Topic 8) Transport in mammals

🩸 Topic 8: Transport in Mammals

8.1 The Circulatory System

• Circulatory Systems Overview

  • Mammals possess a closed double circulatory system.

  • Blood circulates through the heart twice during each complete circuit:

    • Pulmonary circulation: Transports deoxygenated blood from the heart to the lungs for gas exchange.

    • Systemic circulation: Delivers oxygenated blood from the heart to the rest of the body.

• Major Blood Vessels

  • Pulmonary Artery: Carries deoxygenated blood from the right ventricle to the lungs.

  • Pulmonary Vein: Transports oxygenated blood from the lungs to the left atrium.

  • Aorta: Distributes oxygenated blood from the left ventricle to the body.

  • Vena Cava: Returns deoxygenated blood from the body to the right atrium.Google Sites+3Save My Exams+3Save My Exams+3Save My Exams

• Blood Vessels and Their Functions

  • Arteries: Carry blood away from the heart under high pressure.

  • Arterioles: Smaller branches of arteries leading to capillaries.

  • Capillaries: Microscopic vessels where exchange of gases, nutrients, and wastes occurs.

  • Venules: Small vessels that collect blood from capillaries.

  • Veins: Return blood to the heart under low pressure; contain valves to prevent backflow.Studocu

• Tissue Fluid and Lymph

  • Tissue fluid surrounds cells, providing a medium for exchange.

  • Formed from blood plasma that leaks out of capillaries.

  • Excess tissue fluid is collected by the lymphatic system and returned to the bloodstream.

8.2 The Heart

• Heart Structure

  • A muscular organ located in the thoracic cavity.

  • Divided into four chambers:

    • Right Atrium: Receives deoxygenated blood from the body.

    • Left Atrium: Receives oxygenated blood from the lungs.

    • Right Ventricle: Pumps deoxygenated blood to the lungs.

    • Left Ventricle: Pumps oxygenated blood to the body.

• Valves of the Heart

  • Atrioventricular Valves:

    • Tricuspid Valve: Between the right atrium and ventricle.

    • Bicuspid (Mitral) Valve: Between the left atrium and ventricle.

  • Semilunar Valves:

    • Pulmonary Valve: At the base of the pulmonary artery.

    • Aortic Valve: At the base of the aorta.

  • Valves ensure unidirectional blood flow and prevent backflow.Studocu

• Cardiac Muscle

  • Specialized muscle tissue capable of continuous contraction.

  • Composed of myocytes connected by intercalated discs, allowing synchronized contraction.

• Cardiac Cycle

  • Systole: Contraction phase where blood is pumped out of the heart.

  • Diastole: Relaxation phase where the heart chambers fill with blood.

  • The cycle ensures efficient blood flow through the heart and to the lungs and body.Study Rocket

• Electrical Conduction System

  • Sinoatrial (SA) Node: Pacemaker initiating the heartbeat.

  • Atrioventricular (AV) Node: Delays impulse before it passes to the ventricles.

  • Bundle of His: Conducts impulses to the ventricles.

  • Purkinje Fibers: Distribute impulses throughout the ventricles.www.slideshare.net+7Google Sites+7Studocu+7Course Hero | Own the study hourStudy Rocket

• Coronary Circulation

  • The heart muscle itself is supplied with blood by the coronary arteries.

  • Blockage in these arteries can lead to myocardial infarction (heart attack).