Topic 1 - Lifestyle, Health and Risk

What makes up CVD

Heart disease, blood vessels disease, stroke

UK common causes of death

CVD is the most common cause of death in the UK and globally
2nd most common cause of death in the UK is Dementia and Alzheimer's disease

Risk factors (most important risk factors in order)

High blood pressure
Unhealthy diet
High LDL cholesterol
Diabetes
Air pollution
Excess weight
Smoking (including passive smoking)
Kidney dysfunction

Risk factors (contributory factors)

Stress
Not enough exercise
Family history (genetics)
Ageing
Being male

Different ways to get oxygen to cells

diffusion
respiration via lungs
spiracles (holes in the exoskeleton)

factors affecting rate of diffusion: concentration gradient

the higher the concentration gradient, the greater the rate of diffusion

factors affecting rate of diffusion: surface area

the larger the surface area, the greater the rate of diffusion

factors affecting rate of diffusion: diffusion distance

the greater the diffusion distance, the lower the rate of diffusion

factors affecting rate of diffusion: temperature

the higher the temperature, the greater the rate of diffusion

factors affecting rate of diffusion: molecule size

the larger the molecule, the slower the rate of diffusion

mass flow system definition

a mass flow system transports substances in bulk down a pressure gradient. this enables substances to move long distances at a sufficient rate

why is a mas flow system needed

the majority of the cells in a multicellular organism are not in contact with the organism's surroundings. as such, a mass flow system is needed to transport glucose and oxygen from the outside of the organism to every cell in the body
the larger the organism, the greater the distance that oxygen and glucose must travel, and greater the amount needed

requirements for a mass flow system

• circulatory fluid
• contracting pump to move fluid
• tubes through which fluid can circulate

examples of mass flow systems

circulatory system
digestive system
respiratory system
lymphatic system

circulatory system: materials moved and pump

blood
heart and contractile blood vessels

digestive system: materials moved and pump

food, water
muscles surrounding intestines

respiratory system: materials moved and pump

air
intercostal muscles, diaphragm

lymphatic system: materials moved and pump

lymph
contraction of skeletal muscle

what are the two circuits in a double circulatory system

pulmonary (lungs) and systemic (body)

what is a closed circulatory system

the blood remains contained inside the blood vessels the whole time

open circulatory systems

the blood is not fully contained in the blood vessels
the heart pumps blood into the body cavity, and tissues are bathed in blood
when the heart muscle relaxes, blood is drawn back into the heart through values
the blood is called haemolymph, as it has been mixed with tissue fluid

closed circulatory system

blood is enclosed in blood vessels
blood is kept at high pressure throughout the body
the oxygen concentration gradient is high, as oxygenated and deoxygenated blood do not mix (in mammals)

advantages of having a closed circulatory system

can maintain pressure
concentration gradient remains high

blood flow cycle in closed circulatory system

heart -> arteries -> arterioles -> capillaries -> venules -> valves -> veins

are veins or arteries larger

veins are

why is pressure lost throughout blood flow

pressure is lost due to friction between the blood and blood vessel walls

how is the direction of blood flow maintained?

valves are present in blood vessels, which prevent the backflow of blood, and thus maintain a one-way system

Single circulatory system

blood passes through the heart once as it circulates the body
blood circulation to organs is organised in series

double circulatory systems

blood passes through the heart twice as it circulates the body
blood circulation to organs is organised in parallel

advantages of double circulation

each circuit can have different blood pressure
pulmonary = low pressure, systemic = high pressure
blood passes through lungs or gills slowly, maximising exchange of oxygen and carbon dioxide
oxygenated blood is then pumped to the body at high pressure

why is there low pressure in the pulmonary system

it means that the blood moves slower, meaning that there is more time for diffusion
also, it ensures that the thin alveoli are not damaged by high blood pressure

why does the systemic system have high blood pressure

the blood needs to travel a far distance, and needs to get through all the organs of the body

advantages of a parallel vascular system

• high oxygen concentration gradient for all organs
• parallel arrangement greatly reduces resistance to blood flow
• blood speed high so rate of oxygen delivery high

single circulatory system
animal, motion through heart, pressure, series/parallel

fish
blood passes through the heart once
low pressure oxygenated blood
vascular system in series

double circulatory system
animal, motion through heart, pressure, series/parallel

birds, reptiles, amphibians, and mammals
blood passes through the heart twice
high pressure oxygenated blood -> better oxygen supply
vascular system in parallel

circulation in amphibians
chambers of the heart
single/double
disadvantage

3 chambers
double circulatory system
oxygenated and deoxygenated blood mix in the artery
less oxygen is delivered to organs than in complete double circulation

location of the heart in the body

middle region of the thorax
the apex points to the left

what is the pericardiu

a double-layered, fluid-filled sac that surrounds the heart and blood vessels

outer structure of the pericardium

the outer layer is fibrous
it is made from collagen rich connective tissue - it is inelastic and protects from overexertion of the heart, trauma and infection

inner structure of the pericardium

the inner serous pericardium folds back on itself forming a fluid filled cavity around the heart - this lubricates the heart's movements

structure of the heart

which arteries branch from the aorta

coronary arteries
subclavian arteries
carotid arteries
brachiocephalic artery

where does the coronary artery lead

myocardium - the heart muscle

where do the subclavian arteries lead

arms

where do the carotid arteries lead

head

heart valves

aortic semilunar valve
pulmonary semilunar valve
tricuspid valve
bicuspid valve

where is the aortic semilunar valve found

between the left ventricle and the aorta

where is the pulmonary semilunar valve found

between the right ventricle and the pulmonary artery

where is the tricuspid valve found

between the right atrium and the right ventricle

there is the bicuspid valve found

between the left atrium and the left ventricle

structure of the tendinous cords

ineslastic
attach the heart valves to the papillary muscles

what is the function of the tendinous cords

help the valve open
stop the valve from inverting

the heart wall

fibrous pericardium
parietal pericardium
visceral pericardium (epicardium)
pericardial cavity
myocardium (heart muscle)
endocardium

Why is injuring an artery more dangerous than injuring a vein?

as the blood is at a higher pressure, leading to faster blood loss

Why is no body cell more than 0.05mm away from a capillary?

to maintain a short diffusion distance

function of the arteries

transport blood away from the heart

blood oxygenation in the arteries

oxygenated

blood pressure in the arteries

high (70-120 mmHg)

function of the veins

blood transport to heart

blood oxygenation in the veins

deoxygenated

blood pressure in veins

low (5-10 mmHg)

function of the capillaries

exchange of oxygen and carbon dioxide between blood and cells

blood oxygenation in the capillaries

changes from oxygenated to deoxygenated

blood pressure in the capillaries

low (10-22 mmHg)

structure of the arteries

from outside to in:
collagen-rich connective tissue
elastic tissue
smooth muscle
lumen
endothelium
plaque

structure of the vein

larger lumen than artery
from outside to in:
collagen-rich connective tissue
elastic tissue
smooth muscle
lumen
endothelium

rough diameters of artery vs. vein vs. capillary

arteries and veins have the same diameter (but different lumen)
capillaries are very very small

artery wall structure

thick muscle and elastic layer
small lumen

veins wall structure

thin muscle and elastic layer
large lumen

capillaries wall structure

very thin - endothelium: one cell thick
very small lumen (RBCs travel in single file)

arteries, veins, capillaries: valves?

arteries and capillaries have no valves, but veins do

what is systole

contraction of the heart

what happens to the arteries during systole

arteries expand following heart contraction

what happens to the arteries after diastole

arteries recoil (elastic recoil) following heart relaxation

function of valves in the veins

valves prevent the backflow of blood in the veins due to low pressure in the veins

how is blood moved along the veins

veins pass between skeletal muscles
muscle contraction exerts pressure on vein and propels blood forward
when the skeletal muscle relaxes, pressure in the vein decreases and the valves prevent the backflow of blood

what enters the body cells from the capillaries

oxygen and nutrients (amino acids and glucose)

what leaves the body cells into the capillaries

carbon dioxide and waste (urea)

which blood vessel has no collagen in its wall

capillary

explain how the structure of an artery wall is adapted both to withstand and to maintain high blood pressure

more collages provides strength to withstand high blood pressure
muscle contraction allows constriction of lumen/artery
elastic fibers allow the lumen to stretch and to recoil back to its original size

explain how the structure of a vein relates to its function

large lumen reduces resistance to blood flow back to heart
valves prevent the backflow of blood
thin muscular tissue maintains pressure
smooth endothelium reduces resistance to blood flow

explain why a blood clot in an artery leading to the brain could cause a stroke

reduce blood flow
less/no oxygen and glucose reaches the brain
less aerobic respiration
less ATP produces
brain needs lots of ATP/energy to function
lactic acid is produced via anaerobic respiration
lactic acid inhibits enzymes

explain how the structure of an artery is related to its functions

elastic fibres: allow stretching to accommodate higher pressure
smooth muscle: muscle can contract to generate a higher pressure
smooth endothelium: reduce friction between the blood and the blood vessel walls - reduce friction to blood flow
narrow lumen - to maintain a high blood pressure
collagen - avoids rupture/damage

Explain why the atrioventricular valves need to close

the ventricle needs to contract and force blood into the arteries
so valves need to close to prevent the backflow of blood into the atria on contraction

what is blood made from

55% plasma
<1% WBCs and platelets
45% RBCs

what is plasma made from

9% proteins, waste and nutrients
91% water

which nutrients are in plasma

glucose, fatty acids, ions, amino acids, salt, vitamins, minerals

which proteins are in plasm

hormones
enzymes
antibodies
blood clotting factors

which wastes are in plasma

urea
carbon dioxide

what else in in plasma

salt
a bit of dissolved oxygen

chemical formula of water

H2O

how are the H and O atoms joined in water

by covalent bonds

water shape

V-shaped molecule
105 degrees

dipolar nature of water

oxygen is more electronegative that hydrogen
it attracts shared electrons more, therefore creating a dipole

bonds between water molecules

dipolar water molecules attract each other and form intermolecular bonds called hydrogen bonds

what type of molecule is water

dipolar

water as a good solvent: significance

water is a good solvent for other polar molecules, like salt molecules, as it is polar itself
hydrophillic molecules can be transported by water easily
vital biochemical reactions can take place in the aqueous cytoplasm

water as a poor solvent: significance

water is a poor solvent for hydrophobic molecules
lipids form a bilayer membrance
lipids can only be transported in blood in combination with other proteins (lipoproteins)

thermal properties of water

high specific heat capacity
high latent heat of vaporisation
high latent heat of fusion

what does it mean if water has a high specific heat capacity

it takes a lot of energy to increase its temperature