- Common pulse sites.

Common pulse sites

The pulse may be palpated in any place that allows an artery to be compressed against a bone. 

In Upper limb:

• Axillary pulse: located inferiorly of the lateral wall of the axilla 
• Brachial pulse: located on the inside of the upper arm near the elbow, frequently used in place of carotid pulse in infants (brachial artery).
• Radial pulse: located on the lateral of the wrist (radial artery). 
• Ulnar pulse: located on the medial of the wrist (ulnar artery).

In Lower limb:

• Femoral pulse: located in the inner thigh, at the mid-inguinal point, halfway between the pubic symphysis and anterior superior iliac spine (femoral artery).
• Popliteal pulse: Above the knee in the popliteal fossa, found by holding the bent knee. The patient bends the knee at approximately 124°, and the physician holds it in both hands to find the popliteal artery in the pit behind the knee (Popliteal artery).
• Dorsalis pedis pulse: located on top of the foot, immediately lateral to the extensor of hallucis longus (dorsalis pedis artery).
• Tibialis posterior pulse: located on the medial side of the ankle, 2 cm inferior and 2 cm posterior to the medial malleolus (posterior tibial artery). It is easily palpable over Pimenta's Point.

- Importance of ECG (EKG).

Importance of ECG (EKG).

• The Electrocardiogram (ECG or EKG) is a graph that records the electrical activity of the heart.
• The ECG records these electrical cardiac currents (voltages,potentials) by means of metal electrodes placed on the surface of the body.

- Reading Music and ECG.

Some people have compared learning to read EKGs with learning to read music.

In both instances, one is faced with a completely new system not rooted in conventional language and full of unfamiliar shapes and symbols.

But there really is no comparison. The simple lub-dub of the heart cannot approach the subtle complexity of a Beethoven string quartet, the multiplying tonalities and rhythms of Stravinsky's Rite of Spring, or even the artless salvos of a rock-and-roll band. 

Source: Only EKG Book You'll Ever Need,,Thaler, Malcolm S. The 5th Edition, p.g 4

- Blood Pressure and Mean Arterial Pressure.

Blood Pressure and Mean Arterial Pressure

Blood pressure (BP) or "arterial blood pressure"  is the pressure exerted by circulating blood upon the walls of blood vessels.

It  is one of the principal vital signs.

During each heartbeat, blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure.

The blood pressure in the circulation is principally due to the pumping action of the heart. (1)

Differences in mean blood pressure are responsible for blood flow from one location to another in the circulation. The rate of mean blood flow depends on the resistance to flow presented by the blood vessels.

Mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous losses of energy.

- Congestive Heart Failure Animation.

Congestive Heart Failure Animation

- Cardiac output.

 Cardiac output

Cardiac output: is the volume of blood being pumped by the heart in one minute.

Cardiac output = Stroke Volume × Heart rate.

Cardiac output is usually expressed in liters/minute.

 Cardiac output is changed by change of heart rate and stroke volume.

- Pressure Reflexes and Mean Arterial Pressure.

Pressure Reflexes and Mean Arterial Pressure.  

When Mean Arterial Pressure rises Baroreceptors fire, signal goes to the medulla, parasympathetic activity goes up, Sympathetic Activity goes down, which ends up resulting in an decrease in cardiac output and peripheral resistance and so decrease Mean Arterial Pressure.

- Cardiac Cycle.

Cardiac Cycle.

The cardiac cycle is a term referring to all or any of the events related to the flow or blood pressure that occurs from the beginning of one heartbeat to the beginning of the next. (1)

A single cycle of cardiac activity can be divided into two basic phases - diastole and systole.

- Isovolumetric Contraction.

Isovolumetric Contraction  

This video talks about the isovolumetric contraction of the ventricles.

- Regulating Stroke Volume.

Regulating Stroke Volume

There are three primary mechanisms that regulate EDV and ESV, and therefore SV.

- What Stroke Volume is and How to Calculate it?

What Stroke Volume is and How to Calculate it?  

This video talks about what stroke Volume is,the difference between end diastolic volume and end systolic volume.


Ventricular stroke volume (SV) is the difference between the ventricular end-diastolic volume (EDV) and the end-systolic volume (ESV).

-Action Potentials and Contraction in Cardiac Muscle Cells

Action Potentials and Contraction in Cardiac Muscle Cells 

This videos shows how the Action potential is generated in cardiac muscle cells and how this results in Contraction of the Heart.

 When the action potential happens, calcium ions are released from the Sarcoplasmic reticulum, causing the plateau.

 Calcium ions then trigger muscle contraction.

- How Adrenaline and Acetylcholine Affect Heart Rate?

How Adrenaline and Acetylcholine Affect Heart Rate?  
This video discusses the effect of Adrenaline and Acetylcholine on heart rate.

- How Blood Flows Through the Heart.

How Blood Flows Through the Heart.  

This video explans the process of how blood flows through the heart.

It shows blood entering via the vena cave to the Right atrium, then getting pumped into the right ventricle, to the pulmonary vein to the lungs, to the left atria, left ventricle and then via the aorta to the rest of the body.

- Net Hydrostatic Pressure and Filtration Pressure.

Net Hydrostatic Pressure and Filtration Pressure  

This video explains what Net Hydrostatic pressure is and how to calculate it.

Also shows how filtration pressure is determined by Net Hydrostatic Pressure and Osmotic pressure.

Lastly, it shows how High Blood Pressure can lead to Edema...

 Enjoy!

- The Pacemaker Potential of the SA Node and the AV Node.

The Pacemaker Potential of the SA Node and the AV Node  

- Heart Anatomy Animated Video..

Heart Anatomy Animated Video..

A Doctor walks you through an animated video about the amazing human heart.

- Quick facts about heart anatomy and physiology.

Quick facts about heart anatomy and physiology.

• Your heart is located between your lungs in the middle of your chest, immediately behind and slightly to the left of your sternum.
• In this location, it is protected by the sternum  in front, the spinal column in back, and the ribs and lungs on the sides.
•  It weighs approximately 250 to 300 grams (9 to 11 oz) in females and 300 to 350 grams (11 to 12 oz) in males.(1)
• The heart is about the size of a human fist.
• The pericardium is a double-walled sac containing the heart and the roots of the great vessels. Pericardium is a tough double layered membrane which covers the heart. The space between the two layers of it is filled with a pericardium fluid which protects the heart from any kind of external trauma..the outermost fibrous pericardium and the inner serous pericardium.
• The heart actually pumps blood through two very distinct circulatory systems  ... Systemic system and Pulmonary system..
• The systemic system is the system in which fresh oxygenated blood pumps out through the arteries and in which deoxygenated blood returns to the heart through the veins.
• The pulmonary system is the system  in which Deoxygenated blood is pumped out of the heart through the pulmonary arteries into the lungs, and recharged oxygenated blood returns to the heart through the pulmonary veins. It is this recharged oxygenated blood that gets pumped out through the systemic circulatory system..
• The only veins which carry oxygenated blood are the 4 pulmonary veins.
• The only artery which carry deoxygenated blood is the pulmonary artery.

*References:- 

(1)Kumar, Abbas, Fausto: Robbins and Cotran Pathologic Basis of Disease, 7th Ed. p. 556

- Conductive system of the Heart.

Conductive system of the Heart.

The Function of the heart is to contract rhythmically and pump blood to the lungs for oxygenation and then to pump this oxygenated blood into the general (systemic) circulation.

The signal for cardiac contraction is the spread of electrical currents through the heart muscle.
 
In normal Conditions, these electrical currents are produced by  pacemaker cells of the Sinoatrial node (SAN), located on top of the right atrium near the opening of the superior vena cava at a rate of 100 per minute.

- Heart.

The human heart is a myogenic muscular organ,which pumps blood throughout the blood vessels by repeated, rhythmic contractions.

The heart is principally composed of cardiac muscle and connective tissue. Cardiac muscle is an involuntary striated muscle tissue found only in this organ and responsible for the ability of the heart to pump blood.

Heart rate:- is the number of heartbeats per unit of time, typically expressed as beats per minute (bpm). 

Heart Structure

The heart is made of four chambers, and blood flows through them in order:
 right atria>> right ventricle>> left atria>> left ventricle.

Between the right and left sides, though, the blood goes through the lungs to exchange carbon dioxide it collected in the body for oxygen it can carry to the body.

Blood enters the right atria from the venous system, and exits the left ventricle through the aorta into the arterial system.

Blood flows from the atrium to the ventricle during a heart beat based on the synchronous contraction of the heart muscle. Between each atrium and ventricle, there is a valve.

Valves are also found where the heart and aorta, and heart and pulmonary artery meet.

 Heart valves:

1. Tricuspid valve - separates the right atrium and ventricle.
2. Pulmonary valve - separates the right side of the heart from the pulmonary circulation.
3. Mitral valve - separates the left atrium and ventricle.
4. Aortic valve - separates the left side of the heart and the aorta.

The wall of the human heart is composed of three layers: (1,2)

1. The outer layer is called the epicardium, or visceral pericardium since it is also the inner wall of the pericardium.
2. The middle layer is called the myocardium and is composed of cardiac muscle which contracts.
3. The inner layer is called the endocardium and is in contact with the blood that the heart pumps.Also, it merges with the inner lining (endothelium) of blood vessels and covers heart valves.

*References:

1. Pratiyogita Darpan (April 2009). Competition Science Vision. Pratiyogita Darpan. pp. 55–. Retrieved 7 June 2012. 
2. "Heart". MedicaLook. Medicalook.com. Retrieved 2010-05-03