afferent cvs lt. bodydeltauniv.edu.eg/new/dentistry/wp-content/uploads/hr-cop.pdf · nervous...

NERVOUS

• Higher centers

• afferent

PHYSICAL • thermal

CHEMICAL

• Bl. gases

• hormones

• chemicals

Regulation of the HR

CVS

Body

RT.

LT.

A- Impulses from Higher Centers:

1- The Cerebral Cortex (CC):

a- Voluntarily: yoga players

b- Emotions: fear, anger tachycardia,

while sudden shocking news bradycardia.

2-The Hypothalamus:

in calm sleep and in severe emotion ++ ant. Hypothalamus ++ parasymp. bradycardia .

in mild emotion, stress, and ms exercise ++ post. Hypothalamus ++ symp tachycardia.

3-The Respiratory Center

( )during insp. and () during exp.

1- Afferent Impulses from Circulatory System

A) from Right Side of Heart:

Bainbridge Reflex: venous return HR.

B) from left Side of Heart:

Marey's Law: ed level of ABP HR.

ed level of ABP HR.

a- Impulses from sk. ms (Alams Smirk Reflex):

Ms contr. ++ CAC and -- of CIC HR.

b- Impulses from Pain Receptors:

Mild or moderate pain ++ CAC and -- CIC reflex tachycardia

Severe visceral pain reflex bradycardia.

1) Changes in Blood Gases:

CO2 excess, O2 lack and ed H+ conc. ----- at 1st stim. then paralysis.

2- Changes in Blood Hormones:

1- Adrenaline Small dose HR due to direct ++ of SAN.

2-Noradrenaline generalized VC ABP HR.

3- Thyroxin: Directly ++ SAN tachycardia

1- ed Blood Temp. 2- ed Blood Temp.

bl. temp 1°C 1°C HR by 10 b-/m-

HR by 10 b-/m-

But, In diphtheria and typhoid fever,

toxins have direct effect on cardiac ms noHR

Cardiac Output

Def (COP): volume of bl. pumped by each ventr. per min (also called minute volume) = SV × HR = 70 ×70 = 4900 ml / min i.e. about 5L/min

Stroke Volume (SV)

* Volume of blood pumped by each ventricle / beat.

SV = EDV – ESV = 130 – 60 = 70 ml

Preload:

Vol of blood in the ventricle at the end of diastole (E.D.V)

According to starling law: Increase in VR (inc. EDV) >> increase in COP

respiratory movement.

pumping action of the heart.

gravity.

skeletal muscle contraction and One-way valves in veins prevent backflow of blood

Physiological variation in H.R (from 50-100) beat / m produce no change in COP

Excessive changes in HR lead to decrease in COP ?

(after load)

is the resistance against which the blood is pumped. An increase in ABP needs more effort from the left ventricle to pump the same quantity of blood. The COP may be normal but the left ventricle is strained.

4-Force of myocardial contraction

According to starling law increase (EDV), This lead to increase the force of ventricular contraction& increase in SV &COP.

loss of blood from the CVS

I)According to Site of hge:

– External.

- Internal.

II) According the Amount of blood loss:

a) Mild: loss of few CC.

b) Moderate: 20-30% of person blood.

c) Severe: >30% of person blood.

III) According the Rate of blood loss:

a- Arterial, b-venous, c- cap.

1. ABP: ed

2. Pulse: rapid, weak and feeble.

3. Resp.: rapid, deep (1st) then rapid and shallow.

4. Skin: pale, cold, moist and slightly cyanotic- Cutaneous veins: collapsed.

5. Oliguria ( urine volume)

1. CVS: HR and VC….. Restore ABP

2. Contraction of blood reservoir (spleen)

3. Resp. changes: RR and TV (depth)

4. Blood changes: platelet plug, clotting, erythropoeisis

5. Kidney changes: increase renin and erythrpoitin, oligouria.

6. Hormonal : increase aldosterone, ADH, cortisol, angiotensin II

1. Restoration of plasma volume: thirst and aldosterone-----Increase salt and water

2. Replacement of plasma proteins

3. Restoration of RBCs

4. Tissue repair

5. Recanalization of closed bl.v