other to form a plug
Forming blood clot steps
- damage to tissue releases platelets, which rupture and release serotonin and thromboplastin
- serotonin causes localised vasoconstriction, directing blood away from the damaged area to minimise blood loss
- thromboplastin catalyses conversion of inactive prothrombin into active thrombin
- thrombin catalyses the conversion of soluble fibrinogen into insoluble fibrin
- fibrin forms a mesh of fibres that trap RBCs and platelets, causing a clot
*REFER TO FLOW CHART IN NOTES
Angina
A type of chest pain caused by reduced blood flow to the heart. A narrowing of coronary arteries causes reduced O2 to heart muscles (anaerobic respiration)
Myocardial infarction (heart attack)
When part of the heart is completely starved of oxygen, usually due to blockage by a clot, so muscle cells cannot respire aerobically
Aneurysm
a bulging, weakened area in the wall of a blood vessel due to blood accumulating behind a restricted area
Stroke
the result of the cutting off of blood to the brain, starving it of oxygen
Risk
the probability of occurrence of some unwanted event or outcome
Risk factors
aspects that increase the chance of the harmful outcome
Correlation
when a change in one variable is accompanied by a change in another variable
Causal link
when a change in one variable is responsible for a change in the other
Null hypothesis
a hypothesis that says there is no statistical significance between the two variables
CVD risk factors
- diet (e.g., lipoprotein and salt levels)
- smoking (chemicals in smoke physically damage artery lining and also cause them to constrict)
- gender (oestrogen gives women some protection from CVD before menopause)
- high blood pressure
- genetics (can inherit tendency to e.g., HBP, poor cholesterol metabolism etc.)
- inactivity (regular vigorous exercise reduces blood pressure and raises HDL)
- age (elasticity and width of arteries decrease with age)
Epidemiologists
scientists who study patterns in the occurrence of disease and look for correlations between a disease and specific risk factors
Atherosclerosis steps
- the endothelium becomes damaged e.g., due to high blood pressure, toxins from cigarette smoke etc.
- damage triggers inflammatory response
- atheroma forms from buildup of chemicals accumulated by white blood cells, calcium salts, fibrous tissue etc.
- atheromas cause narrowing of arteries, making it more difficult for heart to pump blood and blood pressure to rise
structure and function of arteries
- relatively thick wall - withstands high blood pressure
- smooth muscle - alters diameter of lumen to vary blood flow
- elastic fibres - allows walls to stretch
- lined with smooth layer of endothelial cells - low friction surface to ease blood flow
- narrow lumen - maintains high blood pressure
structure and function of capillaries
one cell thick wall - allows rapid exchange of oxygen and carbon dioxide between blood and tissues
structure and function of veins
- relatively thin wall - blood under low pressure
- very little smooth muscle/elastic fibres - no pulse of blood so no stretching and recoiling
- wide lumen - large volume acts as blood reservoir
- valves - prevents backflow of blood
the cardiac cycle steps (left side)
- blood drains into left atrium from lungs along pulmonary vein
- raising of blood pressure in left atrium forces the left AV valve open
- left atrial systole forces more blood through the valve
- left ventricular muscles start to contract
- this forces left AV valve to close and opens the semilunar valve
- blood leaves along the aorta
Cohort studies
follow a large number of people over an extended period
Case-control studies
a group with the condition (cases) is compared with a group without it (control)
Energy budget
the balance between the amount of energy a person requires compared to the energy they take in through their diet
depends on basal metabolic rate (BMR) and level of activity
Waist:hip ratio
another indicator of obesity
- should not be >0.9 in men
- should not be >0.85 in women
BMI equation
body mass in kg/(height in m)^2
Carbohydrates
substances made of C and H2O with the general formula Cx(H2O)n
the main source of energy in the diet
Saccharides
sugar units that make up carbohydrates
- monosaccharide (one unit)
- disaccharide (two units)
- polysaccharide (many units)
Glucose structure and functions
- the source of the most readily available energy from respiration
- polar
- solubility helps it dissolve in watery plasma for transport
- dissolves in cytoplasm for chemical reactions
- lots of stored chemical potential energy
- a relatively small molecule - important for movement into cells
How disaccharides are made
- when two monosaccharides join by condensation reaction (losing water)
- they join at C atoms 1 and 4, forming a 1,4 glycosidic bond
How disaccharides are split
- hydrolysis reaction (adding water)
- glycosidic bond is broken
Examples of disaccharides
- maltose (two α-glucose molecules)
- sucrose (an α-glucose and a fructose)
- lactose (glucose and galactose joined with a β 1,4 bond because the glucose is in the β form)
examples of monosaccharides
- glucose - (CH2O)n
- galactose
- fructose
starch
- energy storage molecule for plants
- made up of amylose and amylopectin
amylose structure
- straight chains (no branches of α-glucose)
- 1,4 glycosidic bonds between glucose molecules
- chain coils into spiral
amylopectin structure
- chains of α-glucose with 1,4 glycosidic bonds
- has side branches
- branches of α-glucose with 1,6 glycosidic bonds
glycogen structure
- similar structure to amylopectin
- α-glucose chains (1,4 glycosidic bonds)
- heavily branched (approx. every 10 glucose molecules)
- many branches formed with 1,6 glycosidic bonds for quick glucose release
starch structure and function
- made of glucose polymers amylose and amylopectin
- coiled shape (stores lots of glucose)
- insoluble (no problematic osmotic effect)
- amylopectin more easily broken down than amylose due to more branches - gives a mixture of rapid and slower glucose release
lipids functions
- store energy
- waterproofing agent
- insulating agent
triglycerides
a type of lipid
- made of three fatty acids and a glycerol joined by ester bonds
- formed by a condensation reaction
fatty acid facts
- of different lengths
- in mixed triglycerides the three fatty acids are different from each other
- maybe saturated (no double bonds) or unsaturated (double bonds)
properties of saturated and unsaturated fatty acids
saturated
- straight chains
- less fluid membrane than unsaturated
unsaturated
- kink at each double bond
- kink makes membrane more fluid than that of saturated lipids
cholesterol
water-insoluble lipid which has to be carried by proteins in complexes called lipoproteins
there are two kinds, HDL and LDL
LDL
‘bad’ cholesterol
- formed from saturated fats, protein, cholesterol
- bind to cell surface receptors, which can become saturated, leaving LDLs in the blood
- associated with formation of atherosclerosis
- should be maintained at low level
HDL
‘good’ cholesterol
- formed from unsaturated fats, protein, cholesterol
- transport cholesterol from body tissues to liver where it is broken down
- reduces blood cholesterol levels, discourages atherosclerosis
- should be maintained at high level
drugs to reduce risk of CVD
- diuretics - increases urine volume; lowers blood volume and pressure
- calcium channel blockers - lowers blood pressure
- ACE inhibitors - blocks production of ACE, reducing arterial constriction and lowering BP
- statins - lowers LDL cholesterol levels
- anticoagulants - reduce risk of clot formation
- platelet inhibitory drugs - make platelets less sticky
Mass transport system
The bulk movement of gases or liquids in one direction, usually via a system of vessels and tubes
Explanation of dipole nature of water
- covalent bonding occurs between an oxygen atom and two hydrogen atoms
- there is an unequal sharing of electrons between oxygen atom and hydrogen atom
- oxygen has a greater electronegative charge
- therefore oxygen pulls electrons from hydrogen towards its nucleus
- oxygen is partially negative and hydrogen is partially positive
- water is therefore polar
