Today: May 1, 2006 Aging of the Urinary tract Aging of the Lung Aging of the GI tract

Aging of the Urinary Tract

Nephron & Renal Circulation

Table 19-1 Major Functions of the Kidney Water and electrolyte regulation Metabolic products excretion Hydrogen ion excretion and maintenance of blood pH Endocrine functions: Renin-angiotensin secretion (blood pressure) Vitamin D activation (Ca ++ metabolism) Erythropoietin secretion (hematopoiesis)

2. Renal Tubules divided into: Proximal Tubule, mostly reabsorption of water & solutes Loop of Henle, mostly reabsorption of water & salt Distal Tubule, mostly water & salt (under influence of aldosterone) reabsorption and acidification of urine Collecting Duct, water reabsorption under the influence of ADH (antidiuretic hormone from posterior pituitary) 1. Glomerulus: Tufts of capillaries between afferent and efferent renal arterioles. Filtration is through a fenestrated endothelium separated from the basal membrane by podocytes. Filtrate is the same as plasma but without proteins.

Distal and Collecting Tubules function is regulated by ADH (antidiuretic hormone) secreted by neuroendocrine hypothalamus stored and released from the posterior pituitary Juxtaglomerular Apparatus : located between afferent artery and distal tubule secretes the enzyme renin renin acts on the liver protein angiotensinogen to form angiotensin I, and angiotensin is transformed into angiotensin II in the lungs angiotensin II is a very potent hypertensive substance; it also stimulates the release of aldosterone from the adrenal cortex Regulation of Kidney function:

Hypothalamus, Posterior Hypophysis, and their Hormones Hypothalamus

Table 19-2 Common Renal Problems in the Elderly Renal Failure Impaired drug excretion ( Think about kidney when giving a drug) Urinary tract infections Hypertension Miscellaneous disorders: Tuberculosis Nephritis Diabetes, etc.

Table 19-3 Some Signs of Renal Failure Generalized edema Acidosis Increased circulating non-protein nitrogen (urea) Increased circulating urinary retention products (e.g. creatinine, uric acid)

Table 19-4 Selected Causes of Acute Renal Failure PRE-RENAL: (problems BEFORE the kidney) Loss of body fluids Inadequate fluid intake Surgical shock or myocardial infarction RENAL: (problems IN the kidney) Drug toxicity ( Think about kidney when giving a drug) Immune reactions Infectious diseases Thrombosis POST-RENAL: (problems AFTER the kidney) Urinary tract obstruction

Functions of the bladder Filling with urine from the kidneys Micturition: emptying of bladder by muscle contraction and opening of sphincters. Principle muscle: Detrusor muscle (bladder’s body): when it contracts, the bladder empties Sphincters: Internal (involuntary; smooth muscle) and external (voluntary to some degree; skeletal muscle)

For Micturition: 1. Internal and external sphincters have to relax 2. Bladder has to contract (detrosor muscle)

Storage: Table 19-7 Physiologic Requirements for Continence No involuntary bladder contractions Appropriate bladder sensation Closed bladder outlet Low pressure accommodation of urine Motivation to be continent Adequate cognitive function Adequate mobility and dexterity Normal lower urinary tract function

Emptying: Table 19-7 Physiologic Requirements for Continence Normal bladder contraction Lack of anatomic obstruction Coordinated sphincter relaxation & bladder contraction Absence of environmental/iatrogenic barriers

Figure 19-6: Mnemonic device for causes of acute urinary incontinence

Table 19-8 Age-Related Changes Contributing to Incontinence In Females Estrogen deficiency Weak pelvic floor and bladder outlet Decreased urethral muscle tone Atrophic vaginitis In Males Increased prostatic size Impaired urinary flow Urinary retention Detrusor muscle instability

Weakness of pelvic muscles Inability to avoid voiding when bladder full overdistended, non-contractile blood cognitive, emotional problems

Questions What are the major parts of the kidney and what control mechanisms act at each part? What are the muscles involved in micturition? What are the requirements for continence? What are some causes of incontinence? How might these be treated?

Aging and the Lung Functions of the Lung: Regulation of gaseous exchange Immunologic defenses of the body -by phagocytizing particles from inspired air & blood Metabolic functions -by synthesizing, storing or releasing into blood substances like surfactant and prostaglandins Endocrine functions -by transforming angiotensin I into angiotensin II (vasoconstrictor and stimulus for aldosterone secretion)

Two lungs activate gas exchange Chest wall Respiratory muscles Regulation of respiration by CNS centers & nerve tracts Activate ventilation Box 18.1 Pulmonary Respiratory System: Structure

Lung, “Battered” Organ Due to: Air pollution Smoking Air borne infections Oxygen toxicity (e.g. with the use of respirators there is increased free radical production; therefore, simultaneous administration of antioxidants is recommended)

Major Structural Changes in the Alveolar Ducts & Alveoli with Age Amount of elastic tissue Amount of fibrous tissue

TABLE 18-2 Changes with Aging in Respiratory Muscles Muscle strength fatigue when work of breathing (as during physical exercise) Atrophy of some respiratory muscles (primarily Type I muscle fibers of slow, red muscles as in long muscles of back, shoulders) Ratio of glycolytic (anaerobic) to oxidative (aerobic) metabolism Blood supply to muscle

Morphologic ChangesFunctional Consequences * * Tidal Volume: Amount of in and out air moving out of lungs with quiet inspiration/expiration

LUNG Table 18-3 Changes with Age in the Lung Morphological ChangesFunctional Significance ** * * Dead Space: Air in the air ways ** Vital Capacity (VC): Greatest amount of air expired after maximal inspiration ** Reserve Volume (RV)/Total Lung Capacity (TLC)

Table 18-1 Signs of Impaired Pulmonary Respiration with Aging Reduced maximum breathing capacity Less efficient emptying of the lungs Premature airway closure Progressive reduction in blood oxygenation and in PO 2 exchanges between blood and alveolar air Loss of elastic recoil (i.e. springing back of elastic fibers after stretching) Increased rigidity of internal lung structure Weakening of respiratory muscles Decreased elasticity of thorax cage and chest wall Earlier and easier fatigability

Chronic Obstructive Pulmonary Disease (COPD) Comprised of three distinct pathologies: Chronic bronchitis: inflammation of the bronchi and accompanied by hypersecretion of mucus & cough Emphysema: characterized by enlargement of air spaces, destruction of lung parenchyma, loss of lung elasticity and closure of small airways Chronic asthma: constriction of the bronchi

TABLE 18-4 Major Risk Factors for Chronic Obstructive Pulmonary Disease (COPD) Cigarette smoking Air pollution Genetic factors Bronchial inflammation Chronic respiratory tract infections Old age Family history of COPD Male sex

TABLE 18-5 Major Signs of Chronic Obstructive Pulmonary Disease (COPD) Structural Diffuse distention & over- aeration of alveoli Disruption of interalveolar septa Loss of pulmonary elasticity Restructuring of alveoli Increased lung volume Barrel-shaped chest Pathophysiologic Disturbed ventilation Altered air and blood flow Frequently partial obstruction of bronchi Wheezing & more work required for breathing Resulting hypoxia (low O 2 levels) and hypercapnia (high CO 2 levels) Chronic productive cough with mucus Minor respiratory infections

Table 18-6 (con’t.) Therapeutic strategies: 1. Administration of pharmacological agents (bronchodilators, mucus liquefiers, anti-inflammatory agents, protease inhibitors, antibiotics) 2. Administration of O 2 to be used cautiously to prevent acidosis 3. Optimizing function by: -physical exercise to strengthen abdominal muscles and diaphragm to aid in lung ventilation -meeting social, emotional and vocational needs. -use of respiratory aids in the form or aerosols, sprays, etc.

Hematological Profile of Some Older Individuals Hemoglobin Hematocrit RBC number Onset of erythropoiesis after severe bleeding Erythropoietic responses to erythropoietin administration Most of these changes are NOT experienced by centenarians Oxygen delivery to the tissues is NOT solely dependent on the lungs and those changes, but also on changes in the blood!

Reticulocytes are immature red blood cells. If someone is anemic, you can look at their reticulocyte count to figure out if the problem is that they are breaking down too many red blood cells or if the problem is that they can’t make new ones for many reasons (erythropoiesis). If increased reticulocyte count, that means that the body is destroying mature red blood cells, but not having trouble making new ones. If there are very few reticulocytes, it means that the person is anemic because it can’t make new ones (because of nutrient problems or hormone problems.

Questions What are the major changes in the lung with aging (think structure and function) What else is responsible for oxygen delivery other than the lungs? What are some of the changes in the hematologic (blood) system with aging?

Table 20-1 Major Functions of the Gastrointestinal System Digestion: chemical (enzymes) and mechanical (teeth, muscles) food breakdown into small units that can be absorbed by the intestinal epithelium Absorption: active or passive transfer of substances from the GI tract to blood & extracellular spaces Motility: smooth muscle contraction and relaxation regulate digestion & movement of GI content along tract Secretion: synthesis and release of hormones, enzymes, chemical mediators, mucus, intrinsic factor Aging and the GI tract

Aging of Teeth pgs Yellowish brown discoloration (from staining by beverages, tobacco, bacteria) Recession of pulp from crown Narrowing of root canal Roots become brittle and fracture easily Odontoblasts (secrete dentin) become irregular and discontinuous Pulp calcification Osteoporosis of mandibular and maxillary bones contributing to tooth loss Gum recession and infection (peridontitis)

Disturbance of Deglutition pg. 363 Dysphagia (disturbance of swallowing of food) maybe associated with: Increased incidence of non-peristaltic contraction Failure lower esophageal sphincter to relax Reduced amplitude of peristaltic contractions

Major Functions of the Stomach Food reservoir Digestion of food Secretion of gastric juice with digestive enzyme, mucus, hydrochloric acid Secretion of hormones gastrin, glucagon, somatostatin, vasoactive intestinal polypeptide (VIP) Secretion of intrinsic factor –necessary for Vitamin B12 absorption & maturation of RBCs

Vasoactive Intestinal Polypeptide (VIP) Stimulates intestinal secretion of water & electrolytes Relaxes intestinal smooth muscle (including sphincters) Inhibit gastric acid secretion Dilates peripheral blood vessels

Figure 20-2 Changes in Gastric Secretion with Age

Table 20-4 Important Factors for the Maintenance of Optimal Small Intestinal Function Anatomic integrity Normal gastrointestinal secretions. Coordinated gastrointestinal motility, Normal intestinal transport Adequate intestinal blood supply Normal defense mechanisms against toxic injurious agents (bacteria, injury, drugs)

Decreased intestinal absorption with aging Changes in villus shape Increase of collagen Mitochondrial changes Prolonged replication time of cells Decreased villus motility Inadequate blood supply (atherosclerosis) Impaired water barrier restricting diffusion and transport Permeability changes

Table 20-3 Mechanisms of Decreased Intestinal Calcium Absorption with Aging intake of Vitamin D (poor nutrition) Vitamin D conversion in skin (reduced sunlight exposure) intestinal absorption Vitamin D metabolism (hepatic) and activation (renal) cellular calcium binding (decreased receptors)

Major Liver Functions Bile formation Carbohydrate storage and metabolism Regulation of lipid metabolism Manufacture of plasma protein Urea formation Ketone body formation Metabolism of steroid & polypeptide hormones Detoxification of many drugs and toxins

Aging of Liver pg. 370 Atrophy after 60 years and greater after 80 years Cell size variable Increased collagen Alteration in hepatic cell degeneration/ regeneration cycle Alteration in mitochondrial number Decrease in endoplasic reticulum and ability to metabolize drugs

Major Functions of the Bile Emulsification of lipids Activation of enzymes for digestion of lipids Excretion of cholesterol Conjugation of bilirubin to water soluble products Neutralization of acid delivered to duodenum from stomach Excretion of drugs, heavy metals, environmental toxins

Questions What are the major functions of the GI tract? What are the major changes in the GI tract with aging? (Try to think of one from different parts of the GI tract)