BIOM 3200 - Renal System

What does ADH (anti diuretic hormone) help regulate?

- Self and water balance

ADH helps regulate self and water balance by stimulating a(n) [1] in water permeability of the collecting duct, allowing water to be [2].

1. Increase
2. Reabsorbed

Does ADH increase or reduce water excretion?

- Reduce (it helps water retention)

Where is ADH and oxytocin produced? Where is it released?

- Produced: hypothalamus
- Released: posterior pituitary

What type of neurons in the hypothalamus stimulates ADH secretion? Does this raise or lower plasma osmolality and osmotic pressure? What happens to the cell?

- Osmoreceptors neurons
- Rise

What two things do osmoreceptors stimulate?

- Thirst
- Greater release of ADH

What is sensed by stretch receptors in the left atrium? What does this lead to?

- Low blood volume
- Increased ADH secretion

True or false: Upon release into the bloodstream, ADH helps to increase H2O reabsorption in the kidneys.

- True

Where will water be reabsorbed in the kidneys?

- The collecting ducts (to return to the blood and not lost in the urine)

When water is reabsorbed in the collecting ducts, what type of urine is secreted?

- High osmolarity / concentrated urine

What three ion concentrations affect the changes in plasma osmolality?

- Na+
- Cl-
- K+

What is the plasma osmolality threshold for stimulating ADH secretion?

- 280 mOsm/kg

What is the plasma osmolality threshold for stimulating thirst secretion?

- 290 mOsm/kg

What is the average normal plasma osmolality?

- 295 mOsm/kg

When you are over-hydrated, what will your blood volume levels be? What will they stimulate in the left atrium?

- Rise in blood volume
- Stretch receptors in the left atrium

When you are over-hydrated, what will your plasma osmolality levels be? What are they sensed by? What does this do to ADH secretion?

- Decreased plasma osmolality
- Sensed by osmoreceptors
- Inhibit ADH secretion

True or false: When you are over-hydrated, water is more effectively reabsorbed in the collecting duct of the kidneys.

- False. It is less effective because you are not returning it to the blood

What type of urine is secreted when you are over hydrated?

- Diluted / low osmolarity is secreted

Label the following diagram:

1. Low water intake (dehydration)
2. High water intake (over-hydration)
Negative feedback correction

What will happen when you drink too much water and do not urinate? Can you die from this?

- Acute water intoxication
- Yes

What did the frameshift mutation in Avp gene in Brattleboro rats lead to?

- Deficient synthesis and release of ADH

What three symptoms are there when ADH secretion is too low?

- Polyuria (large urine volume)
- Excessive thirst
- Polydipsia (excessive drinking)

What type of diabetes insipidus is linked to an inadequate secretion of ADH?

- Central diabetes insipidus

What type of diabetes insipidus is linked to the inability of the kidneys to respond to ADH?

- Nephrogenic diabetes insipidus

When you are measuring plasma ADH levels, what type of diabetes insipidus is shown when levels are low?

- Central diabetes insipidus

Which type of diabetes insipidus would you give a desmopressin (synthetic ADH) challenge to?

- Nephrogenic diabetes insipidus

Do patients with diabetes insipidus take insulin?

- No, they do not need it, there are no problems with insulin

In healthy children, what pattern does ADH secretion follow? When is ADH level high? What does this cause?

- Circadian rhythm
- High at night
- Causes reabsorption of water and a decrease in nocturnal production of urine

What are three reasons that could lead to someone having nocturnal enuresis (bedwetting)?

- Not producing enough ADH
- Have an insufficient response to ADH
- Have impaired sensory input from bladder

What is the treatment for nocturnal enuresis (bedwetting)?

- Desmopressin

Who has the most body water content? Babies, teens, adults, or old people?

- Babies (average 74%)

Who has more water body content? Males or females?

- Males (average 59% compared to average 50%)

How much water (in thirds) is in the intracellular parts of our body? How much is in extracellular?

- 2/3 intracellular
- 1/3 extracellular

Label the following diagram:

1. Intracellular
2. Extracellular
3. Cytoplasm
4. Interstitial fluid
5. Blood plasma volume

True or false: Water intake \= Water loss

- True

What rule is very overgeneralized?

- Rule of three: 3 mins without air, 3 hours without shelter, 3 days without water, 3 weeks without food

Why is the rule of three over generalized?

- Because water survival depends on many different factors like environment, age, and how nourished you are

Is it possible to survive 8 days without food and drink?

- Yes (ex. woman after earthquake, babies in hospital earthquake)

How long can camels survive in the desert without water?

- Several weeks

True or false: the Arabian camel is able to close down its kidneys to keep water in.

- False. They cannot close kidneys down

What is stored in the humps of an Arabian camel?

- Lipids

True or false. Camels can survive up to weeks based on the lipids in their lumps because lipid metabolism can provide a significant amount of metabolic water.

- False. Most of the water that is produced by the metabolism is evaporated from lungs during respiration, leading to an actual net loss of water

What is it about the kidneys of Arabian camels that helps their ability to retain water? What does this do to ion channel and transporter expression? What does this do to water reabsorption?

- Suppressing cholesterol biosynthesis in the kidneys
- Leads to higher ion channel and transporter expression in kidneys
- Increases water reabsorption

Why does high cholesterol decrease ion channels and transporter function?

- Because it stiffens the lipid bilayer

What about the RBCs of camels help withstand dehydration?

- Shape: oval / ellipsoid, and smaller
- They circulate in larger numbers
- Hb has higher affinity for O2 (for more effective delivery to tissues)

True or false: In camels, the RBC long axis is oriented with blood flow to allow passage through small blood vessels even when blood viscosity is high during dehydration?

- True

How large can the RBCs of camels expand its original volume? What does this prevent?

- 240% (compared to other animals that is 10%)
- This prevents hemolysis (RBC swelling) when they drink large volumes of water to recover from dehydration

The kangaroo rat lives in an arid-desert and it is a small species with high O2 consumption and high respiratory water loss. Can they live without drinking any water?

- Yes (even when it is available)

How do the colonies (burrows) they live in underground help with their adaptations of not drinking any water? (*3 points*)

- They avoid harsh environment
- There is moist air in the burrows to reduce respiratory water loss (higher humidity)
- Some seeds that are stored in their burrows absorb 30% more moisture

True or false: kangaroo rats can obtain 0.75g of water from 1g of seed consumed.

- False. They can only obtain 0.5g of water from 1g seed consumed

Are kangaroo rats nocturnal? How are their feces?

- Yes
- Dry feces

What do the kidneys of kangaroo rats help with avoiding water dehydration through urine?

- They turn concentrate urine to a crystal-like consistency to lose almost no water through the urine

Fresh water has how much dissolved salts by weight? What about the human body? Seawater?

- 0.1% fresh water
- 0.9% human
- 3.5% seawater (about 4x than blood)

What happens to osmolarity when we drink sea water? ADH? Thirst? Kidney's water reabsorption? Dehydration?

- They all increase

What is the physiological problem for marine mammals?

- Their saline levels are similar to humans, and they have no access to fresh water

How do marine mammals obtain water?

- From metabolism of food that have similar salt content to their own blood
o Krill, fish, plankton

Why do marine mammals produce very concentrated urine?

- They have a longer loop of Henle

What do Baleen whales have instead of teeth? What is it made of? How are they arranged?

- Baleen
- Keratin (same material as our fingernails or hair)
- Arranged like the teeth of a comb

How do Baleen whales get food without taking in seawater?

1. Open mouth to fill with water
2. Force water out of mouths
3. Mat on inside of baleen teeth catches plankton (food)

What do hibernating bears live off of from their summers and falls?

- Stored fat reserves

About how many calories can bears burn a day during hibernation? What do they not do during this time?

- Up to 8000 calories a day
- Do not eat, defecate, drink, or urinate

Why is the metabolic rate of hibernating bears cut by 50-60%? What happens to their surface area to mass ratio?

- Loss of body heat is slowed
o High insulating pelt
- Lower surface area to mass ratio

What balances respiratory water loss in hibernating bears? What is the decreased RR (respiratory rate) and HR (heart rate)?

- Metabolic water from lipid
- RR: 1 breath/45 seconds
- HR: 8-19 beats/min

What is broken down from fat metabolism in hibernating bears? What does this lead to?

- Urea
- Resulting nitrogen used to build protein to sustain muscle mass (some bears even gain muscle)

What do the kidneys make urine out of?

- Modified plasma filtrate

What are the four things that the kidneys regulate about the plasma?

1. Volume of blood plasma
2. Concentration of waste products in the plasma (ex. urea)
3. Concentration of electrolytes in the plasma
4. pH of the pasma

What does the kidney secrete to stimulate RBC production?

- EPO (erythroproitein - hormone that signals your bone marrow—the spongy tissue inside most of your bones to make RBCs)

Label the following diagram:

1. Kidney
2. Ureter
3. Urinary bladder
4. Urethra

Urine produced in kidney is drained into the [1]. Then is channeled via long ducts \= the [2] to the urinary bladder. Drain the urine from kidneys by the process called [3]. Urinary [4] is a storage sac for urine. Urinary bladder is drained by the tubular [5].

1. Renal pelvis
2. Ureters
3. Peristalsis
4. Bladder
5. Urethra

What the shape of the bladder when it is empty? When it is full?

- Pyramidal shaped
- Ovoid, bulges up into abdominal cavity

What is the process of wave-like contractions to push urine from the kidneys to the bladder called?

- Peristalsis

What are the two zones of the renal parenchyma?

- Outer renal cortex
- Inner renal medulla

What does the outer renal cortex contain? What is its appearance?

- Contains many capillaries
- Reddish brown and granular

What does the inner renal medulla contain? What is its appearance?

- Contains less capillaries and more microscopic renal tubules
- Stripped in appearance

Label the following diagram:

1. Renal pyramid
2. Renal column
3. Renal pelvis
4. Renal papilla
5. Minor calyx
6. Major calyx
7. Ureter

What divides the renal medulla? What does it divide it into?

- Renal columns
- 6-10 renal pyramids

The broad face of the pyramid faces the cortex, but what is the name of the blunt point of the renal pyramid?

- Renal papilla

What does the renal papilla of each pyramid nestle into? (Hint: like a cup to collect urine)

- Minor calyx

Two or three minor calyces converge to form what?

- A major calyx

A couple major calyces converge to form what? (Hint: it is funnel-like)

- Renal pelvis

What is a tubular continuation of the renal pelvis? Where does this drain the urine to?

- Ureter
- Urinary bladder

One renal pyramid and the overlying cortex \= how many lobes of the kidney?

- One

How much (%) of cardiac output (CO) is received by the kidneys?

- 21%

What artery supplies each kidney?

- Renal artery

What is the renal artery divided into? What do they pass between (hint: through the columns)

- Interlobar arteries

At the boundary of the cortex and medulla (corticomedullar junction), what do interlobar arteries branch into?

- Arcuate arteries

What branch of the arcuate arteries into the cortex?

- Interlobular arteries

What do interlobular arteries subdivide into? Where do they go to?

- A series of afferent arterioles
- Going to the nephron

Label the following diagram:

1. Interlobular
2. Arcuate
3. Interlobar
4. Renal artery
5. Renal vein

How many nephrons are supplied by each afferent arteriole?

- One

Where does the afferent arteriole deliver blood into? (Hint: a spheroidal mass of capillaries)

- Glomerulus

What type of arteriole drains the blood from the glomerulus?

- Efferent arterioles

Where do efferent arterioles deliver blood to? (Hint: another capillary network surrounding the renal tubules)

- The peritubular capillaries

Blood from the peritubular capillaries goes to the [1] vein, then the [2] vein, then [3] vein, then the [4] vein, and then the [5] vena cava to the heart.

1. Interlobular
2. Arcuate
3. Interlobar
4. Renal
5. Inferior

Label the following diagram:

1. Glomerulus
2. Efferent
3. Afferent
4. Arcuate
5. Interlobar
6. Peritubular
7. Interlobular

Where does blood enter the kidneys?

- The glomerulus

Where is blood filtered in the kidney?

- The nephron

Where does urine leave the kidney?

- Collecting duct

Where does blood leave the kidney?

- Renal vein

True or false: all mammals have the simple kidney previously described?

- False: some do (like cats and dogs), but:
o cattle have a lobulated kidney
o marine mammals and bears have a reniculate kidney (more surface area)