Unit 14 Circulatory and Respiratory Systems It is infinitely better to transplant a heart than to bury it to be devoured by worms. -Dr. Christiaan Barnard

Functions of the Circulatory System The Circulatory system transports oxygen, nutrients, and other substances throughout the body. It removes wastes from tissues and transports them to organs that will dispose of them.

Heart Muscle layer is called the myocardium

Coronary circulation Two vessels branching from the aorta.

Heart Attack Myocardial Infarction occurs when a vessel is plugged. The muscle downstream from the vessels is starved of oxygen and starts to die. Prompt medical attention can limit the damage and decrease recovery time. The damaged muscle is replaced by connective tissue.

Sinoatrial node and action potential yll2Oc yll2Oc

Blood Pressure Two numbers are read, systolic and diastolic. The upper number (systolic), measures the pressure of the blood when the heart is contracting. The lower number measures the pressure on the heart between beats when it is resting.

Blood Pressure 17qb_w 17qb_w

Lymph System Primary functions are to drain and return interstitial fluid to the blood. To absorb and return lipids from the digestive system to the blood Filter the fluid of pathogens, damaged cells, debris and cancerous cells

Atherosclerosis Hardening of the arteries occurs when fat, cholesterol and other substances build up on the walls of arteries. This build up forms hard structures called plaques. Over time these plaques can block the arteries.

Stroke A stroke happens when blood flow to a part of the brain stops. Brain cells that need the oxygen and nutrients to survive will quickly die. A blocked artery results in an ischemic stroke. An artery the bursts is called a hemorrhagic stroke

Hypertension When pressure is over 140/90. Can be without symptoms for years. High cholesterol can be a contributing factor. The situation can be a vicious circle of damaged arteries becoming stiffer leading to higher blood pressure

Cholesterol Cholesterol is a lipid that is part of animal cell membranes. It is also used in the synthesis of hormones, bile and Vitamin D. It is transported in the blood by either low- density lipoprotein (LDL) or high-density lipoprotein (HDL)

HDL and LDL HDL – high density lipoprotein. LDL – low density lipoprotein. LDL is a problem because it becomes part of plaque. HDL transports excess cholesterol from tissues to the liver for removal. LDL should be <100 mg/dL HDL should be >50 mg/dL

LDL receptor problem LDL receptors on liver cells take in LDL and the cholesterol they carry. Some people, genetically, have defective LDL receptors. So the liver can’t remove cholesterol from the blood and these liver cells don’t stop producing cholesterol.

Diet caused problems People with high fat diets store excess cholesterol in their liver cells. Those cells stop making LDL receptors and removing cholesterol from blood. The excess cholesterol is then deposited in arteries.

Respiratory System

Medulla Oblongata controls breathing. Rising CO 2 stimulates breathing center to send impulses to diaphragm and chest muscle causing them to contract.

Chronic bronchitis