Chapter 27: The heart and blood vessels
Describe the process of pulse
1. A wave of expansion passes down the walls of arteries following a contraction of the left ventricle 2. The elastic fibres in the artery walls then bring about a contraction of the artery wall 3. Average pulse rate is 72 beat per minute
Give two advantages of a Closed Circulation System
1. Blood can be pumped faster, therefore nutrients can be delivered faster to cells allowing the organism to be more active 2. Blood flow rate to different organs can be changed, E.G. blood flow can be increased to the leg muscles when running
Describe the four stages of heartbeat
1. Blood enters the two atria. All valves are closed. All chambers are relaxed 2. The atria contract, tricuspid and bicuspid valves open, blood is forced down into ventricles 3. Atria relax, ventricles contract, bicuspid and tricuspid valves close, semilunar valves open and blood is forced into the pulmonary artery and aorta 4. Ventricles relax, semilunar valves close. The cycle starts again
Describe how blood is pushed in veins vs arteries
1. Blood is pushed through the veins when body muscles contract and squeeze the veins. The contraction/relaxation cycles of skeletal muscles squeeze the veins forcing the contained blood towards the heart 2. Blood is pushed through the arteries as the heart squeezes the blood out
Describe Arteries in Nine points
1. Carry blood away from the heart 2. Carry oxygenated blood 3. Carry blood under high pressure 4. Have thick muscular elastic walls 5. Have narrow lumen 6. Have a pulse 7. Deep under the skin 8. Have no valves 9. Arteries branch at their ends into tiny arterioles
Describe Veins in Nine points
1. Carry blood towards the heart 2. Carry de-oxygenated blood 3. Carry blood under low pressure 4. Have thin walls 5. Have wide lumen 6. Do not have a pulse 7. Near surface of the skin 8. Have valves to prevent back-flow of blood 9. Veins branch at their beginnings into tiny venules
Give five functions of the circulatory system
1. Carry oxygen from the lungs to the rest of the body 2. Carry digested food from the small intestine to all areas in the body which need it 3. Aid in the disposal of all wastes from the body 4. Distribute heat 5. Fight diseases by using white blood cells to fight off infections
Name and give the function of the three subsystems of the systemic circuit
1. Coronary circulation: Supplies blood to the heart 2. Renal circulation: Supplies blood to the kidneys 3. Hepatic Portal circulation: Supplies blood to the liver, stomach and intestines
Describe the effect of Exercise on circulation
1. Exercise strengthens the heart, improving circulation 2. Dilated arteries are caused by aerobic exercise, improving blood flow to all the organs and less risk of heart disease 3. Exercise increases ability to transport oxygen, increasing energy levels 4. Exercise lowers resting heart rate, increasing heart efficiency
Describe Capillaries
1. Extremely narrow blood vessels which surround the body cells, organs and tissues at the ends of the arteries and at the beginning of the veins 2. Walls are only one cell thick, permitting exchanges of material between the contents of the capillary and the surrounding tissue 3. Function is to supply tissues with substances in the blood and to remove waste from the surrounding cells 4. Exchange of oxygen, carbon dioxide, water, salts etc. between the blood and surrounding body tissues
Describe the effect of diet on circulation
1. High intake of fat causes a build up of cholesterol, blocking arterioles and leading to stroke or heart attack 2. High salt intake raises blood pressure which can cause heart attacks 3. Lack of protein lowers blood pressure
Give five effects of smoking on circulation
1. Nicotine increases the heart rate and blood pressure, putting a bigger workload on the heart and increasing risk of stroke 2. Hardening of the arteries 3. Increased risk of heart disease 4. CO2 reduces the amount of O2 carried by the blood, reducing energy levels 5. Other chemicals in tobacco increase the chance of clots
Describe Hepatic Portal circulation
1. Nutrients are picked up by capillaries in the small intestines and are transported to the liver 2. Excess nutrients are stored in the liver for future needs 3. The liver receives oxygenated blood from a large artery that branches off the aorta
Describe Blood Flow through the Heart
1. Oxygen-poor blood flows from the body into the right atrium, then into the right ventricle 2. The right ventricle pumps the blood to the lungs, where the blood releases waste gases and picks up oxygen 3. The newly oxygen-rich blood returns to the heart and enters the left atrium, then into the left ventricle 4. The left ventricle pumps the oxygen-rich blood to all parts of the body
Give two advantages of a Double Circulation System
1. Separation of oxygen rich and oxygen poor blood 2. Blood pressure can be kept high
Describe Venules
1. Small vessels that drain blood from capillaries into veins 2. Many venules unite to form a vein
Describe renal circulation
1. Supplies blood to the kidneys 2. The kidneys filter waste from the blood 3. Nearly a quarter of the blood that is pumped into the aorta flows to the kidneys
Describe both heart sounds
1. The 'lub' sound is quieter, longer, lower pitched - caused by the bicuspid and tricuspid valves closing 2. The 'dub' sound is louder, shorter, higher pitched - caused by the semilunar valves closing
Describe Coronary Circulation
1. The heart gets blood from two coronary arteries that emerge directly from the aorta, just beyond its semilunar valve 2. The right coronary artery mostly serves the right atrium and right ventricle, and same with left 3. The blood then goes through arterioles into capillaries and then to the heart's cells 4. Venules then carry the blood back to the coronary veins and back to the right atrium
Describe heart rate control
1. The pacemaker receives messages from the brain 2. Two nerves from the medulla oblongata connect to it, influencing its rate of contraction 3. One nerve quickly accelerates the heart rate and the other can quickly reduce it back to resting rate 4. These messages are transmitted as electrical impulses that cause the atria to contract - atrial systole 5. This sends blood to the ventricles 6. The electrical impulse then travels through the septum to the ventricles at the atrio-ventricular node 7. The ventricles contract and force the blood towards the openings of the arteries, pulmonary artery and aorta - ventricular systole
Describe how a Double Circulation System operates
1. The pulmonary circuit pumps blood to the lungs 2. The systemic circuit pumps blood to the body systems (head, limbs, trunk) 3. The right side of the heart pumps blood through the shorter pulmonary circuit while the left side pumps blood through the longer systemic circuit
Describe Arterioles
1. Tiny branches of arteries that transport blood from arteries to capillaries 2. Under the control of the sympathetic nervous system, and construct and dilate to regulate blood flow 3. Main regulators of blood flow and pressure
What are standard healthy readings of blood pressure?
80mm Hg diastolic, 120 mm Hg systolic
What is a portal system?
A blood pathway that begins and ends in capillaries
Briefly describe the structure of the heart
A hollow structure made of cardiac muscle, surrounded by a double membrane called the pericardium. There is fluid between these two membranes called pericardial fluid which helps to reduce friction when the heart beats
What does heart beat consist of?
Alternate contraction and relaxation of the cardiac muscle
What is a heart murmur and what does it indicate?
An abnormal sound of the heart, usually an indication of damaged valves
Blood pressure varies along the circuit, decreasing from...
Artery to arteriole to capillary to venule to vein
Where is blood pressure measured?
At a large artery in the upper arm
Two ___ form the curved top of the heart
Atria
Where is the heart located?
Between the lungs, behind the breastbone, above the diaphragm, slightly to the left of the thorax, and surrounded by the ribcage. Protected in a moistened chamber called the pericardial cavity
What is hypertension (high blood pressure) usually caused by?
Blockages in the arteries
Briefly describe a Closed Circulation System
Blood remains in a continuous system of blood vessels, E.G. in Humans
What is the heart wall made of?
Cardiac muscle
Describe Coronary arteries
Cardiac muscle is supplied with blood by the coronary arteries - these branch from the aorta just above the semilunar valves to the aorta
The average hear's muscle, called ___ ___ , contracts and relaxes about ___ to ___ times per minute
Cardiac muscle, 70, 80
What does the aorta do?
Carries nutrient-rich blood away from the heart
The average adult heart is about the size of a ___ ___ and weighs about ___ grams
Clenched fist, 310
What does the pulmonary artery do?
Connects the heart with the lungs, forming the pulmonary circulation system
What is the bicuspid valve?
Connects the left atrium with the left ventricle
What is the Tricuspid valve?
Connects the right atrium with the right ventricle
Describe Coronary veins
Drain blood from heart wall into the right atrium
Name five things that increase heart rate
Exercise, temperature, stress, emotions and shock
Briefly describe an Open Circulation System
Heart pumps blood into vessels that are open ended, E.G. in Insects
What is the role of muscle and elastic fibres in blood vessels?
Muscle expands to allow increased blood flow through the vessel, elastic fibres bring the blood vessel back to shape
What regulate the speed with which cardiac muscle contracts?
Nerves connected to the heart
What is the exception to the whole oxygenated blood thing in veins and artieries?
Pulmonary ones
Name three things that decrease heart rate
Relaxation, Sleep and Alcohol
A wall, called the ___ , separated the right and left sides of the heart
Septum
What is the name of the instrument used to measure blood pressure?
Sphygmomanometer
Hepatic Portal Circulation system connects the ___ and ___ with the ___
Stomach, intestines, liver
What are the names given to contraction and relaxation of heart muscle respectively?
Systole, Diastole
What is Pulse?
The alternate expansion and contraction of arteries
What is Blood Pressure?
The blood pressing against the blood vessel walls
What cause the sounds of the heart?
The closing of the valves
What causes blood pressure?
The contraction of the ventricles which forces blood into the arteries
What is heart beat controlled by?
The pacemaker in the right atrium, which sends an electrical signal to the cardiac muscle
What are the two largest veins that carry blood into the heart?
The superior vena cava and the inferior vena cava, located near the top of the heart
What is the function of the semilunar valves?
They allow the blood to flow out of the heart into the two main arteries, preventing blood from returning to the heart
What is the function of the heart?
To pump blood around the body
A ___ connects each ___ to the ___ below it
Valve, atrium, ventricle
Two ___ meet at the bottom of the heart to form a pointed base which points towards the left side of your chest
Ventricles