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Review for final. May 2019. Eye. Globe-shaped organ with three layers: Sclera: outer layer, opaque with distinctive white color. Provides strength, structure and shape. Middle choroid: dark blue vascular layer. Supplies blood to eye.
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Review for final May 2019
Eye • Globe-shaped organ with three layers: • Sclera: outer layer, opaque with distinctive white color. Provides strength, structure and shape. • Middle choroid: dark blue vascular layer. Supplies blood to eye. • Retina: Innermost layer, Responsible for reception of visual impulses.
Cornea • The cornea is in the outermost layer of the eye and is primarily responsible for focusing the light that comes into our eyes. • There are 5 layers to the cornea. • The outer layer acts as a kind of shield to the elements and can usually repair itself within a few days of suffering a minor injury. The deeper layers exist mainly to strengthen the eye.
Pupil • Pupil: the black circle in the center • monitor the amount of light that comes into the eye • When there is a lot of light, the pupil contracts to keep the light from overwhelming the eye. • When there is very little light, the pupil expands so it can soak up as much as possible.
Lens • Locatedbehind the pupil • Responsible for allowing the eyes to focus on small details like words in a book. • The lens is in a constant state of adjustment as it becomes thinner or thicker to accommodate the detailed input it receives. • With age, the lens loses a lot of its elasticity which often results in cataracts and presbyopia because the lens cannot adjust as well to its surroundings as it used to.
Retina • area at the back of the eye that receives the refined, visual message from the front of the eye, • it transmits that visual message to the brain using electrical signals.
Eye problems Astigmatism Conjunctivitis Also known as “pink-eye” Description—can be acute or chronic; inflammation of the conjunctiva Pathogen can be viral or bacterial Symptoms- “bloodshot appearance”, pain, swelling, yellow discharge Treatment—antibiotic, proper hand washing • Description—cornea or lens has defective curve. This diffusion causes the light coming into the eye to be focused on more than one point of the retina. May cause double vision. • Treatment—surgery to correct lens or corrective glasses or contact lens
Macular Degeneration Leading cause of vision loss. Caused by deterioration of the central portion of the retina OPTIC NERVE The optic disc is a round area in the back of the eye where retinal nerve fibers collect to form the optic nerve. The optic disc is known as the blind spot because it contains no photoreceptors. CATARACT-clouding of the normally clear lens of your eye GLAUCOMA-Glaucoma is a disease that damages your eye’s optic nerve. It usually happens when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve This Photo by Unknown Author is licensed under CC BY-SA
Cones and Rods • Rods function in dim light, produce images in black and white • Cones function in bright light, produce images in color
Measuring Distance Acuity • Snellen eye charts • Alphabet, floating “E”s, pictures • Patient stands 20 feet away from chart • Start with right eye, establishes continuity • Record right eye, left eye, both eyes • Ishihara is the Color Vision Test
ECG/EKG • The oxygen-rich blood is circulated to the heart muscle through the coronary arteries. • There are two main arteries: • Right coronary artery • Left main coronary artery • both start at the aorta
In order to perform work, the heart needs oxygen and nutrients. • There are two main arteries: • Right coronary artery (RCA) • Left coronary artery (LCA). • The left coronary artery divides into: • Left anterior descending (LAD) branch • Left circumflex branch(LCX) • The right coronary artery and the branches of the left coronary artery provide numerous smaller branches which penetrate the heart muscle, supplying it with blood. • Both coronary arteries originate from the aorta and run along the surface of the heart. • In the majority of human hearts, coronary circulation follows a predictable pattern.
Left Main Coronary Artery Branches quickly into the LAD & LCX. Involves almost 2/3 of the heart muscle Right Coronary Artery (RCA)The RCA supplies blood to the bottom (inferior) portion and part of the back (posterior) portion of the left ventricle. The posterior portion of the septum is also supplied with blood from the RCA. • SA Node 55% • AV Node 90% • AV Blocks Left Anterior Descending Branch (LAD)The LAD supplies blood to the front (anterior) portion of the left ventricle, apical including most of the anterior portion of the septum separating the ventricles. • Bundle Branch Block, AMI, CHF Left Circumflux Branch (LCX)The LCX supplies blood to the left side (lateral) portion and the back (posterior) portion of the left ventricle. • SA Node 45% • AV Node 10% • Lateral & posterior MI
Anatomy of an EKG The EKG, or a measure of this electrical activity of the heart, is comprised of 3 primary parts... 1. P wave---electrical depolarization of the atria...contraction follows... 2. QRS COMPLEX---electrical depolarization of the ventricles...contraction follows... 3. T wave---electrical repolarization of the ventricles...and thus, relaxation...
The 12-Leads The 12-leads include: • 3 Limb leads (I, II, III) • 3 Augmented leads (aVR, aVL, aVF) • 6 Precordial leads (V1- V6)
Willem Einthoven-Dutch (1903) • Einthoven Triangle • Imaginary formation of three limb leads in a triangle using the two shoulders and pubis
Anatomy of a 12-Lead EKG (cont.) View of Posterior Heart Wall • Leads V1 & V2 • Tall R • ST Depression • View of Inferior Heart Wall • Leads II, III, aVF • Looks at inferior heart wall • Leads I and aVL • Looks at lateral heart wall • Looks from the left arm toward heart
The ST segment is probably the single most important element to identify on the ECG when looking for evidence of AMI ( Acute Myocardial infaction) • Ischemia • lack of oxygenation • ST depression or T inversion • Injury • prolonged ischemia • ST elevation • Infarct • death of tissue • may or may not show in Q wave
Hyperkalemia is an elevated concentration of the serum potassium higher than 5.5 mEq/L. • Hyperkalemia normally cause characteristic changes on the electrocardiogram, which are of vital importance to ensure a quick diagnosis and to estimate the the severity of the hyperkalemia. • Severe hyperkalemia is a life-threatening medical condition, for this reason, it is important to recognize its electrocardiographic findings .
If a person does not have nitroglycerin to put under his or her tongue before or during a heart attack use aspirin only.