Urinary System 11 Flashcards
(95 cards)
1
Q
List 5 functions of urinary system
A
- Excretion of unwanted substances
- Water & electrolyte balance
- pH regulation - esp blood
- Hormone production - erythropoietin & calcitriol
- Red blood cell production regulation
- Blood glucose regulation
- Blood pressure, volume and osmolarity regulation
2
Q
5 substances excreted by urinary system
A
Metabolic wastes - urea, uric acid and creatinine
Ions - hydrogen
Medications & toxins
3
Q
Minimum urine content required to clear body waste
A
500ml/day
4
Q
Which organ mostly controls water balance
A
Kidneys
5
Q
What do Urea, Uric acid and Creatinine all contain?
A
Nitrogen - the kidneys specalise in removing nitrogenous wastes
6
Q
What is Creatinine an end product of?
A
Muscle metabolism
7
Q
What is uric acid an end product of?
A
Purine metabolism
8
Q
What is Urea an end product of?
A
Protein metabolism
9
Q
3 Most important electrolytes regulates by the kidneys
A
Sodium
Potassium
Hydrogen
10
Q
What do buffers do?
A
Regulate changes in pH
CO2 is acidic. Kidneys excrete H+ into urine to produce bicarbonate to buffer the pH.
11
Q
How should blood pH remain as?
A
7.35-7.45pH
12
Q
What is the active form of vitamin D?
A
Calcitriol
13
Q
Which organ converts vitamin D into its active form?
A
Kidneys
14
Q
What does the hormone calcitriol do?
A
Stimulates calcium and magnesium uptake from the GIT
Reduces calcium loss in the kidneys
15
Q
Which hormone stimulates erythropoiesis (red blood cell synthesis)?
A
Erythropoietin
16
Q
How is Erythropoietin secreted
A
by kidneys into bloom (10% produced by liver)
17
Q
What is erythropoietin released in response to?
A
Hypoxia - negative feedback system
18
Q
What happens to erythropoietin in renal failure?
A
Production of erythropoietin is inadequate leading to anaemia
19
Q
What is the renal threshold for glucose?
A
9 mmol/L
20
Q
What is normal blood glucose levels?
A
4-7mmol/L
21
Q
What does hypoglycemia indicate?
A
A pathology e.g. diabetes mellitus
22
Q
What can kidneys make glucose from?
A
Amino acid glutamine
It helps to elevate blood sugar levels when hypoglycaemic - glucooneogenesis
23
Q
How does the urinary system regulate blood volume, pressure and concertration
A
- it conserves or eliminates water in urine
- regulates ‘solute’ to help maintain constant blood concentration
- regulate blood pressure by kidneys excreting renin
24
Q
What does renin do
A
It activates the renin-angiotensin aldosterone pathway
Increased renin causes an increase in blood pressure
25
Facts about kidneys
Reddish, bean-shaped organs that are retorperitoneal
Right kidney is lower (due to liver)
Perform major functions of the urinary system and secrete urine into the ureters
26
What 3 layers surround the kidneys?
Renal capsule
Adipose capsule
Renal fascia
27
What is the renal capsule
Deep layer - smooth, transparent sheet of connective tissue
Maintains kidney shape
28
What is the kidney's adipose capsule
Middle layer of the kidney - mass of fatty tissue
Provides protection and support
29
What is the kidney's renal fascia?
Outer, superficial layer
Thin layer of connective tissue that anchor the kidneys
30
What two regions are kidneys divided into?
Renal cortex
Renal medulla
31
What is the renal cortex
Superficial light red area
32
What is the renal medulla
Dark red area composed of
Renal pyramids
Apex of each renal pyramid is the renal papilla
33
What is the nephron
Functional unit of the kidney made from renal pyramids and renal cortex
34
Where does urine formed by the nephron drain into?
Minor and major calyces
35
What is the hilum
On the concave kidney border - the region where blood vessels, lymph vessels, nerves and ureters enter and exit the kidney
36
Where does the kidney's blood supply come from?
Renal artery and renal vein
Kidney receives 20-25% of cardiac output despite its mass only accounting for 0.5% of body weight
37
What are the two parts of the nephron?
Renule corpuscle
Renal tubule
38
What is in the renal corpuscle
Glomerulus - tangled capillary network that receives blood
Bowman's capsule
39
3 sections of the renal tubule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
40
What is the key role of the renal tubule?
Important role in reabsorption and secretion
41
Which hormone acts on the distal convoluted tubule to reabsorb water?
Antidiuretic hormone
42
Where does the nephron sit?
Renal corpuscle and both convoluted tubules - in renal corext
Loop of Henle - extends into renal medulla
43
What do the two ureters do?
Transport urine from the renal pelvis to the urinary bladder
44
How long are ureters and where do they sit in the body
25-30cm
Retroperitoneal
45
What propels urine along ureters?
Peristaltic contractions
46
What is the physiological valve
Valve that prevents the backflow of urine in the ureters
47
Three layers of the uteters
1. inner mucous membrane
2. muscularis
3. outer adventitia
(same as the bladder)
48
Info on the ureters inner mucous membrane
Contains transitional epithelium which is able to stretch
Contains mucus secreting goblet cells for protection
49
What is the ureters muscularis made from
Smooth muscle - creates peristaltic contractions to move urine
50
What is the ureters adventitia made from and what does it contain?
Connective tissue
Contains blood and lymph vessels and nerves
51
What is the urinary bladder
Hollow, muscular organ that is a reservoir for urine
52
How full is the bladder when the desire to urinate occurs?
200ml
53
What is the total capacity of the bladder?
600-700ml
54
What is the small triangular area of the bladder called?
Trigone
55
What are the three layers of the urinary bladder?
1. Inner mucosa layer
2. Muscularis
3. Adventitia
(same as the uretas)
56
In the bladder what is the transitional epithelium supported by
Connective tissue
57
What is another name for the muscularis in the urinary bladder?
Detrusor
58
What is the sphincter called in the muscularis
Internal urethral sphincter - involutary
59
What is the adventitia in the urinary bladder?
Connective tissue (same as the urethra)
60
What is the urethra?
Tube leading from the bladder to the exterior of the body - passageway for discharging urine
60
What does the male urethra pass through?
Prostate
60
What is the typical length of the female and male urethra?
Female 4cm
Male 20cm
61
What is the key difference beween the internal urethral sphincter and the external urethral sphincter
Internal = involuntar
External = voluntar
62
What are the 3 basic processes of urine formation?
1. Glomerular filtration - in the renal corpuscle
2. Tubular reabsorption - renal tubules
3. Tubular secretion - renal tubules
63
4 ways glomerular capillaries are adapted for filtration
1. large surface area
2. 50 x more leaky that normal capillaries
3. Efferent artieriole is less than the afferent arteriole
64
What can and what can not pass through the glomerular capilleries into the Bowman's capsule?
CAN- water and small molecules - amino acids, mineral salts, hormones , creatinine, urea, uric acid
CAN NOT - blood cells, plasma proteins and other large molecules- leukocytes, platelets
65
What 3 pressures does glomerular filtration depend on?
1. Blood pressure - promotes
2. osmotic pressure - opposes
3. capsular hydrostatic pressure - opposes
66
What is the glomerular filtration rate?
The amount of filtrate formed in the renal corpuscle of both kidneys each minute
67
What is a normal glomerular filtration rate?
over 90ml/min (males 125ml/min, females 105ml/min)
68
How is glomerular filtration rate calculated?
Through a blood test
69
What is glomerular filtration rate used to determine?
Severity of kidney disease
70
What is colloid osmotic pressure?
Osmotic pressure exerted by proteins
71
What can damage to glomerular capillaries lead to?
Plasma protein loss into urine
Albumin leaks into the filtrate
Less albumin in the blood makes it hypotonic making fluid via osmosis from blood to tissues - can lead to oedema
72
In tubular reabsoption how about of the glomerular filtrate is reabsorbed into the bloodsteam
Around 99%
73
What are the main components of the glomerular filtrate that are reabsorbed
Water
Amino acids
Glucose
Electrolytes
74
Where does most reabsorption occur?
In the proximal convoluted tubules
75
What substances get excreted into tubular fluid?
Waste products - creatinine, urea
Certain drugs
Exess ions
76
5 hormones that affect kidney reabsorption of sodium, chloride, calcium and water
1. angiotensin II
2. Aldosterone
3. Antidiuretic hormone
5. Atrial natriuretic peptide
6. Parathyroid hormone
77
What does the renin angiotensin-aldosterone system do?
Increases blood pressure
78
What are the 4 main stages of the renin angiotensin-aldosterone system
If systolic BP is below 100mmHg the afferent arteriole walls stretch and...
1. enzyme renin is released by kidneys into blood
2. angiotensinogen ins converted into angiotensin I in the liver
3. Angiotensin I is converted into angiotensin II by agiotensin-converting enzyme (ACE) in lungs
4. Angiotensin II causes release of aldosterone from the adrenal cortex
79
What does angiotensin II trigger?
Vasoconstriction to increase blood pressure
80
What hormone does angiotensin II trigger the pituitary gland to release?
Anti-diuretic hormone
81
What does aldosterone do?
Increases renal sodium and water reabsorption
82
What does antidiuretic hormone do?
Reduces water concentration in the blood by increasing water reabsorption in the kidneys
Posterior pituitary secretes ADH
83
What does atrial natriuretic peptide do?
Inhibits the reabsorption of sodium and water into the renal tubules
Increase urine output, reduces blood volume which lowers blood pressure
84
What does parathyroid hormone do?
Released by the parathyroid gland in response to low blood calcium levels
Stimulates renal reabsorption of calcium and magnesium
Increases osteoclast activity
Stimulates calcitriol release
85
Stages of urine flow
1. formed in nephron
2. drains into papillary ducts (in the renal pyramids)
3. drains into the minor and major calyces
4 drains into the renal bladder
5. drains into the bladder through the ureters
86
What does micturition mean
Discharge of urine from the bladder
87
When do the bladder stretch receptors transmit nerve impules
When the bladder exceeds 200-400ml
88
What triggers the mituration reflex in infants and adults
Infants - contraction of the detrusor muscle
Adults Conscious initiation and stop mituation
89
Where is the mituration reflex
Spinal cord levels S2 and S3
90
How much urine do we typically produce in 24 hours?
1-2l
91
pH of urine
4.5-8 (average 6)
92
Composition of urine
Water 96%
Urea 2% uric acid and creatinine
Ammonia
93
How does the urine system effect other systems?
Integumentary - vitamin D precursor
