Renal: The Kidney Structure and Function Flashcards
What are the 7 Renal Functions?
- Regulation of Water and Electrolyte Balance
- Excretion of Metabolic Waste
- Excretion of Bioactive Substances
- Regulation of Arterial Blood Pressure
- Regulation of Red Blood Cell Production
- Regulation of Vitamin D Production
- Metabolism
Our input of water and electrolytes is enormously variable. How do the Kidneys respond?
The kidneys respond by varying the output of water of minerals in the urine to maintain homeostasis
Our bodies continuously form end products of metabolic process. What are most excreted by the Kidneys?
- Urea (from proteins)
- Uric Acid (from nucleic acids)
- Creatinine (from Muscle creatine)
- Hemoglobin breakdown products
- Metabolites of various hormones (from endocrine system)
Drugs are actively or passively excreted by the kidney?
Both.
Hormones in the blood are mostly removed where in the body but are removed in parallel to renal? processes.
Liver
Balance of what molecules achieve regulation of blood volume?
Na and H2O balance
Angiotensin is an example of what substance released by the Kidneys?
Vasoactive substance that actively regulate smooth muscle in peripheral vasculature
What is released by the kidney and controls erythrocyte production by the bone marrow?
Erythropoietin
True/False: Vitamin D increases absorption of Calcium by the gut
True
True/False: CNS is an obligate user of fat, protein, ketone bodies?
False. Blood Glucose
Whenever carbohydrate intake is stopped, our body synthesizes new glucose from non-carbohydrate precursors of glucose (amino acids and glycerol). What is this called?
Gluconeogenesis
What is crucial to maintaining acid-base homeostatsis?
Renal ammonioagenesis
True/False: Nephron is a functional unit of the Kidney
True
True/False: Only Plasma is moved into the Nephron
True
What part of the Nephron is mainly Filtration?
Glomerulus
What are the parts of the Nephron? (in order of processes)
- Renal Corpusle (Glomerulus and Bowman’s Capsule)
- Proximal Tubule
- Loop of Henle
- Distal Tubule
- Collecting Duct
What part of the Nephron is segmented and mainly Reabsorption?
Proximal Tubule
What complex part of the Nephron creates a concentration gradient by low and high osmolarity levels?
Loop of Henle
What part of the Nephron has Regulation (Acid-Base Balance) and some Re-absorption?
Distal Tubule
What part of the Nephron has mainly H2O reabsorption (regulated by ADH)?
Collecting Duct
Blood enters capillaries of the Glomerulus by afferent arteriole and leaves Bowman’s capsule through efferent arteriole. What enters the remaining Nephron?
Only Plasma
What drains from Bowman’s capsule?
Proximal Tubule
What are the 2 segments of the Proximal Tubule?
- Proximal convoluted tubule
2. Proximal straight tubule
What are the parts of the Loop of Henle?
- Descending thin limb
- Ascending thin limb
- Ascending thick limb
Loop of Henle
Create and maintains a medulla osmotic gradient
What demarks the area between the Loop of Henle and the Distal Tubule?
Macula Densa
Is there a Distal Convoluted Tubule and Distal Straight Tubule?
No. Only the Distal Convoluted Tubule
Last portion of the independent Nephron and functions as the concentrating mechanism of the nephron
Collecting Duct
Before the Distal Convoluted Tubule, the cells in any given segment are homogeneous. What are the 2 different cell types in the Distal Tubule?
- Principal cells (primary cell type)
2. Intercalated cells (alpha and beta)
What are the 2 types of Nephrons and their populations?
Cortical (80%)
Juxtamedullary (20%)
True/False: Nephrons do not differ in location and structures.
False. Have similar structures, but differ in their location and length of segments which leads to important consequences (length of Loop of Henle).
Kidneys receive how much cardiac output and how many Liters per minute?
Kidney receives 20% of cardiac output. 1 Liter/Min
What are the 2 capillary systems of the Kidney coming off the efferent arteriole?
- Peritubular capillaries (cortical nephron)
2. Vasa Recta (juxtamedullary nephron)
True/False: Afferent arteriole and Efferent arteriole are sites of regulation
True
True/False: 1 Renal Artery branches 1 million times to form 1 million nephrons
True
Peritubular capillaries extend from….
Cortical efferent artierioles and are profusely distributed throughout the cortex
juxtamedullary glomeruli long efferent arterioles extend
Downward into the outer medulla, where they divide many times to form bundles of parallel vessels called the VASA RECTA
Whole blood enters the glomerulus, but only plasma is filtered by the glomerular capillaries. What is this called?
Renal Plasma Flow
Blood is filtered by the glomerulus…approached by the afferent and exits through the efferent arteriole
Renal Blood Flow
What is the Renal Plasma Flow equation?
RPF = RBF*(1-HCT)
ex: RPF = 1L/min*(1-.4)=600 ml/min
A substance is filtered into Bowman’s space and excreted in the urine. How many cell membranes must it cross in order to exit the body?
- No cellular membranes are crossed in the glomerulus. Substances must pass through TIGHT DEFINED SPACES, but not across any cellular membranes.
What is Macula Densa cell’s role?
Sensory cells of Flow Rate.
Low Flow–> Macula Densa cells tell Juxtaglomerular cells need more filtrate for more flow. Juxtaglomerular cells release Renin in response
High Flow–> Turn off Renin secretion
What is Juxtaglomerular cell’s role?
Release Renin into blood supply.
Where are Macula Densa cells located?
Macula Densa cells are only found connected to the glomerulus. All glomeruli are found in the cortex.
Process by which water and solutes leave the vascular system through the filtration barrier and enter Bowman’s space
Filtration
Process of moving substances into the tubular lumen from the cytosol of epithelial cells that form the walls of the nephron
Secretion
Process of moving substances from the lumen across the epithelial layer into the surrounding interstitium
Reabsorption
Reabsorption has a 2-step process:
Resabsorbed substances move from the interstitium into surrounding blood vessels
Exit of the substance from the body
Excretion
Substance is broken down into smaller component molecules
Catabolism
Substance T is present in the urine. Does this prove that it entered the renal tubule by filtration at the glomerulus?
No. Substance T could have been filtered to enter the urine OR Substance T could have been secreted into the urine.
Substance J is not normally present in the urine. Does this prove that it is neither filtered nor secreted?
No. Substance J may have been filtered, but 100% of it could have been reabsorbed back into the blood stream. Thus it could have been filtered, but not appear in the urine.
