Renal Physiology Quiz

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Questions and Answers

What is the primary function of aldosterone in the body?

Decrease blood volume

Increase reabsorption of potassium

Increase excretion of water

Increase reabsorption of sodium (correct)

Which hormone triggers the conversion of calcidiol to calcitriol in the kidneys?

Aldosterone

Insulin

PTH (correct)

Vitamin K

Which animal species has the highest number of nephrons per kidney?

Dogs

Humans

Cats

Cows (correct)

What is a distinctive feature of the juxtamedullary nephron compared to the cortical nephron?

Located near the medulla/cortex junction Signup and view all the answers

Can nephrons regenerate fully if damaged?

No, never Signup and view all the answers

Which part of the kidney contains the renal corpuscle?

Renal cortex Signup and view all the answers

How do the efferent arterioles of nephrons contribute to urine concentration?

Form long straight capillaries (vasa recta) Signup and view all the answers

What percentage of total body weight is made up of intracellular fluid (ICF)?

40% Signup and view all the answers

Intracellular fluid (ICF) is found where in the body?

In the cells Signup and view all the answers

Which of the following fluids is considered part of extracellular fluid (ECF)?

All of the above Signup and view all the answers

What makes up the extracellular fluid (ECF) and is located within the ears?

Endolymph and Perilymph Signup and view all the answers

How is water primarily brought into ro formed in the body?

More than 1 answer choice is correct Signup and view all the answers

Which organ plays a central role in regulating the volume and ion concentration of extracellular fluid (ECF)?

The kidneys Signup and view all the answers

What is NOT listed as a way water is lost from the body?

Inhaling vapor in lungs Signup and view all the answers

Why won't injecting fluids in one ECF location affect other locations?

The body has barriers preventing fluid movement. Signup and view all the answers

What is the primary role of renin in the RAAS pathway?

Respond to low blood pressure by its release from the kidneys Signup and view all the answers

What is the primary function of the glomerulus?

Forming primary urine Signup and view all the answers

What is the function of aldosterone in the RAAS pathway?

Promote reabsorption of sodium and water in the kidneys Signup and view all the answers

Which structure reabsorbs water, sodium, and chloride in the kidney?

Thin limbs of Henles Loop Signup and view all the answers

Why do ACE inhibitors work to lower blood pressure?

By inhibiting the conversion of angiotensin 1 to angiotensin 2 Signup and view all the answers

Why do substances like myoglobin, hemoglobin, and albumin stay within the blood?

They have a high molecular weight Signup and view all the answers

What is the direct effect of angiotensin 2 on blood vessels?

Cause vasoconstriction Signup and view all the answers

Which statement is true in regards to the influence of charge on glomerular filtration?

Cations are most easily filtered Signup and view all the answers

What is the end result of aldosterone promoting sodium and water reabsorption in the kidneys?

Increase in blood volume and blood pressure Signup and view all the answers

What happens to substances bound to transport proteins in terms of kidney filtration?

They are too big to be filtered Signup and view all the answers

Which component of RAAS is responsible for converting angiotensinogen into angiotensin 1?

Renin Signup and view all the answers

Which part of the nephron is responsible for absorbing most of the water and solutes?

Proximal tubules Signup and view all the answers

What happens to tubular filtrate as it passes through the nephron's tubular system?

It gets modified by tubular reabsorption to become 'final urine' Signup and view all the answers

What is the main property of substances that are filtered through the glomerulus?

Small molecular size Signup and view all the answers

What initiates the RAAS pathway in response to low blood pressure?

Release of renin from the kidneys Signup and view all the answers

What is the main driving force for filtration of fluid from glomerular capillaries into Bowmans Space?

Glomerular capillary hydrostatic pressure Signup and view all the answers

What characteristic makes cationic substances more easily filtered in the glomerulus?

Positive charge Signup and view all the answers

What is the difference between osmolality and osmolarity in relation to temperature dependence?

Osmolarity is temperature dependent, while osmolality is not. Signup and view all the answers

Which type of fluid undergoes constant modification through tubular reabsorption to become 'final urine'?

Tubular fluid Signup and view all the answers

What does osmotic/oncotic pressure do with regards to the movement of water?

Pulls water towards the higher concentration of solutes Signup and view all the answers

What triggers the release of ADH, leading to the production of more concentrated urine?

Increased osmolality of plasma Signup and view all the answers

Study Notes

Urinary Tract System

Consists of the urinary bladder, ureters, urethra, and kidneys

RAAS (Renin Angiotensin Aldosterone System)

Pathway:
- Step 1: Kidneys sense low blood pressure, releasing renin from the juxtaglomerular apparatus (JGA)
- Step 2: Renin converts angiotensinogen into angiotensin 1
- Step 3: ACE converts angiotensin 1 into angiotensin 2
- Step 4: Angiotensin 2 causes vasoconstriction, increasing blood pressure and stimulating adrenal glands to secrete aldosterone
- Step 5: Aldosterone promotes sodium and water reabsorption in the kidneys, increasing blood volume and pressure

Glomerular Filtration

Glomerulus filters blood, forming primary urine
Majority of water and solute absorption occurs in the proximal tubules
Thin limbs of Henle's Loop reabsorb water, sodium, and chloride
Glomerulus has a semi-permeable membrane, filtering molecules based on molecular weight
Filterability is impacted by electrical charge and plasma protein binding

Body Water

60% of total body weight is water
20% of water is extracellular fluid (ECF), including plasma, interstitial fluid, and transcellular water
40% of water is intracellular fluid (ICF)
ECF includes transcellular water in various bodily fluids (e.g., lymph, cerebrospinal fluid, aqueous humor)

Water Balance

Water is gained through drinking, eating, and metabolic water production
Water is lost through urine, sweat, exhaled water vapor, and feces
Kidneys regulate and stabilize ECF volume and ion concentration

Calcitriol Synthesis

Pathway:
- Step 1: Low calcium levels trigger PTH release
- Step 2: PTH stimulates kidney enzyme 1-alpha hydroxylase to convert calcidiol into calcitriol
- Step 3: Calcitriol increases intestinal calcium reabsorption, increasing blood calcium levels

Nephrons of the Kidneys

Functional units of the kidneys
Humans have approximately 1 million nephrons per kidney
Nephrons can partially regenerate but cannot be replaced
Two types of nephrons: cortical and juxtamedullary
Cortical nephrons have short Loops of Henle and use peritubular capillaries for blood supply
Juxtamedullary nephrons have long Loops of Henle and use long straight capillaries (vasa recta) for blood supply

Nephron Structure

Renal corpuscle (Malpighian body) is located in the renal cortex
Primary urine accumulates in Bowman's Space
Tubular fluid is modified by tubular reabsorption and becomes "final urine"

Osmolality and Osmolarity

Osmolality is the number of osmoles of solute per kilogram of solvent
Osmolality is not temperature-dependent, making it suitable for living organisms
Osmolarity is temperature-dependent
Osmotic/oncotic pressure pulls water towards higher solute concentrations

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Description

Test your knowledge on the distribution of body water, including the composition of extracellular fluid (ECF) and intracellular fluid (ICF). Identify where transcellular water is located within the body.