Cardiovascular System Module

Cardiovascular System Module

• The module covers functional characteristics of different special circulations including coronary, pulmonary, cerebral, skeletal muscle, and cutaneous.

Functional Characteristics of Special Circulations

• The lecture contents include details on coronary, pulmonary, cerebral, skeletal muscle, and cutaneous circulations.

Coronary Circulation

• Functional characteristics of coronary vessels are discussed.
• O2 consumption in heart tissues is explained.
• Coronary blood flow is detailed.
• Regulation of CBF (Intrinsic and extrinsic) is examined.

Coronary Circulation: Blood Vessels

• Two coronary arteries (right and left) arise from the aorta.
• Little anastomoses (connections) exist between the two coronary arteries.
• Coronary capillaries run parallel to cardiac muscle fibers.
• Venous drainage occurs via the coronary sinus and anterior cardiac veins.

Coronary Blood Flow and O2 Consumption

• At rest, coronary arteries receive about 70% of O2 in the blood.
• Other tissues receive about 25% of O2.
• Coronary venous blood has a low O2 reserve.
• During rest, coronary blood flow is approximately 250 ml/minute.
• During severe exercise, coronary blood flow can increase to 3-4 times the resting rate (reaching 1 L/min).

Phasic Changes in Coronary Blood Flow

• During ventricular systole, coronary blood flow (CBF) decreases.
• During diastole, CBF increases, peaking during isometric relaxation.
• Ischemic necrosis (myocardial infarction), which is often due to poor blood flow, can impact mainly the left ventricle (and not as severely on the right ventricle).

Regulation of Coronary Blood Flow

• Intrinsic Regulation (autoregulation): The ability of the heart to maintain constant blood flow in response to changing O2 demand.
• Extrinsic Regulation: Including nervous, mechanical, and chemical factors.

A) Intrinsic or Autoregulation of CBF

• O2 demand is the main factor for local blood flow regulation.
• Mechanism involves direct relaxing effects on smooth muscle and the release of substances like adenosine, K+, H., CO2, bradykinin and PGI2 inducing vasodilation.

B) Extrinsic Regulation of CBF

• Nervous system: Sympathetic stimulation increases coronary blood flow, while parasympathetic stimulation has the opposite effect.
• Mechanical factors: Heart rate, blood pressure (ABP), and cardiac output (COP) affect CBF.
• Chemical factors: substances like nitroglycerin and nitrates cause coronary dilation.

Cerebral Circulation

• Functional characteristics of cerebral vessels are covered.
• Cerebral blood flow and its measurement are described.
• Regulation of CBF (Intrinsic and extrinsic) is reviewed.
• The cerebral circulation is characterized by numerous blood vessels, a circular arrangement (Circle of Willis) and very sensitive to oxygen and glucose levels.

Cerebral Circulation; Blood Supply

• The cerebral circulation receives approximately 15% of the cardiac output (COP).
• The brain's blood flow is highly sensitive to oxygen levels (hypoxia).
• Blood flow through the grey matter is usually higher than the white matter.
• The autoregulation range of blood pressure is from 60 to 150 mmHg.
• Important factors involved in the regulation are chemical and mechanical, such as changes in the blood flow in response to the concentration of CO2, O2 & H+ ; intracranial pressure (ICP).

Pulmonary Circulation

• Functional characteristics of pulmonary vessels are provided.
• Pulmonary blood flow and its measurement are detailed.
• Regulation of pulmonary blood flow (PBF) (Intrinsic and extrinsic) is assessed.

Pulmonary Circulation; Blood Vessels

• Pulmonary circulation is the passage of blood from the right ventricle through the lungs and to the left atrium.
• The process takes about 7 seconds.
• Lungs receive blood from pulmonary and bronchial arteries.
• Pulmonary blood flow is regulated by intrinsic (local O₂ and chemical signaling) and extrinsic factors (nervous, chemical etc.).

Regulation of Pulmonary Blood Flow

• Intrinsic regulation of pulmonary blood flow is discussed.
• Extrinsic regulation includes chemical, nervous, and mechanical factors. This part details the impact of cardiac output, peripheral resistance and various nervous factors involved in pulmonary blood flow regulation.

Skeletal Muscle Circulation

• Functional characteristics of skeletal muscle blood vessels.
• Regulation of skeletal muscle blood flow in resting and exercising conditions.

Skeletal ms blood vessels and blood flow

• The skeletal muscle's primary function is contraction.
• This high activity leads to the need for a large blood flow to supply it with oxygen and nutrients.
• Skeletal muscle receives roughly 20% of cardiac output at rest. This increases significantly during exercise (by over 20 times).

Regulation of skeletal ms Blood Flow

• There are 2 main regulatory factors for skeletal muscle blood flow: Nervous and Local control.

Skin or Cutaneous Circulation

• Functional characteristics and regulation of cutaneous blood flow.
• Temperature regulation is a primary role to cutaneous circulation.

Cutaneous Circulation

• The major function of the skin's blood flow is to maintain the body temperature.
• The blood vessels in the skin are classified in nutritive and non-nutritive vessels.

Regulation of Cutaneous Blood Flow

• Mechanism of nervous and local metabolite regulation on cutaneous blood flow are covered.

Explore the functional characteristics of special circulations, including coronary, pulmonary, cerebral, skeletal muscle, and cutaneous systems. This quiz delves into the nuances of coronary circulation, blood flow, and oxygen consumption in heart tissues. Understand the intricate details of how blood vessels and flows are regulated in various contexts.