Introduction to the Human Cardiovascular System

Introduction to the Human Cardiovascular System

• The cardiovascular system acts as the body's transport system, carrying blood, heart, and blood vessels.
• It delivers nutrients and removes waste products from tissues throughout the body.
• The transport medium is blood, a liquid flowing within a closed tubular system.

Function of the Cardiovascular System

• The system transports nutrients and hormones.
• It removes waste products.
• It enables gaseous exchange (oxygen and carbon dioxide).
• It plays a role in immunity.
• Blood vessels carry blood, oxygen, carbon dioxide, nutrients, and wastes.
• The heart pumps blood through blood vessels.

Components of the Cardiovascular System

• Blood: Composed of blood cells (erythrocytes, leucocytes, thrombocytes) and plasma.
• Heart: A four-chambered, hollow muscular organ roughly the size of a fist.
• Blood Vessels: A closed network of tubes including arteries, capillaries and veins.

Blood

• Blood cells include erythrocytes (red blood cells), leucocytes (white blood cells), and thrombocytes (platelets).
• Plasma is the fluid portion of blood.

Heart

• The heart is a four-chambered, hollow muscular organ, roughly the size of a fist.
• Its location is superior to the diaphragm, left of the midline, and anterior to the vertebral column, behind the sternum.

Functions of the Heart

• Generates blood pressure.
• Routes blood (separates pulmonary and systemic circulations).
• Ensures one-way blood flow (via heart valves).
• Regulates blood supply (adjusts contraction rate and force based on metabolic needs).

Blood Vessels

• A closed network of tubes that includes arteries, capillaries, and veins.
• Arteries: Thick-walled tubes carrying oxygenated blood away from the heart.
• Capillaries: Microscopic vessels enabling nutrient and gas exchange between blood and tissues.
• Veins: Thin-walled tubes carrying deoxygenated blood toward the heart.
  • Structural Components of a Blood Vessel:
  • Tunica Intima: Innermost layer of the blood vessel.
  • Tunica Media: Middle layer of the blood vessel.
  • Tunica Adventitia: Outermost layer of the blood vessel.

Arteries

• Carry oxygenated blood away from the heart.
• Are thicker-walled than veins.
• Have a small lumen (the interior space).
• Have no valves.
• Branch repeatedly.

Classification of Arteries

• Elastic arteries (e.g., aorta and its major branches)
• Muscular arteries (e.g., renal, testicular, radial, tibial arteries)
• Arterioles ->0.1 mm; Terminal arterioles.

Capillaries

• Microscopic vessels connecting arteries and veins.
• Enable exchange of nutrients and gases between blood and tissues.
• There are two types of capillaries in the body:
  • Continuous
  • Fenestrated
• Sinusoids: Large irregular vascular spaces that are found in several organs (e.g. liver, spleen)

Veins

• Carry deoxygenated blood back to the heart.
• Are thinner-walled than arteries.
• Have a large, irregular lumen.
• Have valves to prevent backflow.
• Factors responsible for venous return include muscle contraction, negative intrathoracic pressure, pulsation of arteries, gravity, and valves.

Anastomosis

• Communication between blood vessels.
• End Arteries: Terminal branches that don't connect with other arteries in adjacent areas (e.g., retina, regions of the brain).
• Arteriovenous anastomosis: Specific connections (e.g., in skin of nose, lips, external ear)
• Lateral arteries: accompanying extra arteries to an area.

Circulation

• Coronary Circulation: Blood flow within the heart.
• Pulmonary Circulation: Blood flow between heart and lungs.
• Systemic Circulation: Blood flow between heart and body cells.
• Fetal Circulation.

Systemic and Pulmonary Circulation

• Pulmonary Circuit: Blood flow from the heart to the lungs and back.
• Systemic Circuit: Blood flow from the heart to the body and back.

Portal Circulation

• Blood flow between two capillary beds before draining into systemic veins. (e.g., blood flow between the intestines and the liver)

Coronary Circulation: Arterial Supply

• Arteries that supply the heart muscle (myocardium) with blood.

End Arteries

• Central artery of retina.
• Arteries of spleen, liver, kidneys, metaphyses of long bones.
• Central branches of cerebral cortex and other areas

This quiz covers the essential components and functions of the human cardiovascular system. Explore how blood, the heart, and the blood vessels work together to transport nutrients, remove waste, and facilitate gas exchange. Test your knowledge on this vital system that plays a crucial role in overall body function.