11/21/2014 How the Body Ages: Some Normal Changes1/4How the Body Ages: Some Normal ChangesWhatHappens?Why?Mental functionDifficultyrememberingor coming upwith the rightwordDifficultyconcentratingDifficultylearning newmaterialThe nerve cells in the brain release different amounts of some chemicalmessengers (which send impulses from cell to cell), and the number ofreceptors on nerve cells may decrease. Thus, the brain does not send orprocess impulse as well or as quickly.Physical activityUnsteadinessor loss ofbalanceStructures in the inner ear that help with balance stiffen and deteriorateslightly.The part of the brain that controls balance (cerebellum) may degenerate.Dizziness orlight-headednesswhen standingThe heart does not pump enough blood to the head because the heart isless able to respond to changes in position.The nervous system signals the heart to increase blood flow less effectively.The blood vessels do not constrict enough to maintain normal bloodpressure when a person stands.Loss of musclestrengthThe number and size of muscle fibers decrease.The body produces less growth hormone and (in men) less testosterone,which help maintain muscles.DifficultymovingLess flexibilityLess joint fluid is produced.The cartilage between bones in joints becomes stiffer and may erode.Tendons and ligaments become stiffer and weaker.Muscle tissue is lost, replaced by fatty or fibrous tissue, decreasing strength11/21/2014 How the Body Ages: Some Normal Changes2/4and making muscles stiffer.DifficultyexercisingstrenuouslyThe heart cannot keep up with the demand for more blood during exercise.It cannot speed up as quickly or pump as fast as it used to, partly becausethe heart and blood vessels become stiffer and less elastic. Also, the heartdoes not respond as quickly or as well to chemical messengers thatnormally stimulate it to speed up.The lungs cannot keep up with the demand for oxygen during exercise.Less air is taken in with each breath, and the lungs do not absorb as muchoxygen.The sensesNeed forreadingglassesThe lens of the eye stiffens, making focusing on close objects more difficult.Difficultyseeing in dimlightThe retina of the eye becomes less sensitive to light.The lens of the eye becomes less transparent.Difficultyadjusting tochanges inlight levelsThe pupils react more slowly to changes in light.Darkened areas in the lens of the eye increase glare.Dry eyes The number of cells that produce fluids to lubricate the eyes decreases.The tear glands produce fewer tears.DifficultyunderstandingwordsAge-related hearing loss (presbycusis) develops, which often affects mainlyhigh frequencies (which include consonantsthe sounds that help peopleidentify words).Loss of hearing Age-related hearing loss (presbycusis) develops.Earwax accumulates.Loss of taste Taste buds become less sensitive.People detect odors less well because the lining of the nose becomesthinner and drier and the nerve endings in the nose deteriorate.11/21/2014 How the Body Ages: Some Normal Changes3/4Dry mouth Less saliva is produced.Eating problemsDifficultyswallowingThe mouth is dry.The muscles involved in swallowing weaken, and coordination is impaired.People may not chew food enough because teeth are missing or denturesdo not fit well. Then, chunks of food are too large to swallow.The bones at the top of the spine change, tipping the head forward and thuscompressing the throat.Disinterest ineatingTaste decreases, making food less appetizing.Smell decreases, making food less appetizing.The mouth is dry, leading to loss of taste.Chewing may be difficult because teeth are missing, jaw muscles are weak,or dentures do not fit well.Swallowing is difficult.Skin and hairWrinklesMore tears inthe skinThe fat layer under the skin, which acts as a cushion, thins.The body produces less collagen and elastin, which make the skin toughand elastic.Dry skin Glands in the skin produce less oil.Bruises andbroken bloodvesselsBlood vessels in the skin become more fragile.Slow healing ofwoundsThe number of blood vessels in the skin decreases.Cells responsible for healing wounds act more slowly and decrease innumberDifficultyadjusting tochanges intemperatureThe fat layer under the skin, which helps conserve body heat, thins.The number of sweat glands decrease, and the sweat glands produce lesssweat. Sweat helps cool the body.11/21/2014 How the Body Ages: Some Normal Changes4/4The number of blood vessels decreases, and blood flow in the deep layersof the skin decreases. As a result, the body cannot remove heat from bodyas well.Decreasedsensation andsensitivity topainThe number of nerve endings in the skin decreases.Gray or whitehairThe hair follicles produce less pigment (melanin).Thinning orloss of hairHairs, which must be replaced periodically, grow more slowly, and somehair follicles stop producing new hair.Sexual functionDryness of thevaginaLess estrogen is produced.Erections thatdo not last aslong, are lessrigid, or takemore timeLess testosterone is produced.Blood flow to the penis decreases.Copyright 2009-2014 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Whitehouse Station, N.J., U.S.A.PrivacyTerms of UsePermissions