Urinary System Flashcards

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1
Q

what are the urinary organs?

A

kidneys, ureters, bladder and urethra

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2
Q

write a short note on the kidneys

A

location: either side of the vertebral column under the diaphragm.
structure: bean shaped, red/brown, fist size. covered in connective and adipose tissue

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3
Q

describe the structure and location of the ureters

A

Extend from kidney to bladder. Small muscular tubes which are 25cm in length, 5-7mm diameter. Consist of smooth muscle. Peristalsis occurs here. Lined by transitional epithelium, underlying connective tissue, muscularis and adventia (fibrous layer with blood vessels)

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4
Q

what is the Hilum

A

where the renal artery enters the kidney, and the renal vein and ureters exit the kidney

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5
Q

write a note on the bladder

A

Balloon shaped. Thin and transparent. Holds 400-600mls urine. Has 2 sphincters where urethra exits.

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6
Q

write a sentence on the urethra

A

extends from bladder to outside. 4 cm in length in women, 20cm in men

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7
Q

what are the 4 functions of the kidneys

A

excretion of metabolic waste. maintenance of salt/water balance. pH maintenance. hormone secretion

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8
Q

what wastes are excreted by kidneys

A

Nitrogenous waste:
1. urea ( formed in liver - ammonia + CO2)
2. Creatinine: produced by creatine phosphate in muscles
3. Uric acid: nucleotide metabolism waste (purines). Uric acid dissolves in blood and is filtered by kidneys

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9
Q

explain the water/salt balance function of kidneys

A

Salt balance influences blood volume as water follows salt. So, increased salt in blood = increased blood volume. A higher blood volume then = hypertension. Kidneys regulate the amount of ions in blood

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10
Q

How do the kidneys maintain pH

A

Blood should be pH of 7.4. Kidneys excrete H+ and reabsorb HCO3- to maintain pH

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11
Q

What hormones are secreted by the kidneys?

A

Renin which stimulates aldosterone secretion which reabsorbs sodium ions.
Erythropoietin: stimulates RBC production.

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12
Q

What relationship do the kidneys have with vitamin D

A

They activate vitamin D. This vitamin activates calcitrol which promotes Ca2+ absorption in the digestive tract.

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13
Q

What are the three regions of the kidney?

A

cortex, medulla and pelvis

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14
Q

what is a nephron?

A

an independent urine forming unit

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15
Q

function of renal artery?

A

oxygenated blood to kidneys

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16
Q

function of afferent and efferent arterioles?

A

afferent: blood to glomerulus which supplies the nephrons.
Efferent: blood away from glomerulus

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17
Q

function of peritubular capillaries?

A

supplied by efferent arteriole. travel along nephrons and allow reabsorption and secretion between blood and inner lumen.
They surround the proximal and distal tubules and the loop of Henle (called vasa recta here)

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18
Q

function of renal veins?

A

carry filtered blood away

19
Q

what are the functions of the nephrons

A
  1. initial filtration of blood
  2. selective re-absorption of filtered substances back into blood
  3. secretion of unwanted substances
20
Q

the nephron has two components, what are they?

A

tubular and vascular

21
Q

what are the parts of the tubular component

A

Bowmans capsule, Proximal convoluted tubule (PCT), Loop of Henle, Distal convoluted tubule (DCT), collecting duct

22
Q

write a note on Glomerular (Bowmans) capsule

A

located at the beginning of tubular component of nephron. Performs first step of blood filtration. Glomerulus is enclosed in a sac.
Outer layer: squamous epithelium
Inner layer: made of podocytes (long cytoplasmic extensions)
Allow the passage of materials but not blood (aka glomerular filtration)

23
Q

write a note on the Proximal Convoluted Tubule (PCT)

A

This is beside glomerulus. Lined with cuboidal epithelium. Has microbilli for increased surface area for filtrate absorption. Cells of PCT have many mitochondria for active transport energy

24
Q

write a note on the function and structure of the Loop of Henle

A

This can be divided into descending and ascending limbs.
Epithelium lining has special filtration abilities that can re-absorb water and concentrate the filtrate.

25
Q

where does the ascending limb of the loop of henle deliver fluid to?

A

distal convoluted tubule

26
Q

Write a note on the Distal convoluted tubule

A

Is lined by cuboidal cells with no microvilli
This tubule is important for active secretion of ions and other materials. Also reabsorbs sodium ions from urine. Toward the end of the DCT, osmotic flow of water helps to concentrate the urine

27
Q

explain the structure and function of the collecting ducts?

A

the distal convoluted tubule (DCT) opens into a collecting tubule that is lined by simple cuboidal epithelium. The collecting tubules can reabsorb sodium and retain passive water.
Groups of these collecting tubules open into a collecting duct that descends into the medulla. The ducts allow passive water movement into interstitial fluids. The lining cells can secrete H+ ions into lumen

28
Q

what 3 processes take place in nephron

A

filtration, reabsorption and secretion

29
Q

what are the three subsections of blood volume regulation

A

Glomerular filtration, tubular reabsorption, tubular secretion

30
Q

explain glomerular filtration in relation to blood volume regulation

A

Glomerular blood pressure causes water & small molecules to be filtered from glomerulus to Bowman’s capsule - only 20% is filtered out

31
Q

Average glomerular filtration rate?

A

125ml/min

32
Q

What influences GMR?

A
  1. Renal blood flow & blood pressure
  2. Filtration coefficient - surface of the glomerular capillaries available for filtration & permeability of capillary-Bowman’s capsule interface
33
Q

Does GFR fluctuate with BP?

A

No

34
Q

Explain tubular reabsorption in terms of blood volume regulation?

A

Moving substances in the filtrate back into the blood through peritubular capillaries - 180L pass through capillaries - 1.8L excreted - occurs mainly in PCT but some in DCT - active transport, passive adsorption, & transcytosis

35
Q

What occurs when concentration reaches transport maximum/renal capacity?

A

Molecules e.g. glucose which would not normally be found in urine are excreted.

36
Q

Describe the active process of Na reabsorption.

A

(1) Na+ is the central “ion” involved in tubular reabsorption
(2) water follows Na+ by osmosis
(3) K+, Cl-, HCO3
- follow water by diffusion
(4) Na+ reabsorption uses 6% body energy at rest.

37
Q

Describe tubular secretion in terms of blood volume regulation.

A

Movement from extracellular fluid into nephron - K & H secreted to maintain homeostasis - metabolites - active process

38
Q

What influences the excretion rate of a substance?

A

Filtration rate & if it is reabsorbed or secreted

39
Q

What hormones are synthesised by kidneys?

A

renin & erythropoietin

40
Q

What hormones are important for kidney function?

A

ADH & aldosterone

41
Q

What is aldosterone?

A

Regulate Na & K levels - increase water retention - increases blood volume & blood pressure

42
Q

What is ADH?

A

Increase water absorption in collecting ducts - affects tissue permeability - homeostasis

43
Q

What is micturition?

A

Bladder - hollow organ - smooth muscle - 600ml - stores urine - at 250ml - stretch receptors & sensory neurons -signal to spinal cord - urinary bladder contracts, sphincter opens