1 The Heart and General Circulation rev 6-11 The heart and blood vessels are collectively known as the cardiovascular system The heart is a hollow muscular organ whose contractions creates the force and pressure which moves blood throughout our body The heart is a pump It secretes hormones that help regulate blood pressure and the body’s fluid and electrolyte balance.

2 Lab 9-The Heart and General Circulation Arteries carry blood away from the heart Veins carry blood to the heart Arteries and veins are connected to each other by capillaries The right side of the heart receives returning blood that is low in oxygen (deoxygenated) Blood moves from the right side of the heart to the lungs where it becomes oxygenated. Blood is returned to the left side of the heart which circulates it throughout the body

3 Lab 9-The Heart and General Circulation Anatomy of an Artery, Vein and Capillary Both arteries and veins have an inner layer of simple, squamous epithelium cells, a middle layer of smooth muscle, and an outer connective layer. Arteries have thicker muscular layers than veins because they must be able to withstand the high pressures generated by the heart. Veins are thinner walled and have valves to help keep the blood moving, against gravity, to the heart.

4 Lab 9-The Heart and General Circulation –Vein valves prevent the backflow of blood. The smallest arteries are called arterioles; the smallest veins are called venules. These connect via capillaries. All blood vessels except capillaries have smooth muscles in their walls. Capillaries are a thin layer of squamous cells which allows for exchange of nutrients, wastes and gases.

5 Lab 9-The Heart and General Circulation Layers of an artery –innermost layer is the endothelium is a layer of flattened, squamous epithelial cells which fit so closely together that they create a slick surface so that blood can flow smoothly. –middle layer which is primarily smooth muscle with elastic connective tissue –outermost layer is a supporting layer of connective tissue which anchors vessels to surrounding tissues

6 Lab 9-The Heart and General Circulation Veins –like the walls of arteries, the walls of veins consist of 3 layers of tissue. Outer 2 layers are much thinner than those of arteries veins have larger diameters than arteries –the pressure in veins is much lower than that in arteries which is why their walls are not as strong as arteries

7 Lab 9-The Heart and General Circulation –veins can act as a blood volume reservoir –the larger diameter of veins allows them to stretch to accommodate large volumes of blood at low pressures –because veins can stretch, it is more difficult for them to return blood to the heart against the force of gravity –people who spend a lot of time on their feet may get varicose veins because of this

8 Lab 9-The Heart and General Circulation Factors which help veins to return blood to heart –contraction of skeletal muscles as we move and muscles contract and relax, they press against veins and help push blood to the heart one way valves in the veins

9 Lab 9-The Heart and General Circulation –the work of the skeletal muscles helps the valves pump blood. This is called a skeletal muscle pump –movements associated with breathing also help pump blood. This is called a respiratory pump and helps to push blood from the abdomen to the chest and to the heart. when we breathe, there are pressure changes in the thoracic and abdominal cavities during inhalation, abdominal pressure increases and squeezes abdominal veins

10 simultaneously, pressure within the thoracic cavity decreases which dilates the thoracic veins and thus propels the blood. The Heart External anatomy-- heart has blood vessels attached to it –the large vessels are the aorta which transports blood away from the heart to the entire body. the pulmonary trunk (pulmonary vein and artery) which transports blood to and from the lungs.

11 Lab 9-The Heart and General Circulation –The superior and inferior vena cava which return blood to the right atrium the 4 chambers of the heart are the –2 atria: the right atrium and the left atrium –2 ventricles: the right and left ventricles blood enters the heart through the right atrium, flows through an atrioventricular valve into the right ventricle

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13 Lab 9-The Heart and General Circulation From the right ventricle, to a pulmonary valve to the pulmonary artery to the lungs oxygenated blood returns to the heart through the pulmonary vein and enters the left atrium flows through another atrioventricular valve to the left ventricle then through another valve to the aorta to the entire body

14 Lab 9-The Heart and General Circulation the heart muscle has its own supply of blood vessels: coronary arteries and coronary veins (see pictures on page 119 of lab manual) All of the chambers of the heart fill at the same time note that the pulmonary circulation has the oxygen level of the arteries and veins reversed

15 Lab 9-The Heart and General Circulation –the heart pumps 2 “circuits” at the same time-- the right ventricle to the pulmonary trunk and the left ventricle to the entire body –the outer wall of the left ventricle is thicker than the right ventricle this ventricle does more work than any other chamber--it must overcome the pressure of the aorta in order to pump blood into it

16 REMINDER Look at the bulleted lists on lab manual pages 120 and 121 –you will need to know where these items are located for the lab test Use the models and charts to help you locate these; don’t try to find them in the fetal pig

17 Lab 9-The Heart and General Circulation In general, blood vessels are named for the body cavity which they pass through The aorta modifies its name as it enters different body areas –aortic arch as it leaves heart –thoracic aorta: where aorta straightens out –abdominal aorta: when aorta goes through the diaphragm –after this, the aorta splits to go into each leg; it now becomes the femoral artery

18 Lab 9-The Heart and General Circulation Main arterial branches of the aorta (see page 126) –brachiocephalic (first branch off aorta) artery –carotid artery –subclavian (underneath clavicle) artery –renal artery (kidney) –external/internal iliac (ileum=hip bones) arteries –femoral artery

19 Lab 9-The Heart and General Circulation Major veins(see page 127) –superior vena cava –inferior vena cava (is the major vein in thoracic, pelvic, and abdominal cavities) –jugular vein

20 REMINDER Pathway of circulation; you need to know this –follow instructions on page 121 Do the sounds of the heart and the heart rate activities (page 121)

21 Lab 9-The Heart and General Circulation Functional Anatomy Contraction of the heart muscle is called systole –during systole, blood is pumped out of, or ejected from, the heart into the circulatory system Relaxation of the heart muscle is called diastole –during diastole, the heart fills with blood

22 Lab 9-The Heart and General Circulation Blood Pressure –When blood pressure is taken, the higher number is the systolic pressure the lower number is the diastolic pressure You will be taking each other’s blood pressure with an automatic blood pressure cuff wrap the cuff snugly around your partner’s arm(with the velcro side facing you, not your partner) the cuff is placed around the upper part of the arm so the bottom edge rests immediately above the elbow

23 Lab 9-The Heart and General Circulation REMINDER page 1 of 3: 1. Use the sheep heart and the models to view internal anatomy. Learn all the heart structures on the models. Remember to label figure 13.5 to include the heart chambers--atria and ventricles. 2. Locate all blood vessels from the bulleted lists on pages on the models. Use the figures on lab manual pages to help you. 3. See the instructions on page 121 for the pathway of circulation and follow this activity.

24 REMINDER page 2 of 3: 4. Do the sounds of the heart and the heart rate activities 5. Perform the blood pressure activities on pages We will also begin dissecting the fetal pig today. Remember that everyone needs to participate in the dissection. a.Tie long hair back so it doesn’t mix with the inside of the pig when you bend down to look at it.

25 REMINDER page 2 of 3: 7. You need to locate the following endocrine glands: thyroid, thymus, and pancreas (see diagram on page 104 of the lab manual). a)DO NOT locate the adrenal glands; they are very hard to find. b)Remember to use Table 11.1 to help you learn about these glands, their hormones and the function of these hormones.