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BRS/POM MOCKS > BRS MOCK 10 - DEV2, small bowel > Flashcards

BRS MOCK 10 - DEV2, small bowel Flashcards

1
Q

What is the chorion?

A

Outer membrane that surround the fetus while it is still being formed.

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2
Q

What is the connecting stalk?

A

Links developing embryo unit to chorion.

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3
Q

What are trophoblastic lacunae?

A

Large spaces filled with maternal blood formed by the breakdown of maternal capillaries and uterine glands.

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4
Q

What do trophoblastic lacunae become?

A

Form placenta by becoming intervillous spaces and maternal blood spaces.

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5
Q

What does the amnion form in the 5th week?

A

Fluid filled sac that encapsulates and protects the fetus.

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6
Q

What forms the chorion?

A

Yolk sac and trophoblast.

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7
Q

What do outgrowths of cytotrophoblast from chorion give rise to?

A

Chorionic villi.

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8
Q

What does fluid accumulation in amnion result in?

A

Contact with chorion forming the amniotic sac.

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9
Q

What are the 2 layers of the amniotic sac?

A

Amnion on the inside. Chorion on the outside.

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10
Q

What is the allantois?

A

Outgrowth of yolk sac that grows along connecting stalk from embryo to chorion.

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11
Q

What does the allantois develop into and how?

A

Becomes coated in mesoderm and vascularises to form the umbilical cord.

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12
Q

How are primary chorionic villi formed?

A

Cytotrophoblasts form finger like projections through synciotrophoblast layer into maternal endometrium.

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13
Q

Secondary phase of chorionic villi development

A

Growth of fetal mesoderm into the primary villi.

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14
Q

Tertiary phase of chorionic villi development

A

Growth of umbilical artery and vein into the villus mesoderm providing vascalature.

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15
Q

What kind of structure do terminal villus have and why is this important?

A

Convuluted knot of vessels. Covered with trophoblasts. Slows blood flow enabling exchange between maternal and fetal blood.

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16
Q

How does the thickness of cytotrophoblast layer around terminal villus change through pregnancy?

A

Decreases. Allows for faster exchange later on in pregnancy.

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17
Q

Maternal blood vessel branching before reaching endometrium

A

Uterine artery branches to give arcuate arteries. Arcuate arteries branch to give radial arteries. Radial arteries branch to give basal arteries. Basal arteries branch to give spiral arteries. Spiral arteries invade endometrium.

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18
Q

When do the basal arteries form the spiral arteries?

A

During menstrual cycle endometrium thickening.

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19
Q

What results in spiral artery remodelling?

A

Extra villus trophoblast cells invade down into maternal spiral arteries forming endovascular extra villus trophoblast. Endothelium and smooth muscle of blood vessels is broken down.

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20
Q

How are spiral arteries remodelled?

A

Opens up spiral artery to form low pressure, high capacity conduit for maternal blood flow.

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21
Q

How is oxygen exchanged across placenta?

A

Diffusion.

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22
Q

How is glucose exchanged across placenta?

A

Facilitated diffusion.

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23
Q

How are electrolytes exchanged across placenta?

A

Diffusion and active transport.

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24
Q

How is calcium exchanged across placenta?

A

Actively transported by magnesium ATPase calcium pump.

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25
Q

How are amino acids exchanged across placenta?

A

Active transport.

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26
Q

What cardiovascular and pulmonary changes occur in the mother during pregnancy?

A

Maternal cardiac output increases (stroke volume and heart rate increase). Maternal blood volume increases (greater number of erythrocytes and plasma). Pulmonary ventilation increases.

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27
Q

Where does gas exchange take place in the fetus?

A

Placenta.

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28
Q

What is meconium? What makes up meconium?

A

Meconium is the earliest stool of an infant. Amniotic fluid and bile.

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29
Q

What drives fetal organ maturation?

A

Corticosteroids.

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30
Q

What occurs in labour?

A

Immune cell infiltration, inflammatory cytokine and prostaglandin secretion.

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31
Q

What are the two phases of the first stage of labour?What occurs in the first stage of labour?

A

Latent phase - Slow dilation of cervix. Active phase - rapid dilation of cervix.

32
Q

What occurs in the second stage of labour?

A

Maximal myometrial contractions to deliver fetus.

33
Q

What occurs in third stage of labour?

A

Expulsion of placenta and fetal membranes. Post partum repair.

34
Q

Why does the cervix need to be remodelled?

A

Its stretch resistant and rigid at first. Needs to dilate later on in pregnancy.

35
Q

How is the cervix remodelled for labour?

A

Softening in first trimester. Monocyte infiltration and IL6,IL8 secretion along with hyaluron deposition in weeks before birth causing ripening. Dilation is caused by breakdown of hyaluron due to increased expression of hyaluronidases, MMP’s break down collagen.

36
Q

What hormone initiates labour?

A

Corticotrophin releasing hormone. Rises exponentially towards end of pregnancy.

37
Q

What does corticotrophin releasing hormone from fetus do in labour?

A

Promotes fetal ACTH and cortisol release. Increase in cortisol induces positive feedback and drives placental production of CRH. Stimulates DHEAS production by the fetal adrenal cortex which is a substrate for oestrogen production.

38
Q

Why do progesterone receptors on uterus switch when approaching term?

A

High progesterone maintains uterine relaxation. Expression of progesterone receptor B and C instead of progesterone receptor A. Progesterone receptor B and C are repressive isoforms and result in uterus becoming unresponsive to progesterone action.

39
Q

What hormones does the uterus respond to nearer term?

A

Unresponsive to progesterone and sensitised to oestrogen action.

40
Q

What stimulates oxytocin release in labour?

A

Stretch receptors and rising oestrogen levels.

41
Q

What inhibits oxytocin receptor expression in early pregnancy?

A

High levels of progesterone. Keeps uterus relaxes early on.

42
Q

What promotes oxytocin receptor expression near labour?

A

High oestrogen levels.

43
Q

How does oxytocin increase uterine contraction?

A

Increase connectivity of myocytes in myometrium. Lower membrane potential threshold for contraction. Enhance liberation of intracellular calcium stores.

44
Q

What are the primary prostaglandins involved in labour?

A

PGE2, PGF2alpha, PGI2.

45
Q

What hormone drives prostaglandin action?

A

Oestrogen.

46
Q

How does oestrogen drive prostaglandin action?

A

Activates phospholipase A2 enzyme which generates more arachidonic acid for prostaglandin synthesis. Stimulation of oxytocin receptor expression promotes prostaglandin release.

47
Q

What is PGE2 involved in?

A

Cervix remodelling. Promotes leukocyte infiltration into the cervix, IL8 release and collagen remodelling.

48
Q

What is PGF2 involved in?

A

Myometrial contractions. Promotoes connectivity of myocytes and reduces threshold for actional potential for contraction.

49
Q

What is PGI2 involved in?

A

Myometrial smooth muscle relaxation to allow blood flow into uterus. (constant contraction wouldn’t be good for blood flow)

50
Q

Apart from steroid hormones and prostaglandins what other compounds are involved in cervix remodelling?

A

Relaxin and nitric oxide.

51
Q

How do myometrial muscles in the uterus form the birth canal?

A

Contractions start at the fundus and spread down. Muscle contractions are brachystatic - fibres do not return to full length upon relaxation. This causes lower segment and cervix to be pulled up forming birth canal

52
Q

What occurs after fetal delivery?

A

Shrinkage of uterus. This results in folding of fetal membranes and area of contact of placenta with endometrium to shrink. Clamping of umbilical cord stops fetal blood flow to placenta which results in collapsing of villi and haematoma formation between decidua and placenta. Contractions expel placenta and fetal tissues.

53
Q

Function of mesentery?

A

Anchors small bowel and large bowel while still allowing for some movement. Conduit for blood vessels, nerves and lymphatic vessels.

54
Q

Where are villi innervated from?

A

Nerve plexus from submucosa layer.

55
Q

What cells are found at crypts of lieberkuhn?

A

Stem cells and paneth cells.

56
Q

Function of glycocalyx?

A

Serves as protection from intestinal lumen. Controls rate of absorption from intestinal lumen.

57
Q

What does mucous do in the bowels?

A

Facilitates passage of material in bowel by acting as a lubricant.

58
Q

What do paneth cells do?

A

Regulate intestinal flora and engulf some bacteria.

59
Q

What do granules in paneth cells contain?

A

Lysozyme, glycoproteins and zinc.

60
Q

What distinguishes the duodenum from the jejunum and ileum?

A

Presence of brunner’s glands.

61
Q

What distinguishes the jejunum from the ileum?

A

Ileum has thin wall while jejunum has thick wall.

62
Q

What is migrating motor complex?

A

Cycles of smooth muscle contraction sweeping throughout the gut.

63
Q

Where does pancreatic amylase act and what does it digest?

A

Digestion of complex carbohydrates in lumen of small bowel.

64
Q

Factors for optimum pancreatic amylase activity?

A

Chloride ions and neutral pH.

65
Q

Where does digestion of simple carbohydrates occur at?

A

Brush border.

66
Q

How are glucose and galactose absorbed?

A

Secondary active transport by SGLT1 (sodium/glucose cotransporter 1) carrier protein on apical membrane.

67
Q

How is fructose absorbed?

A

GLUT5 by facilitated diffusion on apical membrane.

68
Q

What transporter do simple sugar enter the interstitial space and then the blood?

A

GLUT2 on basolateral membrane.

69
Q

Where does protein digestion start? What digests it?

A

Lumen of stomach by pepsin.

70
Q

What inactivates pepsin?

A

Alkaline conditions of duodenum.

71
Q

What transporter on enterocytes absorb small peptides?

A

PepT1.

72
Q

What happens to small peptides absorbed by enterocytes?

A

Digested in the cytoplasm of the enterocytes. Intracellular digestion.

73
Q

What are the steps of lipid digestion?

A

Secretion of bile salts and pancreatic lipases. Emulsification of lipids. Lipase activated by co-lipase. Enzymatic hydrolysis of ester linkages. Solubilisation of lipolytic products in bile salt micelles (holds lipolytic products).

74
Q

What happens when monoglycerides and fatty acids enter the enterocytes?

A

Reconstructed back into triglycerides by Monoglyceride acylation, Phosphatidic acid pathway. Incorporated in chylomicrons and secreted across basement membrane by exocytosis into lymph vessel.

75
Q

Function of ileocaecal valve?

A

Allows passage of material into colon and prevents back flow of bacteria into ileum.

BRS/POM MOCKS (23 decks)

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