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