Chapter 23- Circulation Anemia Aorta Arteries Arterioles Atherosclerosis Atrium AV node Blood Blood pressure Capillaries Capillary beds Cardiac cycle Cardiac output Cardiovascular disease Circulatory system Closed circulatory system Diastole Erythrocytes Fibrin Fibrinogen Heart attack Hypertension Inferior vena cava Leukemia Leukocytes Open circulatory system Pacemaker Plasma Platelets Pulmonary arteries Pulmonary circuit Pulmonary veins Pulse Red blood cells SA node Stem cells Superior vena cava Systemic circuit Systole Veins Ventricle White blood cells

Circulation System of internal transport of O 2, CO 2, nutrients and wastes – Necessary when chemicals can’t reach body by diffusion alone – Needs to have contact with all tissues, blood vessels move blood to capillaries where diffusion takes place – Maintains homeostasis- exchanges molecules with interstitial fluid, controls make up of environment cells are in, controls blood make up

Transport in other life forms Hydra- no circ system- direct diffusion in gastrovascular cavity Grasshopper- open circ system- (no distinction between blood and interstitial fluid) – blood pumped through tubular heart to cells Fish- closed circ system- only 2 chamber heart (1 atrium, 1 ventricle) Vertebrate cardiovascular system shows evolution gill breathing  lung breathing Fish have 1 circuit blood flow Mammals have 2 circuit, pulmonary- to/from lungs systemic- to/from body

The heart Left side of heart- receives and pumps O 2 rich blood (to body) Right side- receives and pumps O 2 poor blood (to lungs) Human heart is size of clenched fist – Atria- receive blood – Ventricles- pump blood (more muscular) – Valves- regulate direction of flow – Rt atrium  Rt ventricle  lungs  left atrium  left ventricle  body  (rt atrium and all starts over)

Arteries Thick muscular walls- carries blood away from heart (smaller= arterioles) – Pulmonary artery- only artery that pumps O 2 poor blood – Aorta- largest blood vessel (2.5cm diameter), pumps to entire body

Veins Thinner walls, have valves, flows toward heart (smaller= venules) – Pulmonary vein- only vein that pumps O 2 rich blood – Superior vena cava- O 2 poor blood back from upper body – Inferior vena cava-O 2 poor blood back from lower body

Capillaries Very thin (1 cell thick), diffusion can take place

The Heart

Heartbeat cycle – Cardiac cycle- complete sequence of filling and pumping – Diastole- heart is relaxed, filled with blood – Systole- atria contract, then ventricles contract – Cardiac output- volume of blood/min left ventricle pumps – “lub-dub”- blood against valves, valves shut

Pacemaker (SA, sinoatrial node)- maintains pumping rhythm, works with AV, atrioventricular node- to ensure atria contract then ventricles – Heart is also controlled by physiological or emotional cues and hormones

Heart attack Failure of heart to function because blood can’t get to heart muscle – Heart muscle tissue that dies (due to loss of blood flow) can’t be replaced – Cardiovascular disease- 40% of US deaths/yr- diseases of heart and blood vessels – Atherosclerosis- plaques (common site of blood clot formation) narrow arteries, blood can’t flow

Blood Pressure Force exerted by blood on vessel walls – Pulse- rhythmic stretching of arteries – Ventricle contraction- creates pressure (systolic) between contractions (diastolic) – Blood pressure + velocity- highest in aorta and arteries

Blood Pressure – Normal BP 120/80 – 120- systole- force during contraction – 80- diastole- force during relaxation – Sphygmomanonmeter- BP cuff – Hypertension- high BP Heart works harder = enlarged/weakened Increase risk of heart attack, stroke, heart disease, ruptured vessels (aggravates plaque formation)

Smooth muscle in arteriole walls regulates blood distribution – Only 5-10% of capillaries have blood flowing at a given time! – Sphincters open and close flow to capillary beds

Blood flow in capillary beds

Capillaries Walls thin enough for substances to pass through – Move by diffusion – Endocytosis and exocytosis – Difference in BP and osmotic pressure pushes fluid through capillary walls – BP pushes fluid out,osmotic pressure draws fluid in

Blood Specialized circulatory fluid – 45% blood cells- RBC’s, WBC’s, platelets- bits of cytoplasm pinched off of large cells – 55% plasma- which is 90% water, 10% salts, proteins, transported substances Salts- regulate osmotic balance, pH Proteins- (same as salt) + clotting

Blood composition

Red Blood Cells 25 trillion in blood stream Lack nuclei and mitochondria- pushed out to make room for hemoglobin Each cell holds 250 million hemoglobin molecules Formed in bone marrow, circulate 3-4 months Low hemoglobin or # of RBC’s = anemia- low iron, body can’t get enough O 2

White Blood Cells Many types- fight infection, prevent growth of cancer cells Basophil- release chem’s Ex: histamine (dilates blood vessels, allows WBC’s to get to injury site) Neutrophils and monocytes- phagocytes- “eat” bacteria, foreign materials, remove cellular debris Eosinophil- kill parasitic worms, help reduce allergy attacks Lymphocyte- KEY cell in immunity- produce antibodies, attack pathogen infected body cells and cancer cells **most WBC’s time is spent in interstitial fluid NOT blood, #’s greatly increase when body is fighting infection

Clotting Platelets + fibrinogen (protein)- activated to form clot when a vessel is injured Platelets turn sticky to plug hole Clotting factor is released by platelets  activates prothrombin converting into thrombin which converts fibrinogen into fibrin which traps blood cells until connective tissue forms permanent patch

Leukemia Cancer of WBC’s- patients have excess WBC’s that don’t function properly