Lecture 20 - Human Circulatory and Respiratory System

Respiratory & Circulation System 

Functions of the Circulatory System 

• Transport 

• Temperature Regulation 

• Protection 

Transport 

• Transport oxygen, nutrients, waste products, immune system cells, and hormones throughout the body 

Temperature Regulation 

• Helps maintain a body temperature that is optimum for metabolic function 

  • Vasoconstriction and vasodilation

Protection 

• Immune system cells transported throughout the body aid in fighting foreign invaders 

  • Platelets & white blood cells 

Open Circulatory 

• Hemolymph bathes organs directly then diffuse back into heart through sinuses 

Closed circulatory system 

• Blood transported through vessels into capillaries where diffusion of gases and nutrients occurs 

Open Circulatory System 

• Arthropods and mollusks 

• Less efficient 

• Lack of capillaries 

• Hemolymph transports nutrients & wastes 

• Tissues & cells bathed in mesolymph 

• Slow, uncontrolled blood flow

Closed Circulatory System 

• Vertebrates & annelids 

• More efficient 

• Capillaries present 

• Blood transport gases, nutrients, and waste 

• Blood delivered directly to cells 

• Fast, controlled blood flow

What is Blood? 

Plasma (55% of blood) 

• Liquid portion of blood that holds blood cells in suspension 

• Ions & proteins regulate osmotic & pH balance 

Formed elements (45% if blood) 

• Red blood cells 

• White blood cells 

• Platelets

• Red Blood Cells (erythrocytes)

• Oxygen transport 

  • Contain hemoglobin 

  • Lack nucleus & most organelles 

  • 95% of all blood cells in the body

• White Blood Cells (leukocytes) 

• Immune response to disease & foreign invaders (pathogens) 

• Platelets 

• Cell fragments that aid in blood clotting 

Hemogoblin 

• An oxygen carrying protein made up of 4 polypeptide chains 

  • Each hemoglobin can transport four oxygen molecules bound to seats of iron molecules 

    • Approximately 250 million hemoglobin per red blood cell

Oxygen Transport 

• Oxygen binding to hemoglobin is controlled by the particle pressure of oxygen, which is the force of oxygen molecules against the body (the amount of oxygen present) 

Blood Vessel Tissue: 

• Endothelium,

• smooth, muscle,

• connective tissue 

Veins (venules) 

• Vessels carrying blood back to the heart 

  • Valves 

Capillaries

• Thinly walled vessels where gas, nutrient and waste exchange occurs. 

  • Lack smooth muscle

Arteries (arterioles) 

• Vessels with thick walls that carry blood away from the heart 

Exchange of Capillaries 

• Capillaries are so small that RBCs pass through single-file 

• Gases, nutrients and waste move via diffusion

Cardiovascular system: 

• organ system that circulates blood through a network of vessels, transporting nutrients, gases and hormones to cells throughout the body.

Heart: 

• hollow muscular organ that pumps blood through the circulatory system by rhythmic contraction.

•  Atria: 

• chambers that receive blood entering the heart.

•  Ventricles: 

• chambers that pump blood out of the heart.

Pulmonary circuit:

•  circuit of blood flow between the heart and the lungs.

Systemic circuit: 

• circuit of blood flow between the heart and the rest of body

Semilunar valve 

• Valve between ventricles and aorta or pulmonary artery 

Atrioventricular valve 

• Valve between atria and ventricles 

Diastole: cardiac cycle

• Period of heart relaxation when the heart fills with blood 

Systole: Cardiac cycle

• Period of heart contraction when blood is forced out of the heart 

Blood Pressure 

1. Pressure from the cuff closes the artery.

2. The cuff is deflated allowing blood to pulse into the arm. 

• Systolic pressure is measured.

3. Cuff deflates to point that pulse can no longer be heard or felt.

Heart Rate: 

• Frequency of cardiac cycle 

  • Usually expressed as beats per minute (BPM)

Interpretation:

• Blood pressure and velocity decreases in the arterioles and capillaries.

•  Blood flow is slowest in capillaries where exchange of gases, nutrients and waste occurs.

•  Blood flow (velocity) increases in venules and veins

Directing the Flow of Blood 

•  Precapillary sphincters can contract and reduce the blood flow to certain areas of the body.

•  Muscle contractions in the extremities aid in pushing blood back to the heart. 

  • Valves in the veins ensure one-directional blood flow.

Diaphragm: 

• sheet of skeletal muscle that extends along the bottom of the rib cage.

  • Expands and contracts to force air into and out of lungs.

Breathing Control

•  Occurs in medulla oblongata and pons.

•  Monitors blood pH.

  •  Exercise = more O 2 needed and more CO 2 produced.

  •  Lower pH signals for increase in depth and rate of breathing.

Hyperventilation

when ventilation of CO 2 exceeds body’s production of C

Carbon Dioxide Transport

• Carbon dioxide transported from tissue by erythrocyte.

  •  7% transported as carbon dioxide in blood.

  •  23% of carbon dioxide and most of the hydrogen ions are attached to hemoglobin.

  •  70% transported as bicarbonate in plasma.

Cardiovascular Disease

Kills more than 750,000 people in the U.S annually.

Hypertension

• high blood pressure.

•  Heart attack: 

• damage or death of cardiac muscle due to blockage of coronary artery.

Stroke

• death of nervous tissue due to lack of O2.

Atherosclerosis

• hardening of arteries by accumulation of fatty deposits (plaque).

  •  Low-density lipoproteins (LDL)

  •  High-density lipoproteins (HDL)

Coronary arteries: 

• arteries that supply the heart with blood.

Low-density lipoproteins (LDLs): 

• carry cholesterol from the liver and small intestine to outlying tissues.

Treatments for Cardiovascular Disease

• Angiogram

•  Angioplasty

  • Stents

Bypass Surgery: 

•  Uses arteries from leg to bypass blockage of coronary artery.

 Coronary artery:

•  Artery supplying blood to the heart.

Lymphatic system: 

• system of vessels and nodes that returns interstitial fluid, proteins, and cells back to the blood.

  •  Separate from the circulatory system.

•  Lymph: 

• fluid of the lymphatic system.

•  Lymph nodes: 

• lymphatic organs that filter lymph and contain defensive cells that fight disease.