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MBBS > 203 UG - Physiology > Flashcards

203 UG - Physiology Flashcards

1
Q

The excretory function of kidney - What does the kidney excrete?

A

Metabolic waste

  • urea
  • creatinine
  • uric acid
  • bilirubin

Foreign chemicals
- drugs

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2
Q

List the functions of kidney (7)

A

Regulation of H2O & electrolyte balance
Regulates body fluid osmolarity & electrolyte conc
Regulates bp by excretion of Na2+ & H2O
Regulation of acid base balance
Production of erythropoietin
Formation of 1,25 dihydroxycholecalciferol
Gluconeogenesis

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3
Q

Pathway of renal blood supply

A

Aorta → renal artery → interlobar artery → arcuate artery → interlobular artery → afferent arteriole → glomerular capillary

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4
Q

Pathway of renal blood drainage

A

Efferent arteriole → peritubular capillaries → interlobular vein → arcuate vein → interlobar vein → renal vein

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5
Q

Nephron pathway

A

Glomerulus → Bowman’s capsule → PCT → Loop of Henle → Macula densa → DCT → Collecting tubule

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6
Q

Cortical nephrons

A 
70-80% of nephrons
Glomeruli in cortex
Short loops of Henle reaching outer medulla
Peritubular capillaries
Excretion function
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7
Q

Juxta-medullary nephrons (5)

A

20-30% of all nephrons
Glomeruli at junction between medulla & cortex
Long loops of Henle reaching inner medulla
Vasa recta
Concentration of urine

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8
Q

Urinary excretion rate of a substance =

A

filtration rate - reabsorption rate + secretion rate

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9
Q

What is the main function of kidney?

A

Excretion

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10
Q

What does excretion of kidney depend on?

A

Filtration, reabsorption & secretion

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11
Q

Which nephron is involved in concentrating urine?

A

Juxta-medullary nephrons

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12
Q

Filtration fraction =

A

Glomerular filtration rate (GFR) / Renal plasma flow (RPF)

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13
Q

Normal glomerular filtration rate (GFR)

A

125 ml/min

180 L/day

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14
Q

Normal renal plasma flow (RPF)

A

625 ml/min

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15
Q

What are the 3 layers of glomerular capillary membrane?

A
  1. Fenestrated endothelium - -ve charged
  2. Basement membrane - contains collagen & -ve charged proteoglycans
  3. Epithelial cells - podocytes w foot process & slit pores in between - -ve charged
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16
Q

What are the properties of substances that are filtered in the kidney?

A

Depends on size & charge

Small & positive

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17
Q

Sodium & glucose are ______ filtered;
Albumin is ______ filtered.
(kidney filtration)

A

freely; poorly

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18
Q

Why are positively charged substances more easily filtered in the kidney?

A

Filtration membrane is negative, positive and negative attract

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19
Q

Minimal change neuropathy

A

Negative charges of filtration membrane lost

  • autoimmune disease
  • proteinuria - albuminuria
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20
Q

GFR =

A

Kf × net filtration pressure

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21
Q

Forces Favoring Filtration

A

Glomerular hydrostatic pressure

Bowman’s capsule colloid osmotic pressure

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22
Q

Forces Opposing Filtration

A

Bowman’s capsule hydrostatic pressure

Glomerular capillary colloid osmotic pressure

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23
Q

Why is Bowman’s capsule colloid osmotic pressure usually 0?

A

Proteins are not filtered

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24
Q

Kf depends on?

A

Area & permeability of filtration membrane

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25
Q

Why is high blood flow needed for kidney excretory function?

A

High O2 consumption related to sodium reabsorption

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26
Q

Renal blood flow = ?

A

(Renal artery pressure - renal vein pressure) / total renal vascular resistance

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27
Q

Tubulo-glomerular feedback

A

Mediated by the juxta-glomerular apparatus

Macula densa sense less NaCl → signal JG cells secrete renin → dilate afferent arteriole → more filtration

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28
Q

GFR depends on?

A

Kf

Starling forces

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29
Q

What is autoregulation in kidney?

A

Maintains renal blood flow & GFR in spite of changes in BP

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30
Q

What helps in autoregulation?

A

Tubulo-glomerular feedback

Myogenic mechanism

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31
Q

Smooth muscles are ______;

Skeletal muscles are ______

A

involuntary; voluntary

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32
Q

Internal sphincter is ______;

External sphincter is ______.

A

involuntary (smooth muscle); voluntary (skeletal muscle)

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33
Q

2 major parts of bladder

A

Body

Neck

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34
Q

Mucosa of trigone vs mucosa of other parts of bladder

A

Mucosa of trigone is smooth

Others are folded - rugae

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35
Q

Detrusor

A

Smooth muscle of bladder

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36
Q

Main innervation of the bladder

A

Pelvic nerve - connect spinal cord through sacral plexus: S2, S3, S4

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37
Q

Movement of urine from the kidney to the bladder

A

Urine formed in collecting duct → enters minor calyx → contraction of smooth muscle in calyx, pelvis, ureter → moves urine to bladder

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38
Q

Peristaltic activity is ______ by parasympathetic stimulation; ______ by sympathetic stimulation.

A

increased; decreased

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39
Q

What prevents vesicoureteral reflux?

A

A special one-way valve system in the ureter

40
Q

Micturition reflex

A

Caused by stretch of bladder when filled w urine → sensory info carried to sacral segment of spinal cord → pelvic nerve → motor impulses (through parasympathetic nerves) → contraction of detrusor & relaxation of internal sphincter

41
Q

Self regenerative of micturition reflex

A

Initial contraction of the bladder activates the stretch receptors to cause a greater increase in sensory impulses from the bladder and posterior urethra → further increase in reflex contraction of the bladder
→ cycle is repeated until the bladder has reached a strong degree of contraction.

42
Q

Effect of higher centers on micturition reflex

A

Facilitatory & inhibitory centres in brainstem & cortex

- keep micturition reflex inhibited until it’s needed

43
Q

What initiates voluntary control of micturition?

A

Initiated by contracting abdominal muscles

44
Q

Micturation reflex is a ______ reflex.

A

spinal

45
Q

What are the male & female gonads?

A

Male - testis

Female - ovary

46
Q

SRY

A

Sex determining region of Y
Present → testes → produce TDF (Testis-determining factor)
Absent → ovaries

47
Q

Differentiation of internal genitalia - male

A

SRY present → Leydig cells produce testosterone → proliferation of Wolffian duct → epididymis, vas deferens, seminal vesicles, ejaculatory duct

SRY present → Sertoli cells produce AMH → regression of Mullerian duct

48
Q

Differentiation of internal genitalia - female

A

SRY absent → absence of testosterone → regression of Wolffian duct

SRY absent → absence of AMH → progression of Mullerian duct → uterus, fallopian tubes, inner vagina

49
Q

Differentiation of outer genitalia - male

A

Testosterone converted to DHT by 5α-reductase → development of penis, scrotum, prostate

50
Q

Differentiation of outer genitalia - female

A

Absence of testosterone → development of outer vagina, female external genitalia

51
Q

Androgen insensitivity syndrome

A

Genotype: XY - w testes
Phenotype: Female - w external genitalia & vagina

52
Q

5α-reductase deficiency

A

Testosterone ↛ DHT

Male internal genitalia
Female external genitalia

53
Q

Abnormalities in SRY

A

During crossing over SRY may go to X chromosome → female w male external genitalia

Male chromosome lack SRY → male w female external genitalia

54
Q

Turner syndrome

A

XO

Nondisjunction of chromosomes during meiosis
Female internal & external genitalia

55
Q

Klinefelter syndrome

A

47 XXY

Male external genitalia & 2° sexual characteristics

56
Q

Down syndrome

A

Trisomy 21

Nondisjunction of autosome

57
Q

True hermaphroditism

A

Have both testes & ovary

雌雄同體

58
Q

How is puberty activated?

A

Release of gonadotropins during adolescence

59
Q

First sign of puberty - males

A

Gonadarche - enlargement of testes

60
Q

First sign of puberty - females

A

Thelarche - development of breast

61
Q

Oogenesis

A

Primordial germ cell → oogonium (w primordial follicle) → primary oocyte (w primary follicle) →

Meiosis I
→ secondary oocyte (w mature follicle) → ovulated secondary oocyte

62
Q

When does meiosis II occur during oogenesis?

A

During fertilisation

63
Q

When does meiosis I occur during oogenesis?

A

During puberty

64
Q

Ovarian cycle (10)

A
  1. GnRH acts on anterior pituitary → release FSH & LH
  2. Primordial follicles become primary follicles
  3. Develop many layers of granulosa cells
  4. Increase FSH → growth of 6-12 primary follicles - granulosa cell layers increase
  5. Theca cell layer (internal & external) develops outside granulosa
  6. Granulosa cells secrete fluid rich in estrogen - forms antrum
  7. Estrogen increases FSH receptor
  8. 1 follicle w many FSH receptors will mature to ovulate (14th day)
  9. Increase in estrogen decreases FSH
  10. Other follicles - atresia
65
Q

LH surge

A

Just before ovulation LH levels increase → the release of ovum from the ovary

66
Q

Corpus luteum

A

Remaining follicle w/o ovum after ovum released

67
Q

Hormones of Menstrual cycle

A

FSH → stimulates estrogen → inhibits FSH
→ stimulate LH → inhibits estrogen
→ stimulate progesterone → inhibits LH

68
Q

Corpus luteum is maintained during?

A

first 3 months of pregnancy, by hCG

69
Q

3 phases of the uterine cycle

A

Proliferative - endometrium becomes thicker
Secretory - secretes hormones for pregnancy/menstruation
Menstruation - shedding of endometrium

70
Q

Which phase of the uterine cycle is fixed?

A

Secretory phase - 12 days

Corpus luteum regresses 12 days after formation

71
Q

Regulation of hormones in menstrual cycle

A

Mostly - negative feedback - estrogen & progesterone provide negative feedback to the hypothalamus and pituitary gland

In days 12 - 14 - positive feedback - estrogen provides positive feedback to the hypothalamus and pituitary gland → LH surge → ovulation

72
Q

Indication of ovulation

A

Pregnanediol level in urine - indicates progesterone secretion
Body temp increase by 0.5°C

73
Q

Liver dysfunction increases ______ levels in the blood

A

oestrogen

74
Q

Function of female sex hormone - oestrogen

A

Female secondary sexual characteristics

75
Q

Function of female sex hormone - progesterone

A

Prepares uterus for implantation

Prepares breast for milk secretion - increase alveoli & lobules in breast

76
Q

Oestrogen causes the ______ phase in menstrual cycle.

A

proliferative

77
Q

Milk secretion is stimulated by?

A

Prolactin

78
Q

Milk ejection requires?

A

Oxytocin

Contraction of myoepithelial cells

79
Q

Why does menopause occur?

A

Primordial follicles degenerate after 45 years

Decreased secretion of oestrogen → menstrual cycles stop

80
Q

Ovulation is caused by?

A

LH surge

81
Q

What causes LH surge?

A

Positive feedback by oestrogen

82
Q

______ causes proliferative changes in uterus;

______ causes secretory changes in uterus

A

Ostrogen; Progesterone

83
Q

Where is egg fertilized?

A

Amupulla of fallopian tube

84
Q

What cells facilitate implantation?

A

Trophoblast cells

85
Q

Arterial supply & venous drainage of placenta

A

Arterial supply: uterine artery

Venous drainage: uterine veins

86
Q

What increases foetal oxygenation?

A

High affinity of HbF
High RBC
Double Bohr effect

87
Q

What secrete hCG?

A

Syncytial trophoblast cells of blastocyst

88
Q

Function of hCG

A

Maintains corpus luteum for 3 months

89
Q

Corpus luteum secretes?

A

Progesterone & estrogen

90
Q

High levels of hormones during pregnancy for?

A

Preventing ovulation & menstruation

91
Q

What happens after 3 months in pregnancy, after corpus luteum degenerates?

A

Placenta takes over - placental synctial trophoblast cells secrete estrogen & progesterone

92
Q

Maternal changes during pregnancy

A 
↑ requirement for hormones & nutrients
↑ salt & water retention
↑ BMR
↑ blood volume
↑ CO
93
Q

Positive feedback of parturition

A

Helped by oxytocin

  1. Baby’s head stretches cervix
  2. Cervical stretch excites fundic contraction
  3. Fundic contraction pushes baby down & stretches cervix more
  4. Cycle repeats
94
Q

What hormone helps in the development of ducts in the breast?

A

Oestrogen

95
Q

What hormone helps in the development of alveoli & lobules in the breast?

A

Progesterone

96
Q

What causes amenorrhea in pregnancy?

A

High levels of estrogen and progesterone

MBBS (28 decks)

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