Chapter 47-1, 2

Circulatory System

Blood: the "chemical highway" that connects the many cells of an organism • Carries nutrients, oxygen to each cell • Carries wastes away from cells (CO 2 , urea) to kidneys, lungs, skin • Carries enzymes, hormones, water, antibodies around body for distribution

Components of Blood

• Men, on average, have about 10-12 pints • Women, on average, have about 8-10 pints • each cc (cubic mL) of blood contains about 4 million RBCs and 7,000 WBCs

Plasma

• • Plasma = 60% of blood; straw-colored fluid about 90% of the plasma is water carries most CO hormones, etc.

2 , nutrients, plasma proteins, • • • plasma proteins: albumin (to maintain high osmotic potential) fibrinogen (clotting) globulins (immunity, antibodies)

Red Blood Cells

• • • • • • Called “erythrocytes” Transport oxygen; about 30 trillion in bloodstream contain HEMOGLOBIN (red pigment protein) which acts like an "oxygen magnet"; iron non-nucleated (cannot repair themselves) short lifespan (120-130 days) Replaced from bone marrow stem cells

White Blood Cells

• • • • • • • called “leukocytes” 1 or 2 WBC for every 1,000 RBC larger than RBC, have nucleus, no hemoglobin, colorless Can migrate outside of vessels (RBC’s cannot) to directly cleanse tissues (lymph) Some act by: phagocytosis of bacteria/viruses/etc. Others make antibodies (proteins) that attack microorganisms "Pus"-dead WBC; new WBC form in spleen, bone marrow

Platelets

• • • colorless, oval/irregular shaped smaller than RBCs "little bags of chemicals" that function in clotting and plugging up breaks in vessels Blood Clotting- a complex series of chemical reactions, involving platelets and plasma "clotting factors". Often referred to as the "clotting cascade".

Thromboplastin (produced in liver) Prothrombin------------------------------>Thrombin Fibrinogen---------------------------------------------> Fibrin 15 CF’s involved in this conversation (Hemophiliacs usually genetically lack Factor VIII)

clotting animation

The Cardiovascular System

Vascular Circuitry

Heart--->Arteries--->Arterioles--->Capillaries--->Venules--->Veins--->Heart (etc)

Arteries

• • • • thick, muscular walls, elastic, to allow for high pressure made of layers of endothelium/muscle/connective tissues Narrow down into smaller arterioles

Veins

• • • • • • carry blood back toward the heart thinner walls (than arteries) less elastic (less pressure to withstand) have valves to prevent backflow endothelium, muscle, connective tissue layers narrow down into smaller diameter venules

Arteries –vs- Veins (anatomy)

Capillaries

• • • • Diffusion the site of all exchange with cells in very close contact with all cells Lined with a single layer of epithelium smallest diameter of all vessels -only about 5 micrometers in diameter- (RBCs pass in single file)

Atherosclerosis

• …is a disease affecting arterial blood vessels. • Main cause: cholesterol buildup in arteries (plaques) • It is commonly referred to as • "hardening" of the arteries.

It is caused by the formation of multiple plaques within the arteries • This often leads not only to clogs, but also hypertension (high blood pressure), which both may result in heart attacks.

The Heart

•

Evolution of the Heart

simplest (in earthworms) are enlarged, muscular portions of a blood vessel = "aortic arches" •Mollusks= tube shaped heart with

open circulation

•Vertebrates= multi-chambered heart with

closed circulation

•multiple chambers serve to separate oxygenated/ deoxygenated blood •Atrium (receiving chamber) •Ventricle (pumping chamber)

The Human Heart

is made of epithelial, nerve, connective tissues and cardiac muscle (infatiguable) Four chambers (2 atria, 2 ventricles)

septum

- dividing wall between right and left side of heart

valves

at strategic locations prevent backflow Do right and left seem backward? That's because you're looking at an illustration of somebody

else's

heart. To think about how your own heart works, imagine wearing this illustration on your chest.

separation into chambers prevents mixing oxygenated, deoxygenated blood Did you know that your heart beats over 100,000 times a day? Get "heart smart" by checking out these amazing heart facts.

The Human Heart

• • • Superior and Inferior Vena Cava lead into heart (right atrium) Pulmonary artery brings blood to lungs; pulmonary vein returns oxygenated blood to the heart Aorta leads out to systemic circulation • • semilunar valves: prevent backflow between vessels/chambers atrioventricular valves: (mitral and tricuspid) between atria & ventricles; allow one-way flow between atria and ventricle

Trace the Path of Blood Through the Heart “ How Stuff Works ” narrated animation of cardiac parts & cycle How your heart works (animation)

Initiation and Regulation of Heartbeat

• Cardiac muscle is able to initiate its own impulse • • • • Sinoatrial Node (SA)- "pacemaker" in Right Atrium; initiates beat through both Atria; stimulates another area near center of heart called AV Node Atrioventicular Node (AV)...then impulse is carried to the ventricles by the BH Bundle of His (BH) = like the transfer of an electrical current along a circuit Heart Rate (bpm) is modified by the Autonomic Nervous System (vagus nerve) – Parasympathetic Nerves- slow down HR – Sympathetic Nerves- increase HR

To assess

heart rate

(BPM), take your arterial pulse!

@ rest?

After exercise?

1. Oxygen-poor blood (shown in blue) flows from the body into the right atrium.

2. Blood flows through the right atrium into the right ventricle.

3. The right ventricle pumps the blood to the lungs, where the blood releases waste gases and picks up oxygen.

4. The newly oxygen-rich blood (shown in red) returns to the heart and enters the left atrium.

5. Blood flows through the left atrium into the left ventricle.

6. The left ventricle pumps the oxygen-rich blood to all parts of the body.

How much blood does the heart pump?

• The heart pumps the equivalent of 5,000 to 6,000 quarts (about 6800 L) of blood each day! • Total volume of blood pumped by heart per minute = “cardiac output” • • • Cardiac Output = Heart Rate x Stroke volume (L/min) = (BPM) x (L/beat) [ex: 72 BPM x 0.07 L/beat = 5 L/min.]

Blood Pressure Regulation

• Blood Pressure arterial BP >>> venous BP 120 = systole; ventricles contract (empty);arteriole diameter enlarged 80 =diastole; ventricles relax (fill) • • • Cardiovascular Regulating Center (in medulla) controls activity of the nerves regulating the smooth (circular) muscle contraction of the blood vessel also controls strength of heartbeat, HR receives and interprets and responds to sensors through the cardiovascular system (esp. in the walls of the vessels) baroreceptors, CO 2 receptors

• • • • •

The Lymphatic System

Under arterial pressure, the BP exceeds the osmotic potential, thus forcing some plasma and WBC out into tissues.

This “lymphatic fluid” is collected by Lymph vessels which clean the tissue/ cellular debris (such as bacteria) out of the body cells.

Lymph flows thru Lymph Nodes to be cleaned These also make Lymphocytes (WBC’s) Lymph re-enters the circulatory vessels via the Subclavian Veins in the neck (back into bloodstream)