6a: Heart & Blood Vessels Flashcards
What is the Heart Walls made of?
- cardiac muscles
Explain the mammal “Double Circulation”:
There are 2 types of Circulation:
1. pulmonary circulation: right side of the heart sends deoxygenated blood from the body along the pulmonary artery to the lungs
2. systemic circulation: pump on the left side, sends oxygenated blood from the lungs along the aorta to the rest of body
Why is it an Advantage for the Human Heart to have 2 separate pumps, rather than 1?
- the right hand side generates pressure to send blood to the lungs, and pressure drops (e.g for gas exchange in capillaries)
- however, the left side of the heart needs the left ventricle to generate more pressure for the blood to travel around the whole body at a fast enough rate for a high metabolic rate to be generated
What are the “Coronary Arteries”?
- set of arteries that deliver oxygenated blood to the cardiac muscle that makes up the walls of the heart
Why does the Cardiac Muscle need a rich supply of blood?
- for a good supply of O2 + glucose, for high rates of aerobic respiration, to produce lots of ATP for muscle contraction
What does the Septum do?
- separates the left and right chambers of the heart
Where does the Atria receive blood from?
What type of blood passes through the Vena Cava + pulmonary vein?
-veins (right atrium receives from vena cava, and left atrium receives from pulmonary vein)
- deoxygenated for Vena Cava, Oxygenated for Pulmonary Vein
What is the difference in size of Atrium + Ventricles?
What is the difference in size of the left + right ventricles?
- ventricles have much thicker muscular walls
- left ventricle has much thicker muscular walls than the right
Why are the walls of the Left Ventricle thicker than those of the right?
- left ventricle needs to contract with more force and generate a higher pressure, so that it can pump the blood all around the body, rather than just the lungs
What is the function of the Atrioventricular and Semilunar valves?
- prevent backflow of blood
.AV: prevent backflow of blood from ventricles to atrium
.Semilunar: prevent backflow of blood from artery to ventricle
one complete sequence of contraction and relaxation is called a _____ _____
cardiac cycle
Where does blood flow from?
- down a pressure gradient (high pressure to low)
How many times does the heart roughly contract + relax a minute?
70
Explain Diastole:
- heart relaxes during which time the atria again fills up with blood from Vena Cava and Pulmonary Vein
- the atrioventricular valves will be closed at the start of
diastole however, as the blood enters the atria pressure
builds up and forces the valve open to allow blood to start
filling into the ventricles. This is called passive filling.
Explain Atrial Systole:
- blood fills the atria from vena cava and pulmonary vein
- as the atrial muscle contracts, there is an increase in pressure of atria above that of the ventricles
- this forces the atrioventricular valves to open further and more blood flows into the ventricles
Explain Ventricular Systole:
- ventricle muscles contract
- volume of ventricles decrease, pressure therefore increases
- this causes the atrioventricular valves to close, preventing back-flow of blood into the Atria
- blood is pushed upwards towards the arteries at the top of heart
- this forces semilunar valves open, so blood flows into aorta + pulmonary artery
Why are semi-lunar valves closed during diastole?
- pressure is higher in arteries than ventricles, causing valves to close to prevent backflow of blood into ventricles
Why do Atrioventricular Valves close during Ventricular Systole?
- greater pressure in ventricles than atria, so backflow of blood is prevented
Why do semilunar valves open during Ventricular Systole?
- greater pressure in the ventricles than arteries, so blood is pushed upwards forcing the semilunar valves open
Why is the pressure difference much higher for Ventricles, rather than Atrium? (left side of heart)
- left atrium only travels to the left ventricle, so only requires much thinner muscular walls, so weaker contraction occurs, so lower pressure difference
- left ventricle has thicker muscle tissues and stronger muscle contraction, so pressure difference is higher