Circulation & Respiration 10/1 /13

Circulation & Respiration 10/1/13 • Finish Photosynthesis….. • Human: Circulatory systems • Function • Double circulation • Blood pressure • Heart sounds & EKGs

Circulatory System: • Major function: • Transport of • Gases • Nutrients • Differences in circulatory systems: • Open vs. closed circulation • Open: • Closed: • Closed circulation

Double circulation • crocodiles, birds and mammals • oxygenated and deoxygenated blood separates into 2 distinct circuits • systemic circulation • oxygenated blood • de-oxygenated blood • pulmonary circulation • de-oxygenated blood • oxygenated blood • 2 atria and 2 ventricles • major advantage

Vertebrate Heart: • blood flows through • comes into the • valves maintain • heart is a muscle Need to be able to follow the path of blow through body. 12.11b

Vertebrate heart • septum separates • blood enters from • through one-way • out one-way fig12.10 & 12.11

Heartbeat: 2 phases • Heart valves open and shut in response to pressure gradients • ventricles contract – • ventricles relax -

Conduction system of heart: • intrinsic control of heartbeat • SA node • spontaneously sends out • AV node • slight delay allows atria to finish contracting • electrical impulse travels from AV node fig12.13 • Extrinsic control –

Electrocardiogram (ECG or EKG) • record of electrical impulses during the cardiac cycle • P wave – • QRS complex – 3 • T wave –

Blood flow: away from heart • Arteries • Conduct blood • Layers of smooth muscle • Arterioles see fig 12.1

Blood flow:Capillaries • site of • single-celled layer of endothelium on a basement membrane

Capillaries • blood enters capillary on • pressure forces some • Most of the fluid that leaves will be recaptured by the venule end of the capillary • Proteins • Lymphatic system fig 12.2 also see 12.8

Fig. 12.17 see fig 12.1 • Blood flow: return to heart • Venules • Small, • Veins • Thinner and • Need help returning blood to the heart • One-way valves

see figure 12.14

Blood Pressure: • pulse: • systolic pressure • diastolic pressure Normal pressure:

Pressure varies in different vessels: • pressure drops as • pressure drops • branching of vessels • pressure lowest in • moves slowest through fig 12.16

Adaptive functions • Blood pressure • Baroreceptors are stretch receptors in certain arteries • Communicate with • Brain and other nerves can act to • System must adapt to changing conditions • Exercise • Blood must be routed to different areas in proportion to their need for oxygen and nutrients • increase flow: • Epinephrine –

Composition of Blood • connective tissue • cells within a matrix • matrix is liquid plasma

Role of Erythrocytes - Red Blood Cells • erythrocytes • formed within bone marrow • biconcave disk - • carries oxygen (releases oxygen) • attached to hemoglobin molecule

Leukocytes - White Blood Cells: • five types of WBCs • neutrophils • lymphocytes • monocytes • eosinophils • basophils • originate in the

Role of thrombocytes - Platelets: • critical for • originate in the • travel within the • injury to vessel - • platelets stick

fig 12.6 Blood Clotting: • platelets adhereto • blood in surrounding tissues activate plasma proteins • positive feedback loop • continues to produce it until • eventually clot

Coronary Heart Disease • atherosclerosis • fatty plagues accumulates inside the walls of coronary arteries -- reduce blood flow to heart muscle • cholesterol is a • low density lipoprotein (LDL) • high density lipoprotein (HDL)

Additional problems with circulatory system: • Heart Attack: (myocardial infarction) • results from • Hypertension: • consistently • 140/90 is high // 200/100 is dangerous • increase risk of • caused by

Additional problems with circulatory system: • Stroke: • causes • symptoms: numbness, weakness, loss of balance or even paralysis • treated w/in 3 hours with drugs increases chances of recovery • Congestive Heart Failure: • atherosclerosis or defective heart valves cause strain on heart & eventually weakens it

Circulation & Respiration 10/1 /13