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Chapter 13. Heart Rate and Blood Pressure. The Cardiac Cycle. Each Heartbeat is called a Cardiac Cycle Step 1: the two atria contract at the same time This pushes blood into the ventricles Step 2: the two ventricles contract at the same time
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Chapter 13 Heart Rate and Blood Pressure
The Cardiac Cycle • Each Heartbeat is called a Cardiac Cycle • Step 1: the two atria contract at the same time • This pushes blood into the ventricles • Step 2: the two ventricles contract at the same time • The Right Ventricle pushes the blood into the Lungs • The Left Ventricle pushes the blood into the Body • Step 3: all the chambers relax • The atria fill with blood returning to the heart
Systole This refers to the heart muscle contracting • Diastole This refers to the heart muscle relaxing Ventricular Systole Atrial Diastole Ventricular Diastole Atrial Systole
What Controls the Heartbeat? • There are two areas that control how fast the heart beats. • Intrinsic Control inside the heart there are nerves that control the heart beat • Extrinsic Control a part of the brain controls the heart beats
Intrinsic Control • In the upper right atrium there is a sinoatrial node (SA node) • In the lower right atrium there is a atrioventricular node (AV node) • These nodes are made of muscle but is mostly made of nervous tissue
Intrinsic Control • The SA node starts the heartbeat and sends out an electrical pulse that causes the atria to contract. • When the electrical pulse reaches the AV node there is short delay. This delay allows the atria to finish their contraction. • The AV node sends the signal down the Atrioventricular bundle, which then branches into Purkinje Fibres. • This signal sent by the AV node causes the ventricles to contract
SA node (Sinoatrial node) Atrioventricular Bundle Purkinje Fibres AV node (atrioventricular node) Atrioventricular Bundle
Its time for a Review Break • Draw a picture of the heart from your memory. • No books no notes. Just a pen and paper. • Right atrium, left atrium • Right ventricle, left ventricle • Atrioventricular valves • Semilunar valves • Pulmonary trunk, aorta, pulmonary veins, superior vena cava, inferior vena cava • ChordaeTendineae • Septum • AV node and SA node
Extrinsic Control • A part of the brain controls the heart and controls how fast or slow the heart rate will be • The part of the brain that controls the heart is called the Medulla Oblongata
The heartbeat is part of your autonomic nervous system • The autonomic nervous system is the part of the nervous system that you do not think about. It happens automatically • Ex./ heartbeat, peristalsis, gall bladder squirting bile. • The autonomic nervous system has 2 parts • The Sympathetic Nervous System • The Parasympathetic Nervous System
The Parasympathetic Nervous System • The is the system that takes over when you are resting. • Your body is relaxed • You are at rest • Your body sends its blood to its stomach so it can digest food • Your heart rate decreases because you are at rest
The Sympathetic Nervous System • This is the system that takes over when something is threatening you and your “flight or fight” reaction takes over or if you are very stressed (physically or mentally) • Your body sends blood to the large muscles in your body, so it can have more energy to run or fight • Your body releases several different hormones that cause an increase in heart rate • Brain sees or smells or hears something that causes fear or stress. It sends a message to the adrenal glands to release hormones like epinephrine and norepinephrine. These hormones increase heart rate
Parasympathetic • Sympathetic • Parasympathetic • Heart Rate Low • Blood is around your digestion system • Hormones released into your blood • Heart rate is faster • Blood moves into muscles to Beat this Ninja up • Heart rate starts to slow down • You are Eating and watching TV • Suddenly a Ninja jumps though the window and tries to KILL you • You easily Beat the Ninja and go back to watching TV
The Pulmonary Circuit • Blood leaves the Right Ventricle to go to the Lungs It goes through the pulmonary Trunk • The pulmonary Trunk branches off into pulmonary arteries • The pulmonary arteries Branch and branch until they are capilliaries in the lungs to exchange gases • The blood returns to the Left Atrium oxygenated • The blood comes back through the pulmonary Veins
Systemic Circuit • Systemic means spread throughout this refers to the cells in our body. They are spread throughout our bodies • Blood leaves the heart via the Aorta • Blood then branches off into many different arteries • Blood comes back to the heart through many different veins
Arteries • Subclavian Artery • Mesenteric Artery • Renal Artery • Iliac Artery • Carotid Artery • Coronary Arteries • Veins • Subclavian Vein • Hepatic Portal Vein and Hepatic Vein • Renal Vein • Iliac Vein • Jugular Vein • Coronary Vein
Blood Flow • Blood Velocity • Arteries have the highest blood flow • It gets slower and slower the narrower the tubes get until capillaries, which is the slowest • The capillaries turn to venules and the blood starts to move faster • The venules turn to veins and it is moving a little faster
Arteries Arteriole Capillary Venule and Vein
Blood Flow • Blood Pressure • The pressure that is put against the wall of the blood vessel • Arteries will have the highest pressure • Veins will have the lowest pressure • Two types of pressure • Systolic Pressure Ventricles contract • Diastolic Pressure Ventricles relax
Blood Flow • Blood Pressure • The pressure is high coming out of the heart and it slowly decreases • The pressure decreases because it gets farther away from the Heart • Pressure gets very low in the Veins. The body relies on the veins and the muscles to move blood back to the heart
Blood Pressure Problems • Hypotension • Low Blood Pressure • Blood vessels widen • Caused from hormone changes, heart problems • Hypertension • High Blood Pressure • Narrow blood vessels • Caused from Stress, obesity, hormone problems