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Biol 227 Exam 5
Pulmonary circuit - Correct Ans-- Right side of heart; carries blood to the lungs for gas exchange and returns it to the heart
- leaves through pulmonary trunk, artery
- comes through pulmonary veins
- goes into left atrium Systemic circuit - Correct Ans-- left side of heart; supplies oxygenated blood to all tissues of the body and returns it to the heart
- more blood vessels
- Enter Right atrium
- inferior and superior Vena cava Left side of heart - Correct Ans--Fully oxygenated blood arrives from lungs via pulmonary veins
- Blood sent to all organs of the body via aorta Right side of heart - Correct Ans--Oxygen-poor blood arrives from inferior and superior venae cavae
- Blood sent to lungs via pulmonary trunk (arteries) Base of heart - Correct Ans-Wide, superior portion of heart, large vessels attack here apex of the heart - Correct Ans-Tapered inferior end, tilts to the left Pericardium - Correct Ans--Double-layered membrane surrounding the heart.
- allows heart to beat without friction, provides room to expand, yet resists excessive expansion
- anchored to diaphragm inferiorly and sternum anteriorly
- same as epicardium and visceral pericardium
- most deep Parietal pericardium - Correct Ans-- Pericardial sac
- superficial fibrous layer of connective tissue
- deep, thin serous layer Visceral pericardium (epicardium) - Correct Ans-- serous membrane that directly covers the heart
- adipose in thick layer in some places
- coronary blood vessels travel through this layer Pericardial cavity - Correct Ans-Space inside the pericardial sac filled with 5 to 30 ml ot pericardial fluid
Pericarditis - Correct Ans-inflammation of the pericardium Levels of the pericardium (superficial to deep) - Correct Ans-- Pericardial sac
- fibrous layer
- serous layer
- pericardial cavity
- epicardium Myocardium - Correct Ans-- Layer of cardiac muscle proportional to work load
- muscle spirals around heart which produces wringing motion *does all the work *contract and put pressure on blood flow *high to low pressure Endocardium - Correct Ans-- Smooth inner lining of heart and blood vessels
- slick internal lining allows for blood to flow easy
- covers the valves surfaces and is continuous with endothelium of blood vessels
- simple squamos epithelium
- expose to external environment through blood
- like epithelium Fibrous skeleton of the heart - Correct Ans-- Framework of collagenous and elastic fibers *prevents heart from over-expanding
- provides structural support and attachment for cardiac muscle and anchor for value tissue
- electrical insulation between atria and ventricles; important in timing and coordination of contractile activity
- isolates electrical signals Levels of the heart wall (superficial to deep) - Correct Ans-Epicardium, myocardium, endocardium Right and left atria - Correct Ans-- Two superior chambers
- same size as ventricles volumetrically
- not a lot of myocardium
- can expand very much
- receive blood returning to heart
- the only place they have to apply pressure to ventricle valves
- No blood= collapsed
- Auricles (seen on surface) enlarge chamber Right and left ventricles - Correct Ans-- Two inferior chambers
- pump blood into arteries
- ton of myocardium; left has 3x as right
What happens when the ventricles relax? - Correct Ans--pressure drops inside ventricles > semilunar valves close as blood attempts to back up into the ventricles from the vessels > AV valves open > blood flows from atria to ventricles What happens when the ventricles contract? - Correct Ans--AV valves close as blood attempts to back up into the atria > pressure rises inside of the ventricles > semilunar valves open and blood flows into great vessels Blood flow through the heart - Correct Ans- 1 - Superior & Inferior Vena Cava 2 - Rt Atrium, 3-Right AV (Tricuspid) Valve 4 - Rt Ventricle 5 - Pulmonary Valve 6 - Pulmonary Artery 7 - Lungs-pick up oxygen 8 - Pulmonary Veins 9 - Lt Atrium 10 - Left AV (Mitral) Valve (Bicuspid) 11 - Lt Ventricle 12 - Aortic Valve 13 - Aorta 14 - Body Coronary circulation - Correct Ans--5% of blood pumped by heart is pumped to the heart itself through the coronary circulation to sustain its strenuous workload
- 250 ml of blood per min
- needs abundant O2 and nutrients Right Coronary Artery (RCA) (part of coronary circulation) - Correct Ans--Branches off the ascending aorta. Supplies the right atrium and sinoatrial node (pacemaker), continues along the coronary sulcus under the right auricle, and gives off two branches of its own (right marginal branch and posterior interventricular branch).
- Right marginal branch: supplies lateral aspect of right atrium and ventricles
- Posterior interventricular branch: supplies posterior walls of ventricles left coronary artery (LCA) (part of coronary circulation) - Correct Ans--branches off the ascending aorta
- anterior interventricular branch: supplies blood to both ventricles and anterior two- thirds of the interventricular septum
- circumflex branch: passes around left side of heart in coronary sulcus
- gives off left marginal branch and then ends on the posterior side of the heart
- supplies left atrium and posterior wall of left ventricle What is angina pectoris? - Correct Ans-- chest pain caused by inadequate flow of blood and oxygen to the heart
- myocardium shifts to anaerobic fermentation, producing lactate and thus stimulating pain
- starving for O
- Pain is felt in pectoralis major muscle because neurons get confused What is a myocardial infarction (MI)? - Correct Ans-- Occurs when the blood flow to part of the heart is blocked and the heart muscle becomes damaged and / or dies. It is caused because of a blood clot that blocks the coronary artery which provides oxygen to the heart.
- Atheroma (blood clot or fatty deposit) often obstructs coronary arteries
- Heavy pressure or squeezing pain radiating into the left arm Venous drainage - Correct Ans-Most coronary blood returns to right atrium by way of the coronary sinus which has three main inputs: great. Cardiac, posterior interventricular, and left marginal veins Great cardiac veins ( part of venous drainage) - Correct Ans-- Travels alongside anterior interventricular artery
- collects blood from anterior portion of heart
- empties into coronary sinus Middle cardiac vein (posterior interventricular) (part of venous drainage) - Correct Ans-- Found in posterior sulcus
- collects blood from posterior portion of heart
- drains into coronary sinus Left marginal vein ( part of venous drainage) - Correct Ans-Empties into coronary sinus Coronary sinus (part of venous drainage) - Correct Ans-- Large transverse vein in coronary sulcus on posterior side of heart
- collects blood and empties into right atrium Cardiomyocytes - Correct Ans-- striated, short, thick, branched cells, one central nucleus surrounded by light-staining mass of glycogen
- Repair of damage of cardiac muscle is almost entirely by fibrosis (scarring) Intercalated discs - Correct Ans--junctions between cells anchor cardiac cells
- Interdigitating folds: folds interlock with each other, and increase surface area of contact
- Mechanical junctions tightly join cardiomyocytes
- Desmosomes—mechanical linkages that prevent contracting cardiomyocytes from being pulled apart from each other
- Electrical junctions (gap junctions) allow ions to flow between cells; can stimulate neighbors
- Entire myocardium of either two atria or two ventricles acts like single, unified cell
Parasympathetic nerves - Correct Ans-slow heart rate Pathway begins with nuclei of the vagus nerves in the medulla oblongata Extend to cardiac plexus and continue to the heart by way of the cardiac nerves Fibers of right vagus nerve lead to the SA node Fibers of left vagus nerve lead to the AV node Little or no vagal stimulation of the myocardium systole vs diastole - Correct Ans-Systole = contraction Diastole = relaxation
- repolarizing
- more potassium
- filling w/ blood Although "systole" and "diastole" can refer to contraction and relaxation of either type of chamber, they usually refer to the action of the ventricles Sinus rhythm - Correct Ans-the normal (optimal) heart rhythm arising from the sinoatrial node Ectopic focus - Correct Ans-any region of spontaneous firing other than the SA node
- May govern rhythm if SA node is damaged
- Nodal rhythm—if SA node is damaged, heart rate is set by AV node, 40 to 50 bpm
- Other ectopic focal rhythms are 20 to 40 bpm and too slow to sustain life SA node - Correct Ans-Starts at −60 mV and drifts upward due to slow Na^+ inflow Gradual depolarization is called pacemaker potential When it reaches threshold of −40 mV, voltage-gated fast Ca^(2+) and Na^+ channels open Faster depolarization occurs peaking at 0 mV K^+ channels then open and K^+ leaves the cell Causing repolarization Once K^+ channels close, pacemaker potential starts over There is little or no "hyperpolarization" with K+ channels staying open too long, or too much K+ moving out of the cell How often does the SA node fire? - Correct Ans-Every 0.8 seconds (75bpm) Impulse conduction to the myocardium - Correct Ans-firing of SA node excites atrial cardiocytes and stimulates two atria to contract almost simultaneously. signal travels at a speed of about 1 m/sec through the atrial myocardium and reaches the AV node in abiout 50 msec. in the AV node, signal slows down to about 0.05 msec. bcus cardiocytes here are thinner, and have fewer gap junctions over which the signal can be transmitted. this delayes signal so it can allow the ventricles time to fill with blood before contracting. signals travel through AV bundle and purkinje fibers very quickly. entire ventricular myocardium depolarizes within 200 msec after the SA node fires causing ventricles to contract when they are in unison. papillary muscles contract and begin taking up slack in the tendinous chords an instant before ventricular contraction causes
blood to surge against AV valves. ventricular systole begins at apex of heart, which is first to be stimulated, and moves upward- pushing blood up toward the SL valves. bcus of spiral arrangement of ventricular cardiocytes, ventricles twist slightly as they contract like someone is wringing a towel. Electrical Behavior of the Myocardium - Correct Ans-Depolarization phase (very brief) Stimulus opens voltage-regulated Na^+ gates (Na^+ rushes in), membrane depolarizes rapidly Action potential peaks at +30 mV Na^+ gates close quickly Plateau phase lasts 200 to 250 ms, sustains contraction for expulsion of blood from heart Voltage-gated slow Ca^(2+) channels open admitting Ca^(2+) which triggers opening of Ca^(2+) channels on sarcoplasmic reticulum (SR) Ca^(2+) (mostly from the SR) binds to troponin triggering contraction Repolarization phase: Ca^(2+) channels close, K^+ channels open, rapid diffusion of K^+ out of cell returns it to resting potential Has a long absolute refractory period of 250 ms (compared to 1 to 2 ms in skeletal muscle) Prevents wave summation and tetanus which would stop the pumping action of the heart What is the resting membrane potential of the myocardium - Correct Ans--90mV, depolarize only when stimulated Electrical Behavior of the Myocardium - Correct Ans-1. Na+ gates open
- Rapid depolarization
- Na+ gates close
- Slow Ca2+ channels open
- Ca2+ channels close, K+ channels open (repolarization) Electrocardiogram (ECG) - Correct Ans-Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs, and chest Electrocardiogram waves - Correct Ans-P wave
- SA node fires, atria depolarize and contract
- Atrial systole begins 100 ms after SA signal QRS complex
- Ventricular depolarization
- Complex shape of spike due to different thickness and shape of the two ventricles
- Atrial repolarization is happening as well during this time, but its electrical activity is "masked" by the larger activity of the ventricles ST segment
- Ventricular systole
- Corresponds to plateau in myocardial action potential
Ventricular filling - Correct Ans-Ventricles expand and their pressure drops below that of the atria AV valves open and blood flows into the ventricles Filling occurs in three phases: Rapid ventricular filling: first one-third Diastasis: second by one-third; slower filling P wave occurs at the end of diastasis Atrial systole: final one-third; atria contract End-diastolic volume (EDV) achieved in each ventricle (about 130 mL of blood) Isovolumetric contraction - Correct Ans-Atria repolarize, relax and remain in diastole for rest of cardiac cycle Ventricles depolarize, causing QRS complex, and begin to contract AV valves close as ventricular blood surges back against the cusps Heart sound S_1 occurs at the beginning of this phase "Isovolumetric" because although ventricles contract, they do not eject blood Pressures in aorta and pulmonary trunk are still greater than those in the ventricles Cardiomyocytes exert force, but with all four valves closed, the blood cannot go anywhere Ventricular ejection - Correct Ans-Begins when ventricular pressure exceeds arterial pressure and semilunar valves open Pressure peaks in left ventricle at about 120 mm Hg and 25 mm Hg in the right First: rapid ejection—blood spurts out of ventricles quickly Then: reduced ejection—slower flow with lower pressure Ejection lasts about 200 to 250 ms - corresponds to plateau phase of cardiac action potential T wave of ECG occurs late in this phase Stroke volume (SV) is about 70 mL Ejection fraction is about 54% of EDV (130 mL) 60 mL remaining blood is end-systolic volume (ESV) = EDV - SV Isovolumitric relaxation - Correct Ans-T wave ends and ventricles begin to expand Blood from aorta and pulmonary trunk briefly flows backward filling cusps and closing semilunar valves Heart sound S2 occurs "Isovolumetric" because semilunar valves are closed and AV valves have not yet opened Ventricles are therefore taking in no blood When AV valves open, ventricular filling begins again Cardiac cycle in a resting person - Correct Ans-Atrial systole lasts about 0.1 second
- fast because atria pushes blood with gravity Ventricular systole lasts about 0.3 second
- more myocardium to contract Quiescent period, when all four chambers are in diastole, lasts about 0.4 second Congestive heart failure (CHF) - Correct Ans-Results from the failure of either ventricle to eject blood effectively Usually due to a heart weakened by myocardial infarction, chronic hypertension, valvular insufficiency, or congenital defects in heart structure Left ventricular failure—blood backs up into the lungs causing pulmonary edema Shortness of breath or sense of suffocation Right ventricular failure—blood backs up in the vena cava causing systemic or generalized edema Enlargement of the liver, ascites (pooling of fluid in abdominal cavity), distension of jugular veins, swelling of the fingers, ankles, and feet Eventually leads to total heart failure Cardiac output (CO) - Correct Ans-amount ejected by each ventricle in 1 minute Cardiac output = heart rate x stroke volume About 4 to 6 L/min at rest A RBC leaving the left ventricle will arrive back at the left ventricle in about 1 minute Vigorous exercise increases CO to 21 L/min for a fit person and up to 35 L/min for a world-class athlete Cardiac reserve - Correct Ans-the difference between a person's maximum and resting CO Increases with fitness, decreases with disease Pulse - Correct Ans-surge of pressure produced by heart beat that can be felt by palpating a superficial artery Infants have HR of 120 bpm or more Young adult females average 72 to 80 bpm Young adult males average 64 to 72 bpm Heart rate rises again in the elderly Tachycardia - Correct Ans-resting adult heart rate above 100 bpm Stress, anxiety, drugs, heart disease, or fever Loss of blood or damage to myocardium Bradycardia - Correct Ans-resting adult heart rate of less than 60 bpm In sleep, low body temperature, and endurance-trained athletes Positive chronotropic agents - Correct Ans-Factors that raise the heart rate Negative chronotropic agents - Correct Ans-Factors that lower the heart rate Cardiostimulatory effect - Correct Ans-some neurons of the cardiac center transmit signals to the heart by way of sympathetic pathways
Also respond to hypoxemia (oxygen deficiency in blood) usually by slowing down the heart Stroke volume - Correct Ans-Preload—the amount of tension in ventricular myocardium immediately before it begins to contract Increased preload causes increased force of contraction Exercise increases venous return and stretches myocardium Cardiomyocytes generate more tension during contraction Increased cardiac output matches increased venous return Contractility refers to how hard the myocardium contracts for a given preload Affected by several chemicals, including electrolyte imbalances (K+ and Ca++) Afterload—sum of all forces opposing ejection of blood from ventricle Largest part of afterload is blood pressure in aorta and pulmonary trunk Opposes the opening of semilunar valves Limits stroke volume Hypertension increases afterload and opposes ventricular ejection Examples of stroke volume - Correct Ans-Increased preload or contractility increases stroke volume Increased afterload decreases stroke volume Exercise and Cardiac output - Correct Ans-Exercise makes the heart work harder and increases cardiac output Proprioceptors signal cardiac center At beginning of exercise, signals from joints and muscles reach the cardiac center of brain Sympathetic output from cardiac center increases cardiac output Increased muscular activity increases venous return Increases preload and ultimately cardiac output Increases in heart rate and stroke volume cause an increase in cardiac output Exercise produces ventricular hypertrophy Increased stroke volume allows heart to beat more slowly at rest Athletes with increased cardiac reserve can tolerate more exertion than a sedentary person Indicate which is the proper sequence of blood flow through the circulatory system: i. Right atrium ii. Left atrium iii. Right ventricle iv. Left ventricle v. Pulmonary artery vi. Pulmonary vein vii. Lungs viii. Systemic tissues ix. Aorta x. Venae cavae
a. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 b. 10, 2, 4, 5, 7, 6, 1, 3, 9, 8 c. 10, 1, 3, 5, 7, 6, 2, 4, 9, 8 d. 10, 1, 2, 3, 4, 5, 7, 6, 9, 8 e. None of the above sequences are correct - Correct Ans-c. 10, 1, 3, 5, 7, 6, 2, 4, 9, 8 The systemic circulation: a. Receives more blood than the pulmonary circulation b. Receives blood from the left ventricle c. Is a high pressure system compared to the pulmonary circulation d. Receives blood from the left ventricle and is a high pressure system compared to the pulmonary circulation e. All of these answers - Correct Ans-d. Receives blood from the left ventricle and is a high pressure system compared to the pulmonary circulation The direction of the impulse through the conduction system of the heart for each cardiac cycle is normally: a. AV node, SA node, AV bundle, Purkinje fibers b. AV node, AV bundle, SA node, Purkinje fibers c. AV bundle, AV node, Purkinje fibers, SA node d. SA node, AV node, AV bundle, Purkinje fibers e. SA node, AV bundle, AV node, Purkinje fibers - Correct Ans-d. SA node, AV node, AV bundle, Purkinje fibers Autorhythmic cells: a. Make up 1% of the heart b. Are able to develop action potentials without CNS input c. "Drift" in and out of threshold at specific rates d. Allow for coordinated muscle contraction in the heart e. All of the above are true of autorhythmic cells - Correct Ans-e. All of the above are true of autorhythmic cells The autorhythm properties of conducting cells in the heart is due to: a. The decrease outward movement of K+ from these cells b. The constant inward movement of Na+ into the these cells c. An increased movement of Ca++ into the cells d. The use of a localized neurotransmitter found only in the conducting cells of the heart e. All of the above EXCEPT D are correct statements concerning autorhythmicity - Correct Ans-b. The constant inward movement of Na+ into the these cells
The period lasting from closure of the AV valve to opening of the aortic valve is known as: a. Isovolumetric ventricular contraction b. Isovolumetric ventricular relaxation c. The rapid ejection phase d. The rapid filling phase e. None of these answers - Correct Ans-a. Isovolumetric ventricular contraction The volume of blood remaining in the ventricles after they have contracted and the semilunar valves have closed is known as the: a. Stroke volume b. Isovolumetric ventricular contraction c. End systolic volume d. Ejection fraction e. Cardiac output - Correct Ans-c. End systolic volume The cardiovascular center for systemic control is located in the: a. Carotid sinus b. SA node c. Medulla oblongata d. Primary motor cortex e. Arterioles - Correct Ans-c. Medulla oblongata Which of the following will not increase stroke volume? a. Increased end-diastolic volume b. Increased contractility of the heart c. Increased end-systolic volume d. Increased stretch of the cardiac muscle fibers during ventricular filling e. Iincreased venous return - Correct Ans-c. Increased end-systolic volume What force continues to drive blood through the vasculature during ventricular diastole? a. Ventricular contraction forces blood into the vasculature during ventricular diastole b. The elastic recoil of the stretched arterial walls provides the force to continue blood flow in the remaining vascular system during ventricular diastole c. Sympathetic stimulation produces arterial vasoconstriction, which drives the blood forward into the arterioles during ventricular diastole d. Skeletal muscle contraction squeezes the blood forward from the arteries during ventricular diastole e. Respiratory movements produce pressure changes in the chest, which establishes a pressure gradient that drives blood forward from the arteries into the microcirculation -
Correct Ans-The elastic recoil of the stretched arterial walls provides the force to continue blood flow in the remaining vascular system during ventricular diastole Elastic recoil of large arteries occurs during: a. Ventricular diastole b. Ventricular systole c. During the entire cardiac cycle d. Only when cardiac output is very low e. Both A and D are true statements - Correct Ans-a. Ventricular diastole The prime defect in heart failure is: a. A decrease in cardiocyte contractility, making a "weak" heart b. An increase in stroke volume c. A decrease in heart rate d. An increase in EDV (EFFECT) e. A decrease in an individual's cardiac reserve - Correct Ans-a. A decrease in cardiocyte contractility, making a "weak" heart Organs that recondition the blood: a. Receive disproportionately large percentages of the cardiac output b. Can withstand temporary reductions in blood flow much better than can organs that do not recondition the blood c. Must receive a constant blood supply in order to maintain homeostasis d. Both (a) and (b) above e. Both (a) and (c) above - Correct Ans-e. Both (a) and (c) above A. stroke volume if EDV is 130ml and ESV is 30ml B. stroke volume if EDV is 140ml and ESV is 60 ml a. A is greater than B b. B is greater than A c. Both A and B are equal - Correct Ans-a. A is greater than B A. Cardiac output if stroke volume is 70ml and heartrate is 70 bpm B. Cardiac output if stroke volume is 60ml and heartrate is 80 bpm a. A is greater than B b. B is greater than A c. Both A and B are equal - Correct Ans-a. A is greater than B A. volume of blood in ventricles at isometric ventricular relaxation B. volume of blood in ventricles at isometric ventricular contraction
e. Slight vasoconstriction of veins increases stroke volume - Correct Ans-b. Decreased end diastolic volume increases cardiac output If a disease caused an increase in blood pressure, what event must occur in total peripheral resistance to maintain the same degree of blood flow to tissues? a. Resistance must also increase to meet flow demands b. Resistance must decrease to maintain consistent blood flow c. There is no relationship between blood pressure and peripheral resistance, so no homeostatic response is required d. Total peripheral resistance cannot be altered or changed homeostatically e. An increase in blood pressure must effect blood flow to tissues, altering resistance would not have a homeostatic effect - Correct Ans-b. Resistance must decrease to maintain consistent blood flow Blood flow is affected by: a. Pressure differences b. The viscosity of the blood c. The amount of friction in the blood vessels d. The length and diameter of the blood vessels e. All of these answers - Correct Ans-e. All of these answers Which is NOT true of blood pressure: a. Its maximal during ventricular systole b. It decreases the farther away from the heart c. It increases with increasing resistance d. It decreases with increasing vessel diameter e. It can be increased by direct parasympathetic activity - Correct Ans-e. It can be increased by direct parasympathetic activity If the arterial blood pressure is recorded at 132/84, what is the mean arterial pressure? a. 100 mm Hg b. 93 mm Hg c. 108 mm Hg d. 48 mm Hg e. None of these answers - Correct Ans-a. 100 mm Hg Which of the following factors is most important in matching the blood flow through a specific tissue with the metabolic needs of that tissue? a. Sympathetically induced vasoconstriction of the arteries supplying a tissue forces more blood to flow into the tissue
b. Parasympathetically induced vasodilation of the capillaries within a tissue allows more blood to flow into the tissue c. Local changes within a tissue resulting from increased metabolic activity can produce local arteriolar vasodilation to allow more blood to flow into the tissue d. Widespread venous vasoconstriction allows blood to dam up at the tissue level e. The amount of blood flowing through each tissue remains constant through reflex controls to ensure that metabolic needs are continuously met - Correct Ans-c. Local changes within a tissue resulting from increased metabolic activity can produce local arteriolar vasodilation to allow more blood to flow into the tissue Functions of respiration - Correct Ans--Gas exchange: O2 and CO2 exchanged between blood and air
- Communication: speech and other localization
- Olfaction: sense of smell
- Acid-Base balance: influences pH of body fluids by eliminating CO
- Blood pressure regulation: by helping in synthesis of angiotensin II
- Blood and lymph flow: breathing creates pressure gradients between thorax and abdomen that promote flow of lymph and blood
- Expulsion of abdominal contents: breath holding assists in urination, defecation, and childbirth (valsalva maneuver) Principal organs of the respiratory system - Correct Ans-- nose, pharynx, larynx, trachea, bronchi, lungs
- incoming air stops in the alveoli
- millions of thin-walled, microscopic air sacs
- exchanges gases with the bloodstream through the alveolar wall, and the flows back out Conducting zone - Correct Ans--includes those packages that serve only for airflow
- No gas exchange
- Nostrils through major bronchioles Respiratory zone - Correct Ans-- consists of alveoli and other gas exchange regions Upper respiratory tract - Correct Ans--head and neck
- nose through larynx Lower respiratory tract - Correct Ans--organs of the thorax
- trachea through lungs Nose - Correct Ans--Functions of the nose
- warms, cleanses, and humidifies inhaled air
- detects odors
- serves as a resonating chamber that amplifies voice
- Nose extends from nostrils (external nares) to posterior nasal apertures (choanae) - posterior openings (often called internal nares)
