6.2 THE BLOOD SYSTEM Flashcards
ESSENTIAL IDEA
the blood system continuously transports substances to cells and simultaneously collects waste product
WHAT IS TRANSPORTED IN THE BLOOD?
oxygen nutrients antibodies hormones heat carbon dioxide urea
COMPONENTS OF BLOOD
plasma
erythrocytes-RBC
leucocytes-WBC
platelets
PLASMA
dissolves or carries all other components of blood, nutrients, wastes
ERYTHROCYTES RBC
transport oxygen in haemoglobin M
LEUCOCYTES WBC
phagocytes- engulf pathogens and dead cells
lymphocytes- (B/ T cells) for the immune response
PLATELETS
clotting of blood following damage to cells or erythrocytes
ARTERIES
carry high pressure blood away from the heart to tissues that need it
CAPILLARIES
very small <10 um D
penetrate every tissue
blood moves slowly under low pressure providing opportunities for the exchange of substances
VEINS
carry the blood at low pressure back to the heart using valves to ensure blood flow in the correct direction
ARTERIOLES
smaller arteries
VENULES
smaller veins
STRUCTURE OF ARTERIES
OUTER LAYER
thick muscular wall and fibrous outer layer help the artery to withstand high pressure
STRUCTURE OF ARTERIES
LUMEN
relatively small lumen (to the wall) maintains high blood pressure
STRUCTURE OF ARTERIES
MUSCLE
muscle contracts to decrease the size of the lumen
this causes an increase in blood pressure and
maintains high blood pressure between the pulses of high pressure blood traveling from the heart
STRUCTURE OF ARTERIES
FIBRES
elastic fibres stretch to increase the lumen with each pulse of blood
after the pulse of blood passes the fibres recoil decreasing the lumen size
helping maintain a high blood pressure
STRUCTURE OF CAPILLARIES
WALL
permeable walls that allow gas exchange of materials between cells in tissue and blood in the capillary
STRUCTURE OF CAPILLARIES
THICKNESS
wall is one cell thick which allows easy diffusion of substances in and out of the capillary due to the short diffusion distance
STRUCTURE OF CAPILLARIES
S.A
due to the massive number of capillaries present and the small lumen the surface area available for the exchange of substances is very large
STRUCTURE OF CAPILLARIES
WALLS AND MEMBRANES
the wall and membrane contain pores to further aid the diffusion of substances
CAPILLARIES ADAPTATIONS
permeable membrane one cell thick wall pores surface area low pressure
STRUCTURE OF CAPILLARIES
PRESSURE
blood travels slowly at low pressure allowing more opportunity for exchange
STRUCTURE OF VEINS
LUMEN/PRESSURE
the large lumen means that the blood is under low pressure
STRUCTURE OF VEINS
PRESSURE/WALLS
because there is less pressure to resist the walls of the veins are thinner and less elastic than arteries
they also contain less muscle than arteries
STRUCTURE OF VEINS
PRESSURE/ VALVES
because of the low pressure valves are required to prevent the backflow of blood and thus ensure that the blood moves towards the heart
WILLIAM HARVEY
discovery of the circulation of the blood with the heart acting as the pump
DOUBLE CIRCULATION
blood passes through the heart twice on one circuit of the body
DEOXYGENATED BLOOD
low O2 high CO2
returns to the heart via the right atrium
its is pumped form the right ventricle to the lungs, where CO2 is offloaded and O2 picked up= oxygenated
OXYGENATED BLOOD
high O2 low CO2
enters the left atrium
pumped from the left ventricle to the body, where O2 is used for respiration and CO2 is collected as a waste product
= deoxygenated
back to right atrium
DEOXYGENATED TO OXYGENATED BLOOD
CYCLE
HEART DIAGRAM
https://image.slidesharecdn.com/biok6-160120014846/95/bioknowledgy-presentation-on-62-the-blood-system-17-638.jpg?cb=1455344238
BEATING OF THE HEART IS DUE TO
myogenic muscle contraction
MYOGENIC
the myocyte ( the muscle cell) itself is the origin of the contraction and it not controlled externally
WHICH REGION OF THE MYOCYTES CONTROLS THE RATE OF THE HEART BEAT?
sinotrial node (pacemaker)
WHICH REGION OF THE MYOCYTES CONTROLS THE RATE OF THE HEART BEAT?
sinotrial node (pacemaker)
SAN
impulse is sent from the sinotrial node, causing the atria to contract
the impulse is conducted to the
AV node where it passed through nerves to the muscle of the ventricles, causing them to contract
MYOGENIC INITIATION OF THE CONTRACTION MEANS THAT
the heart does not stop beating
it is not a conscious process
THE HEART RATE CAN BE INCREASED/ DECREASED BY
impulses bought to the heart through two nerves from the medulla of the brain
THE HEART RATE IS CONTROLLED BY
the autonomic nervous system
the part of the nervous system that responds automatically to changes in body conditions
WHEN EXERCISING
more CO2 is present in the blood
this is detected by chemoreceptors in the brain’s medulla oblangata,
resulting in a nerve signal being sent to the SA node to speed the heart rate
when CO2 level falls another nerve (vagus) reduces the heart rate
ADRENALINE
causes a rapid increase in the heart rate in fight of flight responses, preparing the body of action
DIASTOLE
atria and ventricles relaxed
blood flows into the heart from veins
AV valves opens
SL vavles closed heart sound 2
ATRIAL SYSTOLE
atria contract
ventricles relaxed
blood pushed into atria
AV valves open
SL valves closed
VENTRICULAR SYSTOLE
atria relaxed
ventricles contract
blood pushed into arteries
AV valves closed heart sound 1
SL valves closed
VENTRICULAR PRESSURE INCREASES AS
ventricle contracts
this forces blood into the aorta, increasing aortic pressure
VENTRICULAR VOLUME
increases as atrial contraction forces blood into the ventricle
decreases as ventricular contraction forces blood into the aorta
increases as blood returns to the heart following systole
HEART SOUND 1
caused by the closing of the AV valves at ventricular contraction
HEART SOUND 2
caused by closing of SL valves after systole (pressure in ventricle is lower than in aorta- backflow of blood closes valves)
CARDIAC CYCLE
https://image.slidesharecdn.com/biok6-160120014846/95/bioknowledgy-presentation-on-62-the-blood-system-23-638.jpg?cb=1455344238
ATHEROSCLEROSIS
degenerative disease
area of the artery wall become damaged
cholesterol builds up in damaged areas
this eventually forms a plaque and the artery wall loses elasticity
as build-ups of cholesterol and plaque form, the lumen narrows, restricting blood flow
if plaque ruptures, blood clotting is triggered
BLOOD CLOTS
coronary thrombosis
CORONARY HEART DISEASE
atherosclerosis can lead to blood clots, and if these clots occur in myocardial tissue
= coronary heart disease
MYOCARDIAL INFARCTION/ HEART ATTACK
occurs if a coronary artery becomes completed blocked
coronary muscle tissue dies as a result of lack of blood and oxygen
RISK FACTORS IN CORONARY HEART DISEASE
genetic age sex smoking diet exercise obesity stress
RISK FACTORS IN CORONARY HEART DISEASE
GENETIC
some people are predisposed for high cholesterol levels/ high blood pressures
RISK FACTORS IN CORONARY HEART DISEASE
AGE
older people are at greater risk due to less elasticity in arteries: ruptures more easily
RISK FACTORS IN CORONARY HEART DISEASE
SEX
males are at greater risk than females
RISK FACTORS IN CORONARY HEART DISEASE
SMOKING
constricts blood vessels
increases blood pressure/ heart rate
decreases oxygenation of heart muscle
increased fibrinogen and platelets in blood lead to more clotting
RISK FACTORS IN CORONARY HEART DISEASE
DIET
increases fat/ cholesterol/ LDL in blood
leads to plaque formation in arteries
RISK FACTORS IN CORONARY HEART DISEASE
EXERCISE
lack of exercise increases due to weakened circulation
RISK FACTORS IN CORONARY HEART DISEASE
OBESITY
increase blood pressure
leads to plaque formation in arteries
RISK FACTORS IN CORONARY HEART DISEASE
STRESS
stress has been linked to increased cortisol hormones in the blood, causing increased atherosclerosis
