27 - The cardiovascular system. Systemic and pulmonary circulation. The heart as an organ functional morphology of the pericardium. Endocardium and myocardium. Innervation of the heart. Myocardial blood supply.

section

cardiovascular system

what is the blood pressure of systemic and pulmonary circulation

pulmonary and systemic circulation

heart

pericardium

myocardium

endocardium

innervation of heart

5 effects of ANS on heart - sympathetic and parasympathetic

myocardial blood flow

cardiovascular system

• consists of the heart , blood vessels and 5-6 L of blood.

• Responsible for transporting oxygen nutrients, powered - the heart.

• Functions:

  • Transportation: transports blood etc, hormones

  • protection: WBCs phagocytosis etc

  • Regulation: homeostatic control inc temperature ,pH

what is the blood pressure of systemic and pulmonary circulation

• Systemic circulation - blood pressure normally about 120 mmHg - high pressure circuit.

• Pulmonary circulation - blood pressure - about 20 mmHg - low pressure circuit.

pulmonary and systemic circulation

1. Pulmonary circulation: from the right ventricle to left atrium

   • Deoxygenated blood enters the vena cava→ right atrium

   • Increase in pressure in the right atrium causes the right atrioventricular valve to open allowing blood to enter the right ventricle.

   • The right ventricle contracts pumping the deoxygenated blood out of the heart to the lungs where oxygen added.

   • This blood the returns to the left part of the heart.

   • Right ventricle ---> pulmonary trunk ---> great pulmonary arteries ---> small pulmonary arteries ---> pulmonary arterioles ---> alveolar capillaries ---> pulmonary venules ---> pulmonary veins ---> left atrium

2. Systemic circulation:

   • Left atrium → left ventricle carry oxygenated blood to the rest of the body.

   • It removes waste from tissues and comes deoxygenated blood to the right side of the heart.

   • Left atrium→Left ventricle ---> aorta ---> great arteries ---> small arteries in organs and tissues ---> arterioles ---> capillaries in the tissues -- > venules ---> veins ---> right atrium

heart

• layers of heart: pericardium, epicardium, myocardium, endocardium

• The heart is a muscular organ.

• It is divided into 4 chambers: upper left and right atria and lower left and right ventricles.

pericardium

• double layered fibrous sac which covers heart

• Fibrous pericardium: most superficial layer. dense and loose connective tissue which acts to protect the heart.

• Serous pericardium: made of 2 layers

  • parietal pericardium which fused to and inseparable from the fibrous pericardium

  • visceral pericardium which is a part of the Epicardium.

• the space between the 2 layers of serous pericardium in the pericardial cavity is filled with serous fluid which protects the heart from any kind of external shock.

• Both of these layers function in lubricating the heart to prevent friction during heart activity.

myocardium

• Cardiac muscle (involuntary and striated).

• Thick layer that does the pumping

• Consists of cardiomyocytes (working cells for contraction) and peacemaker cells (conductive system cells)

endocardium

• The innermost layer that lines the heart chambers.

• It smooths blood flow, reducing friction.

• Secretes ANP (Atrial Natriuretic Peptide), which causes vasodilation.

• Nutritional function for the heart.

innervation of heart

• The heart is innervated by PSN and SNS.

• The vagus nerve

• Activation of SNS

5 effects of ANS on heart - sympathetic and parasympathetic

The ANS has 5 effects on the heart:

1. Inotropic: strength of contraction

2. Bathmotropic: excitation of cardiomyocyte

3. Chronotropic: frequency of contraction

4. Dromotropic: conduction of impulses through cardiomyocytes

5. Tonotropic: tone of cardiomyocyte

• ………………………………………………………………………………….

sympathetic - positive tropic effect ( increased that stated above)

parasympathetic - negative tropic effect (decreases that stated above)

myocardial blood flow

1. The heart gets blood through the right and left coronary arteries.

2. It needs a lot of oxygen: about 250 ml/min.

3. Cardiac muscle has many capillaries (about 2000–4000 per mm²) —more than other muscles.

4. Blood flows better during diastoles than systole because the heart is relaxed.

5. There are two layers of blood vessels: Epicardial (outer) Subendocardial (inner)

6. Beta-adrenergic stimulation (like adrenaline) increases blood flow to the heart.