Exam II: General Concepts Flashcards
3 Main Components of the Cardiovascular System
- Heart
- Blood
- Arteries/Veins
Composition of Blood
- Formed elements: heavier elements/cellular material including the RBC, WBC, and platelets
- Plasma at the top, which is serum/liquid part outside the cells; contains water, Ab, proteins, electrolytes
Plasma is important because it is related to lymph
Location of the Heart
The apex of the heart ends at the 5th intercostal/nipple area
The heart sits on the diaphragm; the fibrous pericardium is fused to the diaphragm
The sternum is protecting the front, along with the ribs
The sternum is divided into 3 parts: manubrium is the top part, which is fused at the 2nd rib with the body of the sternum
The aortic arch and trachea bifurcation, pulmonary trunk that divide in the right and left = all behind the 2nd rib area/protected by the sacrum
At the 5th intercostal space= apex of the heart in a healthy normal heart
Right around rib 3 the top of the heart is there with the inferior and superior vena cava
The heart is about the size of your fist and between the 3rd and 5th ribs
Layers of the Heart
The fibrous parietal serous layer is the lining under pericardial sac
- Epicardium: outside layer of the heart also known as the visceral serous layer
- Fat is a good source of fuel right on the heart containing blood vessels + areolar connective tissue
- Myocardium: middle layer; see lots of blood vessels because need good vascularization or have an MI
- Endocardium: innermost layer; areolar connective tissue with endothelium (simple squamous epithelium in contact with blood)
Two Pumps of the Circulation
4 chambers of the heart divided into the pulmonary (send blood to lungs) and systemic circulation (send blood to the rest of the body)
Left side of heart has bigger ventricle because needs more pressure to pump the blood through the body
The aorta and big veins= systemic
Pulmonary artery= low O2 blood; pulmonary vein= high O2 blood from the heart
Great Vessels of the Heart
Bring in blood from the body:
Superior vena cava: bringing from the abdomen, thorax
Inferior vena cava: lower limbs and pelvis
Both go to the right atrium
Blood that is leaving:
Aortic arch sending blood to rest of the body
Pulmonary trunk that branch into right and left pulmonary artery
Chambers of the Heart
2 atria and 2 ventricles
Interventricular septum: separating the two ventricles
Interatrial septum: separating the two atria, which doesn’t close until birth
Valves of the Heart
Valves associated with fibrous skeleton and anchored to fibrous rings
Cartilage around the valves can calcify as we get older and not work as well
Valve: ensure unidirectional flow and prevent backflow
Pulmonary trunk is associated with the pulmonary valve
Aortic trunk associated with aortic valve
Mitral and bicuspid valves
Pathway Through the Heart
Go through inferior or superior vena cava into the right atrium, which will contract and will go through tricuspid/right atrioventricular valve, then to the right ventricle and tricuspid valve closes
Right ventricle contracts and goes up through the pulmonary semilunar valve to the pulmonary trunk into the right and left pulmonary arteries to the lungs to get gas exchange
Pulmonary veins come from lungs with fully O2 blood, to the left atrium, through the bicuspid valve/mitral/left atrioventricular valve, then the left ventricle and bicuspid valve closes to generate pressure and prevent backflow, and then the blood goes behind the pulmonary trunk area to the aortic semilunar valve leading to the aorta (ascending arch and descending arch) through the body and then the cycles starts again
Layers of the Blood Vessels
- Tunica Intima: endothelium + basement membrane; innermost layer and in contact with the blood
- Tunica Media: smooth muscle; middle layer
- Tunica Adventitia: connective tissue; outermost layer and fuses with the vascular bundle
The artery and veins have the same layers, but different thickness
Comparison of Arteries vs. Veins
Elastic Artery: tunica media is largest with layer of elastin to allow for recoiling and generation of pressure to close cusps and prevent backflow; pulmonary trunk and aorta
Muscular Artery: renal, carotid; thick muscular wall with external and internal elastic lamina
Arteriole: fewer muscular thickness/smaller
Venules: fewer muscle cells than arteries
Medium sized vein: add VALVES to prevent backflow of the blood
Large veins: with valves still
Bigger blood vessels need their own blood supply = vasa vasorium
Arteries have a thicker tunica media
Innervation of the Heart
To maintain normal BP, we have specialized structures that relay back info to the brainstem that will in turn control blood supply and pressure
Aortic body: cells that are the associated with the cranial nerves/ vagus nerve X
Bifurcation of the carotid bodies: chemoreceptors that relay info about pressure and content of the blood via carotid sinus nerve to nerve IX
Veins/Valves
Varicose veins: the valves don’t function properly and don’t ensure unidirectional flow
Why don’t we have varicose veins within the deep muscle? We have another pump (skeletal muscle associated with the vein), and as we move/walk/run we are pumping/compressing it to help with blood flow
Musculoskeletal pump: doesn’t work well with superficial veins, but works well for deep veins
Problem with deep veins: DVT from lack of movement causing blockage and embolism
3 Types of Capillaries
- Continuous: not much leakage; blood brain barrier because don’t want blood mixing with tissue
- Fenestration: leak only small molecules, mostly fluid; glomerulus because we want passage of fluids
- Sinusoidal: missing half the walls with large fenestrations to allow bigger molecules to come out; liver, spleen (large pooling of blood)
Portal Circulation
Two in the Body:
- Hepatic Portal System – involves drainage of the gastrointestinal tract (1st capillary bed) and liver (2nd)
- Hypothalamic Hypophyseal Portal System – involves the delivery of hormones to the hypophysis
Arterioles to 1st capillary bed to vein to 2nd capillary bed, then into another vein then back to the heart
Artery to capillary to an artery to capillary to vein = glomerulus because efferent and afferent arteries
Anastomosis
Have arteries that connect to each other; artery to artery connections and don’t have to come from the same spot
Blood vessels to small intestine
Anatomic: two arteries that go to tissues and DO NOT CONNECT
Functional: have a connection somewhere; if ligation in one of the arteries, the blood flow will still go to the tissues they both supply
Vascular Shunting
We do not always have the capillary beds fully used; need ability to close them because we wouldn’t have enough blood for the body otherwise
During digestion in the intestine the capillary beds are open completely, but once that ends they close down
Exercising: open vascular beds in muscles and lungs to get more O2 and blood flow
Shunting: do this via pre-capillary sphincter (have ability to close) so when the muscle constricts it closes off the passages to the capillaries
Pathway of Lymph Flow
Have cell products/debris, pathogens, fluids, etc. entering the lymphatic system via the lymphatic capillaries/plexus, which are filtered by lymph nodes containing lymphocytes and macrophages, exit the nodes via the hilum uni-directionally especially because the presence of valves, then goes into blood vessels
Blood vessels enter the heart circulation, capillary beds, then interstitial fluid back into the lymph capillaries
Lymphatic System
The lymphatic system (lymph nodes, spleen, etc.) returns excess tissue fluid back to the venous system. Lymph is rich in macromolecules, large proteins and particulate matter
Comprised of:
- Lymph and channels
- Lymphoid tissue
Functions to:
- Transport lymph and cells
- Absorption and transport of fat
- Defense mechanisms
Lymphatic Vessels
Lymph vessels begin as blind ended pouches, and are highly permeable with a very low pressure
Lymph channels drain lipids from the GI tract
Lymph vessels are absent from:
- Epidermis
- Hair and nails
- Cornea
- Articular cartilage
- CNS
- Bone marrow