Cardiovascular System Flashcards
Blood
Highly specialised connective tissue
Several cell types suspended in plasma
7% total body weight
pH 7.4 (7.35-7.45)
Blood Function
Transport:
Gases in solution>oxygenated blood from lungs to tissues>collects deoxygenated blood (CO2) from metabolic processes back to lungs.
Nutrients>amino acids, fatty acids & glucose (digestion), from digestive system to liver.
Waste products>collects urea and creatinine (metabolism result), transport to kidney and liver for excretion
Hormones and Enzymes>endocrine glands to target tissues
Regulation:
Volume and Constituents of Body Fluids>water (plasma) to tissues, maintain osmotic balance (fluids and cells), plasma proteins (albumin) controls fluid flow between compartments
Body temperature>conducts heat around body to surface (lost by peripheral vasodilation)
Acid-Base balance>maintains constant internal pH (buffers present), absorb H+ ions in acidic blood or release H+ ions in alkaline blood
Infection Defence>WBCs in blood prevent infection (antibodies and antitoxins)
Clotting>prevents excessive blood loss from wounds, prevents entry for infection
Blood Composition
Albumin, Prothrombin and Fibrinogen produced by liver
Plasma: Liquid part, separates in centrifuge>90% water, CO2, H2O, nutrients, waste, hormones, enzymes and antibodies/antigens. Mineral salts~ Na+, K+, Ca2+, Mg2+, Cl-, HCO3- maintains osmotic balance and buffers.
Ca2+>blood clotting, muscle contraction
Proteins>maintain osmotic pressure (too large to pass out), prevents water leaking into extracellular spaces.
Albumin>holds water in blood
Fibrinogen+Prothrombin>clotting
Immunoglobulins>antibodies produced by immune system
Blood Cells (solid component of blood)
Erythrocytes
Erythrocytes:
RBCs>most numerous>6-8m per mm3 of blood>transport O2>small amount of CO2>biconcave disc shape>7um diameter>haemoglobin (conjugated protein with Fe2+)>no nucleus so more HbO8>thin, flexible cell membrane (capillaries)>shape and thin membrane = large SA for gas exchange>O2 diffuses into cell (O2+Hb=HbO8)
Formation~undifferentiated stem cells, erythropoiesis>stem cells>erythroblasts(nucleus)> normoblasts (HbO8, nucleus shrinks)> reticulocyte (nucleus strands) “Howell-Jolly” bodies>erythrocyte ~ takes 4-7 days
Shortage of erythrocytes= acute haemorrhage, iron deficiency anaemia> reticulocytes released to make up deficit
Lifespan: 120 days (spleen/lymph nodes destroy)
Fe2+ recycled, rest is converted to bilirubin (excreted in bile)
Methylene blue>stains reticulocytes
Erythropoietin>hormone for RBC production
Blood Cells
Leucocytes
WBC>less numerous than RBC>nuclei>2 types: granulocytes + agranulocytes (dependent on granule visibility under a microscope when stained)>defence against infection Granulocytes: Bone marrow (70% leucocytes)>segmented/lobes nucleus>polymorphonucleocytes (PMNs) = many shaped nuclei>Neutrophils = take up natural dyes, stain purple, immature then nucleus is band shaped (curved), 90% of granulocytes, move through endothelial lining of blood vessels, phagocytosis NEUTROPHILIA=PRESENCE OF INFECTIVE PROCESS NEUTROPENIA=CERTAIN VIRAL INFECTIONS >Eosinophils=take up acidic dyes, stain red, regulate allergic and inflammatory processes, secrete enzymes to inactivate histamine EOSINOPHILIA=PARASITIC INFECTION RESPONSE >Basophils=take up basic/alkaline dyes, stain blue, secrete histamine (increase inflammation) + heparin (natural anticoagulant) Agranulocytes: Clear cytoplasm>Lymphocytes (2nd most common WBC, 80% all agranulocytes), main cell types of immune system, formed in lymphoid tissue, specific immune response (B lymphocytes=antibodies, T lymphocytes=cellular immune response)>Monocytes= horseshoe-shaped nucleus, largest leucocyte, small numbers, phagocytic, become macrophages when they migrate to tissue and mature
Blood Cells
Thrombocytes
Platelets>cell fragments formed in bone marrow>large cells (megakaryocytes)>small discs, no nuclei>present in large quantities>blood clotting
THROMBOCYTOPENIA=REDUCED NUMBER OF PLATELETS > bone marrow dysfunction or infection/chemotherapy
Blood Clotting:
Damage to blood vessel>thrombocytes stick to wound, produce thromboplastin>thromboplastin and calcium turn prothrombin to thrombin>thrombin acts as clotting factor, fibrinogen to produce fibrin>fibrin sticks to thrombocytes (clot forms)>normal clotting time is 2-5 minutes
Heart
Right side: Pulmonary
Left side: Systemic
4 chambers separated by septum
Conical shape, lies left of midline, base above and cranial to apex, close to sternum, caudal surface of 6th rib
Muscular organ, contracts rhythmically, enclosed in double layer serous sac, pericardium, lies in mediastinum
Walls of ventricles have thicker muscle layer (myocardium) than atria, pump blood into arteries, thickest is LV (pump all over body)
Layers:
Inner=endocardium>continuous with endothelial lining of blood vessels
Middle=myocardium>made of cardiac muscle
Outer=epicardium>forms serous layer of pericardium
Valves:
Right atrioventricular (AV) valve = tricuspid between RA and RV>3 fibrous flaps that attach to a fibrous ring
Left AV valve = bicuspid/mitral between LA and LV>2 cusps
Free edges of AV valves attached to papillary muscles by fibrous threads “chordate tendineae” ~ AV valves open>blood fills ventricles from atria>valve shuts (prevent backflow)
Base of major vessels, semilunar valves prevent backflow back into ventricle> pulmonary: base of pulmonary artery (leaves RV)>aortic: base of aorta (leaves LV)
Circulation of Blood
1: Deoxygenated blood
2: Right side of body
3: Cranial/caudal vena cava
4: Blood into RA
5: Full with blood, contracts
6: Force blood to RV (via right AV valve)
7: Full with blood, contracts
8: Blood to Pulmonary Artery via Pulmonary Valve
9: Blood to lungs, oxygenated
10: Pulmonary vein (left side)
11: LA
12: Full with blood, contracts
13: Blood to LV (via left AV valve)
14: Full with blood, contracts
15: Aorta (via aortic valve)
16: Body
17: O2 to tissues, CO2 collected
18: Back to heart by veins
Conduction of the Heart
Heartbeat at Sino Atrial Node (SAN)
- area of modified muscle cells in RA wall
- autonomic nerves take effect and impulse to contract arises
- both atria (atrial systole)
Impulse to AtrioVentricular Node (AVN)
- top of interventricular septum
- impulses along Bundle of His
- Bundle of His into LV+RV into Purkinje fibres
- bottom of ventricles to aorta and out (ventricular systole)
Circulatory System
Network of blood vessels>mammals (double circulation)> systemic (heart,body,heart)> pulmonary (heart,lungs,heart)> allows rapid distribution of O2 blood under high pressure> blood passes through heart twice in complete circuit of the body
Blood Vessels
Arteries
Blood AWAY from the heart, transport O2 blood to capillary beds
EXCEPTION: PULMONARY ARTERY CARRIES DEOXYGENATED BLOOD TO THE LUNGS
Have thick walls, 3 layers:
- tunica intima= endothelial lining (continuous throughout)
- tunica media= smooth muscle, elastic tissue
- tunica adventitia= fibrous outer coat of vessel
Enter tissues and give off side/collateral vessels, link to form a network (anastomoses)
Some tissues/organs have end arteries instead
Branch off and become smaller+narrower = arterioles
Blood Vessels
Capillaries
Small, thin-walled, permeable vessels
Single layer of endothelial cells:
- exchange of gases
- uptake of nutrients
- removal of metabolic waste products
Small diameter, slow movement of blood and easy diffusion between blood and tissues
Capillary bed= extend between arterioles and venules
Blood Vessels
Veins
Blood TOWARDS the heart, thin walls carry deoxygenated blood under low pressure.
EXCEPTION: PULMONARY VEIN CARRIES OXYGENATED BLOOD FROM LUNGS TO THE HEART
Fewer smooth muscle and elastic fibres, veins carrying blood against pull of gravity contain semilunar valves to prevent backflow
Venules are smallest veins and collect deoxygenated blood from capillary beds
Foetal Ciruclation
Placenta>roles of lungs, kidneys, digestive tract>blood provides O2 + nutrients, removes waste products>umbilical arteries and veins carry blood to and fro (vein is nutrient-ladened)>shunts/bypasses
Foramen ovale>opening in septum but closes after birth
Ductus arteriosus>vessel that connects pulmonary artery and aorta, close after birth (ligamentum arteriosus)
Ductus venosus>shunt in liver that connects the umbilical vein to caudal vena cava, closes at birth (falciform ligament)
Lymphatic System
Function:
- return excess tissue fluid to circulating blood
- remove bacteria/foreign particles (lymph nodes)
- produce lymphocytes (antibodies)
- transport products of fat digestion + fat-soluble vitamins from lacteals of intestinal villi to circulation
Contains:
Capillaries= excess TF collected
Vessels= like veins, valves prevent backflow
Ducts= drain lymph into blood vessels
Tissues= spleen, thymus, tonsils
Lymph Nodes= filters lymph of bacteria etc > masses of lymphoid tissue, bean-shaped, indebted region (hilus), afferent lymphatic vessels (carry lymph to nodes), fibrous connective tissue capsule, network of tissue (trabeculae), lymph modules=lymphocytes, lymph flows through space/sinuses
Node Types:
Submandibular= 2-5, jaw
Parotid= caudal to temperomandibular joint of jaw
Superficial cervical= 2 each side, shoulder joint
Superficial inguinal= 2 each side, groin
Popliteal= tissue of gastrocnemius muscle
