This Week's

Circulatory system Heart Ventricle Atrium Arteries Aorta Subclavian Cardiac Carotid Renal Remoral Pulmonary Veins Subclavian	Vena cava Iliac Capillaries Throughfare channels Blood Plasma Erythrocytes Leucocytes Platelets Clotting Thromboplastin Thrombin Fibrinogen Fibrin	Lymph Respiratory system Lungs Vital lung capacity Diaphragm Pharynx Trachea Bronchi Bronchioles Alveoli External respiration Internal respiration Heart attack Stroke

What is the largest blood vessel in the body?

Read this standardized test practice passage and answer the questions. You have five and a half minutes to complete the assignment.

 

Cardiovascular Technologist

You know that muscles don't make a noise when they contract. Listen to the sound of a heart beating. What causes the sound of a heartbeat? What causes the sound known as a heart "murmur"?

(22 min)

Parts of the circulatory system:

Heart

• Each ventricle pumps about 35cm³ of blood with each contraction.
• At rest, the heart pumps about 5 quarts of blood a minute.
• During extreme exertion it can pump 40 quarts a minute.
• Your heart beats about 3 million times in one year.
• The beat of the heart can be graphed using an electrocardiogram, EKG.
  

  Look at the heart diagram above to answer these questions: Where does blood go when it leaves the right side of the heart? Where does blood go when it leaves the left side of the heart?

Arteries

• Thick walled vessels with blood under high pressure.
• Arteries carry blood away from the heart.

  Important arteries: Aorta - from the left ventricle of heart to the body. Subclavian artery - from aorta to right arm. Cardiac artery - from aorta to the heart. Common carotid arteries - one branches from the aorta, another branches from the subclavian artery. These branches go up each side of the neck to the head. Renal artery - from aorta to the kidneys. Femoral arteries - inside of thigh supplying blood to the legs. Pulmonary artery - the left and right pulmonary arteries carry blood from the right heart ventricle to the lungs.

Veins

• Thin walled vessels with blood under low pressure.
• Have valves to keep blood from flowing backward.
• Veins carry blood toward the heart.

  Important veins: Subclavian veins - return blood from the arms to the heart. Superior vena cava - up the left side of the body to return blood to the right atrium of the heart. Iliac veins - return blood from the legs to the vena cava.

Capillaries

• Capillaries are so small that cells must move through them in single file. The capillary walls are only one cell thick, making it possible for the exchange of materials between the blood and body cells.
• While the diagram on this page suggests that all blood must move through small capillaries to get from arteries to veins, this is not actually true. Larger blood vessels, known as throughfare channels, allow blood to bypass a capillary bed.
• Every pound of body fat adds almost 200 miles of capillaries.
• The average adult has a system of blood vessels over 80,000 miles long.

Blood

(20 min)

• Your body contains about 5 liters of blood composed of the following:
• Plasma:  (chem lab 146)
  • The straw-colored liquid part of blood.
    • 90% water
    • 10% dissolved salts, sugars, fats, & proteins
  • Vertebrate blood salt content is about 9g/L (0.9%). Eighty percent of this blood salt is NaCl.
  • Plasma makes up about 55% of the blood volume.
• Erythrocytes: (red in picture)
  • RBCs, red blood cells, carry the respiratory gases O₂ and CO₂.
  • There are about 2.5 X 10¹³ RBCs in the body.
    • Males average about 5.4 million erythrocytes per cubic millimeter of blood.
    • Females average about 4.8 million erythrocytes per cubic millimeter of blood.

  • Your bone marrow produces about 1 Billion red blood cells every day.

    The red bone marrow of essentially all bones produces RBCs from birth to about five years of age. Between the ages of 5 to 20, the long bones slowly lose their ability to produce RBCs. Above age 20, most RBCs are produced primarily in the marrow of the vertebrae, the sternum, the ribs, and the pelvis.

  • The life span of a red blood cell is about 120 days.
  • If the majority of blood cells are red, why does blood look blue under the skin?
• Leukocytes: (blue in picture)
  • WBCs, white blood cells, fight infection.
  • Five basic types of WBCs are produced in the red bone marrow.
• Platelets: involved in the clotting of blood.
  • Also produced by the red bone marrow, platelets are not really cells.
  • Blood clotting is a two-part process:

    1.	Platelets are destroyed by tissue fluids at a wound site releasing thromboplastin. Thromboplastin reacts with calcium and prothrombin (produced by the liver) in the blood plasma to produce thrombin.
    2.	Thrombin reacts with fibrinogen, a soluble protein found in the blood, to produce fibrin. The tiny threads of fibrin overlap to form a "web" which traps blood cells. As more and more of the blood cells are trapped, the break in the blood vessel is eventually plugged. (fibrin fibers are yellow in the picture above.)

Blood Pressure & Pulse (Vital Signs):

Blood pressure consists of two measurements: the systolic pressure and the diastolic pressure. If the two measurements were 110 and 70, the blood pressure would be described as "one-ten over seventy".

• Systolic pressure, the first and highest number, is the force the heart places on the walls of the blood vessels as it pumps with each heartbeat.
• Diastolic pressure, the second and lowest number, is the pressure on the walls of the blood vessels when the heart relaxes between beats.

Both of these measurements are important. A high systolic pressure indicates strain on the blood vessels when the heart is attempting to pump blood. If the diastolic pressure is high, it means the blood vessels have little chance to relax between heartbeats.

Occasional high blood pressure is common. Anxiety, exercise, or nervousness can cause a high reading. Sustained high blood pressure can increase the risk of premature strokes and heart attacks. A pressure of 140/90 or higher is considered unhealthy.

Go to Anatomy Class to learn how to find your own pulse.

Subsystems of the circulatory system: Systemic circulation Blood moves between the heart and the bulk of the body. Pulmonary circulation Blood moves between the heart and the lungs. Coronary circulation Blood moves through the vessels that supply the heart muscle. Hepatic portal circulation Blood moves from the digestive tract to the liver.

Do NOT come into contact with the blood of another person. The danger of disease transmission is much too great.

See pictures from inside a cardiac operating room.

The lymphatic system:

About three liters of fluid, lymph, leak from blood vessels into body tissues each day. A system of low-pressure vessels, the lymphatic system, collects this fluid and returns it to the circulatory system.

(27 min)

Lungs

• Each lung weighs about 600 grams.
• The surface area of your lungs is about 1,000 square feet, 20 times more than the surface area of your skin.
• Total lung capacity of an adult is between 5 and 6 liters.
• A normal breath exchanges about ¹/₂ liter of gas.
• Vital lung capacity is the maximum amount of air that can be exhaled at one time.

• A large sheet of muscle at the bottom of the rib cage.
• When you inhale, this muscle drops and the rib cage raises.
  • This motion increases the volume of the lung cavity causing a low pressure area.
  • External air pressure forces air into the lungs.
• How you breathe

• A muscular organ at the back of the throat.
• The respiratory and digestive systems branch here.
• The epiglottis is located in the pharynx.

• Also called the windpipe.
• A non-muscular tube leading from the pharynx to the lungs.
• There are rings of cartilage spaced along this tube to keep it open.

• The two branches of the trachea leading to the lungs.

• The smallest branches of the bronchial tubes.
• Why does asthma make it hard to breathe?

• The air sacs at the end of each bronchioles.

External respiration- exchange of gases between atmosphere and blood. Internal respiration - exchange of gases between blood and body cells.

The respiratory system is involved when we have a cold or the flu.
While the two are similar, it is quite easy to tell which one you have caught.

Concept Understanding: The cells in blood are mainly produced in the marrow of which bones? Describe hemoglobin and its function in blood. Who invented the stethoscope, and why? What is a megakaryocyte and where is one found? Answer the following questions about the lymphatic system: How does circulation in the lymphatic system differ from circulation in the circulatory system? Three quarters of the lymph in the body empties into one vein. Which one? The heart is not responsible for moving lymph through the lymph vessels. What muscles are responsible for this motion? What happens in the lymph nodes? What role does the lymphatic system play in fighting infection? Besides the vessels and nodes, list three body organs that are part of the lymphatic system. Define the term "T-cells". How are the two types of acquired immunity, natural immunity and artificial immunity, different? Use one paragraph to describe the difference between a heart attack and a stroke. After reading your paragraph, the reader should know what part of the body is involved with each, a basic description of each, and the underlying cause for each.

30 Second CPR Guide

The aorta is the largest blood vessel in the body.