1. Cardiovascular System Week 11 Dr. Walid Daoud A. Professor

2. Arterial Blood Pressure ____________________________________________________________________________________________________________________________________________ Factors which determine ABP & Pulse P.: F = ∆ P F = ∆ P R CO = ABP – Rt. Atrial P (zero) CO = ABP – Rt. Atrial P (zero) TPR TPR CO = ABP CO = ABP TPR TPR ABP = CO x TPR ABP = CO x TPR = SV x HR x TPR = SV x HR x TPR

3. Arterial Blood Pressure ____________________________________________________________________________________________________________________________________________ Factors which determine ABP & Pulse P.: 1-Stroke volume: SV ↑ SP more than DP → ↑ pulse P. SV ↑ SP more than DP → ↑ pulse P. 2-Heart rate: ↑ HR ↑ DP due to shortening of diastole. ↑ HR ↑ DP due to shortening of diastole. 3-Total peripheral resistance: ↑ TPR ↑ DP. 4-Elasticity of aorta and arteries: Atheroscerosis: Atheroscerosis: ↑ SP and ↓ DP → ↑ Pulse pressure. ↑ SP and ↓ DP → ↑ Pulse pressure. SP is determined by SV mainly. SP is determined by SV mainly. DP is determined by TPR mainly. DP is determined by TPR mainly.

4. Regulation of ABP ____________________________________________________________________________________________________________________________________________ ABP is regulated by 3 mechanisms: 1-Nervous mechanisms (Rapid). 2-Capillary fluid shift mechanism (Intermediate) 3-Hormonal and renal mechanisms (Slow).

5. Nervous Mechanism ______________________________________________________________________________________________________________________________ Cardiovascular centers in medulla: 1-Pressor area: CAC and VCC. 2-Depressor area: CIC and VDC. Activity of centers is modified by afferents from: 1-Receptors inside cardiovascular system. 2-Receptors outside cardiovascular system. 3-High centers and blood gases changes:.Mild ↓ O 2, ↑ CO 2 → ↑ ABP..Mild ↓ O 2, ↑ CO 2 → ↑ ABP..Severe ↓ O 2, ↑ CO 2 → ↓ ABP and death..Severe ↓ O 2, ↑ CO 2 → ↓ ABP and death.

6. Cardiovascular centers ______________________________________________________________________________________________________________________________ Depressor Area (DP) Pressor Area (PA) Central & Dorsal to PA Lateral reticular formation Site Cardiac inhibitory center (CIC) Cardiac stimulatory center (CSC) Type Vasodilator center (VDC) Vasoconstrictor center (VCC)

7. Cardiovascular centers ______________________________________________________________________________________________________________________________ CICCSC Parasympathetic: vagus Sympathetic ↓ Atrial properties:↓ HR ↑Atrial properties: ↑ HR ↓ HR →↑ CO→ ↓ ABP ↑Vent. properties: ↑ SV →↑ CO→ ↑ ABP VDCVCC It inhibits VCC Produces continuous vasoconstrictor tone VC of arteries ↑ TPR ↑ABP VC of veins ↑ VR ↑CO ↑ABP

8. Capillary fluid shift mechanism ____________________________________________________________________________________________________________________________________________ ↑ blood volume ↑ ABP ↑ capillary hydrostatic pressure ↑ filtration from plasma to tissue fluid ↓ plasma volume ↓ VR ↓ ABP. ↓ ABP ↓ capillary hydrostatic pressure ↓ filtration at arteriolar end of capillaries ↑ reabsorption at venular end ↓ plasma volume ↑ VR ↑ ABP. i.e, tissue fluid acts as a reservoir of plasma. i.e, tissue fluid acts as a reservoir of plasma.

9. Hormonal Regulation of ABP ____________________________________________________________________________________________________________________________________________ Kidney regulates ABP by regulating plasma volume and extracellular fluid volume. When ABP drops: 1-Renin-angiotensin system. 2-Atrial mechanoreceptors.

10. Arterial Pulse ___________________________________________________________________________________________________________________________________________ It is a propagated wave that travels along the wall of arteries as blood is forced into aotra. Clinical significance of palpation of radial pulse: 1-Rate. 1-Rate. 2-Rhythm. 2-Rhythm. 3-Pulse deficit. 3-Pulse deficit. 4-Force of ventricular contraction. 4-Force of ventricular contraction. 5-Force equality on both sides. 5-Force equality on both sides. 6-State of arterial wall. 6-State of arterial wall.

11. Capillary Circulation ____________________________________________________________________________________________________________________________________________ Equilibrium with interstitial fluid and exchange of materials across capillary wall occur by 2 mechanisms: 1- Diffusion. 1- Diffusion. 2- Filtration. 2- Filtration.

12. Diffusion ____________________________________________________________________________________________________________________________________________ It is passive occurs on both directions and concerned with H 2 O & dissolved substance. Factors affecting diffusion rate:.Factors in substance: 1-Concentration gradient. 1-Concentration gradient. 2-Solubility. 2-Solubility. 3-Molecular weight. 3-Molecular weight. Factors in capillary permeability: 1-Liver capillaries. 1-Liver capillaries. 2-Muscle, skin, heart and lung capillaies. 2-Muscle, skin, heart and lung capillaies. 3-Kidney and intestine capillaries. 3-Kidney and intestine capillaries.

13. Filtration ____________________________________________________________________________________________________________________________________________ It is a passive flow across capillaries in one direction. It is the bulk transport of H 2 O, electrolytes and crystalloids. Factors affecting filtration: 1-Forces tending to move fluid outwards:. Hydrostatic capillary pressure.. Hydrostatic capillary pressure.. Interstitial fluid colloidal OP. Interstitial fluid colloidal OP 2-Forces tending to move fluid inwards:. Colloidal OP of plasma proteins.. Colloidal OP of plasma proteins.. Hydrostatic pressure of interstitial fluid.. Hydrostatic pressure of interstitial fluid.

14. Variation in the bulk flow ____________________________________________________________________________________________________________________________________________ 1- Decrease colloidal OP of plasma proteins: Liver and kidney diseases ↑ filtration. Liver and kidney diseases ↑ filtration. 2-Increase capillary blood pressure as in venous obstruction ↑ filtration. venous obstruction ↑ filtration. 3-Increase capillary permeability as in activity, inflammation, albumin goes out ↑ filtration. 4-Decrease hydrostatic pressure of tissue fluid ↓ filtration. ↓ filtration.

15. Edema ____________________________________________________________________________________________________________________________________________ Excessive infiltration of plasma fluid into tissue fluid leading to accumulation of tissue fluid. Edema may be generalized or localized. Causes: 1-↑ capillary blood pressure: cardiac edema, pregnancy edema and localized edema. 2-↓ colloidal OP of plasma proteins: nutritional, hepatic and renal edema. 3-↑ capillary permeability: allergy, inflam. 4-Lymphatic obstruction: Filaria, cancer.

16. Venous Circulation ____________________________________________________________________________________________________________________________________________ Central venous pressure (CVP): Pressure in right atrium & veins opening into it. Normal value: 0-2 mmHg. CVP fluctuates with respiration & cardiac cycle. Importance: - CVP ↓ in hemorrhage. - CVP ↑ in heart failure.

17. Functions of Veins ___________________________________________________________________________________________________________________________________________ 1-Transport vessels. 2-Capacitance vessels or blood reservoir: Capacity is a ratio= Change in volume Capacity is a ratio= Change in volume Change in pressure Change in pressure

18. Effects of gravity on venous return ________________________________________________________________________________________________________________________________________________ 1-Orthostatic hypotension. 2-Pressure in different veins during orthostasis.. Pressure in leg veins.. Pressure in leg veins.. Pressure in superior sagital sinus. Pressure in superior sagital sinus

19. Mechanisms helping venous return against gravity in standing position ____________________________________________________________________________________________________________________________________________ 1-Sympathetic vasoconstrictor tone. 2-Muscular pump. 3-Thoracic pump. 4-Cardiac suction:. Atrial suction.. Atrial suction.. Ventricular suction.. Ventricular suction.

20. Comparison of Pulmonary & Systemic Circulation Systemic Circ. Pulmonary Circ. Right: 0.5 mmHg Left: thick 27 mm 120/0 mmHg 120/80(90 mmHg) 0.5 m/sec Thicker, more smooth mus TPR= 18 mmHg/L/min Smaller, exposed to +ve pressure DeoxygenatedVD Left: 5 mmHg Right: thin 9 mm 25/0 mmHg Pulm. valve opens before & closes after aortic valve. 25/10(15 mmHg) 0.5 m/sec Very thin, little sm. Mus. TPR= 2 mmHg/L/min Larger, exposed to –ve pressure 10 mmHg OxygenatedVc Atrial P. Vent. Wall Vent. P. Valves Artery wall P Blood velocity Small arteries Arterioles R= P FCapillariesVeins Effect of O2

21. Coronary Circulation ____________________________________________________________________________________________________________________________________________ Anatomical considerations: Right & left coronary arteries arise from coronary sinuses behind aortic valve. Left coronary artery supplies anterior & lateral parts of left ventricle. Right coronary artery supplies right ventricle and posterior part of left ventricle. Venous blood of left ventricle drains into coronary sinus (75% of coronary blood). That of right ventricle goes through small anterior cardiac veins directly to right atrium.

22. Regulation of coronary blood flow ______________________________________________________________________________________________________________________________________________ 1-Autoregulation (intrinsic mechanism): ↑ cardiac work → hypoxia, ↑ CO2, ↑ H +,↑ K +, ↑ cardiac work → hypoxia, ↑ CO2, ↑ H +,↑ K +, Lactate, prostaglandins & adenosine ------→ Lactate, prostaglandins & adenosine ------→ Coronary VD. Coronary VD. 2-Mechanical regulation:.During systole → ↓ coronary blood flow..During systole → ↓ coronary blood flow..During diastole → ↑ coronary blood flow..During diastole → ↑ coronary blood flow. 3-Neural factors:.Sympathetic: α-adrenergic (VC),β-adren (VD).Sympathetic: α-adrenergic (VC),β-adren (VD).Parasympathetic (vagus): VD..Parasympathetic (vagus): VD.

23. Cardiovascular homeostasis in health & disease ____________________________________________________________________________________________________________________________________________ Circulatory shock: It is inadequate tissue perfusion due to ↓ CO Types & causes: 1-Hypovolemic: Hge, burn, trauma, surgery. 2-Disributive: fainting, anaphylaxis. 3-Cardiogenic: MI, CHF, arrhythmias. 4-Obsructive: obstruction of blood flow.

24. Hemorrhagic Shock _ _________________________________________________________________________________________________________________________________________ Manifestations: ↓ ABP ↑ Heart rate ↑ Respiratory rate ↓ skin temperature Pallor Pallor Thirst Thirst Oliguria Oliguria Acidosis. Acidosis.

25. Compensatory reactions to hemorrhagic shock ____________________________________________________________________________________________________________________________________________ Rapid compensatory reactions: 1-Nervous factors. 2-Humoral factors. Long-term compensatory reactions: 1-Correction of plasma volume. 2-Correction of plasma proteins. 3-Correction of red cell mass.