Renal/Urinary System Flashcards
Functions of the renal system:
- Formation of urine
- Elimination of waste products
- Homeostasis of
- acid-base balance
- water balance
- electrolyte balance
- blood pressure regulation
- erythropoietin (RBC production)
- vitamin D activation
- glucogenesis
Describe the order that fluid moves through the kidneys:
Nephron Collecting duct Renal papillary duct Minor calyx Major calyx Renal pelvis Ureter Urinary bladder
What position are the kidneys in?
Upper, posterior abdominal wall (between T12-L3)
What are the kidneys protected by?
Thick outer fibrous capsule
Surrounded by fat
Lower ribs
Function of the ureters:
Drain urine from the kidneys to the bladder by peristalsis
Features of the ureters:
- Enter the bladder posteriorly
- Fibrous coat, muscular layer and inner lining of mucous membrane, which protects epithelial cells from the varying pH levels.
Function of the bladder:
The bladder is a reservoir for urine
Where is the bladder situated?
Situated in the pelvic cavity but extends into the abdominal cavity when full
Layers of the bladder:
- Outer layer of loose connective tissue
- 3 layers of smooth (detrusor) muscle and elastic fibres
- Inner and outer layers = longitudinal muscle fibres
- Middle layer = circular muscle fibres
What is the urethra?
A muscular (smooth muscle) tube carrying urine from the bladder and out of the body
What is the urethral junction?
At the urinary bladder, the urethral junction is a thickening of muscle acting as an internal sphincter to prevent bladder leakage.
Describe the external urethral sphincter:
The external urethral sphincter is striated muscle under voluntary control.
Describe the nephron:
A nephron is the functional unit of the kidneys that regulates substances in the blood by filtering it, reabsorbing what is needed, and excreting the rest as urine.
Describe the structure of a nephron:
For each nephron, an afferent arteriole flows into the glomerulus (which is a high-pressure capillary bed). Blood is filtered by the glomerulus to produce filtrate which is collected by the Bowman’s capsule, which surrounds the glomerulus.
Filtrate travels through the rest of the tubule to the proximal convoluted tubule (PCT), loop of Henle and distal convoluted tubule (DCT), before exiting the nephron into common collecting ducts shared by many nephrons.
Describe the renal arterioles:
The renal artery enters the kidney branching into renal arterioles.
An afferent arteriole enters the Bowman’s capsule of each nephron forming a capillary network (glomerulus). An efferent arteriole leaves the glomerulus and surrounds the rest of the nephron.
Features of the glomerular capillaries:
They are lined with fenestrated endothelium to aid filtration due to increased pores. They are leaky as they are 1000 times more permeable than other capillaries.
What are the 3 stages of urine formation?
Filtration, reabsorption and secretion
What is bladder capacity?
The amount of urine a bladder can hold
30mls x age + 30mls