Flashcards in A&P Chapter 23 Renal System Deck (45):
What is the primary function of the Renal System?
To maintain homeostasis by regulating concentrations of WATER and SOLUTES in the blood.
It DISPOSES of metabolic wastes, excess water, excess ions and toxins while RETAINING the proper amount of H2O, the proper concentrations of ions (especially Na+ and K+), the proper nutrients and anything else needed in the blood.
What is the secondary function of the Renal System?
It regulates the blood pressure to keep it within normal ranges.
What are the organs of the Renal System?
The Right and Left Kidneys which sit in the RETROPERITENEAL space at about the 12th rib.
The Ureters which deliver urine to the bladder.
The Urinary Bladder which stores urine until it is excreted.
Describe the Kidneys
They are located high in the abdominal cavity posterior to the PERITONEUM. The RIGHT kidney is slightly inferior to the left.
They are approx. 150g and ~12X6X3cm.
The lateral surface is convex and the medial surface is concave with a HILUS/HILUM where the blood vessels, nerves, ureters and lymphatic vessels enter/exit.
Describe the internal structure of the Kidneys
The outer surface is the CAPSULE which is a dense irregular connective tissue covering.
Directly deep to that is the CORTEX which is a solid region.
Deep to the cortex is the MEDULLA which contains 8-12 cone shaped masses called RENAL PYRAMIDS. The pyramids are separated by RENAL COLUMNS.
The PELVIS of the kidneys is the hollow medial region with extensions called Calyses. They connect to the ureters to deliver urine to the bladder.
Trace the blood flow through the Kidney, name all ARTERIES AND VEINS IN ORDER.
Renal Arteries, Lobar Arteries, Interlobar Arteries, Arcuate Arteries (reside BETWEEN the Cortex and Medulla), Interlobular Arteries (which travel into both the cortex and medulla), Afferent Arterioles, Glomerulus, Efferent Arterioles, Peritubular Capillaries, ----> Interlobular Veins, Interlobar Veins, Lobar Veins, to the Renal Vein.
Which blood vessels in the Kidneys are Elastic? Which are Muscular? What vessels run between the Pyramids in the Renal Columns? Which vessels run between the cortex and medulla? Which vessels run into the cortex and the medulla?
The Renal Arteries are Elastic.
The Lobar and Interlobar Arteries are Muscular arteries.
The Interlobar Arteries and Veins run through the renal columns between the pyramids.
The Arcuate Arteries and Veins run between the renal cortex and medulla.
The Interlobular Arteries and Veins run into the cortex and medulla.
Where is the only PORTAL ARTERIOLE?
Between the capillaries in the Glomerulus and the Peritubular capillaries, this is the only place where an artery runs between the two capillary beds rather than a vein.
Where do ALL the Glomeruli reside?
In the RENAL CORTEX.
What is the series of tubes that filters out plasma from blood passing through the Glomerulus?
What type of Epithelia makes up the Nephron?
A Simple Squamous Epithelium
Trace the flow of the fluid that eventually becomes urine through the parts of a Nephron.
The Afferent arteriole delivers blood into the Glomerulus, the plasma filters into the GLOMERULAR CAPSULE, then into the PROXIMAL CONVOLUTED TUBULE then to the LOOP OF HENLE then to the DISTAL CONVOLUTED TUBULE and then to the COLLECTING DUCT.
How many nephrons does a kidney contain?
About 1 Million.
The Proximal Convoluted Tubule of a Nephron ALWAYS exists in which part of the kidney?
The RENAL CORTEX.
What parts of a Kidney make a single Lobe?
A Renal Pyramind, the Cortex above it and the Capsule above it.
What parts of a nephron make up the Renal Cortex? Which parts make up the Renal Medulla/Pyramid? What is found in the Renal Columns?
The cortex consists primarily of convoluted tubules and the Medulla/Pyramid is primarily the Loops of Henle and the Collecting ducts.
Blood vessels and connective tissues are found in the Renal Columns.
Describe the Functional Steps of filtration/reabsorption in a nephron.
1. Glomerular filtration creates a plasmalike filtrate from the blood.
2. Tubular reabsorption (occurring in the proximal convoluted tubule, loop of henle and distal convoluted tubule via the peritubular capillaries) removes useful solutes from the plasmalike filtrate and returns them to the blood.
3. Tubular secretion removes additional wastes from the blood and adds them to the filtrate.
4. Concentration occurs, water is removed from the urine/put back into the blood and wastes are concentrated.
What are the types of pressure involved in filtration and reabsorption?
Hydrostatic Pressure and Osmotic Pressure
What drives Hydrostatic Pressure?
The weight of water/blood pressure.
What drives Osmotic Pressure?
The different concentration of solutes on different sides of a membrane.
Explain Filtration with respect to the Various Pressures involved.
The Capillary Blood Pressure (Hydrostatic) moves plasmalike liquid out of the capillaries. (at 60mmHg, the highest BP in any capillary network)
Colloid Osmotic Pressure in the Glomerular capsule moves some back in at 32mmHg
The Capsular Pressure moved 18mmHg back in to the Glomerulus.
The Result is a Net Filtration Pressure of 10mmHg.
Describe the Structure of the Glomerulus and the Glomerular Capsule
The Glomerulus is a capillary bed, it is made of a SIMPLE SQUAMOUS EPITHELIUM that is FENESTRATED, it has holes for filtration. The basement membrane of the glomerulus fuses with the basement membrane of the Glomerular capsule. The Glomerular Capsule is made of a SIMPLE SQUAMOUS EPITHELIUM (the cells are called PODOCYTES) with slits between the cells for filtration.
Describe the Size of Filtration between the Fenestra, Basement Membrane and the Filtration Slits in the Podocytes.
The Fenestra are ~75nm stopping anything larger than that.
The Basement Membrane between the Endothelium of the Capillaries and the Podocytes will stop anything larger than ~7nm.
The filtration slits in the Podocytes will stop anything that's ~30nm.
Thus only things that are smaller than ~7nm can be filtered from the blood into urine.
What are the general rules about what can be filtered and what can't?
All cells and molecules larger than 7nm stay in the blood.
NEUTRAL MOLECULES 3-7nm pass through to the urine, IONS 3-7nm DONOT pass through to urine.
ANYTHING smaller than 3nm gets filtered into urine so things like Na+, K+, Glucose, Amino Acids, Fatty Acids, Water etc. all get filtered out of the blood.
What part of the nephron does the filtered fluid enter first? What network of capillaries reabsorbs substances that the body needs?
The Proximal Convoluted Tubule, The Peritubular Capillaries.
How do the Nephrons concentrate urine? What has to happen for this to occur?
By allowing 99-100% of the water to be reabsorbed into the Peritubular Capillaries.
There needs to be a HIGH concentration gradient in the extracellular fluid of the medulla surrounding the loops of henle. The LOW osmolarity closer to the cortex allows water to stay in the filtrate(urine) as it passes deeper in the Renal Pyramid the osmolarity gets HIGHER and water will diffuse out of the collecting ducts into the extracellular fluid and then it will diffuse back into the peritubular capillaries.
What affects the cells of the collecting duct allowing water to pass through to the extracellular fluid and thus the peritubular capillaries?
Antidiuretic Hormone produced by the POSTERIOR Pituitary gland. The more ADH the more water will be reabsorbed and the more concentrated the urine will be. The less ADH the less concentrated the urine will be and less water gets reabsorbed.
What structure of the Nephron regulates Blood Pressure?
The Juxtaglomerular apparatus. It detects BP in the AFFERENT ARTERIOLE leading into the Glomerulus.
What does the JUXTAGLOMERULAR APPARATUS secrete if it detects a low blood pressure? How does the hormone raise BP?
The Hormone Renin. Renin in the presence of Angiotensinogen converts to Angiotensin 1 secreted by the Liver which in the presence of ACE from the lungs will become Angiotensin 2 which tells the hypothalamus to make you want to drink, increasing fluid intake, it raises BP by vasoconstriction and it tells the kidneys to retain more water thus raising BP.
Outline the structures of the Kidneys Urine passes through after it leaves the collecting ducts.
It passes from the collecting ducts to a minor calyx, from there it passes through a major calyx to the Pelvis of the Kidney to the Ureter and then to the bladder.
How many minor calysis are there? How many Major Calysis are there?
1 Minor Calyx per Renal Pyramid and 2-3 Major Calyx.
Describe the Ureters
They are retroperitoneal, they pass anterior to the common iliac arteries and veins. They have a Very thick muscular wall. They deliver urine to the posterior and inferior urinary bladder.
What are the layers of the Ureter?
A Mucosa: It is made of transitional epithelium and the Lamina Propria which is loose areolar connective tissue.
A layer called the Muscularis: This is the thick wall of Smooth Muscle.
Then the Adventita: this is dense irregular connective tissue.
What distinguishes an Adventita from a Serosa?
If the dense irregular connective tissue is lined with a simple squamous epithelium on the outer surface it is a Serosa, if not it's an Adventita.
Describe the Urinary Bladder
Located in the pelvis posterior to the pubic bone. It's superior surface is covered by the peritoneum.
In FEMALES it is ANTERIOR to the uterus and vagina.
In MALES it is ANTERIOR to the rectum and superior to the prostate.
In Males what structure is directly inferior to the urinary bladder?
In Females what structure is directly posterior to the urinary bladder?
The Uterus and Vagina
What are the layers of the Urinary Bladder?
The Mucosa which is Transitional Epithelium and the Lamina Propria.
The Muscularis: the thick layer of smooth muscle.
The Adventita which covers most of the urinary bladders surface.
The Serosa covers the superior surface of the bladder and has a layer of simple squamous epithelia.
What is the DETRUSOR muscle?
The Muscularis layer of the urinary bladder, it's the thick layer of smooth muscle.
What direction does the bladder fill?
Superiorly, remember the ureters enter in the posterior on the inferior side.
Describe the Urethra
The inner layer is a Mucosa, the epithelium varies from a transitional epithelium to a stratified squamous a3t the end. IN MALES there is a section of stratified columnar epithelium in the middle. There is a Lamina Propria in both females and males.
The second layer is a Muscularis which is a thick layer of smooth muscle.
The outer layer is the Adventita which is made of a dense irregular connective tissue.
The Uretha also contains 2 sphincters. One proximal to the bladder called the INTERNAL SPHINCTER which is made of smooth muscle and is not voluntary. The EXTERNAL URETHRAL SPHINCTER is skeletal muscle and under conscious control.
The opening to the outside world is called the EXTERNAL URETHRAL MEATUS.
Can urine be modified in the ureter, bladder or urethra?
NO It must be modified INSIDE the kidney.
What is CYSTITIS?
When bacteria and other organisms travel through the urethra into the bladder causing infection.
What is PYELONEPHRITIS?
When bacteria that made it's way inside the bladder travels up the ureters to the Kidneys.