What's HAPpening?!

This blogsite briefly describes the anatomy (structure) and physiology (function) of our body's cardiovascular and respiratory systems using figures and tables from "Essentials of Human Anatomy and Physiology" by Elaine N. Marieb.

The Cardiovascular System

Our Cardiovascular System uses blood to transport oxygen, nutrients, cell wastes, hormones, and other substances to and from cells. The beating heart pumps the blood throughout and around our body.

Gross Anatomy of the Heart

These figures illustrate the structure and shape of the human heart. It contains four chamgers: left & right atria and left & right ventricles. Although very small, it is a very powerful, and important, organ in your body.

Heart Valves

The heart contains four valves that enable blood to flow, in a single direction, through the four heart chambers.

Systemic and Pulmonary Circulations

The heart acts as a double pump. The right side is the pulmonary circuit pump and receives oxygen-poor blood. The left side is the systemic pump and supplies oxygen- and nutrient-rich blood to the entire body.

The Intrinsic Conduction System of the Heart

The Intrinsic Conduction System sets the heart's basic rhythm. It includes the sinoatrial (SA) node (often called the pacemaker) that initiates depolarization waves that begin each heartbeat.

The Cardiac Cycle

A cardiac cycle referes to the events of one complete heart beat. These events occur during three periods: mid-to-late diastole, ventricular systole, and early diastole.

***In Figure 11.6, the blue areas indicate oxygen-poor blood and the red areas indicate oxygen-rich blood.

Blood Vessels

Blood Vessels form the "vascular system" of our bodies. It is a closed transport system that enables the blood to circulate throughout our body. The three main types of blood vessels are: arteries, veins, and capillaries.

Structure of Blood Vessels

Artery and vein walls are made up of three tunics: tunica intima, tunica media, and tunica extern. Capillaries, however, are only comprised of tunic intima. See Figure 11.8 below.

Major Arteries

Arteries carry oxygen-rich blood away from the heart. The major arteries in your body are shown in Figure 11.11.

Major Veins

Veins carry oxygen-poor and carbon dioxide-rich blood back to the heart. The major veins in your body are shown in Figure 11.12.

Pulse

Your pulse is a pressure wave created with each beat of your heart's left ventricle. When you feel for your pulse, you usually feel for it on your wrist or neck. There are actually more sites on your body where your pulse can be palpated (felt).

Fun fact: In a normal resting person, the average pulse/heart rate is 70-76 beats per minute (bpm).

The Respiratory System

Our respiratory system regulates the gas exchanges between the blood and external environment.

Major Respiratory Organs

The major organs of the respiratory system are the nose, pharynx, larynx, trachea, bronchi, and the lungs (which contain air sacs known as alveoli).

Most of these organs act as passageways that purifty, humidify, and warm air the enters the lungs. They are shown in Figure 13.1 below.

The Respiratory Membrane

Gas exchanges occur only in the alveoli of the lungs. The respiratory membrane (air-blood barrier) consists of alveolar and capillary walls. Gas exchange happens by diffusion through this membrane. Oxygen passes from the alveolar air into the capillary blood and carbon dioxide leaves the blood and into the alveoli. An illustration of the respiratory membrane is shown in Figure 13.6 (below).

Pulmonary Ventilation a.k.a. Breathing

There are two phases in breathing: inspiration (inhalation) and expiration (exhalation).

When we inhale, our chest expands, decreasing the intrapulmonary pressure, which creates a vacuum to allow air to enter the lungs.

When exhalaing, our chest depresses, increasing the intrapulmonary pressure and causing air to flow out of the lungs.

A comparison of our rib cage during inspiration and expiration is displayed in Figure 13.7 a & b (below).

Nonrespiratory Air Movements

Breathing is not the only way for air to exit, or enter, the lungs. Nonrespiratory air movements can be voluntarily produced, but are typically a result of reflex activity. Some examples of these movements are listed and described in Table 13.1 below.