Circulatory System Chapter 37

Circulatory System Why do we need one? ◦Diffusion is too slow for large multicellular organisms. They need a transport system. The heart, blood and vessels make up the human circulatory system.

Heart Four-chambered double-pump. Left side pumps oxygen rich blood to the body. Right side pumps oxygen poor blood to the lungs.

The Heart Made of cardiac muscle. Pacemaker initiates beat. Valves keep blow flowing forward. ◦Lub-dup sound when they close. The septum divides the heart into right and left sides.

Circulatory Pathways

Blood Vessels Arteries – carry blood away from the heart. ◦Thick, elastic walls. Pulse. ◦Aorta is largest blood vessel in the body. Veins – carry blood back to the heart. ◦Thinner walls and less elastic. ◦Veins have valves. Capillaries - exchange of materials. ◦Walls are one cell thick. ◦Every cell touches a capillary.

Section 37-1 Capillary Connectiv e tissue Smooth muscle Endothelium Valve Venule Endothelium Arteriole Vein Artery

Blood Fluid tissue that bathes all cells of the body. Carries nutrients and oxygen to the cells and wastes and carbon dioxide away from the cells. Helps regulate body temperature. Some components help fight disease. Composed of plasma and cells.

Plasma Liquid part. Mostly water. Carries dissolved carbon dioxide, nutrients, wastes, hormones, antibodies, vitamins, salts and various proteins.

Blood Cells Red blood cells (erythrocytes) ◦Carry oxygen; most numerous; no nuclei White blood cells (leukocytes) ◦Fight disease; less numerous; multinucleate Platelets (thrombocytes) ◦Clot the blood

Section 37-2 Figure Blood Clotting Break in Capillary Wall Blood vessels injured. Clumping of Platelets Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin.. Clot Forms Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood..

Lymphatic System Network of vessels that return fluid back to the blood. Lymph nodes filter bacteria and microbes from the fluid. The thymus gland in the neck matures T lymphocytes. The spleen removes damaged blood cells from circulation.

Section 37-2 Superior vena cava Lymph nodes Thymus Heart Thoracic duct Spleen Lymph vessels

The Respiratory System Chapter 37

Respiration Cellular respiration – the release of energy stored in food. Takes place in mitochondria. Breathing – exchange of gases.

Human Respiratory System Basic function is to exchange oxygen for carbon dioxide. Pathway of airflow: ◦Nose ◦Pharynx ◦Larynx ◦Trachea ◦Bronchi ◦Bronchioles ◦Alveoli

Section 37-3 Figure The Respiratory System

Cilia and Mucus Line the entire respiratory passageway. Filters and moistens air.

Gas Exchange Oxygen and carbon dioxide exchange places by diffusion in both the lungs and the body cells.

Alveoli Bronchiole Capillary Section 37-3 Figure Gas Exchange in the Lungs

Breathing Active phase – chest muscles and diaphragm contract; chest cavity increases in size; air rushes in. Passive phase – muscles relax; chest cavity decreases in size; air is forced out.

Air inhale d Diaphragm Rib cage rises Air exhale d Diaphragm Rib cage lowers InhalationExhalation Section 37-3 Figure The Mechanics of Breathing

Air inhale d Diaphragm Rib cage rises Air exhale d Diaphragm Rib cage lowers InhalationExhalation Section 37-3 Figure The Mechanics of Breathing