A&P2 Lecture 04

Filtration

is the process by which water and solutes flow from the blood into the capsular space in the renal corpuscle.

Reabsorption

is the movement of water and solutes from the filtrate in the renal tubule into the blood.

Secretion

is the movement of selected solutes from the blood of the peritubular capillaries into the renal tubule for excretion.

Through which pathway are most water and solutes reabsorbed in the kidney tubule?

transcellular

What stimulates reabsorption of sodium ions in the late distal convoluted tubule and collecting duct.

Aldosterone

What stimulates water reabsorption in the collecting duct to form a small volume of concentrated urine.

ADH

What stimulates the excretion of NaCl and water in the urine to lower blood volume and increase urine output.

ANP

What move out of capillary if ___ is higher than ___.

hydrostatic pressure; colloid osmotic pressure

Which segment plays a crucial role in establishing the concentration gradient within the renal medulla?

Loop of Henle

The funnel-shaped structure that collects urine from the kidney and funnels it into the ureter for transport to the bladder is called:

Renal pelvis

Paired tubes that transport urine from the kidneys to the urinary bladder.

Ureters

Temporary storage reservoir for urine before it exits the body.

Urinary Bladder

Tube that transports urine from the bladder to the outside of the body.

Urethra

The maintenance of the correct pH level in the body.

Acid-Base Balance

Regulation of minerals in the body to maintain fluid balance and function.

Electrolyte Balance

Which of the following organs transport urine from the kidneys to the bladder using peristaltic contractions?

Ureters

During the urine voiding reflex, the contraction of the external urethral sphincter:

Prevents involuntary urine flow

Inward extensions of cortical tissue in the renal medulla, separating the renal pyramids.

Renal Columns

Which of the following regions is considered the longest part of the male urethra?

Penile urethra

During urination, the sphincter that relaxes and allows the passage of urine is called:

Internal urethral sphincter

Which structure in the urinary system is primarily responsible for storing urine before excretion?

Bladder

How do the kidneys filter waste products from the blood?

By selectively filtering substances through the glomerulus

Formed when minerals like calcium crystallize in the kidneys, obstructing urine flow

Kidney Stones

Cone-shaped masses in the renal medulla with a striated appearance, involved in urine formation.

Renal Pyramids

Surrounding the renal capsule is a layer of adipose tissue known as:

Perirenal fat

A characteristic dip on the kidney's medial surface where the ureter and blood vessels enter and exit.

Renal Hilum

The countercurrent multiplication in the kidney is a physiological process that occurs within the:

Loop of Henle

In the renal medulla, what is the main function of the vasa recta?

Maintenance of the osmotic gradient

Why is the renal hilum crucial for kidney function?

It serves as the entry and exit point for the ureter and blood vessels.

Collects urine from the papillae of the renal pyramids and funnels it into the major calyces.

Minor Calyx

A connective tissue structure that anchors the kidneys to surrounding tissues and supports them in place

Renal Fascia

Microscopic functional unit of the kidney responsible for filtering blood and producing urine.

Nephron

A group of fenestrated capillaries within the renal corpuscle that are highly permeable.

Glomerulus

Sheath of tissue surrounding the glomerulus, also known as Bowman's capsule, containing podocytes.

Glomerular Capsule

Nephrons located at the boundary of the renal cortex and medulla with long nephron loops, specializing in concentrated urine.

Juxtamedullary Nephrons

Nephrons located primarily in the renal cortex with shorter nephron loops, making up 80% of all nephrons.

Cortical Nephrons

Tubule that collects filtrate from multiple nephrons and further modifies it, leading to the papillary duct.

Collecting Duct

First segment of the renal tubule located in the renal cortex, with microvilli to increase surface area.

Proximal Tubule

Final segment of the renal tubule located in the renal cortex, involved in further filtrate modification.

Distal Tubule

Winding tube in the nephron that modifies filtrate through the proximal tubule, nephron loop, and distal tubule.

Renal Tubule

What is the primary function of the nephron in the kidney?

To filter blood and produce urine

What are the two main components of the nephron?

Renal corpuscle and renal tubule

Why are fenestrated capillaries and podocytes critical in the renal corpuscle's filtration process?

They allow selective permeability, enabling efficient filtration of blood while retaining larger molecules like proteins.

How do the proximal tubule, nephron loop, and distal tubule of the renal tubule differ in function?

The proximal tubule reabsorbs nutrients, the nephron loop concentrates urine, and the distal tubule regulates ion balance.

What is the role of microvilli in the proximal tubule of the nephron?

Microvilli increase the surface area for reabsorption of essential nutrients and ions from the filtrate.

How do cortical nephrons differ from juxtamedullary nephrons in terms of structure and function?

Cortical nephrons have shorter loops and are more involved in filtration, while juxtamedullary nephrons have longer loops important for urine concentration.

The interlobar veins are formed by the convergence of which smaller veins within the kidney?

Arcuate veins

The cortical radiate arteries supply blood to which part of the kidney?

Renal cortex

What waste products are primarily removed by the kidneys?

Urea and creatinine

Initial process in urine formation where blood pressure forces water and solutes into the capsular space, forming filtrate.

Glomerular Filtration

Process of reclaiming essential substances like water, electrolytes, and glucose from filtrate back into the bloodstream.

Tubular Reabsorption

If the kidneys filter approximately 180 liters of blood-derived fluid daily, about how much of this fluid is reabsorbed?

Approximately 99% of the fluid is reabsorbed.

Final excretory product of the kidneys, formed after filtration, reabsorption, and secretion processes.

Urine

Why is the proximal tubule critical for the kidney's function?

It is the main site for reabsorbing glucose, amino acids, and ions.

The podocytes in the glomerulus are characterized by:

Long branching extensions called foot processes.

Which part of the filtration membrane can contract to assist in controlling the rate of glomerular filtration?

Mesangial cells

The first layer of the filtration membrane with large pores that allow passage of blood components except cells and platelets.

Fenestrated Endothelium

A thin extracellular matrix gel layer in the filtration membrane that repels negatively charged plasma proteins.

Basal Lamina

Cells with foot processes that form filtration slits, the finest layer of the filtration membrane.

Podocytes

How does the paracellular route move solutes:

Transports solutes between cells, through the intercellular space

Which of the following findings in urinalysis is most likely indicative of a urinary tract infection (UTI)?

Presence of leukocytes

Kidneys' intrinsic ability to maintain a stable glomerular filtration rate despite changes in blood pressure.

Renal Autoregulation

A mechanism where macula densa cells adjust arteriole diameter based on sodium chloride levels.

Tubuloglomerular Feedback

A hormone that increases blood pressure by vasoconstriction and promoting sodium reabsorption.

Angiotensin II

A hormone that increases sodium reabsorption in the distal tubule and collecting duct, raising blood volume.

Aldosterone

Which of the following fluids contains only nitrogenous wastes and substances that are unneeded or in excess?

Urine

Which of the following pigments is mainly responsible for the yellow color of the urine?

Urochrome

A difference in solute concentration that drives water reabsorption via osmosis.

Osmotic Gradient

The plasma concentration at which a substance begins to appear in the urine.

Renal Threshold

The maximum amount of a substance that can be reabsorbed per unit time, reflecting the number of transport proteins available.

Transport Maximum

Water channels in cell membranes that facilitate water reabsorption following osmotic gradients.

Aquaporins

A hormone that reduces sodium reabsorption, leading to increased sodium excretion in urine.

Atrial Natriuretic Peptide (ANP)

A hormone that increases water reabsorption, reducing urine volume.

Antidiuretic Hormone (ADH)

Which of the following parts of a nephron completely reabsorbs glucose?

Proximal convoluted tubule

Pathway where substances pass through tubule cells during reabsorption.

Transcellular Route

The segment of the nephron where about 65% of reabsorption occurs, featuring prominent microvilli to increase surface area.

Proximal Tubule

The majority of the reabsorption process occurs in:

Proximal convoluted tubule

How does the distal convoluted tubule help regulate the body's acid-base balance?

Through hydrogen ion secretion

The proximal tubule can reabsorb almost 100% of which of the following substances?

Glucose

Antidiuretic hormone (ADH) can regulate the reabsorption of which of the following by the distal tubules?

Water

What would be the primary characteristic of urine produced by the kidneys in the absence of ADH?

Dilute

How does the descending loop of Henle contribute to urine concentration?

Allowing the water to pass but not the solutes