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Love Datingnakedfemales En En Events AnnualMeeting2011 Index Dating Naked Females

(just like soap does – you can float a bottlecap on water until you add a surfactant like soap).  In this case the water is in the form of a film that coats each and every alveolus.  If it weren’t for these surfactants, the surface tension of this layer would collapse the delicate alveoli – causing the lungs to “collapse” after each breath.  This surfactant is produced by the lungs during the last part of pregnancy.  
Think about it
1.      Why does the trachea have cartilaginous rings?
2.      Why is it important for air to be moist when it enters the lungs?  Many desert mammals have extremely convoluted nasal cavities.  How might these large and complex nasal cavities conserve water during exhalation?
3.      When you catch a cold, you get a runny nose.  Is snot your body’s way of combating a viral invader, or is the virus simply using you to reproduce and spread itself?  The common cold generally doesn't land you in bed:  is this evidence of you're own abilities to "fight" the virus, or is the virus manipulating you to maximize its exposure to uninfected individuals?
4.      What is the function of the eustachian tubes?
CIRCULATORY SYSTEM
Objectives
1.   Identify and describe the function of the main organs and structures in the circulatory system.
2.  Trace the flow of blood through the pulmonary and systemic circuits.
3.  Describe how the circulatory and respiratory systems work together to bring about the integrated functioning of the body.
4.  Understand portal circulation.
5.  Understand mammalian fetal circulation from a mechanical, physiological, and evolutionary perspective.
The circulatory (or cardiovascular) system is responsible for transporting nutrients, gases, hormones, and metabolic wastes to and from individual cells.  Actually, the loading and unloading take place in capillaries.  Oxygen is added to the blood (and carbon dioxide removed) in the capillaries of the lungs.  In the capillaries of the small intestine, nutrients are added to the blood, while in the capillaries of the kidneys the blood is cleansed of various metabolic wastes and excess ions.
In mammals, the circulatory system is divided into a pulmonary circuit, which involves blood flow to and from the lungs, and the systemic circuit, which involves blood flow to and from the rest of the body.  Your pig has been doubly injected (red for arteries, blue for veins).  However, note that in reality, arteries and veins are defined by the direction of blood flow, not by the oxygen content of the blood contained therein.
1.  The Heart (Fig. 6)
           You may remove as much thymus as you need to in order to view the heart.  Carefully remove the pericardial sac from the heart.  In living animals, the pericardial cavity is filled with fluid that acts as a shock absorber to protect the heart from injury.  Identify the coronary artery and coronary vein lying in the diagonal groove between the 2 ventricles.  These vessels supply and drain the heart (the heart is a muscle and as such has the same requirements of any other organ).  When the coronary artery becomes obstructed, a heart attack may occur.  It is the coronary arteries that are "bypassed" in coronary bypass surgery.  Note that the atria have external flaps, known as auricles.
In an adult mammal (fetal circulation will be discussed below), deoxygenated blood flows into the right atrium from the anterior and posterior vena cavae.  It then makes the following circuit:  right ventricle, pulmonary trunk, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aortic arch, aorta, and on into the systemic circulation.  On the heart model, trace this path and find the above as well as the following structures:
• right atrioventricular valve
• atrioventricular valve
• right semilunar valve (between right ventricle and pulmonary trunk)
• left semilunar valve (between left ventricle and aorta)
• papillary muscles:  support chordae tendinae
• chordae tendinae:  support AV valves, preventing eversion
2.  Major veins of the systemic circulation, anterior to the heart (Fig. 7a)
           Following the path of deoxygenated blood, find the external jugular vein, which drains the head and neck, and the internal jugular vein, which drains the brain.  Note the vagus nerve running between the right common carotid artery and the internal jugular vein (the vagus nerve is responsible for slowing the heart, constricting bronchi, and stimulating the stomach and gallbladder).  The jugular veins meet with the subclavian vein to form the brachiocephalic vein.  The right and left brachiocephalic veins join to form the anterior (cranial) vena cava.  Note, however, that the mass of veins (and arteries) anterior to the heart may not look exactly like what you see in the figure.  For example, do the external and internal jugulars join before reaching the brachiocephalic?  Does your pig even have a subclavian vein? or do the subscapular (from the shoulder) and axillary (from the arm) veins empty straight into the brachiocephalic vein?  How substantial is the brachiocephalic vein?  or do the subclavian and jugulars empty straight into the vena cava?  Make sure you examine other pigs to appreciate the variability of these vessels.

Fig. 6.  The heart and major arteries and veins.
3.  Major arteries of the systemic circulation, anterior to the heart (Fig. 7b)
Viewing the major thoracic arteries may require moving (but not removing) some of the thoracic veins (attempt the former before resorting to the latter since you will see them on the lab practical).  Like the veins, however, there is a great deal of variation in the branching patterns of the brachiocephalic trunk and the left subclavian artery.  The first large vessel that branches from the aortic arch is the brachiocephalic trunk.  This artery soon branches into the right subclavian and the common carotid arteries (as well as sending vessels along the inner and outer walls of the rib cage).  The subclavian arteries carry blood to the forelimbs, the carotid arteries carry blood to the head.  The carotid branches into an internal carotid, which goes to the brain, and the external carotid, which goes to the face.  In desert-dwelling ungulates, the internal carotid forms an arterial "capillary" bed (rete) over the nasal passages and then reforms the carotid artery and delivers blood to the brain.  Because the nasal passages represent the intersection of hot dry outside air and moist internal body surfaces, a great deal of evaporative cooling takes place there.  Instead of expending energy (and water) to cool their entire bodies, these mammals can allow their bodies to heat up to brain-damaging temperatures while their brain aLove Datingnakedfemales En En Events AnnualMeeting2011 Index Dating Naked Females iB::الموضوع::أحتاج لمساعدة عاجلة v Naked rLove Datingnakedfemales En En Events AnnualMeeting2011 Index Dating Naked Females iB::الموضوع::أحتاج لمساعدة عاجلة j v q q Dating Dating

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