8.5 The Heart Flashcards
Heart
Organ used to pump blood around the body
Cardiac muscle
Contracts and relaxes in a rhythmic pattern. Does not get fatigued like skeletal muscle.
Pericardial membrane
Mechanical protection for the beart and big vessels. Lubrication reducing friction between heart and other structures
Right atrium
Deoxygenated blood enters from upper body and head in the superior vena cava. And from lower body in the inferior vena cava. As blood flows in, pressure increases in until the atrio-ventricular valve opens allowing blood into the right ventricle.
Right ventricle
Intakes blood from right atrium. Contracts as tricuspid valve closes. Pumps deoxygenated blood through semilunar valves into the pulmonary artery.
Left atrium
Intakes oxygenated blood from pulmonary vein. Pressure increases and bicuspid valve opens.
Left ventricle
Intakes blood from left atrium. Contracts after the left atrium contracts and pumps blood through the semilunar valve into the aorta and around the body.
Septum
Inner dividing wall of the heart preventing the mixing of deoxygenated blood and oxygenated blood
Cardiac cycle
Describes events in a single heartbeat, lasting around 0.8 seconds in a human adult
Diastole
Relaxation of heart. Atria and ventricles fill with blood. Pressure builds in the heart but artery pressure is minimal
Systole
Atria and ventricles contract. Pressure inside heart is at a low at the end, blood pressure in the arteries is at a maximum
Sino-atrial node SAN)
Starting region of electrical excitation, causing atria to contract, initiating the heartbeat.
Atrio-ventricular node (AVN)
Region that picks up the SAN impulse. Stimulates bundle of His.
Bundle of His
Made up of purkyne fibres, splits into 2 branches and conducts wave of excitation to the bottom of the heart
Electrocardiogram (ECG)
Measures spread of electrical excitation in the heart.
