Recording Electrical Potentials from a Partially Depolarized Mass of Syncytial Cardiac Muscles •Depolarized represented by negative charges. •Polarized represented by positive charges. •The depolarization spreads in all directions through the heart, the potential differences persist for only a few thousandths of a second. •The actual voltage measurements can be accomplished only with a high-speed recording […]
Current flow in the Cardiac cycle Read More »
Introduction •When the cardiac impulse passes through the heart, electrical current also spreads from the heart into the adjacent tissues surrounding the heart. A small portion of the current spreads all the way to the surface of the body. If electrodes are placed on the skin on opposite sides of the heart, electrical potentials generated
Concept of Electrocardiogram Read More »
Composition and Properties of Urine •Appearance –almost colorless to deep amber; yellow color due to urochrome, from breakdown of hemoglobin (RBC’s) •Odor – as it stands bacteria degrade urea to ammonia •Specific gravity –density of urine ranges from 1.000 -1.035 •Osmolarity – (blood – 300 mOsm/L) ranges from50 mOsm/L to 1,200 mOsm/L in dehydrated person
Urine composition, control and storage Read More »
Negative Feedback Control of GFR Renal Autoregulation of GFR • BP ® constrict afferent arteriole, dilate efferent • BP ® dilate afferent arteriole, constrict efferent •Stable for BP range of 80 to 170 mmHg (systolic) Cannot compensate for extreme BP Sympathetic Control of GFR •Strenuous exercise or acute conditions (circulatory shock) stimulate afferent arterioles to
Glomerulus filtration rate (GFR) control Read More »
Nephron •True proportions of nephron loops to convoluted tubules shown •Cortical nephrons (85%) –short nephron loops –efferent arterioles branch off peritubular capillaries •Juxtamedullary nephrons (15%) –very long nephron loops, maintain salt gradient, helps conserve water –efferent arterioles branch off vasa recta, blood supply for medulla Nephron Diagram Urine Formation Preview Filtration Membrane Diagram Filtration membrane
Nephron Basic unit of kidney Read More »
Kidney Functions •Filters blood plasma, eliminates waste, returns useful chemicals to blood •Regulates blood volume and pressure •Regulates osmolarity of body fluids •Secretes renin, activates angiotensin, aldosterone –controls BP, electrolyte balance •Secretes erythropoietin, controls RBC count •Regulates PCO2 and acid base balance •Detoxifies free radicals and drugs •Gluconeogenesis Nitrogenous Wastes •Urea –proteins®amino acids ®NH2 removed
Function and Anatomy of kidney Read More »
1-Cleavage •Fertilization of the chick egg occurs in the oviduct, before the albumen and shell are secreted to cover it. •Like the egg of the zebrafish, the chick egg is telolecithal, with a small disc of cytoplasm—the blastodisc(zygote)—sitting atop a large yolk. •Like fish eggs, the yolky eggs of birds undergo discoidal meroblastic cleavage. •Cleavage
Stages of Cleavage in birds Read More »
Introduction to stem cell •A stem cell can be defined as a relatively undifferentiated cell that when it divides produces •(1) one cell that retains its undifferentiated character; and •(2) a second cell that can undergo one or more paths of differentiation. •Thus, a stem cell has the potential to renew itself at each division
The Stem Cell Concept A brief view Read More »
Steps involve in activation of egg metabolism 1-Release of intracellular calcium ions •The release of Ca+2 that occurs when the sperm enters the egg is critical for activating the egg’ s metabolism and initiating development. •Calcium ions release the inhibitors from maternally stored messages, allowing these mRNAs to be translated •They also release the inhibition
The activation of egg’s metabolism Read More »
Introduction to hormonal control of metamorphosis •The control of metamorphosis by thyroid hormones was first demonstrated in 1912 by Gudernatsch, who discovered that tadpoles metamorphosed prematurely when fed powdered horse thyroid glands. •In a complementary study, Allen (1916) found that when he removed or destroyed the thyroid rudiment of early tadpoles (thyroidectomy), the larvae never
Hormonal Control of frog Metamorphosis Read More »
