CARDIO

1. structure & function of lungs

2. function & significance of upper respiratory system

3. heart physiology 

cardiac cycle

cardio function

• transport nutrients, hormones
• remove waste products
• gaseous exchange
• immunity
• blood vessels transport blood 
• pumps blood through blood vessels

heart 

• middle mediastinum inside pericardium
• oblique behind sternum
• 1/3 to right
• blood flow downward, forward, to the left

covering - provide protection against friction (friction-free), prevent overfilling, protect & anchor heart + wall

• fibrous pericardium - conical sac
• base attach diaphragm
• anterior attach sternum by sterno pericardial ligaments
• posterior - principal bronchi, esophagus, descending aorta 
• lateral - phrenic nerve 
• serous pericardium 
• visceral pericardium = epicardium = mesothelium & CT
• parietal cavity with fluid 
• parietal pericardium 
• myocardium = cardiac muscle & involuntary, striated, branched fiber = pump
• endocardium = simple squamous = cover valve, continuous with blood vessels

external 

• apex = LV
• base = LA & RA & pulmonary veins & SVC & IVC
• inferior = diaphragmatic = LV & RV
• anterior = sternocostal = A & V

chamber 

• 2 atria
• coronary sulcus/atrioventricular groove 
• auricle 
• pectinate muscle 
• RA
• crista terminalis 
• fossa ovalis
• anulus ovalis  
• LA
• 2 ventricle 
• anterior & posterior interventricular groove 
• RV
• trabeculae carnea
• papillary muscle
• moderator band 
• crescenteric 
• LV - no moderator band 
• 3x thicker with 6x intraventricular pressure - supply systemic circulation
• circular
• interatrial septum 
• interventricular septum 
• atrioventricular orifice = AV opening, guard by AV valve 

valve

• AV 
• tricuspid = RA RV
• 3 leaflet
• papillary muscle pull chordae tendineae = fibrous string
• bicuspid/mitral = LA LV
• 2 leaflet
• papillary muscle pull chordae tendineae
• semilunar 
• pulmonary 
• 3 cusp 
• open when RV contract
• aortic
• 3 cusp
• open when LV contract

skeleton

• CT plate 
• form fibrous ring around AV & semilunar valve 
• serve as electrical insulation
• rigid site for cardiac muscle attach

blood supply

• R coronary artery
• smaller
• posterior IV supply V
• marginal supply R
• L CA
• anterior IV supply V
• circumflex supply L

nerve 

• sympathetic - cervical & upper thoracic of sympathetic trunk
• parasympathetic - vagus nerve 

cardiac conduction system 

• sinoatrial node = pacemaker @ RA
• AV node = RAV valve 
• bundle of  His = IV septum divide into R L bundle branches
• Purkinje fibers = from apex into lateral walls

disorder

• atherosclerosis 
• occlusive coronary atherosclerosis = coronary artery narrow as cholesterol accumulation
• aneurysm = bulge of blood vessel - burst 
• peripheral vascular ds = clogged carotid artery in head & neck, renal artery, iliac artery supply lower abdomen, femoral artery, popliteal artery supply lower leg - slow blood flow 
• congestive heart failure 
• coronary artery disease
• myocardial infarction
• blood clot
• angina pectoris = ischemia of muscle 

congenital defect

• ventricular septal
• coarctation of aorta = aorta narrow - LV workload high
• tetralogy of fallot - multiple defect

aging

• sclerosis & thickening of valve flaps
• decline in cardiac reserve
• fibrosis of cardiac muscle
• atherosclerosis 

sound 

• lub = AV valve close
• dup = semilunar valve close
• murmur = blood backwash thro valve/stenosis 

bypass graft

• saphenous vein
• internal mammary artery in chest
• radial artery in arm

muscle 

• striated, short, fat, branched, interconnected, uni nucleated 
• endomysium = tendon & insertion
• intercalated disc
• behave as functional syncytium
• automaticity 
• long 250 ms absolute refractory period 

development

BV

• artery = carry blood away from heart
• vein
• capillary = gas & nutrient 

structure 

• tunic externa = collagen fiber - vasa vasorum 
• tunic media = smooth muscle & elastic fiber - SNS
• tunic interna/intima = endothelial 
• lumen = space with blood 
• capillary = endothelium with sparse basal lamina 
• 1 cell thick tunic interna 
• pericyte 
• continuous 
• skin, muscle, brain
• fenestrated - pore
• small intestine, kidney, endocrine gland
• sinusoid - large intercellular cleft 
• liver, BM, lymphoid tissue

capillary bed

• microcirculation of interwoven networks of capillaries 
• terminal arteriole 
• sphincter
• vascular shunt
• metarteriole
• true capillaries 
• venule 

vascular anastomoses = BV merge, vein common 

• arterial 
• thoroughfare channels 

physiology

autorhythmic cells

• smaller than contractile cells
• not many myofibrils
• no organized sarcomere
• unstable membrane potential
• myogenic
• funny channel open at -60 mV, sodium influx 
• reach threshold -40 mV, voltage gated calcium open = depolarize
• calcium close K efflux = rapid repolarize
• no refractory period
• duration 150 msec

contractile cells

• intercalated disc
• more mitochondria than skeletal muscle
• less sarcoplasmic reticulum
• larger T tubule
• voltage gated sodium open & close at 20 mV = depolarize
• slight K efflux = temporary repolarize 
• voltage calcium fully open = plateau
• calcium close, K fully open, K efflux = repolarize
• resting membrane potential -90 mV
• long refractory period 
• duration 200 msec

cardiac cycle = sequence of events as blood enter atria leaves ventricle = electrical conduction system

• SA myogenic at 70-80 potential/min = 75 times/min
• depolarization spread thro atria via gap junction & internodal pathways to AV node = 0.1 sec
• action potential travel to Bundle of His to LR AV bundles to Purkinje cells to apex & ventricular walls

• rest = atria & ventricle diastole
• atrial systole = ventricular filling
• isovolumetric ventricular contract = AV valve close = lub 
• ventricular ejection = intraventricular pressure higher = semilunar valve open 
• isovolumetric ventricular relaxation = intraventricular pressure drops below aortic pressure = semilunar valve close = dup 

cardiac output = blood amount pumped by each ventricle in 1 min

• CO = HR x stroke volume 
• increased HR: SNS - low bp or blood volume, epinephrine, thyroxine, exercise
• decreased HR: PNS, high bp, decreased venous return 
• SV = end diastolic volume x end systolic volume 
• factors affect SV
• preload = stretch 
• contractility
• increased: sympathetic stimuli, hormones, calcium, drugs
• decreased: acidosis, high EC K+, calcium channel blockers
• afterload
• Frank-Starling Law = more stretch, stronger contraction