The Renal System Flashcards
What makes up the renal system?
2 Kidneys
2 Ureters
Urinary bladder
Urethra
What are the function of the kidneys?
Maintaining homeostasis within the internal environment, by regulation of the volume and composition of body fluids
What is Homeostasis?
A self-regulating process by which a living organism can maintain internal stability while adjusting to changing external conditions
What are the key functions of the kidneys?
Elimination, regulation and secretion
What other functions do the kidneys have?
Waste/ balance
Blood pressure
red blood cells
vitamin D
What is renin?
An important enzyme in the control of blood pressure
What is erythropoietin?
A hormone that stimulates the production of red blood cells
Where are the kidneys?
They are on the posterior wall of the abdominal cavity: one on each side of the vertebral column at the level of thoracic and lumbar vertebrae
How much of the cardiac output do the kidneys get?
25%
What sits on the top of each kidney?
An adrenal gland
How big is a kidney?
10cm long
6.5cm wide
3cm thick
weighs about 100-120g each
Where do they kidneys get their blood supply?
The blood supply is from the aorta via the renal artery and returns to the vena cava via the renal vein
What is the medulla?
The inner region of the kidney that is divided into approximately 12 pyramids, containing bundles of tubules.
How is urine carried?
Urine is carried from the renal pelvis to the urinary bladder via the ureter
What is a nephron?
It’s the basic functional unit of the kidney. More than 1 million nephrons per kidney
What are the 3 stages of the renal system?
Filtration
Reabsorption
Secretion
Why are glucose and amino acids not common in urine?
These substances are completely reabsorbed
What do the ureters do?
The ureters transport urine to the bladder by peristalsis
What happens to the bladder when it fills with urine?
The walls distend and it becomes a globular shape. Its capacity is approx 500-600mls although can hold more. It expands upwards and outwards when full and into the abdomen
What lies anterior to the bladder?
Pubic bone separated by a space filled with fatty tissue
What lies posterior to the bladder?
Cervix and ureters
What lies lateral to the bladder?
Lateral ligaments of the bladder and side walls of the pelvis
What lies superior to the bladder?
Body of uterus and intestines
What lies inferior to the bladder?
Upper half of anterior vaginal wall and levator ani muscles
What factors inhibit urine production?
Sleep and muscular activity
What causes the structural and functional changes in the renal system?
the effects of progesterone on smooth muscle
the pressure of enlarging uterus
cardiovascular changes
Describe the physiological changes in the bladder
As the uterus enlarges, the urinary bladder is displaced upward and fattened in the anterior- posterior position. Bladder vascularity increases and muscle tone decreases increasing capacity up to 1000 mls. Trigone elevation occurs with the increase of vascular tortuousity. The muscosa also becomes oedematous and is more vulnerable to trauma and infection. The decrease in bladder tone leads to incompetence of the junction between ureter and bladder, and there may be reflux or urine from bladder to ureters or kidneys
What hormone is involved in the relaxation of bladder smooth muscle?
Progesterone
What is renal haemodynamic?
Flow of blood within the kidneys
How much does renal blood flow increase during pregnancy?
It increases by 35-60% by the end of the first trimester, which then decreases slightly until term. Due to the increased blood volume and cardiac output
Describe postpartum changes?
Rapid and sustained loss of sodium and major diuresis during postpartum period (typically between 2nd and 5th day)
Women should pass urine 6-8 hours after birth
Urine output rises to up to 3000ml, with 500-1000 mls voided at any micturition. By the end of 1st week, urinary excretion of calcium, phosphate, vitamins, glucose return to normal.
Structural changes may take up to three months to disappear, although for most women, these are complete by 6-8 weeks
