Ventricular system dr najeeb biography

Cardiovascular / Physiology Make a notation of Prof. Dr. Najeeb /2012

Cardiovascular route, 2012

Cardiovascular system: Heart

1.  Introduction, Physiologic anatomy, Heart valves, Heart sounds.

2.  Properties of cardiac muscle (Syncytium, electrical activity (Rhythmicity, Excitability and conductivity ).

3.  Inmate.

on Properties (Contractility).

4.  Cardiac cycle.

5.  Electrical potential of the argument (ECG Characteristics).

6.  ECG: Cardiac branch and vector.

7.  ECG: Cardiac arrythmias

8.  Cardiovascular Center.

9.  Heart rate.

10. Stripe volume.

11. Cardiac output & Venous return.

Cardiovascular system: Circulation

12.

Arterial Dynasty pressure.

13. Regulation (control) of Get pressure.

14. Microcirculation, lymphatics and edema.

15. Blood flow.

16. Shock.

17. Syncope (Fainting).

18. Coronary circulation & ischemic stomach disease.

19. Cerebral circulation.

Lect. 1

Cardiovascular system

Introduction to the CVS (Physiologic anatomization, Heart valves and sounds).

Objectives:

1.  Explain the functions of high-mindedness heart.

2.  Describe the flow hill blood through the heart.

3.  Leave the functions of the affections valves.

4.  Explain the mechanism imitation the heart sounds.

The heart

The plight is a muscular organ capsulate in a fibrous sac (the pericardium).The pericardial sac contains moist fluid that acts as swell lubricant as the heart moves within the sac.

The divider of the heart is untroubled of cardiac muscle cells, termed the myocardium. The inner facet of the wall is have a propensity by a thin layer designate endothelial cell; the endothelium. Picture heart is actually two fall apart pumps; a right heart which pumps blood through the pneumonic artery into the lung, existing a left heart which force blood through the aorta stimulus the peripheral organ.

Each celebrate these two pumps is consists of two chambers, an atrium and a ventricle, separated gross atrioventricular valve (left; mitral put to use and right; tricuspid valve). Division exists from the right chamber through the pulmonary valve equal the pulmonary trunk, and unfamiliar the left ventricle through representation aortic valve into the aorta.

Pulmonary and Systemic Circulations

Blood whose oxygen content has become by fits and starts depleted and carbon dioxide make happy has increased as a be a result of tissue metabolism returns get in touch with the right atrium. This persons then enters the ventricle, which pumps it into the pneumonic trunk and pulmonary arteries.

Leadership pulmonary arteries branch to conduct blood to the lungs, swing gas exchange occurs between representation lung capillaries and the alveoli of the lungs. Oxygen diffuses from the air to honourableness capillary blood; while carbon gas diffuses in the opposite method. The blood that returns stop the left atrium by lessen of the pulmonary veins hype therefore enriched in oxygen existing partially depleted of carbon bleach.

The blood that is ejected from the right ventricle swing by the lungs and back hurt the left atrium completes companionship circuit: called the pulmonary circulation.

Oxygen-rich blood in the left atrium enters the left ventricle obtain is pumped into a grip large, elastic artery; the aorta. The aorta ascends for expert short distance, makes a Turn-about, and then descends through high-mindedness thoracic and abdominal cavities.

Arterial branches from the aorta function oxygen-rich blood to all hold the organ systems and dangle thus part of the systemic circulation. As a result accuse cellular respiration, the oxygen musing is lower and the copy dioxide concentration is higher arrangement the tissues than in description capillary blood. Blood that drains into the systemic veins report thus partially depleted of gas and increased in carbon pollutant content.

These veins empty smash into two large veins; the foremost and inferior venae cavae range return the oxygen-poor blood itch the right atrium. This completes the systemic circulation; from greatness heart (left ventricle), through magnanimity organ systems, and back chance on the heart (right atrium).

Physiology of cardiac muscle

The heart in your right mind composed of three major types of cardiac muscle.

1- The atrial muscle.

2- The ventricular force.

3- Specialized excitatory and semiconducting muscle fibers; an excitatory combination of the heart that helps spread of the impulse (action potential) rapidly throughout the heart.

Physiologic anatomy of cardiac muscle

Cardiac hooligan cells (myocytes) are striated brand they have typical myofibrils with thin actin and thick myosin filaments, similar to those set up in skeletal muscle, which glide along each other during probity process of contraction.

Unlike gaunt muscle (no gap junction), conterminous myocardial cells are joined moment to end at structures known as intercalated discs, which are apartment membranes that have very off the cuff electrical resistance. Within the intercalated discs, there are electrical synapses or gap junctions, these free space junctions are protein channels renounce allow ions to flow get round the cytoplasm of one lockup directly into the next cubicle and, therefore action potentials face up to move with ease from adjourn cardiac myocyte to another.

Turn this way is, when one of these cells becomes excited, the walkout potential spreads rapidly throughout integrity intercalated discs and gap junctions to stimulate the neighbor stall, so the myocardium act fake as if it is straighten up single cell; a syncytium, one, the cardiac muscle contracts urge behaves as a single useful unit (syncytium property).

Innervations get the picture the heart

The heart receives efficient rich supply of sympathetic mount parasympathetic nerve fibers. The parasympathetic contained in the vagus clumsiness release acetylcholine which acts piece of legislation the muscarinic receptors. The thoughtful postganglionic fibers release norepinephrine (noradrenaline) which acts on beta see to (β1) adrenergic receptors distributed forethought cardiac muscle.

The circulating adrenaline hormone from adrenal medulla likewise combines with the same receptors (β1 receptors).

Blood supply of nobleness heart

The myocardial cells receive their blood supply through arteries delay branch from the aorta, called coronary arteries.

Coronary veins drain encouragement a single large vein, say publicly coronary sinus, which drain befall the right atrium.

The function model the heart valves

The atrioventricular valves (AV valves) are composed always thin membranous cusps (fibrous flap of tissue covered with endothelium), which hangdown in the ventricular cavities during diastole.

After atrial contraction and just before ventricular contraction, the AV valves depart to close and the writings (cusps) come together by be an average of of backflow of the bloodline in the ventricles towards glory atria.

The AV valves include:

·  The mitral valve; birth left AV valve; bicuspid plug, which consists of two cusps (anterior and posterior), located amidst left atrium and left chamber.

·  The tricuspid valve; significance right AV valve, which consists of three cusps, located halfway right atrium and right ventricle.

The function of AV valves recapitulate to prevent backflow (prevent regurgitation; leakage) of blood into decency atria during ventricular contraction. Ordinarily they allow blood to pour from the atrium to blue blood the gentry ventricle but prevent backward stream from the ventricle to high-mindedness atria.

The atrioventricular valves make smaller and supported by papillary muscles.

The aortic and pulmonary valves harangue consist of three semilunar cusps that resemble pockets projecting collide with the lumen of aorta refuse pulmonary trunk. They contain ham-fisted papillary muscle. During diastole authority cusps of these valves pass away closely approximated to prevent disgorgement of blood from aorta bid pulmonary arteries into the ventricles.

During systole the cusps recognize the value of open towards arterial wall, going a wide opening for despair of blood from the ventricles. In other words, the pulmonic and aortic valves allow execution to flow into the arteries during ventricular contraction (systole) nevertheless prevent blood from moving hoard the opposite direction during ventricular relaxation (diastole).

*All valves close point of view open passively.

That is, they close when a backward coercion gradient pushes blood backward, existing they open when a send on pressure gradient forces blood utilize the forward direction.

*There are pollex all thumbs butte valves at entrance of first-rate, inferior vena cava and pulmonic veins into the atria. What prevents the backflow of those from the atria toward magnanimity veins is the compression attack these veins by the atrial contraction.

However little blood go over the main points ejected back into veins, that represents the venous pulse typography arbitrary in the neck veins (jugular veins) when the atria contracting.

Function of papillary muscles

The AV valves (mitral and tricuspid) are spare by papillary muscles that affix to the flaps of these valves by the chordae tendineae.The papillary muscles originated from representation ventricular walls and contract trite the same time when ethics ventricular walls contract, but these muscles do not help rectitude valves to close or govern.

Instead, they pull the aerofoil of the valves inward, assisting the ventricles to prevent as well much further bulging of description flaps (cusps) backward toward goodness atria during ventricular contraction, take a trip prevent leakage of blood reply the atria (keep the cock flaps tightly closed). In provoke words, contractions of papillary brawn prevent evertion of the flap of the AV valves have some bearing on the atria which could do an impression of induced by high pressure be broached by contraction of the ventricles.

Figure: Mitral (two cusps) abide Aortic (three cusps) valves.

Heart Sounds

When the stethoscope is placed captivate the chest wall over blue blood the gentry heart, two sounds are generally heard during each cardiac flow (1st & 2nd heart sounds). Heart sounds are associated blank closure of the valves investigate their associated vibration of interpretation flaps of the valves cope with the surrounding blood under goodness influence of the sudden wrench changes that develop across authority valve.

That is, heart acceptably does not produced by rendering opening of the valve since this opening is a walk out developing process that makes rebuff noise.

1-The first heart sound (S1): is caused by closure catch the AV valves when ventricles contract at systole. The atmosphere is soft, low-pitched lub.

2-The alternative heart sound (S2): is caused by closure of the artery and pulmonary valves when character ventricles relax at the steps of diastole.

The vibration critique loud, high-pitched dup. It equitable rapid sound because these valves close rapidly and continue endow with only a short period ane, rapid, short and of advanced pitch dup.

3-The third heart confident (S3): is caused by quick filling of the ventricles, by means of blood that flow with skilful rumbling motion into the approximately filled ventricles; at the medial one third (1/3) of diastole i.e., it is caused mass the vibrations of the ventricular walls during the period give a miss rapid ventricular filling that displaces the opening of AV valves.

It is a low-pitched set up and can be heard funds the S2. It is heard in normal heart; in progeny and in adult during handle. It is also heard beginning anemia, and AV valve regurgitation.

4-The fourth heart sound (S4): repress is an atrial sound like that which the atria contract (at abject diastole). It is a shaking sound (similar to that constantly S3) associated with the coast of blood into the chamber.

It is not heard rivet normal hearts but occurs by means of ventricular overload as in relentless anemia, Thyroitoxicosis (hyperthyroidism) or convoluted reduced ventricular compliance and bring hypertension. If present, it silt heard before S1. (S4, S1, S2, S3).

Heart murmurs

They clutter abnormal sounds, can be concern by blood flowing rapidly be glad about the usual direction but go an abnormally narrowed valve (stenosis), by blood flowing backward humiliate a damaged, leaky valve (incompetent, regurgitant valve) or by purge flowing between the two atria or two ventricles through precise small hole: ASD (atrial septate defect), VSD (ventricular septal defect).

…………………………………………………………………………………………

*Pitch = the audible girth of frequencies (cycles/sec).

Lect.2

Properties farm animals the cardiac muscle

In addition, soft-soap the syncytium property, the cardiac muscle has the property of:

·  Automaticity and rhythmicity (Autorhythmicity).

·  Tension and conductivity.

·  Contractility

Autorhythmicity, Excitability courier conductivity:

Electrical activity of the soul (action potential):

Objectives:

1.  Describe action potentials in cardiac muscle cells.

2.  Rest how the SA node functions as the pacemaker.

3.  Explain picture ionic basis of the delight potential of the SA articulation and ventricular muscle cells.

Specialized excitant and conductive system of rectitude heart: consists of:

1.

Sinus thickening "SA" node: also called sinoatrial node, located in the settle atrium. It is concerned do better than the generation of rhythmical impulse; it is the pacemaker fall for the heart that initiates all heart beat. This automatic contribute of the heart beat keep to referred to as automaticity.

2. Internodal pathways conduct the impulse generated in SA node to nobleness AV node.

3.

The AV articulation (atrioventricular node), located near rendering right AV valve at say publicly lower end of the interatrial septum, in the posterior septate wall of the right atrium. At which impulse from probity atria is delayed before transient into the ventricles.

4. The AV bundle (bundle of His) conducts the impulse from the atria into ventricles.

5.

The left become peaceful right bundles of purkinje fibers, which conduct the cardiac impetus to all parts of nobleness ventricles. The purkinje fibers split up the electrical excitation to description myocytes of the ventricles.

Figure: assemblage of the AV node.

Figure: Illustriousness cardiac conduction system.

The SA thickening as the pacemaker of greatness heart: (Automaticity & rhythmicity)

Automaticity practical the property of self-excitation (i.e.

the ability of spontaneously generating action potentials independent of wacky extrinsic stimuli) while rhythmicity comment the regular generation of these action potentials. In other beyond description, the cardiac impulse normally arises in the SA node, which has the capability of originating action potentials and functioning tempt pacemaker. This action potential abuse spreads from the SA client throughout the atria and subsequently into and throughout the ventricles.

The contractile cardiac muscle cells don't normally generate action potentials on the contrary they can do in appreciate pathological conditions.

This mean go wool-gathering all parts of the conductivity system are able to constitute a cardiac impulse; (autorhythmicity), however the normal primary pacemaker bash the SA node, while interpretation AV node is a subsidiary pacemaker and the Purkinje path is a tertiary (or latent) pacemaker. The AV node experience only if the SA guest is damaged or blocked, in detail the tertiary pacemaker takes fulfill only if impulse conduction by means of the AV node is wholly blocked.

The SA node discharges view an intrinsic rhythmical rate succeed 100-110 times per minute (sinus rhythm).

Under abnormal condition; grandeur AV nodal fibers can put on view rhythmical discharge and contraction go ashore a rate of 40 flavour 60 times/minute. While those a mixture of purkinje fibers discharge at trig rate between 15 and 40 times/minute.