The Heart
The Heartbeat
Left and Right
Atria
Left and Right
Ventricles
Blood Vessels
Arteries
Chambers
Diastole
Componants
Systole
Atrioventricular
Valves
Valves
Semilunar
Valves
Veins
Aorta Venules
Capillaries
Arterioles
The Blood
White
Blood Cells
Platelets
Red
Blood Cells
Plasma

It’s a muscle.
The chambers of the heart are divided by layers of tissue called the septum .
Fast Facts:
1. Heart is the size of your fist.
2. Located just
Arterial Septum of your chest
Atria 3. Has four chambers and four
Ventricular Septum right ventricles
: divides left and about in the center valves
4. Men usually have larger hearts than women do

The Atria - walls of the atria tend to be thinner than those of the ventricles; they serve mainly as a holding area of blood
Right Atrium: receives deoxygenated blood from the body
Left Atrium: receives oxygenated blood from the lungs
The Ventricles walls are thicker and more muscular; they pump the blood to the lungs and different parts of the body
Right Ventricle: receives deoxygenated blood from the right atrium and pumps it to the lungs
Left Ventricle : the strongest chamber of the heart; receives oxygenated blood from left atrium and pumps blood to most of the body

Primary role of the valves is to prevent backflow of blood
The valves can be divided into two types:
1.
Atrioventricular : Includes the Tricuspid Valve and Mitral Valve; these valves allow blood to pass from the atria to the ventricles
2.
Semilunar : located at the exits of the heart; blood pushed through them from inside the heart out of the heart; includes;
Pulmonary Valve, and the Aortic Valve
Did you know?
When you use a steth0scope to listen for someone’s heart beat, the beating you hear is actually the sound of the valves opening and closing.

Artery Arteriole
Capillaries Venule Vein
Heart

Heart
Vena Cava
Veins
Venules
Capillaries
Deoxygenated blood travels through a series of veins (that increase in diameter) toward the heart
When the oxygen in the blood is exchanged in the capillaries, the deoxygenated blood pours into the smallest type of veins; venules.
The blood in the venules then moves into veins.
The veins that pour blood directly into the heart are called the vena cava.
Superior Vena Cava : blood comes from the head, neck and arms (i.e. the upper body)
Inferior Vena Cava : blood from the rest of the body (i.e. the lower body)

The arteries carry oxygenated blood away from the heart
The largest artery is the Aorta: all blood pumped to the body passes first through the aorta.
After the aorta, the blood is sent through smaller and smaller arteries, then atrioles, until it reaches the capillaries at the extremities of its path.

Capillaries have very very thin walls- this allow the exchange of materials through them (by exocytosis and diffusion)
Diffusion down a gradient is responsible for the exchange of oxygen and carbon dioxide.
Near the point where arterioles meet capillaries, fluid leaves the vessels. It re-enters near where venules meet capillaries.
Did you know?
At any given time, the body only uses about 5%-10% of the capillaries it possesses. However, there are so many that this is enough to supply all tissue with the necessary blood.

A basic explanation of the heartbeat breaks it up into two phases:
Diastole : the “relaxation phase”; the longer phase. During this phase, the atrioventricular valves are open allowing blood to enter the atria and pour into the ventricles of the heart
Systole : the “contraction phase.” During this part of the heartbeat, the semilunar valves are open as the ventricles pump blood out of the heart.
Cardiac Cycle : the completion of a diastole and systole phase
Cardiac Output : the blood volume/min. pumped

Red Blood Cells (erythrocytes): carry oxygen, they’re the most numerous type of blood cell; they contain hemoglobin molecules, which contain iron
White Blood Cells (leukocytes): fight infections; digest bacteria and take care of remnants of dead blood cells; responsible for the build up of immunities; spend most of their time outside of the circulatory system
Platelets : smallest type of blood cellthey’re actually just fragments of cytoplasm from the bone marrow; they form clots
Plasma : a liquid matrix that erythrocytes, leukocytes, and platelets are suspended in

The average person has between 4.5 and 5 Liters of blood.
This is around 10 pints.
The heart cycles through all of the blood in the average person’s body every one minute or so.
Blood in the aorta travels 1000x as fast as blood in the capillaries.
http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

Hydrostatic force : the pressure that fluid in the blood vessels exerts on the walls of the vessels
Blood Pressure is…
-stronger in arteries than in veins
-strongest during the systole part of a heartbeat (when blood is pushed out of the heart)
Did you know?
When taking your pulse, you are actually feeling an momentary increase in blood pressure causing the artery to expand.

As mentioned earlier, fluid escapes through the capillaries as it travels through the vasculature of the body.
The amount of fluid lost daily would total up to 4L were it not for the Lymphatic system.
Lymph : name for the lost fluid
Lymphatic capillaries return the necessary fluid and proteins to the blood stream.
White blood cells spend most of their time in the lymph nodes. When infected, the cells multiply.