Cardiovascular and Respiratory Systems Your heart will beat about 3.5 billion times in your life!!

The Heart: Anatomy ** Look at your handout

How does the blood flow?? (#s 2-5 on sheet) Superior and inferior vena cava  right atrium  right ventricle  L & R pulmonary arteries  lungs for O2  L & R pulmonary veins  left atrium  left ventricle  aorta  your body. Which of these are O2 rich? O2 poor? Veins carry blood to the heart, arteries carry blood away from the heart. When O2 rich blood leaves heart… goes through arteries, arterioles, capillaries, venules, veins, and back to heart.

Electrical Conduction System SA node (sinoatrial) in the right atrium is the “pacemaker”. Sends electrical impulse to trigger each heartbeat. When SA node contracts, the muscle cells in the 2 atria contract. 1: SA node 2: AV node

Electrical Conduction (cont.) SA impulse travels to AV (atrioventricular) node, between the atria signals cells in ventricles to contract. Nerve fibers send impulses to continue contraction of heart muscle

2 PHASES Systole: Heart contracts and ventricles pump blood into arteries. Diastole: Heart relaxes… allows ventricles to refill with blood. Creates the “lubb dubb” you hear through a stethoscope. Sounds of valves closing.

Respiratory Anatomy: see sheet

Respiration: How we Breath Nose/mouth  pharynx  trachea  2 bronchi  bronchioles (tree)  alveoli (exchange of CO2 and O2 with blood). To inhale, your diaphragm pushes down on abdomen and intercostal muscle contract, so ribs push out. This increase in volume of thoracic cavity = decrease in pressure in cavity, so air moves into lungs…. (pressure moves from higher atmospheric pressure to lower). Opposite happens when you exhale. Stretch receptors in bronchii trigger reflex to stop inhalation.

Nervous System Control of Breathing If exercising… chemoreceptors in arteries detect low pH due to CO2. Why low ph? Message is sent to the vagus nerve… one branch of vagus nerve goes to respiratory center in the brainstem. Nerves go from this center to the diaphragm and intercostal muscles to increase contraction rate. You increase breathing rate! Also, nerves to bronchioles’ smooth muscle, causing them to relax and increase air flow into lungs.

Hormonal Control of Breathing Response to stress… Epinephrine travels through blood to respiratory center in brain… stimulates increase in respiration rate and depth of breathing. Fight or Flight response

How about heart rate control? Chemoreceptors detect decrease in pH from CO2… send a message to vagus nerve. Branch of vagus goes to sinoatrial node (SA) causing it to contract more often, so HR increases. Also, epinephrine travels to SA node, and causes increase in HR.

Why does pH decrease from CO2? Cellular respiration gives CO2. CO2 is carried in blood in the form of carbonic acid. The H+ makes it acidic. Bohr Effect allows blood (hemoglobin) to unload Oxygen when it is at a low pH (high H+ concentration). H2O + CO2  H2CO3  H+ + HCO3-

For this Exam: Study guide All notes on cellular respiration/handout Anatomy handouts for these systems These notes CO2 lab Chapters 7 and 47 in book Quiz from last week GOOD LUCK! Come see me if you need extra help.