Cardiovascular System Flashcards
A healthy adult heart is the size of a fist, and weighs between 250 and 350g. It pumps around _____ liters of blood each day. The heart also generates ______ _________, and regulates blood ______.
The heart is situated in the ________, and is positioned obliquely ______. The base is posterior and _______, and is at the level of the _____ intercostal space. The apex of the heart is anterior, ______, and to the _____, and is at the level of the ______ intercostal space.
A healthy adult heart is the size of a fist, and weighs between 250 and 350g. It pumps around 7200 liters of blood each day. The heart also generates BLOOD PRESSURE and regulates blood SUPPLY.
The heart is situated in the MEDIASTINUM, and is positioned obliquely LEFT. The base is posterior and SUPERIOR, and is at the level of the 2nd intercostal space. The APEX of the heart is anterior, INFERIOR, and to the LEFT, and is at the level of the 5th intercostal space.
Describe the 3 layers of the heart wall (epicardium, myocardium, endocardium).
The epicardium is made up of visceral pericardium
The myocardium is made up of cardiac muscle
The endocardium is the smooth inner surface of heart chambers.
Describe the pericardium.
The pericardium is a closed sac around the heart. The parietal layer touches the mediastinum, while the visceral layer covers the surface of heart. The pericardial space between the visceral & parietal pericardium is filled with fluid.
_______ arteries supply the heart. They branch off of the ______ and run along the surface of the heart.
The ___ ______ ________ extends inferiorly, and is very short. It supplies the heart _______.
The right coronary artery is smaller and extends _______. It supplies the posterior & inferior surface of the heart.
CORONARY arteries supply the heart. They branch off of the AORTA and run along the surface of the heart.
TheLEFT CORONARY ARTERY extends inferiorly, and is very short. It supplies the heart ANTERIORLY.
The right coronary artery is smaller and extends POSTERIORLY. It supplies the posterior & inferior surface of the heart.
What is coronary artery disease?
Coronary artery disease is when there is partial or complete blockage of branches of coronary arteries.
This causes severe pain (angina pectoris) in the chest which indicates acute hypoxia (ischemia) of the myocardium.
The coronary veins are smaller veins which run alongside the coronary arteries. Examples are the _____ ______ _____, _____ cardiac vein, and ______ cardiac vein. They drain into a large ______ on the posterior surface of the heart, called the coronary sinus, which empties into the ______ _______. Some smaller veins open directly into the right atrium.
The coronary veins are smaller veins which run alongside the coronary arteries. Examples are the GREAT CARDIAC VEIN, SMALL cardiac vein, and MIDDLE cardiac vein. They drain into a large SINUS on the posterior surface of the heart, called the coronary sinus, which empties into the RIGHT ATRIUM. Some smaller veins open directly into the right atrium.
What are the 4 chambers of the heart? Which chambers have thick and thin walls?
The heart has 4 chambers: 2 thin walled atria
superiorly & posteriorly, and 2 thick walled ventricles inferiorly & anteriorly. In adults there is no communication between the left and right.
Large veins open into the _____. The atria have thin muscular wall separated by the ______ _______. There are 2 atrioventricular valves- the left is the _____ valve and the right is the _______ valve.
Ventricles have a ______ muscle wall than atria, and are separated by the ___________ ________. They have _______ valves.
Large veins open into the ATRIA. The atria have thin muscular wall separated by the ATRIAL SEPTUM. There are 2 atrioventricular valves- the left is the MITRAL valve and the right is the TRICUSPID valve.
Ventricles have a THICKER muscle wall than atria, and are separated by the INTERVENTRICULAR SEPTUM. They have SEMILUNAR valves.
What is the function of valves?
When the ventricles are ______ (diastole) blood flows into ventricles through the atrioventricular valves. The _______ valves are closed which prevents the backflow of blood from _______ into ________.
When the ventricles _______ (systole), the atrioventricular valves are _______ due to increased pressure, which stops _______ to the atria. When pressure in the ventricles ______ the pressure in the arteries, the semilunar valves open, and blood flows into the _______ _______ (right) and ______ (left).
Valves prevent the backflow of blood.
When the ventricles are RELAXED (diastole) blood flows into ventricles through the atrioventricular valves. The SEMILUNAR valves are closed which prevents the backflow of blood from ARTERIES into VENTRICLES.
When the ventricles CONTRACT (systole), the atrioventricular valves are CLOSED due to increased pressure, which stops BACKFLOW to the atria. When pressure in the ventricles EXCEEDS the pressure in the arteries, the semilunar valves open, and blood flows into the PULMONARY TRUNK (right) and AORTA (left).
What causes the first “lubb” and second “dubb”, and where can they be heard?
The fist “lubb” is at the start of ventricular contraction (systole), when the atrioventricular valves close. It can be heard on the left 5th rib, medial and more lateral.
The 2nd “dubb” is the end of ventricular contraction (diastole) when the semilunar valves close (aortic and pulmonary). It can be heard on the right of left of the sternum, between the 2nd and 3rd rib.
What is the tunica interna, tunica media, and tunica externa?
Tunica Interna: It is 1 layer of endothelial cells made of simple squamous epithelial cells. It prevents platelet aggregation, and secretes substances to control blood vessel diameter.
Tunica Media: This is composed of smooth muscle and elastic tissue
Tunica Externa: This is mainly collagen.
Veins have a poorly developed tunica ______. They are the only blood vessels with ______. Veins follow arteries. Around ____ to _____% of blood resides in the venous system. ___________ can divert this reservoir of blood.
The pressure in the veins is _____. There is a respiratory “pump” when pressure changes in the chest suck blood ______ the heart. There is a muscular “pump” when contraction of _______ _______ pumps blood in limb deep veins. Slow blood flow increase ________ in veins.
Varicose veins occur when vein walls ____ ________. This can be _______ and due to factors such as ______ or prolonged _______. It causes the veins to ______ and _______, causing varicose (swollen) veins. This causes the valve cups to fail to meet (__________ valves) so________ cannot be prevented. This causes blood to collect in the veins and so they further dilate.
Veins have a poorly developed tunica MEDIA. They are the only blood vessels with VALVES. Veins follow arteries. Around 60 to 70% of blood resides in the venous system. VASOCONSTRICTION can divert this reservoir of blood.
The pressure in the veins is LOW. There is a respiratory “pump” when pressure changes in the chest suck blood TOWARDS the heart. There is a muscular “pump” when contraction of SKELETAL MUSCLES pumps blood in limb deep veins. Slow blood flow increase THROMBOSIS in veins.
Varicose veins occur when vein walls LOSE ELASTICITY. This can be HEREDITARY and due to factors such as AGEING or prolonged STANDING. It causes the veins to WEAKEN and DILATE, causing varicose (swollen) veins. This causes the valve cups to fail to meet (INCOMPETENT valves) so BACKFLOW cannot be prevented. This causes blood to collect in the veins and so they further dilate.
Capillaries are the smallest blood vessels, at 5-10 μm. They allow only 1 ___ to pass at a time. The walls are __________ cells. Capillary density varies- for example, it is _____ in muscles and glands, ____ in subcutaneous tissue, and very _____ in cartilage. Capillaries are highly permeable. They are the site for exchange of ______, _____, and _____. The 3 structural types of capillaries are continuous, fenestrated, and sinusoids, with _______ and ________ varying between each type.
Capillaries are the smallest blood vessels, at 5-10 μm. They allow only 1 RBC to pass at a time. The walls are ENDOTHELIAL cells. Capillary density varies- for example, it is HIGH in muscles and glands, LOW in subcutaneous tissue, and very LOW in cartilage. Capillaries are highly permeable. They are the site for exchange of WATER, SOLUTES, and GASES. The 3 structural types of capillaries are continuous, fenestrated, and sinusoids, with DIAMETER and PERMEABILITY varying between each type.
What is arteriosclerosis?
What is atheroscelrosis?
Arteriosclerosis is a degenerative condition in which arteries become less elastic. This increases resistance to blood flow and decreases circulation.
Atherosclerosis is a deposit of material in the artery walls to form plaques. This commonly affects the larger arteries like the coronary artery. It narrows the lume and the walls become less elastic, restricting or blocking blood flow.
What is haematopoeisis, and where does it occur?
Blood production is called haematopoiesis. It occurs in the red bone marrow (and lymph tissue for lymphocytes). Adult red bone marrow is found in the ribs, sternum, femur, humerus, pelvis and T1-12. Yellow marrow replaces red in other bones in adults.
What are the functions of blood?
Blood carries oxygen, carbon dioxide, minerals and nutrients. It also transmits heat and fights infection.
Describe erythrocytes.
Erthrocytes (RBCs) are ‘doughnut’ shaped, and have no nucleus. They move passively in blood. They are biconcave, which increases surface area allowing for rapid gas exchange.
What is the function of erythrocytes?
The function of erythrocytes is gas transport. The haemoglobin binds oxygen with high affinity. 99% of oxygen in blood is transported in red blood cells.
93% of carbon dioxide is transported in red blood cells, with 7% being transported in the plasma.
There are 25 trillion erythrocytes in adult circulation. 1% is replaced daily. Describe how they are replaced.
Old red blood cells are eliminated by phagocytes in the spleen or liver. This is replaced by the division of stem cells, which is called erythropoiesis. Erythropoeisis is stimulated by low oxygen levels, which requires B vitamins & iron. It occurs in the bone marrow.
A decrease in the number of erythrocytes is called anaemia. This is caused by a decrease in hematocrit so a decrease in oxygen carrying capacity. What 5 things can it be caused by?
- bleeding - transiently or chronic (e.g. GI tract ulcer)
- production e.g. iron or B12 deficiency
- numbers (polycytaemia)
- hematocrit, e.g. compensatory at high altitudes
- bone marrow abnormality, similar to chronic leukaemia
Describe blood grouping (ABO)
Blood grouping is determined by antigens on the red blood cell surface. Antibodies bind to antigens, resulting in agglutination (clumping) or hemolysis (rupture) of red blood cells.
Blood type A has antigen A on the surface of RBCs and antibody anti-B in the plasma.
Blood type B has antigen B on the surface of RBCs and antibody anti-A in the plasma.
Blood type AB has antigen AB on the surface of RBCs and neither antibody in the plasma.
Blood type O has neither antigen on the surface of RBCs and antibodies anti-A and anti-B in the plasma.
Describe Reheus’ grouping, and haemolytic disease of the newborn.
Rheuses grouping was first studied in Rhesus monkeys. If someone is Rh positive, this means they have Rh ‘D’ antigens present on the surface of red blood cells, while those who are Rh negative do not. Blood is therefore grouped as A+, A-, B+, etc.
Both types of grouping must be considered for blood transfusion.
Rh blood grouping can result in hemolytic disease of the newborn (HDN), if a Rh negative mother has a Rh positive baby. If the placenta tears in labour the fetal blood leaks & mixes with mum’s. The mum then produces anti-Rh antibodies that cross placenta which causes agglutination and hemolysis of fetal red blood cells. There is no problem in the 1st pregnancy as it occurs late/in delivery and so there is not enough time to harm the baby, but during a 2nd pregnancy the mum is already sensitised so produces lots of anti-Rh antibodies that can harm the 2nd baby if blood mixes. The baby might need a blood transfusion or it can be fatal.
What are the functions of leukocytes (WBCs)?
- to protect from invading microorganisms
- destroy foreign or abnormal cells
- clean up cellular debris (phagocytosis)
What is pus?
Leukocytes accumulate at an infection site. An accumulation of dead white blood cells, and debris/bacteria forms pus.
