urinary

Question 1

Layers Surrounding the Kidney

Answer 1

Renal Capsule: Fibrous sac covering the kidney.
Adipose Capsule: Cushion of fat around the kidney.
Renal Fascia: Anchors the kidney to surrounding structures.

Question 2

Hilus (Hilum)

Answer 2

Entry/exit for blood vessels, nerves, lymphatics, and ureters.

Question 3

Cortex

Answer 3

Outer layer; contains renal corpuscles.

Question 4

Medulla

Answer 4

Inner layer; contains renal pyramids.

Question 5

Renal Pyramids

Answer 5

Contain collecting ducts, apex forms renal papilla.

Question 6

Renal Columns

Answer 6

Inward extensions of cortex between pyramids.

Question 7

Renal Lobes

Answer 7

One pyramid plus surrounding cortical tissue.

Question 8

Glomerulus

Answer 8

Capillary tuft where filtration occurs (fenestrated capillaries).

Question 9

Bowman’s Capsule

Answer 9

Parietal Layer: Simple squamous epithelium.
Visceral Layer: Podocytes with filtration slits.

Question 10

Filtration Membrane

Answer 10

Fenestrated endothelium of capillaries.
Basement membrane.
Filtration slits of podocytes.

Question 11

Proximal Convoluted Tubule (PCT):

Answer 11

Site of most reabsorption (water, ions, nutrients).
Contains microvilli for increased surface area.

Question 12

Loop of Henle

Answer 12

Descending Limb: Reabsorbs water.
Ascending Limb: Reabsorbs ions (Na⁺, Cl⁻).

Question 13

Distal Convoluted Tubule (DCT)

Answer 13

Reabsorption regulated by hormones (ADH, aldosterone).

Question 14

Collecting Duct:

Answer 14

Receives filtrate from multiple nephrons.
Final site for water and ion reabsorption.

Question 15

Filtration

Answer 15

Occurs in glomerulus.
Produces filtrate (similar to plasma but without large proteins/cells).

Question 16

Reabsorption

Answer 16

99% of filtrate reabsorbed.
Occurs in PCT, Loop of Henle, DCT, and collecting duct.
Reabsorbed substances: Water, glucose, amino acids, ions.

Question 17

Secretion

Answer 17

Active process of removing unwanted substances (e.g., drugs, toxins, excess ions) from blood into filtrate.
Occurs in PCT, DCT, and collecting ducts.

Question 18

Juxtaglomerular Apparatus

Answer 18

Juxtaglomerular Cells: In afferent arteriole, secrete renin in response to low BP.
Macula Densa: Chemoreceptors in DCT that monitor solute concentration.

Question 19

Renin-Angiotensin-Aldosterone System (RAAS)

Answer 19

Renin triggers angiotensin II production, leading to aldosterone release.
Aldosterone increases Na⁺ and water reabsorption in DCT.

Question 20

ADH (Antidiuretic Hormone)

Answer 20

Released by posterior pituitary.
Increases water reabsorption in collecting ducts.

Question 21

ANP (Atrial Natriuretic Peptide)

Answer 21

Reduces Na⁺ reabsorption, decreasing blood pressure.

Question 22

Ureters

Answer 22

Transport urine from kidneys to bladder via peristalsis.
Lined with transitional epithelium.

Question 23

Bladder

Answer 23

Stores urine (~500 ml capacity).
Detrusor Muscle: Smooth muscle for contraction during urination.
Lined with transitional epithelium for stretch.

Question 24

Urethra:

Answer 24

Carries urine out of the body.
Males: Prostatic, membranous, and spongy urethra (also carries semen).
Females: Shorter, only for urine.

Question 25

Micturition (Urination)

Answer 25

Reflex controlled by the pons.
Steps:
Bladder fills, stretch receptors send signal to pons.
Parasympathetic stimulation causes:
Detrusor muscle contraction.
Internal urethral sphincter relaxation.
Voluntary relaxation of external urethral sphincter (skeletal muscle).