•Photoreceptors located on retina. •retina contains rods and cones a) Rods used for black-and-white vision when illumination is dim. b) Cones are used for color vision, are shorter than rods. c) Humans have 100 million rods and 3 million cones in each retina. d) Most cones found in fovea.            (1) Location where eye forms its sharpest […]

Synaptic Transmission The process of information transfer at a synapse Plays role in all the operations of the nervous system 1897: Charles Sherrington- “synapse” Chemical and electrical synapses •1921- Otto Loewi •1959- Gurshan and Potter Six Types of synapses Axodendritic: Axon to dendrite Axosomatic: Axon to cell body Axoaxonic: Axon to axon Dendrodendritic: Dendrite to

•Neurotransmitters are the chemicals which allow the transmission of signals from one neuron to the next across synapses. •They are also found at the axon endings of motor neurons, where they stimulate the muscle fibers. •They and their close relatives are produced by some glands such as the pituitary and the adrenal glands. •Neurotransmitter levels

Nerve Action Potential Nerve signals are transmitted by action potentials, which are rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane. Each action potential begins with a sudden change from the normal resting negative membrane potential to a positive potential and then ends with an almost equally rapid change back

The Sinus Node as the Pacemaker of the Heart •In the discussion in last post, thus far of the genesis and transmission of the cardiac impulse through the heart, we have noted that the impulse normally arises in the sinus node. •In some abnormal conditions, this is not the case. A few other parts of

Automatic Electrical Rhythmicity of the Sinus Fibers of heart •Some cardiac fibers have the capability of self-excitation, a process that can cause automatic rhythmical discharge and contraction. •This is especially true of the fibers of the heart’s specialized conducting system, including the fibers of the sinus node. •For this reason, the sinus node ordinarily controls

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

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

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

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