Q/A in Veterinary Cardiology

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كل مايخص علم القلب والاوعيه الدمويه تشريحيا فسلجيا وامراضيا

راح اقدمه على شكل سؤال وجوابه حتى يكون الموضوع عباره عن طرح علمي ومسلي ولايصيبكم بالاحباط والملل

Structure and Function

1 Anatomy of the cardiovascular system
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة] a. The heart: 4 chambers and 4 sets of valves

2 Atria
2 Ventricles
2 AV valves
2 Semilunar valves

b. The systemic circulatory system

Arteries
Arterioles

c. The pulmonary circulatory system

Veins
Venules

2 What is the role of the cardiovascular system?
Via a series of conduits, arteries and capillary beds, to provide nutrients to all organs and via a series of capillary beds and veins to provide a means to remove the effluents of metabolism from these same organs.

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3 What is the role of the heart?
As a muscular pump the heart is required to eject into the circulatory system a volume of blood appropriate for the metabolic activity of the organs.

4 What is the role of the systemic arterial system?
a. Of the large arteriesParticularly the aorta, these vessels have two functions:

They serve as conducting vessels - transfer blood to the periphery
The elastic properties of the vessel wall promote flow through the periphery during diastole as well as systole

b. Of the small arteriesThese are the resistance vessels:

Relative to the size of the lumen of these vessels, they possess an abundant amount of smooth muscle
They control the steady delivery of blood to the capillary beds
They control blood pressure via the degree of contraction of their smooth muscle in the vessel wall

5 What is the role of the systemic venous system?
The veins are responsible for the return of blood to the heart. The veins hold 70% of the blood volume. Contraction of the smooth muscle in the venous circulation increases blood return to the heart. Venodilation reduces the return of blood to the heart.

6 What is the role of the pulmonary arterial system?
The pulmonary arterial system receives the output from the right heart, deoxygenated blood, and delivers it to the lungs for carbon dioxide removal and oxygen loading of blood.

7 What is the role of the pulmonary venous system?
The pulmonary venous tree returns the oxygenated blood to the left heart for propulsion to the rest of the body.

8 How is the function of the pulmonary arterial tree different from the systemic arterial tree?
The pulmonary arteries, unlike the other arteries of the body, carry deoxygenated blood. The pulmonary veins, unlike the other veins of the body, carry oxygenated blood. The pulmonary arteries respond to hypoxia with contraction. The systemic arteries respond to hypoxia with vasodilation.

9 How does the anatomy of the pulmonary arterial tree differ from the systemic arterial tree such that it supports the difference in function between the two systems?
The right ventricle ejects the same volume of blood that the left ventricle ejects. The pulmonary arterial system is a low-pressure system, unlike the high pressures encountered in the systemic arterial system. The pulmonary arterial walls contain less smooth muscle than the systemic arteries. The reduced amount of tone that can be generated in the pulmonary arterial system is responsible for the lower pressures in the pulmonary arterial system. This arterial tone is also known as arterial resistance. Hence the pulmonary arterial resistance is much less than the systemic arterial resistance.

10 What is the role of the capillary beds?
The capillary beds are the site of diffusion of gases, nutrients, and waste products within each organ.

11 What is the role of Starling forces?
Starling forces are the "forces" that are involved with the movement of fluid across the permeable membranes of the capillary beds. Within the capillary, the capillary hydrostatic pressure "forces" fluid out of the capillary and into the interstitium; the interstitial hydrostatic pressure "forces" fluid to leave the interstitium and enter the capillary; the capillary plasma colloid osmotic pressure (also called plasma oncotic pressure) "draws" fluid into the capillary; and the interstitial fluid colloid osmotic pressure (also called oncotic pressure) "draws" fluid into the interstitium. The net movement of fluid across the capillary membrane is affected by both the magnitude of the imbalance between the hydrostatic and osmotic forces and the permeability of the capillary membrane to water. Kf is known as the permeability coefficient.
Thus the net movement of water across the capillary membrane can be expressed via the equation: Kf[(HPc-HPif)-(COPc-COPif)].

HPc = Hydrostatic pressure in the capillary

HPif = Hydrostatic pressure of the interstitial fluid

COPc = Colloidal osmotic pressure of the capillary plasma
COPif = Colloidal osmotic pressure of the interstitial fluid

12 What are the functions of the components of the heart?

a. Pericardium: Limits cardiac distention with cardiac filling. This effect is greatest on the thin walled chambers such as the atria and the right ventricle.
b. Right Atrium: It serves as a storage reservoir for blood returning to the heart via the cranial and caudal vena cavas.
c. Right Ventricle: It must receive all the blood presented to it via the right atrium and expel this blood to the lungs for gas exchange. Since the pulmonary arterial tree is a rather low-pressure system (as compared to the systemic arteries), the right ventricle develops into a rather thin walled chamber (as compared to the left ventricle).
d. Left Atrium: It serves as a storage reservoir for blood returning from the pulmonary veins.
e. Left Ventricle: It must receive all the blood presented to it via the left atrium and expel this blood through the systemic arterial tree to the organs of the body. Since the systemic arterial tree is a rather high-pressure system (as compared to the pulmonary arteries), the left ventricle develops into a rather thick walled chamber (as compared to the right ventricle).
f. The A-V valves: They function to promote the flow of blood (unidirectional flow only) from the atria to the ventricles during diastole. Flow occurs across these valves when the pressure in the ventricles falls below that of the atria. Flow across the A-V valves is characterized by three phases: rapid filling phase at the onset of diastole (responsible for most of the filling of the ventricle), diastasis (minimal flow occurs at this time), and atrial contraction at the end of diastole.
g. Semilunar valves: They function to promote the flow of blood from the ventricles into the arterial trees during systole. Flow occurs across these valves when the pressure in the ventricles exceeds that present in the arterial tree. Flow across these valves is uni-modal (unlike the bimodal nature of flow across the AV valves).

13 What components of the cardiovascular system could be responsible for cardiovascular disease - or - where within the cardiovascular system could malfunction occur?
Disease/malfunction can occur due to abnormalities within the heart:

Obstruction at any valve

Insufficiency of any valve

Failure of the atria to receive blood

Failure of the atria to push blood (contract)

Failure of the ventricles to receive blood

Failure of the ventricles to expel blood

Failure of the arterial tree to maintain pressure

Failure of the arterial tree to lower pressure
Failure of the pericardium to expand with ventricular filling

شكرا دكتور عيسى ...بحق أنه جهد مميز بارك الله فيك ووفقك بالدنيا والأخره

شكرا دكتور عزيز
اسعدني مرورك

تحياتي لشخصك الكريم

Edema Formation

14 What is edema?
Edema is excessive fluid accumulation in interstitial spaces.

15 Where does edema develop?
Edema can develop in any organ or collect as free fluid in body cavities (such as ascites, pleural effusion, pericardial effusion)

16 What factors promote the development of edema?
Edema occurs because of either:

Excessive fluid filtration out of capillaries, which can be due to either:

Elevated hydrostatic pressure usually due to heart failure (see Starlings Forces) or over-hydration
Reduced plasma colloid osmotic pressure (hypoproteinemia) which itself can be due to:
- Excessive protein loss from the kidneys or bowel
- Reduced production from the liver
Increased capillary membrane permeability

Lymphatic obstruction

Lymphatics

17 What is the role of the lymphatic system?
To prevent the accumulation of excessive interstitial fluid especially in the lung. In the absence of lymphatic obstruction lymph flow can increase 20 to 50 times to remove excess fluid accumulation.
Lymph fluid is carried into the thorax and enters the subclavian veins to flow into the cranial vena cava and right atrium.
These vessels continuously remove interstitial fluid and prevent its excessive accumulation.

18 How is lymph formed?
It forms as a result of Starling Forces that promote a net efflux of fluid from the vascular compartment into the interstitial spaces. Plasma protein is also deposited into the interstitial spaces by pinocytosis. This fluid and protein accumulation is removed continuously by lymphatics.

19 What factors promote the flux of fluid?
Into the lymphatic vessels

Excessive production of interstitial fluid
Out of the lymphatic vessels

Excessive hydrostatic pressure in the right side of the heart

Overwhelmed lymphatic flow
Lymphatic obstruction

It's very nice….thank doctor

With my regards

White Antelope

Thankyou verymuch Mayoussa

الدكتور عيسى الغالي ..مشكور وممنون لجهدك الابي بدعم المنتدى ورفده بالمواضيع القيمة والمساهمات الجميله التي لها نكهة خاصة .. نكهة عطرة كعطر الجوري (وهو ورد احمر كبير له رائحة متميزة )ونكهة الرازقي(وردة بيضاء صغيرة) التي تفوح رائحتها وخصوصا ليلا

نتمنى لك دوام السعادة والتوفيق
ارجوا ان تقبل مروري
ا

21 What are the transcapillary exchange mechanisms?
What is diffusion?

The movement of solutes occurs down a concentration gradient utilizing micropores or clefts between adjacent endothelial cells in the capillary wall
What is pinocytosis?

It is the main route for the flow of plasma proteins into the interstitium since capillary pores are too small to allow their passage. Pinocytosis involves the invagination of the capillary endothelial cell membrane to form an intracellular vesicle that contains plasma including plasma proteins. These vesicles cross the capillary endothelial cell from the blood stream side to the interstitial fluid side. The vesicles fuse with the outer membrane of the capillary endothelial cells and discharge their contents into the interstitial space.
What is ultrafiltration?
Involves the movement of fluid as determined and discussed previously under the influence of Starling Forces.

22 Identify the components of the microcirculation

The small arteriole

The capillary

The venule
The microcirculation is the site of gas, nutrient and metabolite exchange

Vascular Control

23 What are the factors that control BP?
Hemodynamic factors:

BP = CO x Arterial resistance

Recall factors that affect CO (HR and SV)
Factors that affect peripheral arterial resistance

24 What affects organ flow?
Blood flow = perfusion pressure / vascular resistance
Perfusion pressure = mean arterial pressure - mean venous pressure

25 What factors affect peripheral vascular resistance (also called total peripheral resistance or systemic vascular resistance)?
Autoregulatory factors (local mechanisms): due to local mechanisms within the tissue. These intrinsic mechanisms predominate over the extrinsic mechanisms for control of blood flow to critical organs (heart, brain, and working skeletal muscle)

Myogenic response: The form of auto-regulation in circumstances characterized by changes in blood pressure without changes in blood flow. This is well recognized in the brain, heart, and working skeletal muscle. Blood flow is altered in response to perfusion pressure in the absence of a change in metabolic rate. The resultant effect of the change in blood flow on metabolites changes arteriolar resistance to normalize blood flow in spite of an altered perfusion pressure.

Metabolic response: The increase in tissue blood flow in response to increased metabolic rate is called active hyperemia.

Increased metabolic rate causes increased tissue metabolites (especially CO2, adenosine, lactic acid, and K) and decreased O2
Increased metabolism causes local arteriole vasodilation with increased blood flow to the tissue
As the increased blood flow removes these metabolic products the stimuli for increased flow is removed so a reduction in blood flow back to resting state occurs.
Another form of metabolic response to tissue perfusion is known as reactive hyperemia, which refers to a temporary increase in blood flow to tissue after a period of restricted flow to this tissue. This occurs due to the accumulation of metabolites as described for active hyperemia.

Extrinsic control factors (nerves/hormones): these mechanisms predominate over the intrinsic mechanism to control blood flow to non-critical organs such as the kidneys, skin, splanchnic, and resting skeletal muscles.

Factors promoting vasoconstriction

Sympathetic stimulation:Alpha1 and alpha2 adrenergic stimulation
Angiotensin II receptor stimulation
Endothelin receptor stimulation
Arginine vasopressin stimulation

Factors promoting vasodilation

Parasympathetic stimulation (vagal): Muscarinic (M3) receptors cause vasodilation via NO
Sympathetic stimulation:
- Beta2 stimulation: causes vasodilation of skeletal muscle arterioles
Natriuretic peptides
Adenosine
Prostacyclin
Endothelium derived relaxin factor
Bradykinin

26 What is the role of Baroreceptors (carotid/aortic arch) in BP control?
Baroreceptors are stretch receptors in the carotid sinus and aortic arch that maintain BP within a normal range and respond to changes in BP to normalize it.

Increase in BP results in an inhibition of the sympathetic outflow from the vasomotor center and increase in vagal tone causing vasodilation as well as a decrease in HR and contractility, which reduce BP
A reduction in BP has the opposite effects.

27 Role of atrial volume receptors:
Cardiopulmonary (stretch) receptors: These receptors located in the left atrium, right atrium, pulmonary arteries, and ventricular endocardium, are activated by increased volume. They send signals to the brain to inhibit sympathetic outflow and increase vagal activity to reduce arterial vasomotor tone and decrease BP.
The converse is also true.

28 What is syncope?
Syncope refers to a sudden and transient loss of consciousness due to the temporary loss of cerebral perfusion. The metabolism of the brain, unlike other organs, is exclusively dependent on perfusion. In contrast to skeletal muscle, for example, storage of high-energy phosphate in the brain is limited, and energy supply depends largely on the oxidation of glucose extracted from the blood. Thus, cessation of cerebral blood flow causes a loss of consciousness within about 10 seconds.

29 What are the causes of syncope?

Sudden changes in heart rate: bradycardia, tachycardia

Obstruction to blood flow: aortic stenosis, pulmonic stenosis, mitral stenosis, tricuspid stenosis, pulmonary artery hypertension, pulmonary artery embolism, obstructive HCM, cardiac tamponade with pericardial effusion

Right to left shunting: Tetralogy of Fallot, Eisenmenger's Syndrome

Reduced preload: dehydration, hemorrhage, hypotensive drugs, cardiac tamponade
Vascular or neurogenic dysfunction: carotid sinus hypersensitivity (vasovagal), post-micturition, post-tussive

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