The heart Flashcards
What is the heart made of?
Cardiac muscle.
Where is cardiac muscle found?
Only in the heart.
What does ‘myogenic’ mean?
The heart can contract and relax without input from the nervous system or hormones.
Why doesn’t cardiac muscle fatigue?
As long as it has oxygen and glucose, it keeps working without getting tired.
What do coronary arteries do?
They supply oxygenated blood to the cardiac muscle.
What happens if a coronary artery is blocked?
It can cause a heart attack (myocardial infarction).
Name the four chambers of the heart.
Left atrium, right atrium, left ventricle, right ventricle.
Why are atria walls thinner than ventricle walls?
Atria only push blood a short distance, while ventricles need to pump blood further at higher pressure.
Why does the left ventricle have a thicker wall than the right ventricle?
It needs to pump blood all around the body, while the right ventricle only pumps to the lungs.
Name the four major blood vessels of the heart.
Aorta, pulmonary artery, pulmonary vein, vena cava.
What is the function of veins?
They bring blood into the heart.
What is the function of arteries?
They carry blood away from the heart.
What does ‘pulmonary’ mean?
It refers to the lungs.
What is the function of the vena cava?
It carries deoxygenated blood from the body to the heart.
What is the function of the pulmonary vein?
It carries oxygenated blood from the lungs to the heart.
What is the function of the pulmonary artery?
It carries deoxygenated blood from the heart to the lungs.
What is the function of the aorta?
It carries oxygenated blood from the heart to the body.
What is the function of heart valves?
To ensure blood flows in one direction (prevent backflow).
What are the two types of heart valves?
Atrioventricular (AV) valves and semilunar valves.
Where are the atrioventricular (AV) valves located?
Between the atria and ventricles.
What are the two AV valves called?
Bicuspid (mitral) valve (left side) and tricuspid valve (right side).
Where are the semilunar valves located?
In the pulmonary artery and aorta.
What is the function of the septum?
It separates oxygenated and deoxygenated blood within the heart.
Why is it important for oxygenated and deoxygenated blood to stay separate?
To maintain a high concentration of oxygen in the blood going to the body.
What is the cardiac cycle?
The sequence of pressure and volume changes in the heart that control blood flow and valve function.
What are the three key stages of the cardiac cycle?
Diastole, atrial systole, and ventricular systole.
What happens during diastole?
Both the atria and ventricles relax, increasing their volume and allowing blood to flow into the atria.
How does pressure change in diastole?
The pressure in the atria increases as blood fills them, but the ventricles remain low in pressure.
What happens during atrial systole?
The atria contract, decreasing their volume and increasing their pressure, forcing blood into the ventricles throught the AV valves
What causes the atrioventricular (AV) valves to open?
The pressure in the atria becomes higher than in the ventricles.
What happens during ventricular systole?
The ventricles contract, decreasing their volume and significantly increasing pressure and forcing blood through the semilunar valves into the pulmonary artery and aorta
What causes the semilunar valves to open?
When ventricular pressure becomes higher than the pressure in the arteries (aorta and pulmonary artery).
What happens to the AV valves during ventricular systole?
They close to prevent backflow of blood into the atria.
When do the semilunar valves close?
When the pressure in the arteries is higher than in the ventricles
What is cardiac output?
The volume of blood ejected from one ventricle per minute.
How is cardiac output calculated?
Cardiac Output = Heart Rate × Stroke Volume.
What is stroke volume?
The amount of blood pumped out of the heart per beat.
How do you calculate heart rate from a cardiac cycle graph?
Find the duration of one cardiac cycle, then use: Heart Rate = 60 ÷ Duration of One Cycle.
If one cardiac cycle lasts 0.28 seconds, what is the heart rate?
214 beats per minute (60 ÷ 0.28 = 214).
What are the four types of blood vessels?
Arteries, arterioles, capillaries, and veins.
What is the function of arteries?
Arteries carry blood away from the heart.
What is the function of veins?
Veins carry blood back to the heart.
What is the function of arterioles?
Arterioles connect arteries to capillaries and regulate blood flow.
What is the function of capillaries?
Capillaries connect arterioles to veins and allow diffusion of gases and nutrients.
How does the lumen size differ between arteries and veins?
Arteries have a smaller lumen; veins have a larger, irregular-shaped lumen.
Why do arteries have thicker walls than veins?
To withstand high blood pressure and help maintain blood flow.
What is the function of the muscular layer in arteries?
It allows arteries to constrict and dilate to control blood flow.
Why do veins have thinner muscular layers than arteries?
Veins carry blood at a lower pressure and do not need to regulate flow actively.
What is the role of the elastic layer in arteries?
It allows arteries to stretch and recoil to maintain blood pressure.
Why do veins have thinner elastic layers?
They carry blood at lower pressure and do not need as much flexibility.
Do arteries have valves?
No, arteries do not have valves.
Why do veins have valves?
To prevent backflow of blood.
How thick are capillaries?
One cell thick.
Why is it beneficial that capillaries are one cell thick?
It provides a short diffusion distance for gas and nutrient exchange.
Why is blood flow slower in capillaries?
To allow more time for diffusion of oxygen, carbon dioxide, and nutrients.
Where are capillaries found?
In villi, alveoli, and nephrons—where diffusion occurs.
What is a capillary bed?
A network of capillaries that increases the surface area for exchange.
How do arterioles differ from arteries?
Arterioles have a thicker muscular layer to regulate blood flow into capillaries.
Why do arterioles need to restrict blood flow before reaching capillaries?
To prevent high pressure from damaging capillaries.
Do capillaries have muscular or elastic tissue?
No, they only have a single layer of cells.
Why does the Av valves close?
To prevent backflow into the atria, creating the first heart sound (“lub”)
How do valves control blood flow?
- Valves open when pressure is higher behind them and close when pressure is higher in front
- The AV valves prevent backflow into the atria and the semilunar valves prevent backflow into the ventricles
How does ventrical systole generate high pressure?
The ventricles have thick muscular walls which contract powerfully to reduce volume and increase pressure
What causes the first and second heart sounds?
- “Lub” - AV valves closing during ventricular systole
- “Dub” semilunar valves closing during diastole
How does blood flow into the heart during diastole?
As both atria and ventricles relax, pressure in the chambers drops, allowing blood to flow from veins into the atria and then ventricles
How does most blood enter the ventricles?
passively before atrial systole
What does it mean for a circulatory system to be ‘closed’?
A closed circulatory system means all blood vessels are connected in a circuit, so blood always remains within the vessels unless they are damaged.
What does ‘double circulatory system’ mean?
It means blood passes through the heart twice in each circuit—once to the lungs (pulmonary circulation) and once to the rest of the body (systemic circulation).
Why do mammals need a double circulatory system?
To control blood pressure—lower pressure for the lungs to prevent capillary damage and higher pressure for the body to ensure oxygen reaches all cells.
Why is blood pressure lower in the pulmonary circulation?
Lower pressure prevents capillary damage and allows more time for gas exchange between alveoli and capillaries.
Why is blood pressure higher in systemic circulation?
Higher pressure ensures blood moves quickly and reaches all respiring cells for aerobic respiration.
What are the four major blood vessels connected to the heart?
- Veins: Vena cava, Pulmonary vein
- Arteries: Pulmonary artery, Aorta
What blood vessels are connected to the lungs?
Pulmonary artery (carries deoxygenated blood from the heart to the lungs) and pulmonary vein (carries oxygenated blood from the lungs to the heart).
What blood vessels are connected to the kidneys?
- Renal artery: Brings oxygenated blood to the kidneys
- Renal vein: Carries deoxygenated blood away from the kidneys to the heart.
What is the function of the coronary arteries?
They supply the heart muscle with oxygenated blood so it can contract and keep beating.
Where does the lymphatic system drain?
The lymphatic system drains into the circulatory system near the vena cavae via the thoracic duct.
What is the lymphatic system?
The lymphatic system is a secondary circulatory system and a major part of the immune system.
What are the components of the lymphatic system?
The lymphatic system consists of :
- lymphatic capillaries
- vein-like lymph vessels with valves
- lymph nodes
- lymphatic tissue in the spleen, thymus, and tonsils.
What do lymph nodes do?
Lymph nodes are sac-like organs that trap pathogens and foreign substances and contain large numbers of white blood cells.
What is the role of lymphatic tissue in the spleen, thymus, and tonsils?
Lymphatic tissue in these organs contains large amounts of white blood cells and is involved in their development.
What is the composition of blood?
Mainly water, plus proteins, ions, nutrients, but no fibrinogen.
What is the composition of lymph?
Mainly water, plus small molecules and lipids.
What is the composition of tissue fluid?
Mainly water, plus proteins, ions, nutrients, and waste products.
What is the composition of serum?
Mainly water, plus small molecules.
What happens to tissue fluid at the venous end of the capillaries?
Once at the venous end of the capillaries under reduced hydrostatic pressure, the water is pulled back into the capillaries by osmosis and an increased hydrostatic pressure in the tissue fluid.
What happens to tissue fluid while bathing the cells?
The tissue fluid loses most of its Oxygen and nutrients but gains waste products such as Carbon Dioxide.
What happens to tissue fluid that does not re-enter the capillaries?
Some tissue fluid is carried to the lymphatic system, which eventually drains back into the bloodstream via two ducts attached to the veins near the heart.
What powers the movement of lymph fluid?
The movement of lymph fluid is powered by hydrostatic pressure of the tissue fluid from the capillaries and contractions of body muscles that squeeze lymph vessels.
How do valves function in the lymphatic system?
Valves ensure that the lymph fluid flows in the right direction.
What occurs in the fluid that drains into the lymph vessel?
Fluid drains into the lymphatic system, passing into larger lymph vessels.
What happens to bacteria in the lymphatic system?
Bacteria are destroyed by macrophages and antibodies produced by lymph nodes.
Where does lymph fluid eventually drain back into?
Lymph fluid eventually drains back into the blood system via the subclavian vein.
What is the composition of lymph fluid?
Lymph fluid is a liquid.
Where is the lymphatic system located?
The lymphatic system is a network of vessels throughoout the body
What is the primary function of red blood cells?
Red blood cells contain hemoglobin, which transports oxygen in the blood.
What is the structure of hemoglobin?
Hemoglobin has a quaternary structure consisting of four polypeptide chains, each containing a heme group with iron, where oxygen binds.
What is haemoglobin affinity?
The ability of hemoglobin to attract and bind oxygen.
What is hemoglobin saturation?
The extent to which hemoglobin is bound to oxygen; 100% saturation means all binding sites are occupied.
What do ‘loading’ (association) and ‘unloading’ (dissociation) mean?
Loading refers to hemoglobin binding oxygen, while unloading refers to oxygen detaching from hemoglobin.
What does the oxyhemoglobin dissociation curve show?
It illustrates how hemoglobin’s oxygen saturation varies with partial pressure, forming a sigmoid (S-shaped) curve.
How does partial pressure affect hemoglobin’s oxygen binding?
At high partial pressure (e.g., alveoli), hemoglobin has a high affinity and binds oxygen. At low partial pressure (e.g., tissues), hemoglobin releases oxygen.
What is cooperative binding in hemoglobin?
The binding of one oxygen molecule changes hemoglobin’s shape, making it easier for additional oxygen molecules to bind.
What is the Bohr effect?
The presence of high CO₂ lowers blood pH, shifting the dissociation curve to the right and reducing hemoglobin’s affinity for oxygen, enhancing oxygen unloading in tissues.
How does pH affect hemoglobin’s oxygen affinity?
Lower pH (more acidic conditions due to CO₂) decreases oxygen affinity, while higher pH increases affinity.
How does fetal hemoglobin differ from adult hemoglobin?
Fetal hemoglobin has a higher oxygen affinity, allowing it to extract oxygen from maternal blood.
Why do llamas have a different hemoglobin adaptation?
Llamas live at high altitudes with lower oxygen levels, so their hemoglobin has a higher affinity for oxygen.
How is dove hemoglobin adapted for flight?
Doves have hemoglobin with a lower oxygen affinity, enabling rapid oxygen unloading to meet their high metabolic needs.
Why does the earthworm’s hemoglobin have a high oxygen affinity?
Earthworms live underground where oxygen levels are low, so they need hemoglobin that can bind oxygen even at low partial pressures.
How does hemoglobin adaptation support different animal environments?
Different species have hemoglobins with varying oxygen affinities to suit their oxygen availability and metabolic demands.
Draw and label The structure of the heart
What is the function of plasma in blood?
Plasma transports substances in solution, including nutrients, hormones, and waste products.
What do red blood cells do in the circulatory system?
Red blood cells carry oxygen from the lungs to the tissues and return carbon dioxide from the tissues to the lungs.
What is the role of white blood cells in the blood?
White blood cells are involved in immune defense, protecting the body from infection.
What role do platelets play in the circulatory system?
Platelets are involved in clotting, helping to seal wounds and prevent excessive bleeding.
What is tissue fluid, and how does it aid the cells?
Tissue fluid surrounds cells and provides them with nutrients and oxygen while removing waste products. It also helps fight infection.
What are the differences between tissue fluid and plasma?
Tissue fluid has no red blood cells.
Tissue fluid has fewer proteins and fewer white blood cells compared to plasma.
How is tissue fluid formed in the capillaries?
Tissue fluid forms when high hydrostatic pressure at the arteriole end of the capillaries forces fluid out, and this fluid surrounds body cells.
How does tissue fluid return to the capillaries?
At the venule end of capillaries, the hydrostatic pressure is lower, and osmosis pulls fluid back into the capillaries, aided by plasma proteins.
How does the lymphatic system relate to tissue fluid?
Some tissue fluid that doesn’t re-enter the capillaries drains into lymph vessels, forming lymph, which is transported through the lymphatic system.
What are the main differences between lymph and tissue fluid?
Lymph has less oxygen and fewer nutrients.
Lymph contains more fatty acids and more white blood cells (lymphocytes).
How is lymph transported through the body?
Lymph is transported through lymph vessels by muscle contractions, and it passes through lymph nodes to filter out pathogens.
What happens to lymph after it passes through the lymph nodes?
After being filtered in the lymph nodes, lymph is eventually returned to the bloodstream.
What is the primary function of the lymphatic system?
The lymphatic system plays a crucial role in immune defense, filtering pathogens and transporting immune cells.
What is the composition of lymph?
Lymph is a liquid similar to tissue fluid but contains more lymphocytes (white blood cells), less oxygen, and more fatty acids.
How does the formation of tissue fluid change in capillaries?
As blood moves through capillaries, hydrostatic pressure forces fluid out at the arteriole end, while osmotic pressure in the capillaries draws fluid back in at the venule end.
