Urinary System Flashcards
(15 cards)
Introduction of the urinary system
What?
The urinary system filters nitrogenous wastes from the blood and help regulate water, electrolyte and acid-base balances
How?
The kidneys filter blood in nephrons and secrete or reabsorb electrolytes under the direction of hormones
Why?
The kidneys are directly involved in maintaining proper blood pressure which is essential for delivering oxygen and nutrients to tissues and for proper filtration of blood by the kidneys themselves
The urinary system has a crucial role in maintaining homeostasis. The primary function is to produce urine as a waste product. It is the main excretory system of the body and consists of :
Kidneys (2) which produce and secrete urine
Ureters(2) convey urine from kidneys to urinary bladder
Urinary bladder collects and stores urine
Urethra through which urine leaves the human body
Why is the right kidney usually lower than the left?
The right kidney is 2-8cm lower than the left kidney because of the large liver which sits superior to it
Kidneys - general points
They are bean-shaped ( roughly oval with a median indentation- Hilum)
It’s approx 11x7x3cm and weigh 150g (adult) it’s held in position by a mass of fat (renal fat pad) Renal fascia encapsulates them (fibrous connective tissue) They receive +_ 20% of the cardiac output. As they need a high blood flow for filtration rather than metabolic demand
Kidneys : internal anatomy
Includes renal cortex, renal medulla , renal pyramids, renal papilla, renal pelvis and calyx
Nephron function
The functional unit of the kidney is called the nephron.
Kidneys : formation of the urine
3 major renal processes
- Glomelular filtration : water and solutes smaller than proteins are forced through the capillary walls and pores of the glomerular capsule into the renal tubule
- Tubular reabsorption: water, glucose, amino acids and needed irons are transported out of the filtrate into tubule cells then enter the capillary blood
- tubular secretion : H+, K+, creatinine and drugs are removed from the peritubular blood and secreted by the tubule cells into the filtrate
Ureters
2 slender tubes carrying urine from the kidneys ( renal pelvis) to the urinal bladder
It’s length is 25 to 35cm (adult) diameter 6mm
It’s got 3 layers of tissue :
Outer covering of fibrous tissue
Middle layer of muscle tissue
Inner layer of epithelial mucosa
How does urine reach the bladder when lying down or standing on their head?
When you are lying down or feet are raised up, fluid is absorbed into your blood stream and removed by your kidney. This increases the need to urinate at night
Urinary bladder
Pear shaped reservoir for urine lying in the pelvic cavity
Size and shape vary depending on volume of urine
When distended( or bloated) bladder rises into abdominal cavity
Ureters empty urine into the bladder
Opens into the urethra at its lowest point/neck
In women, it sits in front of the uterus and in men, it rests on the prostate
Urethra
Female urethra :
4cm long
Lies in front of the anterior wall of vagina
Opening located between the clitoris and vaginal opening
Male urethra :
18-20cm long
Used for both reproductive and urinary systems
Prostrate gland surrounds urethra near neck of the bladder
Urethral glands produce mucous for lubrication during sexual intercourse
Summary of the urinary system functions
Body water regulation Electrolyte regulation Acid-base regulation Excretion of metabolic waste products Regulation of blood pressure Production of renal erythropoietic factor and vitamin D
Developmental aspects - urinary system
Functional kidneys formed and excreting urine by the 3rd month of fetal life ( although exchanges with the mother’s blood through the placenta allow her system to clear waste products from the fetal blood)
Many possible congenital abnormalities; most common: poly cystic kidney and hypospadias
A newborn baby voids 5-40 times per day depending on fluid intake
By 2 months of age , the infant voids approx 400mls of urine per day and the amount steadily increases until adolescence when adult urine output is achieved (>0.5ml/kg/h)
Control of the voluntary urethral sphincter linked to the nervous system development: By 15 months, most toddlers are aware when they have voided. By 18 months they can hold urine in their bladder for about 2 hours. Complete night time control usually does not occur before the child is 4 years old.
During childhood and through late middle age, most urinary system problems are infectious or inflammatory conditions.
Kidney size and function progressively decline with ageing. By age 70:
Rate of filtrate formation is only about half of the middle-aged adult
Bladder shrinkage and loss of bladder tone, causing many elderly individuals to experience urgency and frequency
Nocturia and urinary retention are also common
Urinary system - assessment and urinary elimination patterns
Route : via urethra , use of assistive devices ( catheter, ureterostomy) ; dialysis: peritoneal catheter; haemodialysis : arteriovenous fistula
Character of urine: amount, colour, dilute, concentrated , timing, odour, pH, frothy, sediment, pyuria, haematuria, albuminuria, proteinuria, ketouria
Voiding pattern: frequency, urgency, hesitancy, dysuria, nocturia, oliguria, Anuria, change in stream , enuresis, back pain, polyuria
Urinary control: continence, retention, incontinence, stress incontinence, bladder distension
Fluid balance: positive/ negative ( intake/ output) , weight gain, presence of oedema
Urinary assessment
Urinalysis Glucose Bilirubin Ketones Specific gravity Blood pH Protein Urobilinogen White blood cells
Other urinary system assessments
Blood tests( creatinine, urea and electrolytes, GFR) Plain abdominal x ray Ultrasound scan Doppler ultrasound of renal vessels Intravenous urography CT urogram Angiography/ CT or MRI angiography Isotope scan Renal biopsy
