Download Aging of the Urinary Tract: Aging of the Prostate

Aging of the Urinary Tract:
Kidney
Lower 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)
Renal Glomerulus
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.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
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)
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 affarent 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
Hypothalamus, Posterior Hypophysis, and their Hormones
Hypothalamus
Posterior
Hypophysis
Vasopressin
Antidiuretic
Hormone (ADH)
renal
collecting
ducts
Oxytocin
mammary
gland
smooth
muscles
of uterus
Figure 19-2
Table 19-2
Common Renal Problems in the Elderly
Renal Failure
Impaired drug excretion
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:
Loss of body fluids
Inadequate fluid intake
Surgical shock or myocardial infarction
RENAL:
Drug toxicity
Immune reactions
Infectious diseases
Thrombosis
POST-RENAL:
Urinary tract obstruction
Table 19-6
Drugs and the Aging Kidneys
Questions:
Is the drug excreted primarily by the kidney?
How competent are the kidneys?
What are the side-effects?
What are the consequences of drug toxicity when the kidney
is impaired?
Etiopathology of Renal Drug Toxicity:
High renal blood flow
Increased drug concentration and accumulation in kidney
Increased hepatic enzyme inhibition in the elderly
Increased autoimmune disorders in the elderly
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
• Sphincters: Internal (involuntary; smooth muscle) and external
(voluntary to some degree; skeletal muscle)
Ta ble 19 - 10 Ne ural Cont rol of M ict urition
Parasym pathetic
Nerves
(Cholinergic)
Sympathetic
Nerves
(Adrenergic)
Somatic Nerves
Detrus or
(smooth muscle)
Contraction
+++
Relaxation
+
No ef f ect
Internal sphincter
(smooth muscle)
No ef f ect
Contraction
++
No ef f ect
Externa l sphincter
(striated muscle)
No ef f ect
No ef f ect
Relaxation
++
Muscle (Ty pe)
Figure 19-5
Figure 19-6
Table 19-7
Physiologic Requirements for Continence
Motivation to be continent
Adequate mobility and dexterity
Normal lower urinary tract function
Adequate cognitive function
Table 19-7
Physiologic Requirements for Continence
Storage:
No involuntary bladder contractions
Appropriate bladder sensation
Closed bladder outlet
Low pressure accommodation of urine
Table 19-7
Physiologic Requirements for Continence
Emptying:
Normal bladder contraction
Lack of anatomic obstruction
Coordinated sphincter relaxation & bladder contraction
Absence of environmental/iatrogenic barriers
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
Table 19-9 Management of Urinary Incontinence
Type
Management
Stress
Exercises
Alpha- adrenergic agonists
Estrogen
Surgery
•Weakness of pelvic muscles
Urge
Bladder relaxants
•Inability to avoid voiding when bladder full Surgery
Overflow
• overdistended, non-contractile blood
Functional
• cognitive, emotional problems
alpha- adrenergic antagonists
Catheterization
Habit training
Scheduled toileting
Hygienic devices