4.3 Flashcards
circulation
what is a mass transport system
substances are transported in the flow of a fluid with a mechanism for moving it around the body
what is an open circulatory system
blood circulates in large open spaces
what is a single circulatory system
heart pumps deoxygenated blood to the site of gas exchange (gills) where the blood becomes oxygenated then travels around the rest of the body
what is a double circulatory system
the pulmonary circulation carries deoxygenated blood from the heart to the lungs to be oxygenated then back to the heart so that the systemic circulation can carry oxygenated blood around the body then return to the heart
what are the advantages of the double circulatory system
oxygenated and deoxygenated blood cannot mix so tissues receive much more oxygen
fully oxygenated blood can be delivered quickly to the body tissues at high pressure
define circulation
the passage of blood through the blood vessels
what is the role of the plasma
transport of:
digested food products from small intestine to the entire body
nutrient molecules
excretory products
chemical messengers
and maintains steady body temperature
acts as a pH buffer
how does the plasma maintain the body’s temperature
transfers heat around the system from deep-seated organs and active tissues to the rest of the body
what is haemoglobin
red pigments that carries oxygen and give erythrocytes their colour
how are red blood cells well adapted
do not contain a nucleus to make space for haemoglobin
biconcave disc shape to increase sa:v for faster diffusion of oxygen
transports
what are leucocytes and their general adaptations
cells which defend the body against infection
larger than erythrocytes
can change shape to squeeze through tiny blood vessels
contain a nucleus
have a colourless cytoplasm
some contain granules that can be stained
what are the 3 granulocytes
neutrophils
eosinophils
basophils
what are the 2 agranulocytes
monocytes
lymphocytes
what are the general adaptations of granulocytes
contain granules in the cytoplasm
take up stain so they are obvious under a microscope
have a lobed nucleus
what is the specific role of neutrophils
non-specific immune system
engulf and digest pathogens by phagocytosis
multi-lobed nucleus
most common leucocyte
what is the specific role of eosinophils
non-specific immune system
stained by eosin stain
respond to parasites, allergic reactions and inflammation
what is the specific role of basophils
non-specific immune response
two-lobed nucleus
produce histamines involved in reducing inflammation and allergic reactions
what are the general adaptations of agranulocytes
do not have granules
unlobed nucleus
what is the specific role of monocytes
specific immune system
largest leucocyte
can move out of the blood into tissues to form macrophages which engulf pathogens by phagocytosis
what is the specific role of lymphocytes
specific immune response
very small
large nucleus
what is the role of platelets
involved in the clotting mechanism of the blood
what are megakaryocytes
large cells found in the bone marrow and produce platelets
what is the structure of haemoglobin
large globular protein
4 peptide chains
iron-containing prosthetic groups
quaternary structure
can hold 4 molecules of oxygen to form oxyhaemoglobin
how does oxygen leave a red blood cell
the red blood cell contains a higher concentration of oxygen in the cytoplasm than surrounding tissue therefor oxygen moves out by diffusion down the concentration gradient
why is it important that haemoglobin has a high affinity for oxygen
so that small changes in the proportion of oxygen in the surroundings can have a big effect on saturation of the blood with oxygen
what is the relationship between CO2 partial pressure and affinity of haemoglobin
as CO2 partial pressure increases affinity of haemoglobin reduces
what is the bohr effect
changes in the oxygen dissociation curve of haemoglobin that occur due to rise in CO2 levels and a reduction in the affinity of of haemoglobin for oxugen
what is fetal haemoglobin and how is it adapted for oxygen transfer
only found in developing fetus
has a higher a higher affinity for oxygen than the mothers haemoglobin so when blood runs through the placenta oxygen is transferred to the fetus and a counter current system is used to maximise gas exchange across the entire length of the placenta
what is myglobin and its role
small bright red protein found in muscle tissue of vertebrates giving meat a strong red colour
it has a high affinity for oxygen and is not easily affected by the partial pressure of oxygen therefor acts as a store for oxygen as it is not easily released
what is carbaminohaemoglobin
the compound formed when waste carbon dioxide binds with haemoglobin
what are the 3 ways waste carbon dioxide is removed
carried in plasma
binds with haemoglobin
transported in cytoplasm of red blood cells as hydrogen carbonate ions
what is the role of carbonic anhydrase
controls rate of reaction between carbondioxide and water forming carbonic acid
what is the equation for the hydration of carbondioxide and its dissociation
CO2 + H2O <=> H2CO3 <=> HCO3- + H+
how is the pH of the blood controlled as carbondioxides dissolve and form carbonic acid
the heamoglobin acts as a buffer accepting hydrogen ions to form haemoglobinic acid
what is the need for blood clotting
seals up damaged blood vessels to minimise blood loss
prevents pathogens getting in
how do platelets start the formation of a clot when someone has a cut
when the platelets come into contact with components of the tissue (e.g. collogen fibers of skin) they break open and release serotonin and thromboplastin
what does serotonin do
causes the smooth of the blood vessels to contract therefor narrowing blood vessels and cutting off blood flow to the damaged area
what do thromboplastins do
sets into motion the blood clotting cascade
what is the blood clotting cascade
thromboplastins catalyse production of thrombin from prothrombin which requires calcium ions
thrombin then converts fibrinogen to fibrin which forms a mesh of fibres that cover the wound
more platelets and blood cells become trapped in the mesh
proteins in the platelets contract tigthning the clot forming a scab for protection while the vessels underneath heals
define arteries
vessels that carry blood away from the heart
define veins
vessels that carry blood towards the heart
define capillaries
small vessels that spread throughout the tissues of the body where most substances carried by the blood is exchanged into cells
what is the pulmonary artery
carried deoxygenated blood away from the heart towards the lungs
what is the umbilical artery
carries deoxygenated blood from the fetus to the placenta
what is the lumen
the central space inside the blood vessel
what are arterioles
smallest branches of the artery system
describe the structure of an artery
smaller lumen than vein but elastic walls allow it to stretch
thick wall containing elastic fiber and smooth muscle to withstand large pressure
smooth lining to allow easy blood flow
external tough tissue
state 2 reasons why arteries need a thick elastic wall
to withstand high pressures when the blood is first pumped from the heart
to return to their original lumen in order to squeeze blood along for a continuous flow
where are peripheral arteries found
after arteries but before arterioles
what are venules
smallest branches of veins
what connects the capillaries to arteries and veins
arterioles
venules
describe the adaptations of capillaries
small lumen so blood moves slowly so there is longer time for diffusion
walls are one cell thick for fast diffusion and so that they can fit between cells
blood entering is oxygenated to create a concentration gradient
what is the pulmonary vein
carrys oxygenated blood from the lungs to the heart
what is the umbilical vein
carries oxygenated blood from the placenta to the fetus
describe the structure of veins
large lumen
smooth inner surface for easy blood flow
thin layer of smooth muscle and elastic fibers as veins are very low pressure
tough outer layer made of mostly collogen
which veins return blood directly to the heart
inferior & superior vena cava
what are semilunar valves
half-moon shaped one way valves formed from infoldings of the inner wall found at frequent intervals in the venous system to prevent backflow of blood
how do semilunar valves work
valves close to stop any backflow of blood, only allow blood to travel in one direction (towards the heart)
they are often situated between muscles so that when they contract the veins are squeezed and blood is forced up
what blood enters the left side of the heart
receives blood from the lungs and pumps it around the body
what blood enters the right side of the heart
receives blood from the body and pumps it to the lungs
what separates the two sides of the heart
septum
what are the features of cardiac muscle
it can carry on contracting without rest or getting fatigued
always has a good blood supply
contains a lot of myoglobin for the store of oxygen
where does the inferior vena cava get deoxygenated blood from
lower parts of the body
where does the superior vena cava get deoxygenated blood from
head, neck, arms and chest
describe the route of blood around the heart
deoxygenated blood enters the right atrium via the vena cava
as it fills the pressure builds and the tricuspid valve opens the right atrium contracts and blood is moved to the right ventricle
the right ventricle then contracts and forces the blood into the pulmonary arteries which carries deoxygenated blood to the capillaries of the lungs
oxygenated blood returns to the heart via the pulmonary veins into the left atrium which then contracts and blood flows through the bicuspid valve into the left ventricle
the left ventricle contracts and blood flows out of the aorta all around the body
describe the structure of the tricuspid/atrioventricular valve
made up of three flaps
separates the right atrium and right ventricle
contains tendonous cords to stop the valves from turning inside out
compare and contrast the left and right side of the heart
both: contract to move blood
left: thick wall
produces large force
blood is under high pressure
what is the foramen ovale
a gap in the septum found in fetuses which closes over at birth
what is a systole
a contraction of the heart
what is the difference between an articular systole and ventricular systole
articular - atria contractions
ventricular - ventricle contractions
what is a diastole
when the heart relaxes and fills with blood
what is a cardiac cycle
cycle of contraction (systole) and relaxation (diastole) in the heart
what happens to the valves in a diastole
semilunar valves close
atrioventricular valves open
what happens to the valves in a systole
semilunar valves open
atrioventricular valves close
what is an average heartbeat per minute
70 beats per minute
how is the heart beat myogenic
it contracts without external stimulus
what is the intrinsic rhythmicity
the intrinsic rhythm of contraction and relaxation of the cardiac muscle
what is the sinoatrial node
a group of cells in the right atrium, its the area of the heart with the fastest intrinsic rhythm and acts as the hearts own natural pacemaker
what is the annulus fibrosus
non-conducting tissue that provides support for the heart that spreads between the atria and the ventricles preventing the wave of excitation spreading to the ventricles
what is the atrioventricular node
a group of cells stimulated by the wave of excitation from the SAN and atria, imposing a delay before transmitting the impulse to the bundle of His
what is the bundle of His
a group of conducting fibers in the septum of the heart, it ensures the atria have stopped contracting before the ventricles start
what is the purkyne tissue
conducting fibers that penetrate down through the septum spreading between and around the ventricles for the depolarization to travel through the tissue so that the ventricle contracts starting from the apex
explain the contractions of the heart
depolarisation originates at the SAN (sinoatrial node) causing atrial systole but it does not spread to the ventricle because of the annulus fiber
the AVN (atrioventricular node) is stimulated causing a delay in atrial diastole and passes depolarisation into the bundle of His
which branches into purkyne fibers that causes ventricular systole
what is an ECG
electrocardiogram
what is a cardiovascular disease
diseases of the heart and circulatory system
what is atherosclerosis
a condition in which yellow fatty deposits build up on the lining of the arteries causing them to narrow
how is atherosclerosis caused
damage to the endothelial cells lining the artery which can lead to a build up of lipids then blood platelets form a cap over the fatty plaque which narrows the lumen artery and further damage can cause a clot which may block the whole artery and increase blood pressure and lead to a stroke or heart attack
why is atherosclerosis more common in arteries than veins
because the blood is under higher pressure in the arteries so the endothelium lining is under more strain
what is an atheroma
the plaque formed on the arterial lining
what is an aneurysm
a weakened bulging area of artery wall that results from a build up behind a blockage caused by plaques
what can an aneurysm cause
internal bleeding as the artery wall is weakened and splits open
how can atherosclerosis affect the kidneys
high blood pressure damages tiny blood vessels needed in the kidney for filtering out urea and forces proteins out
how can atherosclerosis affect the retina
the tiny blood vessels supplying blood to the retina can become blocked or leak leading to the retinal cells becoming starved of oxygen and die causing blindness
what can cause a stroke
interruption to the normal blood supply to the brain, blockages or leakages
what is an angina
a condition in which plaques build up and reduce blood flow to the cardiac muscle resulting in pain during exercise
what is a myocardial infraction
heart attack
what in anaerobic respiration
cellular respiration without the presence of oxygen
what can be done to reduce atherosclerosis
regular exercise
losing weight
not smoking
drugs to reduce heart rate and dilate blood vessels
insert a stent
heart bypass
what is a stent
a metal or plastic mesh tube that is inserted into an artery affected by atherosclerosis to hold it open and allow blood to pass through freely
what can cause a myocardial infraction
branches of coronary arteries become completely blocked by a blood clot causing part of the heart muscle to be starved of oxygen
what is thrombosis
a clot that forms in a blood vessel
what are the symptoms of a angina and myocardial infraction
pain in chest and left arm
pain in jaw and breathlessness
what are the symptoms of a stroke
dizziness, confusion, slurred speech, blurred vision, numbness, paralysis
what is a multifactorial disease
a disease that results from the interplay of many different factors rather than having one simple cause
what are the three main risk factors associated with getting atherosclerosis
genes - arteries may damage easily, tendency to develop hypertension, cholesterol metabolism faulty
age - arteries lose elasticity and narrow
sex - men are statistically more likely to suffer from atherosclerosis as oestrogen reduces the build up of plaque
exercise - helps lower blood pressure and blood cholesterol levels
smoking - damages artery lining
weight - increases blood pressure and type 2 diabetes
stress - raises blood pressure and releases cytokines that trigger an inflammatory response increasing plaque formation
diet - lots of saturated fats causes high blood cholesterol levels
what can be done to reduce the risk of atherosclerosis
eating a balanced diet of fats and lots of fruit and vegetables, not smoking, maintaining a healthy weight, regular exercise and reducing constant stress
what is tissue fluid and why is it needed
fluid that surrounds all the cells in the body that is needed for the transportation of substances in and out of a cell
what is not able to move out of the blood in the permeable capillaries
erythrocytes
large plasma proteins
how does water potential facilitate the movement of substances out of the cell and into the blood
plasma proteins and albumin exert an osmotic effect with give the blood a low water potential so water moves into the blood by the oncotic pressure
how does the hydrostatic pressure facilitate the movement of substances out of the blood and into the cell
residual pressure from the heartbeat forces fluid out through the capillaries
why does the hydrostatic pressure of the blood fall through the capillaries
pressure from the pulse is lost
volume of blood in the capillaries is lowered
summarise the movement of substances into and out of capillaries
hydrostatic pressure > oncotic pressure so water moves into capillary & fluid leaves the capillary
