Chapter 25- The urinary system Flashcards
How much fluid does the kidneys filter per day?
200 liters of fluid filtered from blood by kidneys every single day. The kidneys are responsible for maintaining the composition of the body’s extracellular fluids by filtering the blood.
Functions of the kidneys (5)
- Regulate total body water volume and concentration of solutes in water
- Regulate concentration of ions in ECF
- Acid base balance
- Remove toxins, metabolic waste, and other foreign substances
- Hormone production- EPO and renin
Location of the kidneys
Each kidney lies between the parietal peritoneum and dorsal body wall. Kidneys are retroperitoneal organs- during fetal development, they move behind the parietal peritoneum. Extend from T12- L3
Medial portion of the kidneys
Medial portion is concave. Also contains the renal hilum- ureters, renal blood vessels, lymphatics, and renal nerve supply enter here
Where are the adrenal glands located?
Adrenal gland sits immediately superior to each kidney. Not associated with the function of the kidneys, however, if something affects the kidneys, it will usually affect the adrenal glands
Supporting external structures of the kidneys include (3)
- Renal fascia
- Perineal fat capsule
- Fibrous capsule
Renal fascia
Dense connective tissue. Function- anchors kidneys to surrounding structures
Perineal fat capsule
Fat mass surrounding kidneys. Function- cushions kidneys from physical trauma- kidneys not protected by rib cage like some other organs
Fibrous capsule
Thin, transparent capsule. Function- prevents disease from spreading to kidneys from other parts of the body
3 major internal regions of kidneys
- Renal cortex
- Renal medulla
- Renal pelvis
Renal cortex
Function- provides area for glomerular capillaries and blood vessel passage, EPO produced here. All cells responsible for EPO production are found in the cortex
Renal medulla
Contains renal pyramids- packed with capillaries and urine collecting tubules. There are 7 renal pyramids separated by renal columns
Kidney lobe
Consists of the renal pyramid and surrounding columns
Renal pelvis
Funnel shaped tube continuous with ureters. The pelvis branches to form major calyces (calyx), which lead into minor calyces. The function of renal calyces is urine collection and emptying into pelvis
How much blood goes to the kidney per minute
1200 ml
Renal arteries (4)
- Segmental arteries (5)
- Interlobar arteries- travel between kidney lobes
- Arcuate arteries- arch over bases of pyramids
- Cortical radiate arteries- supply cortical tissue
Renal veins (5)
Renal veins trace arterial blood supply.
- Cortical radiate veins
- Arcuate veins
- Interlobar veins
- Renal veins
- Segmental veins aren’t really referenced
Renal plexus
Autonomic nerve fibers and ganglia- sympathetic vasomotor fibers regulate blood supply to each kidney
Sympathetic nervous system function in the kidneys
Sympathetic vasomotor fibers regulate blood supply to each kidney. Function- adjusts diameter of renal arterioles, influences nephron activity. More blood is directed to kidneys in response to excess water- this is how blood vessel diameter affects urine formation. During times of stress, blood flow to the kidneys decreases so it can be diverted to other areas of the body- we don’t need to be making urine during a dangerous/stressful situation.
Nephron
The nephron is the functional unit of the kidney. Function- responsible for forming filtrate and eventually urine in the kidneys
Filtration definition
The mass movement of solutes and water from the plasma into the renal corpuscle and renal tubules. Remember- the kidneys filter blood
Reabsorption definition
The process by which nephrons remove water and solutes from the filtrate formed from filtration and return it to the blood. 99% of filtrate is reabsorbed by the body.
Secretion definition
Process by which excess ions and waste that have been reabsorbed are now put back into the filtrate. Filtration and reabsorption are passive processes, so some things are naturally reabsorbed- they need to be put back in the filtrate so they can actually be gotten rid of
Each nephron contains (2 structures)
- Renal corpuscle
2. Renal tubule