Unit J. Circulation and Blood .

Intro… When you are unicellular there is no need for a transport system… However when you are trillions of cells, a system to transport nutrients (glucose, amino acids) and remove wastes (carbon dioxide, ammonia) is required….

Functions of the Circulatory System: Bring nutrients to the cells. Take wastes away from the cells.

Circulatory System Blood = the medium of transport (carries nutrients & wastes) Blood vessels = pathway for blood Heart = pump that will move blood through vessels There are close to 100,000 km of blood vessels!

5 type of blood vessels Arteries Arterioles (smaller version of arteries) Veins Venules (smaller version of veins) Capillaries – smallest!!!

Arteries (10% of blood) Carry blood AWAY from heart Thick walls to withstand blood pressure Elastic muscle fibers to withstand blood pressure Highest blood pressure Smooth muscle can regulate size

Arterioles Connects to arteries and capillaries Smaller than arteries Can dilate or constrict which regulates blood pressure

Capillaries (5% of blood) Narrow, microscopic tubes, blood cells will pass through single file! Site of nutrient/ waste exchange Thin walls (one cell layer thick!)allow for diffusion Large surface area allows for greater exchange of gases and nutrients Connect arterioles to venules

The blood flow across the capillary bed is regulated by a sphincter muscle on the arteriole side.

Capillary Bed

Venules Connect together to form veins Very thin walls

Veins (70% of blood) Carry blood BACK TO heart Thinner walls Contain valves to prevent back flow Lowest blood pressure Use large muscles groups to help push blood back to heart

Blood vessels - compared

Pulmonary vs. Systemic The cardiovascular system has 2 circuits with 2 functions: Pulmonary = brings blood to/from the lungs Systemic = brings blood to/from the body

1. Pulmonary – from heart to lungs and back to heart Right ventricle pushes deoxygenated blood out of the heart to the lungs CO2 diffuses out, O2 diffuses in at the alveoli of the lungs Oxygen-rich blood returns to the left atrium of the heart

2. Systemic – from heart to EVERY cell of body and back to heart Includes all blood vessels except those in the pulmonary system The left ventricle of the heart pumps oxygenated blood to the cells O2 diffuses out of blood, CO2 diffuses into blood The vena cava returns deoxygenated blood back to the right atrium of the heart

A. In the pulmonary system Oxygenated and Deoxygenated blood A. In the pulmonary system 1. Arteries carry deoxygenated blood. Veins carry oxygenated blood. B. In the systemic system 1. Arteries carry oxygenated blood. 2. Veins carry deoxygenated blood.

Important Blood Vessels: 1. Pulmonary Circuit:

2. Systemic Circuit - Arteries:

2. Systemic Circuit - Veins:

Path of a blood cell You should also be able to describe the flow of blood around the body through any major organ!

For example: Path of blood to kidneys Left ventricle to aorta to renal artery to renal arterioles to capillaries to venules to renal vein to inferior venae cava to right atrium

For example: Path of blood to the intestines Left ventricle to aorta to mesenteric artery to capillaries in the villi to venules to hepatic portal vein to liver hepatic vein to inferior venae cava to right atrium