Cardiac Sustems 2 Flashcards
Electrical properties of the heart
Contractions associated with action potential
Cells interconnected electrically through gap junctions at structures called intercalated cells
Pacemaker potentials
Pacemaker potentials
Transmitted from pacemaker cells in sinoatrial node to atrioventricular node then down to the Bundle of His and out to the Purkinje fibers
Electrocardiogram
P - atrial depolarization
QRS - ventricular depolarization
T - ventricular repolarization
Giraffe drinking
Aortic pressure decreases from 200-150 (vasoconstriction)
Capillary beds in body vasodilate to prevent pooling in arterial system
Blood functions
Phagocytosis Wound plugging Clotting Immune response Storage reservoir (eg for haemoglobin)
Blood contents
Plasma (5%)
Erythrocytes
Leukocytes
Platelets
Leukocytes
Basophils Eosinophil Lymphocyte Neutrophil Monocyte Divisible into granular and agranular + capable of independent movement
Plasma
Fluid matrix in which formed elements are suspended
Water (92%)
Proteins (7%) - fibrinogen, globulin, albumin
Erythropoiesis
Formation of erythrocytes determined by [O2]
Polycythemia
Excess red blood cells
Increased blood viscosity
Higher haematocrit values
Sickle-cell anaemia
Sickle shaped blood cell movement disrupted, depriving downstream tissue blood (ischaemia)
Recessive in sub-Saharan Africans
Granular leukocytes
Neutrophils - phagocytosis
Eosinophils - breaks down clots and kills parasites
Basophils - synthesise and store heparin and histamines
Agranular leukocytes
Lymphocytes - immune response
Monocytes - phagocytosis
Platelets
Fragment of cell cytoplasm enclosed by a membrane
Act as temporary patches for repairs to blood vessels
Permanent clot form as later (involves 30+ chemical substances)
Diving circulatory changes
Limited oxygen stores
Priority given to tissue that cannot tolerate anoxia (brain, heart)
Blood supply to periphery reduced (kidneys etc)
Bradycardia
