300 likes | 450 Vues
Circulatory System. Heart Structure and Function. Our Goal This Section. Describe the parts of the heart and how they work together. Anatomy of the Heart. 4 chambers: 2 atria and 2 ventricles right side feeds the pulmonary circuit left side feeds the systemic circuit. Atria.
E N D
Circulatory System Heart Structure and Function
Our Goal This Section... • Describe the parts of the heart and how they work together
Anatomy of the Heart • 4 chambers: 2 atria and 2 ventricles • right side feeds the pulmonary circuit • left side feeds the systemic circuit
Atria • Receiving chambers • Right Atria accepts blood from the anterior and posterior vena cavae (DEOXYGENATED BLOOD) • Left Atria accepts blood from the pulmonary veins (OXYGENATED BLOOD)
Structure: Location: Function: How it works: Atrioventricular Valves
Structure: Flaps of tissue Location: Separate the atria from the ventricles Function: Ensure no back flow of blood in the heart How it works: when the blood pressure in the atria is greater then the blood pressure in the ventricles - valves open (atrial contraction) allowing blood to enter the ventricles Atrioventricular Valves
ChordaeTendoneae • Tendons • Attach AV valves to ventricles • Prevent AV valves from inverting when the ventricles contract
Contract together to send blood out of the heart Fill with blood when the atria contract Right ventricle contracts causing the AV closed and blood enters pulmonary valve - leads to the pulmonary trunk and then pulmonary arteries Pulmonary arteries take blood to lungs for oxygen In left ventricle the flow of blood is the same except that the blood enters the aortic valve which leads to the aorta Semi-lunar valves Ventricles
Pulmonary Valve (Semi-lunar valve Aortic Valve (Semi-lunar valve) ChordaeTendineae
Septum • Structure: • Keeps _________________ and _________________ circuits separate
Septum • Structure: Muscular wall separating the left and right side of the heart • Keeps pulmonary and systemic circuits separate
1st branches of the aorta Feed heart muscle Coronary veins take blood back to the vena cava when it enters the right atrium Coronary Arteries
Control of the Heart • Sino-atrial (SA) node • Atrio-ventricular (AV) node • Right Atrium • Made of special muscles and nerve cells that can contract without stimuli – will continue beating even outside of the body! • SA nodes is along the wall of the atrial chamber • AV node is deeper, close to the AV valve
SA Node AV Node AV node uses _______________________to stimulate the massive ventricles Purkinje fibers are nerves that begin at the AV node sending impulses through both _______________________ • Causes atrial contraction • Send nerve impulse to the __________________ (causes it to respond) • Nicknamed the ____________________ as it initiates the heartbeat
SA Node AV Node AV node uses PURKINJE FIBERS to stimulate the massive ventricles Purkinje fibers are nerves that begin at the AV node sending impulses through both ventricles • Causes atrial contraction • Send nerve impulse to the AV node (causes it to respond) • Nicknamed the pacemaker as it initiates the heartbeat
Remember Our Goal... • Describe the parts of the heart and how they work together
Our Goal this Section... • Analyse the relationship between heart rate and blood pressure
Heart Beat Double sound caused by the closing of the AV valves followed by the semi-lunar valves. Electrocardiogram (EKG)
Nervous System SA node is connected to the brain by a nerve. Brain will signal the SA node through a nerve to accelerate its contraction if more blood is needed in the tissues or blood pressure too low. Part of brain = medulla oblongata Autonomic
Blood Pressure • Low blood pressure can be harmful • Kidneys function is dependent BP • Hypertension: ________________________ • Hypotension:_________________________ • Body can adjust BP – monitored in the ________________________ of the brain • Arterioles constrict or dilate to raise or lower BP
Blood Pressure • Low blood pressure can be harmful • Kidneys function is dependent BP • Hypertension: high BP • Hypotension: low BP • Body can adjust BP – monitored in the medulla oblongata of the brain • Arterioles constrict or dilate to raise or lower BP
Blood Pressure • Force of blood against the blood vessel walls • Greater when the ventricles are contracting (forcing blood through arteries) – SYSTOLIC PRESSURE • Between contractions the blood pressure is lower – DIASTOLIC PRESSURE • Measured along the brachial artery of the arm
Blood Pressure • 120/80 mmHg is normal • High blood pressure strains tissues being fed by blood • High blood pressure is normal during physical activity • Blood pressure is affected by lifestyle, diet and stress • Plaques can line the insides of arteries and arterioles increasing BP • If plaque block a blood vessel then tissue damage or tissue death may occur • If coronary arteries are blocked then part of heart muscle may die – heart attack