Renal Pt1 Flashcards
Kidneys’ Primary Function
Maintain a stable internal environment for optimal cell and tissue metabolism.
7 ways Kidneys maintain homeostasis
- Electrolyte homeostasis
- Regulation of blood pH
- Regulation of Blood Volume/Blood Pressure
- Osmoregulation
- Hormones Produced by the Kidney
- Excretion of wastes
- Performs gluconeogenesis
Which electrolytes are regulated by the kidneys to maintain homeostasis
Na+, K+, Ca2+, Cl-, HPO42-
Regulation of blood pH by kidneys
1) Removes H+ from blood
2) maintains bicarbonate ions (HCO3-) in blood
Regulation of Blood Volume/Blood Pressure
by kidneys
1) Retention of water = increases BP
2) Elimination of water = decreases BP
Osmoregulation
at 300mOsm/L
Hormones Produced by the Kidney
1) Calcitriol - form of Vitamin D
calcium homeostasis
2) Erythropoietin - RBC production
3) Renin – Blood pressure regulation
Excretion of Wastes
of kidneys
1) Ammonia & Urea (protein metabolism)
2) Bilirubin
3) Creatinine (waste product of creatine phosphate)
4) Uric Acid (purine metabolism – A’s & G’s of DNA)
3) Drugs & toxins
Performs gluconeogenesis
Synthesis of glucose from amino acids
Renal capsule
Tightly adhering capsule covers kidney
Adipose capsule
Fat capsule surrounds each kidney
Renal fascia
Fibrous tissue attaches/suspends kidney
to the posterior abdominal wall
Hilum
Medial indentation where the renal blood vessels, nerves, lymphatic vessels, and ureter enter and exit the kidneys.
Renal cortex
*cortex means outer layer
1) Is the outer layer of each kidney.
2) Contains all of the glomeruli, most of the proximal tubules, and some segments of the distal tubule.
Renal columns
Extend from the cortex down between the renal pyramids.
Renal medulla
1) inner part of each kidney that contains tubules and the collecting duct.
2) Consists of regions called the pyramids.
Minor calyx
1) Receives urine from the collecting ducts through the renal papilla.
2) Apexes of the pyramids project into a cup-shaped cavity that join together to form a major calyx
Major calyx
Joins to form the renal pelvis.
Renal pelvis
Joins the proximal end of the ureter.
A dilated renal pelvis equates to what physiological problem with the kidneys
Hydronephrosis
General location of kidneys
- Left kidney sits higher because Oliver
- Located retroperitoneal at T1 - L3
Protection of kidneys
1) Posteriorly by 11th and 12th rib as well as adipose tissue
2) Anteriorly by adrenal gland and transverse colon
Characteristics of Ureters
1) Are 30 cm long.
2) Are long, intertwining smooth muscle bundles.
3) Pass obliquely into the posterior aspect of the bladder.
4) Peristaltic activity moves urine to the bladder.
5) Micturition compresses the lower end of the ureter to avoid urine reflux.
Bladder Tissue includes?
1) Detrusor muscle (wall)
2) Trigone
3) Transitional epithelium
Characteristics of Urethra
1) Internal urethral sphincter - involuntary (Smooth muscle @ jct. of bladder & urethra)
2) External urethral sphincter (voluntary)
Striated skeletal muscle
3) Between 3 and 4 cm long in females
4) Between 18 and 20 cm long in males
Control of Micturition or urination (voiding) by brain
when volume exceeds 250-300 mL Stretch receptors signal spinal cord and brain
Micturition center in sacral spinal cord triggers reflex:
1) parasympathetic fibers cause detrusor muscle to contract – squeezes out urine and
2) Internal & external sphincter muscles to relax to allow flow
Filling initiates a desire to urinate before the reflex actually occurs
1) conscious control of external sphincter
2) cerebral cortex can initiate micturition or delay it for a limited period of time
Blood flow through the Kidney
Renal arteries»_space;> Segmental arteries »_space;> Interlobar arteries »_space;> Arcuate arteries»_space;> Interlobular arteries »_space;> Afferent arterioles»_space;> Glomerular capillaries»_space;> Efferent arterioles»_space;> Peritubular capillaries »_space;> Vasa recta
Renal arteries
Supply blood to the kidneys
Segmental arteries
branches of the renal artery
Interlobar arteries
Travel between the pyramids
Arcuate arteries
Arch over the base of the pyramids
Interlobular arteries
extend through the cortex toward the periphery of the kidneys and supply the afferent glomerular arterioles.
Afferent arterioles
supply glomerular capillaries
Glomerular capillaries
site of filtration
Efferent arterioles
Convey blood to a second capillary bed
Peritubular capillaries
Surround the proximal and distal convoluted tubules and loop of Henle
Vasa recta
1) Is a network of capillaries for the juxtamedullary nephrons.
2) Influences osmolar concentration of the medullary extracellular fluid, which is important for the formation of a concentrated urine.
Process of Micturition
1) Reflex arc is required for micturition
2) Is stimulated by mechanoreceptors from stretching
3) Bladder fullness is sensed; impulses are sent to the sacral level of the spinal cord
4) When the bladder accumulates 250 to
300 ml of urine, the bladder contracts and the internal urethral sphincter relaxes from activation of the spinal reflex arc (micturition reflex)
5) At this time, the urge to void is felt
6) In older children and adults, reflex can be inhibited or facilitated by impulses coming from brain or voluntary control of micturition
*Mass of kidneys compares to amount of blood received
*Kidneys are less than 0.5% of total body mass, but receive 20-25% of resting cardiac output
Nephron Characteristics
1) 1.2 million per kidney
2) The functional unit of the kidney
3) Contains Superficial cortical nephrons and Juxtamedullary nephrons
Superficial cortical nephrons
Make up 85% of all nephrons, which extend partially into the medulla
Juxtamedullary nephrons
1) Lie close to and extend deep into the medulla and are important for the process of concentrating urine
2) secrete renin
Glomerular filtration
Water & small solutes in blood plasma move across the wall of the glomerular capillaries into glomerular capsule and then renal tubules (PCT –> loop of Henle –> DCT –> Collecting duct)
Tubular reabsorption
As “filtrate” moves along tubule water and many useful solutes reabsorbed = returned to blood
Tubular secretion
“Filtrate” moves along tubule other molecules (wastes, drugs, & excess ions) are secreted into fluid
What happens to Any solutes that remain in the fluid that drains into the renal pelvis
They are excreted as urine
PTH role
PTH stim.s reabsorption of Ca++
Intercalated Cells
Regulates of pH via H+ & HCO3-
Principal cells
regulate ADH and aldosterone
Brush border microvilli
Involved in reabsorption