Lecture one Flashcards
The kidneys perform a variety of functions aimed at maintaining
homeostasis
How do the kidneys maintain homeostasis
- Maintaining stable volume, electrolyte composition, and osmolarity (solute concentration) of the ECF
- Maintain water and electrolyte balance within the narrow range
- Adjust for variations in ingestion of water, salt, and other electrolytes, but also adjust urinary output of these ECF constituents
To maintain homeostasis, urine
composition varies greatly
Other kidney homeostasis mechanisms
- Eliminate the ECF surplus water or a particular electrolyte in the urine
- Can limit urinary losses of the material in short supply and thus conserve it
- Compensate more efficiently for excesses than for deficits
- In some instances the kidneys cannot halt the loss of a valuable substance in the urine
E.g. water deficit - The main route for eliminating potentially toxic metabolic wastes and foreign compounds
- Water eliminated in the urine is derived from the blood plasma
Functions of the kidneys [10]
Maintaining water (H2O) balance in the body
Maintaining the proper osmolarity of body fluids, primarily through regulating H2O balance
Regulating the quantity and concentration of most ECF ions
Maintaining proper plasma volume
Helping maintain the proper acid–base balance
Excreting (eliminating) the end products (wastes) of bodily metabolism
Excreting many foreign compounds
Producing renin
Producing erythropoietin
Converting vitamin D into its active form
Anatomic considerations
https://www.youtube.com/watch?v=1NtPjzm1-74&t=73s
The functional unit of the kidney
The Nephron
The arrangement of nephrons within the kidneys gives rise to two distinct regions:
Renal Cortex
Renal Medulla
Each nephron consists of 2 components
vascular component
tubular component
The dominant part of the nephron’s vascular component is the
glomerulus
Vascular Component of the Nephron blood supply
The renal artery subdivides to form many small vessels known as afferent arterioles
The afferent arteriole delivers blood to the glomerulus
Blood that was not filtered into the tubular component leaves the glomerulus via
the efferent arteriole
The efferent arteriole subdivides into a second set of capillaries,
the peritubular capillaries
The peritubular capillaries re-join to form venules that
ultimately drain into the renal vein, by which blood leaves the kidney
A hollow fluid-filled tube
Tubular Component of the Nephron
Tubular Component of the Nephron is Divided into various segments based on differences in structure and function along its length:
Bowman’s capsule
Proximal tubule
Loop of Henle
Descending loop
Ascending loop
Juxtaglomerular apparatus
Distal tubule
Collecting duct or tubule
Two types of nephrons:
Cortical nephrons
Juxtamedullary nephrons
Cortical nephrons
– glomeruli lie in the outer layer of the cortex
Juxtamedullary nephrons
– glomeruli lie in the inner layer of the cortex
The two nephron types differ most markedly in their
loops of Henle
https://www.youtube.com/watch?v=2PEohSqpp_E
