Friday, 20 July 2012

- 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.

Wednesday, 18 July 2012

- 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.

Tuesday, 17 July 2012

- 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.

Monday, 16 July 2012

- 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.

Sunday, 15 July 2012

- Isovolumetric Contraction.

Isovolumetric Contraction  
This video talks about the isovolumetric contraction of the ventricles.

Saturday, 14 July 2012

- Regulating Stroke Volume.

Regulating Stroke Volume

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

Friday, 13 July 2012

- 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).

Thursday, 12 July 2012

- Normal shape and Waves in ECG/EKG

Normal shape and Waves in ECG/EKG  
  • P wave: represents depolarization of the atrial muscle.
  • QRS complex : represents depolarization of both ventricles.
  • T wave: return of the ventricular mass to its resting electrical state "repolarization"
  • U wave: repolarization of the papillary muscles.

Wednesday, 11 July 2012

-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.

Tuesday, 10 July 2012

- 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.

Monday, 9 July 2012

- 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.

Sunday, 8 July 2012

- 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...


Friday, 6 July 2012

- Temporary Transvenous Pacemaker Review.

Temporary Transvenous Pacemaker Review.
 This video Descripes basics of temporary transvenous pacemaker insertion..

Tuesday, 3 July 2012

- Permenant Pacemaker Placement.

Permenant Pacemaker Placement.  
This Animation discusses what happens during a Permenant pacemaker placement.

Monday, 2 July 2012