Cardiovascular System Flashcards
why do we need a ciculatory system?
- maintain homeostasis
- delivers nutrients & O2 to the cells
- Removes waste materials
- Distributes hormones etc.
what are the 3 major components of the circulatory system?
- blood
- blood vessels
- heart
what is blood and how is it pumped?
the fluid portion of the ciculatory system
pumped by the heart throughout the body via blood vessels, arteries, capillaries and veins
what are the principle functions of blood?
1) transportation
(O2, CO2, nutrients, horomes, wastes)
2) Regulatory
(pH, temperature, osmosis)
3) Protection & defense
(Phagocytosis, clotting)
how much blood does an average human have?
6 Litres
approx 7-8% of our body weight
how can the different components of blood be separated?
Centrifugation
what are the 2 major components of blood?
1) fluid
2) cullular
what does the fluid component of blood contain?
- water
- ions
- plasma proteins
- antibodies (immunoglobulins)
**white part)
what components are in the cellular part of blood?
- erythrocytes (RBC)
- Leukocytes (WBC)
- platelets (fragment of cells)
how many red blood cells do we have per uL of blood?
5-6 million
how many white blood cells do we have per uL of blood?
5000-10000
what is the shape of a red blood cell and why is it like that?
- bi-concave discs packed with haemoglobin (carries the O2), no nucleus
- concave to add more surface area
how are the 4 white blood cells formed? (leukocytes)
- hemocytoblast = stem cell
- myeloid stem cell
- monoblast - monocyte
- myeloblast - eosinophil, neutrophil, basophil
how is lymph produced?
- multipotent (pleuripotent stem cell)
- lymphoid stem cell
- small lymphocyte
what stimulates erythrocyte production?
- low oxygen supply
- hormone erythropoietin (RBC production) from kidney to stimulate red bone marrow
- haemopoeisis = blood production
negative feedback loop
what is the feedback loop to maintain homeostasis for production of erythrocytes?
1) stimulus: hypoxia = inadequate o2 delivery
2) kidney releases erythropoietin
3) erythropoietin stimulates red bone marrow
4) enhanced erythropoiesis increases RBC count
5) blood raises = o2 count raises
what stem cell does leucocytes originate from?
myeloid
how much of the total blood volume does leucocytes make up?
1 %
5000-10000 uL
how long do leucocytes generally live for?
few days
lymphocytes= months or years
what is the function of leucocytes?
combat invaders by phagocytosis
what are the 5 laucocytes and their percentages?
1) neutrophils 60-70%
2) lymphocytes 20-25%
3) monocytes 3-8%
4) eosinophils 2-4%
5) basophils 0.5-1 %
what does “never let monkeys eat bananas” stand for?
N- neutrophil
L- lymphocyte
M- Monocyte
E- Eosinphil
B- Basophil
MOST- LEAST NUMEROUS
what are measured for diagnostic purposes?
the total number of circulating WBS
what is leucocytosis?
any WBC count over 10,000/uL
indicates an infectious process/cancer
what is leucopenia
any WBC count under 5000/uL
indicates severe diesease (AIDS, chemotherapy)
what is stimulated when there are acute bacterial infections?
increase neutrophils
what is stimulated when there are chronic infections?
ncrease monocytes
what is stimulated when there are viral infections
increase lymphocytes and monocytes
what is stimulated when there are allergic reactions?
increase eosinophils and basophils
what is stimulated when ther is parasitic infestation?
increase eosinophils
what is hemoglobin?
protein on red blood cells that oxygen binds to
what is the hemoglobin (Hb) test?
when the blood is hemolysed (broken down) to release hemoglobin, the intensity of the red colour of the resultant fluis is compared to standards
Normal range is 12-18 g/100 mls of blood
(12-18% by weight)
how much plasma is in the whole body?
55% of whole blood
least dense
what is the percentage of buffy coat in blood?
under 1%
leukocytes and platelets
what percentage are erythrocytes in blood?
45% of whole blood
most dense component
how do you calculate hematocrit value?
volume of red blood cells (mm) / total sample volume (mm)
ex: RBC volume - 40 mm
Total sample volume= 100 mm
Haematocrit value = 40%
what are the normal values for hematocrit determination?
males: 40-54% (av. 47%)
Females: 38-46% (av. 42%)
why do males have a higher percent range for hematocrit determination?
due to higher levels of testosterone
why do females have lower percentages for hematrocrit determination?
due to lower testosterone levels and menstral blood loss
what is anaemia?
lower than normal values for hematocrit determination
what is polycythaemia?
higher than normal values for hematocrit determination
more RBC
what is the function of platelets?
to limit blood loss
how are platelets formed?
thrombopietin stimulates megakaryocytes to break down to platelets
how does blood get thick?
by the number of erythrocytes
albumins (proteins) - 55% of plasma proteins
where albium goes, water follows
what is hemostasis?
the reduction and stoppage of blood loss from a damaged blood vessel
what are the three mechanisms for hemostasis?
1) vascular spasm
2) platelet plug formation
3) blood clotting (coagulation)
what is vascular spasm?
blood vessel contraction to make break smaller
first response of a damaged artery
how does vascular spasms work?
smooth muscles contract in the walls of a cut blood vessel to reduce blood flow/loss.
effective for up to 30 minutes
how does platelet plug formations work?
1) platelets stick to collagen fibres that are exposed when the tear happens
2) platelets become activated and swell, projects and becomes sticky, forming a platelet plug.
**after muscles contract in blood vessels**
what happens to blood when it is removed from the body?
thickens and forms a gel
what is serum?
plasma-clotting proteins
what are the two main clotting pathways?
extrinsic
intrinsic
what is extrinsic pathway?
when there is tissue damage with bleeding causing rapid clotting formation
blood leaves blood vessel
what is intrinsic pathway?
damage to the inside of the blood vessel resultin gin slow clot formation
no blood leaves the blood vessel
what are the steps for the extrinsic pathway?
1) tissue is damaged with bleeding
2) damagaed tissues and platelets release thromboplastin into the blood
3) thromboplastin converts a plasma protein (factor x) into prothrombinase (NEEDS CALCIUM)
4) prothrombinase turns into prothrombin
5) prothrombin releases thrombin
6) thrombin converts fibrinogen to fibrin (net like structure)
what is fibrin?
net like structure that surrounds the wound, trapping platelets and RBC
what are the steps fo the intrinsic pathway?
1) damage exposes connective tissue of blood vessel
2) platelets attract to site of damage and release platelet factor 3 (PF3) into blood
3) pf3 activated factor XII
4) factor XII converts to factor X
5) calcium helps convert factor X to prothrombinase
6) prothrombinase turns into prothrombin
7) prothrombin convertd to thrombin
8) active prothrombin converts fibrinogen to fibrin (net like structure)
what happens in hemostasis?
- clot retraction
- as clot retracts, it pulls the edges of the damaged vessel closer together
- decreases risk of further damage
- endothelial cells and repair vessel lining
what are three disorders of hemostasis?
thrombus
embolus
haemophilia
what is thrombus?
blood clot in an unbroken blood vessel
AKA heart attack
what is embolus?
any piece of cell debris carried by the blood flow
can block smaller blood vessels
what is haemophilia?
genetic definciency in the production of clotting factors
blood cant clot
how is there prevention of blood clotting?
blood clotting factors circulate in an inactive form (needs an injury to activate them)
what are anticoagulants?
chemical inhibitors of blood clotting
how does rapid initiation and progression of blood clotting work?
positive feedback
thrombin is formed which stimulates the production of more thrombin (main enzyme of blood clotting)
converts fibrinogen to fibrin
how does thrombin convert fibrogen to fibrin?
1) activating more platelets
2) stimulating production of more prothrombinase
why doesn’t clotting spread?
no active thrombin is set loose in the bloodstream
thrombin not absorbed to fibrin is inactivated by anti-thrombin
heparin also inhibits thrombin activity
what degrades fibrin?
plasmin
what is the importance of vitamin K?
- stimulates the liver to produce prothrombin and other clotting factors
- vitamin K definciency causes bruising and prolonged bleeding
what are anticoagulant drugs?
drugs that delay or prevent undesirable blood clots
ex: aspirin
what are thrombolytic agents?
substances that help dissolve blood clots once they have formed
works by activating plasminogen to plasin
(when already had heart attack)
where is the heart located?
in the mediastinum
area from the sternum to the vertebral column and in between lungs
2/3 is left midline of body (from anatomical position)
what is the pericardium and where is it located?
tough, dense irregular connective tissue that protects and anchors the heart
surrounding the heart
what is the serous pericardium and what are the 2 sections ?
fluid in between
1) parietal layer- fused to fibrous pericardium
2) visceal layer (epicardium)
where is the pericardial cavity located?
between the parietal and visceral pericardium
contains pericardial fluid to reduce friction
what are the three layers of the heart wall?
1) epicardium
2) myocardium
3) endocardium
epicardium facts
visceral layer of serous pericardium
myocardium facts
muscle of the heart
95% of heart is cardiac muscle
the contracting, muscular layer of the heart
endocardium facts
endothelial layer
continuous with lining of large blood vessels
what are the 3 types of blood vessels?
arteries
veins
capillaries
what are arteries?
carry blood away from the heart
what are veins?
carry blood towards heart
what are capillaries?
connects arteries to veins
what is the atria?
part of the heart that receives blood from veins
what are ventricles?
part of the heart that pumps blood out from the heart
what is double circulation?
all of blood flowing from lungs to body
what are the two veins that all blood enters from and which side?
superior vena cava
inferior vena cava
what are the three sources that the atrium receives blood from?
superior vena cava
inferior vena cava
heart
how does blood leave the right atrium?
trincuspid valve (flap)
what is the flow of blood from right atrium to lungs?
right atrium
tricuspid valve
right ventricle
lungs
what are the atrioventricular valves? (AV valves)
valves that open to allow blood flow from atria to ventricles
happens when ventricles are relaxed
chorsae tendineae are slack and papillary muscles are relaxed
prevents back flow to atrium
where does the atrium get its blood from?
the 4 pulimonary veings from the lungs
what does blood leave through to get to left atrium?
bicuspid valve to left ventricle
what is the flow of blood through left side ?
left atrium
left ventricle
aorta
rest of body
what are semi-lunar valves?
valves that open with ventricular contraction
allows blood to flow into pulmonary trunk and aorta
when and why do the semi-lunar valves close?
close with ventricular relaxation
prevent blood from returning to ventricles
why is there a thickness of hart chamber walls?
due to distance
- right ventricle pumps blood to lungs = shorter distance
- left ventricle pumps blood to body = longer distance
what does the left coronary artery do?
distributes blood to left side of heart, left atrium and ventricle, and interventricular septum
what does the right coronary artery do?
generally serves the right atrium and ventricle
what do coronary veins do?
direct blood to a large vein (coronary sinus) to emprty into the right atrium
