Lab E3 Flashcards
The Urinary System
The urinary system is composed of the kidneys, ureters, urinary bladder, and the urethra.
The urinary system is constantly working to maintain the purity and health of the body’s fluids by removing unwanted substances and recycling others.
The kidneys contribute to homeostasis by regulating plasma composition through the elimination of metabolic wastes, toxins, excess ions, and water.
Where are the kidneys located? __________retroperitineal __________upper part of abdominal cavity_____________________________
Where are the kidneys located? __________retroperitineal __________upper part of abdominal cavity_____________________________
Where are the kidneys located? __________retroperitineal __________upper part of abdominal cavity_____________________________
Breaking down of amino acids(from protein) makes urea
Uric acid
nucleic acid breakdown leads to uric acid
Breakdown of fatty acids
ketone bodies in blood = acidic
Aquaporins let water in and out
reabsorption of water in nephron
Breaking down of amino acids(from protein) makes urea
Uric acid
nucleic acid breakdown leads to uric acid
Breakdown of fatty acids
ketone bodies in blood = acidic
Aquaporins let water in and out
reabsorption of water in nephron
Functions of the Kidney
Regulation of the volume, composition, and pH of the body fluids
Regulation of acid-base homeostasis (via the production of ammonia)
Regulation of energy metabolism via gluconeogenesis during fasting conditions
Regulation of plasma osmolarity through the control of aquaporin receptors within the collecting duct
Detoxification of metabolic wastes through excretory mechanisms
Conversion of vitamin D3 into its active form
Synthesis and conversion of important hormones such a erythropoietin and renin.
Anatomy of the Kidney
Renal lobe
contains the renal pyramid
Nephron is the functional unit of the kidney
inside the renal pyramid
lots of nephrons inside one pyramid
Each nephron has a blood supply
Blood before nephron
Filtrate in the nephron
Urine after the nephron
Renal cortex
light pink outside pyramids
Medulla
renal pyramids
Minor calyx -> major calyx -> renal pelvis -> ureters -> bladder -> urethra
urine movement
Cortical nephron
Juxtamedullary nephron
longer loop of henle
the deeper into the pyramid the more ion
more hyperosmotic
water is being pulled into the hyperosmotic area from descending loop of henle so more reabsorption of water out of the tubule
produces more concentrated urine(more of them in desert animals)
Most reabsorption is in the proximal convoluted tubule(PCT)
Sodium, water, and glucose reabsorbed in PCT
Only water reabsorbed in descending loop of henle
Only sodium in ascending loop of henle
Distal convoluted tubule(DCT)
sodium and bicarbonate reabsorption
Collecting duct
water
Renal Blood Flow
Interlobar is between the lobes(between the pyramids)
Interlobular outside the lobes in the cortex
Afferent arterioles feed into the glomerulus
Know
large proteins and red blood cells do not make it out
are not filtered into the filtrate
too big for the pores
no mechanism to reabsorb these substances so bad if leaving
Efferent arteriole
brought back and exiting
Know
large proteins and red blood cells do not make it out
are not filtered into the filtrate
too big for the pores
no mechanism to reabsorb these substances so bad if leaving
Efferent arteriole
brought back and exiting
The Nephron
The main functional unit of the kidney responsible for urine formation
Where is it located? ______cortex and medulla________
Cortical nephrons:
Shorter loops of Henle
About 80-85% of nephrons in humans
Juxtamedullary nephron:
Longer loops of Henle that extend down the renal medulla
Only 15-20% of nephrons in humans
The nephron is composed of: Renal corpuscle = Bowman’s capsule + glomerulus Renal tubule with three distinct parts: -Proximal Convoluted Tubule -Loop of Henle -Distal Convoluted Tubule
Filtration is the process of making filtrate
in the glomerulus and bowmans capsule
Reabsorption
taking back into the blood after being filtrate
filtrate to blood
uses vasa recta and peritubular capillaries
Secretion
put something back in for excretion later on(after filtration)
one of the only mechanism for removing potassium from the body
Excretion
everything that makes it through the entire nephron and let out of the body
Filtration is the process of making filtrate
in the glomerulus and bowmans capsule
Reabsorption
taking back into the blood after being filtrate
filtrate to blood
uses vasa recta and peritubular capillaries
Secretion
put something back in for excretion later on(after filtration)
one of the only mechanism for removing potassium from the body
Excretion
everything that makes it through the entire nephron and let out of the body
Mechanism of Urine Production
The nephron produces urine through three/four main interaction mechanisms:
Filtration – A filtrate of the blood leaves the kidney capillaries and enters the renal tubule
Definition: the movement of water and plasma solutes through the glomerular capillary walls into the urinary space of the Bowman’s capsule.
Reabsorption – Most of the nutrients, water, and essential ions are recovered from the filtrate and returned to the blood
Definition: when a substance is transported from the filtrate, through the tubular cell membrane walls, and eventually into systemic circulation
Secretion – Certain substances are secreted from the blood into the filtrate product to be eliminated
Definition: a substance is transported from peritubular blood vessels into the filtrate product, which will ultimately form urine
Excretion – Process of eliminating or expelling waste matter through the final excretory product, urine
Glomerular Filtration
Initial stage for urine formation
The endothelium of these capillaries are very porous.
They allow fluid, waste products, ions, glucose, and amino acids to pass from the blood into the capsule.
It blocks out bigger molecules like blood cells and proteins so they stay in the blood and exit through the vasa recta.
All the “stuff” that get squeezed out of the blood into the capsule is called filtrate which is then sent along the renal tubule.
Glomerular Filtration Rate (GFR) - volume of filtrate produced by both kidneys per minute
Physiological indicator of renal function
Glomerular filtration is determined by Starling’s pressures
Capillary hydrostatic pressure, interstitial fluid hydrostatic pressure, capillary blood oncotic pressure, interstitial fluid oncotic pressure
GFR = Kf [ (PGC – PBS) - PGC ]
Glomerular filtration
The only step where blood is actually involved
Review Starling’s pressures bullet point
don’t need to know formula but concept
The only step where blood is actually involved
Review Starling’s pressures bullet point
don’t need to know formula but concept
Vast majority of reabsorption in proximal convoluted tubule(PCT)
If there is any glucose in urine its pathological
possibly diabetes
200mg/dL is the threshold for glucose
A diabetic will reach the 400 threshold quicker and has no buffer to absorb up to 200 like normal individuals
Vast majority of reabsorption in proximal convoluted tubule(PCT)
If there is any glucose in urine its pathological
possibly diabetes
200mg/dL is the threshold for glucose
A diabetic will reach the 400 threshold quicker and has no buffer to absorb up to 200 like normal individuals
Proximal Convoluted Tubule
Cell walls are made up of cuboidal epithelial cells containing mitochondria to power pumps that pull sodium ions from the filtrate using active transport
Microvilli to increase surface area to help reabsorb as much of the “good stuff” as possible
The vast majority of renal reabsorption occurs in the proximal convoluted tubule.
- Approximately 67% of sodium and 67% of water reabsorption
- The coupled sodium and water reabsorption is proportional to each other (isosmotic). This mechanism is essential for the maintenance of the chemical integrity of the extracellular fluid composition and general homeostasis.
In a healthy individual there will be ~100% reabsorption of glucose
When plasma glucose is below 200 mg/dL most if not all filtered glucose is reabsorbed
Renal threshold for glucose = 200 mg/dL
If the blood glucose concentration is higher than 200 mg/dL but lower than 350 mg/dL, what can be said regarding reabsorption and excretion? _____________reabsorbtion down and excretion of glucose starts______________________
If the blood glucose concentration is higher than 400 mg/dL what can be said regarding reabsorption and excretion? __reabsorption limit is reached and all additional glucose is excreted_________________
In a healthy individual there will be ~100% reabsorption of glucose
When plasma glucose is below 200 mg/dL most if not all filtered glucose is reabsorbed
Renal threshold for glucose = 200 mg/dL
If the blood glucose concentration is higher than 200 mg/dL but lower than 350 mg/dL, what can be said regarding reabsorption and excretion? _____________reabsorbtion down and excretion of glucose starts______________________
If the blood glucose concentration is higher than 400 mg/dL what can be said regarding reabsorption and excretion? __reabsorption limit is reached and all additional glucose is excreted_________________
Loop of Henle
Starts in the cortex, dips down in the medulla, comes back into the cortex
- Thin descending
- Thin ascending
- Thick ascending
Drives the reabsorb of water by creating a salt concentration gradient in the tissue of the medulla
The ascending portion actively pumps out salt and is impermeable to water
The high concentration of salt in the interstitial fluid of the medulla causes water to passively flow in the descending portion via osmosis
-Thus, the interstitial fluid is __hypertonic__ to the filtrate.
Loop of Henle
Thin descending
water passively flows out
interstitial fluid is hypertonic to the tubule
more solute outside the tubule
Thin ascending
nothing exits
Thick ascending
NaCl exits
Thin descending
water passively flows out
interstitial fluid is hypertonic to the tubule
more solute outside the tubule
Thin ascending
nothing exits
Thick ascending
NaCl exits
Distal Convoluted Tubule
Responsible for the reabsorption of sodium, bicarbonate, and the secretion of ammonium
PTH acts on the DCT to stimulate calcium reabsorption
Impermeable to water
Empties into the collecting duct
Collecting Duct
Contains aquaporins which aid in the reabsorption of water into the blood
Involved in sodium reabsorption and potassium excretion
Angiotensin I to Angiotensin II
MJST have the angiotensin converting enzyme(ACE)
ADH or vasopressin can be interchanged
Aldosterone
retains water and sodium
ADH
retains only water
Without ADH the aquaporins will not work
no water reabsorption in collecting duct
Angiotensin I to Angiotensin II
MJST have the angiotensin converting enzyme(ACE)
ADH or vasopressin can be interchanged
Aldosterone
retains water and sodium
ADH
retains only water
Without ADH the aquaporins will not work
no water reabsorption in collecting duct
Important Hormones
Renin-Angiotensin-Aldosterone System
Low blood volume activates the juxtaglomerular apparatus in a variety of ways to make it secrete renin.
Renin > angiotensin I > angiotensin converting enzyme (ACE) > angiotensin II.
Angiotensin II has a variety of effects but it also causes the release of aldosterone from the adrenal cortex
Important Hormones
Aldosterone
Promotes sodium reabsorption in the DCT and collecting duct
Promotes the retention of water and sodium
Stimulates thirst
Increase blood volume and thus increase in blood pressure
Important Hormones
ADH or vasopressin
In the presence of high ADH the renal mechanisms produce hyperosmotic (concentrated) urine.
In the absence of ADH the renal excretion mechanisms produce hyposmotic (diluted) urine.
ADH increases the permeability of water of the distal convoluted tubule and collecting duct, which are normally impermeable to water. This effect causes increased water reabsorption and retention and decreases the volume of urine produced.
Urinary Bladder
Micturition – medical term for urination
There are two sphincters, or muscular valves, that separate the bladder from the urethra.
- The sphincters must open before the urine can flow into the urethra.
- The internal sphincter is under involuntary control and the external sphincter is under voluntary control.
Volume of Urine
- Bladder typically “feels full” around 150 - 200 mL
- Perceiving a sense of urgency around 300 – 400 mL
- > 600 mL – involuntary urination
External sphincter is voluntary
Internal sphincter in involuntary
Detrusor muscle
Know the volume numbers
Micturate 1.5 -2 liters per day
External sphincter is voluntary
Internal sphincter in involuntary
Detrusor muscle
Know the volume numbers
Micturate 1.5 -2 liters per day
Clinical Applications
Urinary Tract Infection
Most often occurs in sexually active women. Intercourse drives bacteria from the vagina and the anus through the nearby opening of the short urethra.
-The use of spermicides (found on condoms) magnifies the problem because they also kill the natural, “healthy” bacteria and allow pathogenic bacteria to colonize.
Symptoms include a burning sensation during micturition, increased urgency and frequency of micturition, fever, and sometimes cloudy or blood-tinged urine.
The elderly are also susceptible to UTIs due to weakness of the bladder, incontinence, poor bladder emptying, and retention of urine. Symptoms of a UTI in the elderly include mental changes and confusion.
Clinical Applications
Renal Calculi – “Kidney Stones”
4 different types – Calcium oxalate is the most common
Patients experience severe pain
Risk factors – family history, chronic dehydration, obesity, certain diets (such as those with high in protein and/or salt)
Stones less than 5mm in diameter will likely pass without intervention
- Stones >5 mm may become lodged in the ureter blocking the flow of urine and increasing intrarenal pressure
- Lithotripsy – uses shock waves to break up stones
***Calcium oxalate is only kidney stone to know
Basic Anatomy of the Respiratory System
Pulmonary respiration vs. cellular respiration
Upper respiratory tract vs. lower respiratory tract
URT: Structures from nose to larynx
LRT: Structures from larynx and below
Bronchial tree
1° bronchi, 2° (lobar) bronchi, 3° segmental bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs
Conducting zone
Respiratory components that carry air to sites of gas exchange
Filter, humidify, and warm the incoming air
Respiratory zone
Actual site of gas exchange
Composed of the respiratory bronchioles, alveolar ducts, and alveoli
Blood Air Barrier
Pneumocytes
Type I
40% of alveolar cells
Constitutes majority of alveolar surface
Type II
60% of alveolar cells, but only 3-5% of alveolar surface
House surfactant (DPPC)
Reduces surface tension of alveoli to prevent collapse
Macrophages
Dust cells that remove pollutants
The Mechanism of Ventilation
Breathing or pulmonary ventilation has two phases:
Inspiration or inhalation
Active Process
Inspiratory muscles (diaphragm and intercostal muscles) contract to increase the volume of the thorax
Intrathoracic pressure decreases
Diaphragm innervated by phrenic nerve
Expiration or exhalation
Passive process
Inspiratory muscles relax, so the diaphragm moves superiorly, and the rib cage/sternum drops
During a forced expiration: external/internal obliques and transversus abdominis contract
-This decreases the intra-abdominal volume, causing an increase in pressure, which forces the diaphragm superiorly and depresses the rib cage/sternum
Inspiration or inhalation
Active Process
Inspiratory muscles (diaphragm and intercostal muscles) contract to increase the volume of the thorax
Intrathoracic pressure decreases
Diaphragm innervated by phrenic nerve
Inspiration or inhalation
Active Process
Inspiratory muscles (diaphragm and intercostal muscles) contract to increase the volume of the thorax
Intrathoracic pressure decreases
Diaphragm innervated by phrenic nerve
Expiration or exhalation
Passive process
Inspiratory muscles relax, so the diaphragm moves superiorly, and the rib cage/sternum drops
During a forced expiration: external/internal obliques and transversus abdominis contract
-This decreases the intra-abdominal volume, causing an increase in pressure, which forces the diaphragm superiorly and depresses the rib cage/sternum
Expiration or exhalation
Passive process
Inspiratory muscles relax, so the diaphragm moves superiorly, and the rib cage/sternum drops
During a forced expiration: external/internal obliques and transversus abdominis contract
-This decreases the intra-abdominal volume, causing an increase in pressure, which forces the diaphragm superiorly and depresses the rib cage/sternum
