Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Yr 3 Sem 1 > Week 4 > Flashcards

Week 4 Flashcards

1
Q

What is the caecum?

A

First part of the large intestine
~ 7.5 cm in both length & breadth

Receives chyme from the ileum and is continuous with ascending colon

It is a blind intestinal pouch (L. ‘blind’)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where the ileum enters the caecum:

A

The superior & inferior ileocaecal folds form the ileocecal valve

This valve controls passage of chyme through the ileocecal orifice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where is the caecum located?

A

Lies in the RLQ / Rt inguinal region

Corresponds to the Rt iliac fossa – can be palpated through the abdominal wall if distended with gas or faeces

Intraperitoneal: almost entirely covered with peritoneum

However, the caecum has no mesentery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the vermiform appendix?

A

L. ‘worm’

Blind intestinal outpouch arising from the posteromedial aspect of the caecum (inf. to the ileocecal junction)

6 - 10 cm in length

Has a small, twisted lumen (susceptible to blockage)

Intraperitoneal and has a short mesentery or mesoappendix - between the terminal ileum, caecum and appendix

McBurney’s Point
Roughly corresponds to where the appendix attaches to the caecum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the histology of the appendix?

A

Appendix contains masses of lymphoid tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of the appendix?

A

Immunity: produces and stores lymphocytes

Reservoir for beneficial gut bacteria
Helps to recolonise the gut when needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the arterial supply the caecum and the appendix?

A

Caecum: ileocolic a. (terminal branch of SMA)

Appendix: appendicular a. (branch of the ileocolic artery)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the venous drainage of the caecum and the appendix?

A

ileocolic v. –> SMV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the lymphatic drainage of the caecum and the appendix?

A

Ileocolic nodes along the ileocolic artery

Drain into superior mesenteric nodes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the nerve supply to the caecum and the appendix?

A

Intrinsic nn: ENS

Extrinsic nn:
Parasympathetic: CNX Vagus
Sympathetic: abdominopelvic splanchnic nn (lower thoracic segments)

Visceral afferents from appendix: accompany sympathetics to T10 cord segment

Peritoneal nerve supply?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the ascending colon and where is it located?

A

2nd part of the large intestine

Passes superiorly on the right side of the abdominal cavity from the caecum to the liver

Right colic flexure (hepatic flexure)

Lies on posterior abdominal wall and covered by peritoneum anteriorly and on its sides

Example of an organ that has become secondarily retroperitoneal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the transverse colon and where is it located?

A

~ 45 cm long
Largest and most mobile of the large intestine

Variable position, usually hangs across abdomen at level of umbilicus

Passes from Rt colic flexure (hepatic flexure) to the Lt colic flexure (splenic flexure)

Lt colic flexure: more acute, more superior and less mobile than the Rt

Phrenicocolic ligament: runs from Lt colic flexure to the diaphragm

Mesentery of the transverse colon: transverse mesocolon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the arterial supply to the ascending colon and transverse colon?

A

To ascending colon & hepatic flexure:
Branches from SMA
Ileocolic & Rt colic arteries

To transverse colon:
Mainly from middle colic a. (SMA)
Rt colic artery (SMA) & Lt colic artery (IMA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the venous drainage of the ascending colon and transverse colon?

A

To ascending colon & hepatic flexure:
Veins w. same names as arteries
Drain to SMV

To transverse colon:
SMV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the lymphatic drainage of the ascending colon and transverse colon?

A

To ascending colon & hepatic flexure:
Epicolic & paracolic nodes –> ileocolic & Rt colic nodes –>superior mesenteric nodes

To transverse colon:
Middle colic nodes –> sup. mesenteric nodes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the nerve supply to the ascending colon and transverse colon?

A

To asc. colon, hepatic flexure & transverse colon:
Intrinsic nn: ENS

Parasympathetic: CNX Vagus
Sympathetic: T10 - L2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the descending colon and where is it located?

A

Retroperitoneal: covered with peritoneum anteriorly and laterally

Passes from the Lt colic flexure (splenic flexure) down to the iliac fossa

Continuous with the sigmoid colon

18
Q

What is the sigmoid colon and where is it located?

A

S-shaped loop of variable length ~ 40 cm
Links the desc. colon with the rectum

Extends from the iliac fossa to S3 where joins the rectum

Intraperitoneal: has a long mesentery and thus considerable freedom of movement

The rectosigmoid junction is signified by the termination of the teniae coli

19
Q

What is the arterial supply to the descending colon and sigmoid colon?

A

Lt colic a. (IMA)

Superior sigmoid arteries (IMA)

20
Q

What is the venous drainage of the descending colon and sigmoid colon?

A

IMV, which flows into the splenic vein and into the portal system

21
Q

What is the lymphatic drainage of the descending colon and sigmoid colon?

A

Epicolic & paracolic nodes –> inf. mesenteric nodes

22
Q

What is the nerve supply of the splenic flexure, descending colon and sigmoid colon?

A

Intrinsic nn: ENS
Parasympathetic: Pelvic splanchnic nn S2-S4

Sympathetic: lumbar part of the sympathetic trunk & superior hypogastric plexus

23
Q

What are the three features unique to the colon?

A

Teniae coli: the longitudinal m. layer of the muscularis is arranged as three separate, thickened bands

These extend from caecum to the beginning of rectum

The muscular tone puckers the colonic wall into pocket-like sacs called haustra (segmented appearance)

Omental (epiploic) appendices are small, fatty projections of the omentum that hang from the surface of the colon

24
Q

What is the histology of the colon?

A

Mucosa: simple columnar epithelium
Thicker mucosa & deeper crypts compared to rest of GIT

Crypts contain abundant goblet cells – produce mucous to protect wall and ease passage of faeces

Unlike small intestine – no circular folds, villi or brush border

25
Q

What is the rectum and where is it located?

A

Junction between rectum and sigmoid colon is at S3

Follows the curve of the sacrum and coccyx

Ends at the tip of the coccyx, where it turns sharply in a posterior inferior direction (anorectal flexure)

Rectal ampulla: dilated aspect of the distal rectum

The ampulla lies directly above the pelvic floor
It relaxes to accommodate the accumulating faecal mass

Puborectalis m. forms a sling around the inferior part of the rectum and plays an important role in continence

26
Q

What is the rectal peritoneum?

A

Retroperitoneal
Superior 2/3: covered anteriorly & laterally by peritoneum
Middle 1/3: covered anteriorly
Inferior 1/3: no covering as this is subperitoneal

27
Q

What are the peritoneal reflections of the rectum?

A

Females: peritoneum reflecting from the rectum to the posterior aspect of the vagina and uterus

Rectouterine pouch or the ‘Pouch of Douglas’

Males: peritoneum reflecting from rectum to post. Bladder

Rectovesicle pouch

28
Q

What is the arterial supply of the rectum?

A

Proximal rectum: superior rectal a. (IMA)
Mid. & inf. rectum: middle rectal a.

Anorectal junction: internal rectal a.

29
Q

What is the venous drainage of the rectum?

A

Superior rectal veins –> portal venous system

Middle & inferior rectal veins –> systemic system

30
Q

What is the lymphatic drainage of the rectum?

A

Superior 1/2: pararectal nodes
inf. mesenteric & lumbar nodes

Inferior 1/2: internal iliac nodes

31
Q

What is the nerve supply of the rectum?

A

Intrinsic nn: ENS
Parasympathetic: Pelvic splanchnic nn S2-S4

Sympathetic: lumbar part of the sympathetic trunk & superior hypogastric plexus

32
Q

What is the structure of the anal canal and where is it located?

A

Terminal aspect of the large intestine, runs between pelvic diaphragm and anus (~2.5-3.5cm long)

Anal columns: longitudinal folds of mucosa

Anal sinuses: recesses between the columns that exude mucous when compressed by faeces

Two anal sphincters: external (under voluntary control) and internal (involuntary)

Pectinate line (L. ‘comb’) – marks the junction of the superior & inferior parts of the anal canal

Neurovascular supplies reflect embryological differences (superior – endoderm; inferior – ectoderm)

33
Q

What is the arterial supply of the anal canal?

A

Sup. to pectinate line: superior rectal a. (from IMA)

Inf. to pectinate line: inferior rectal a. (from internal iliac a.)
Middle rectal a. forms anastomoses

34
Q

What is the venous drainage of the anal canal?

A

Sup. to pectinate line: internal rectal plexus  sup. rectal v. –> IMV (portal system)

Inf. to pectinate line: internal rectal plexus –> inf. rectal v. (caval system)

External rectal plexus drains peri-anal region

35
Q

What is the lymphatic drainage of the anal canal?

A

Sup. to pectinate line: internal iliac nodes –> lumbar nodes

Inf. to pectinate line: superior inguinal nodes

36
Q

What is the nerve supply of the anal canal?

A

Sup. to pectinate line: inf. hypogastric plexus
Parasympathetic: S2-S4
Sympathetic fibres
Visceral afferents: sensitive to stretch only

Inf. to pectinate line: somatic motor & sensory from pudendal nerve S2-S4
Sensitive to pain, touch & temperature

37
Q

What is the histology of the anal canal?

A

Rectal mucosa: simple columnar epithelium
Anal mucosa: stratified squamous epithelium

Transition reflects the greater abrasion that this region receives
Epithelium merges with the true skin surrounding the anus

38
Q

What is the role of the large bowel? (4)

A

Digestion (minimal)
Enteric bacteria ferment some indigestible carbohydrates and mucin (component of mucus)
Produces short-chain fatty acids (absorbed)
Fermentation also produces gases (~500ml/day) e.g. CH4, dimethyl sufide
Bacteria also involved in vitamin synthesis e.g. B, K

Absorption
Most remaining water, electrolytes (largely NaCl), vitamins produced by bacteria

Propulsion
Haustral contractions & mass movements propel faeces towards rectum
Passage eased by mucous (goblet cells)

Defecation

39
Q

What is the regulation of large bowel motility? (4)

A

Haustral contractions (every 30mins)
Short-lived, slow contractions – mainly in ascending & transverse colon
Initiated by ENS when individual haustra fill with food residue

Mass movements (3-4 times/daily)
Powerful, prolonged contractile waves that force contents towards rectum

Gastrocolic reflex
Presence of food in stomach produces a reflex mass movement

Faecal components
Undigested food residues, mucous, sloughed off epithelial cells
Bacteria
Variable amounts of water

40
Q

What is the defecation reflex?

A

Mass movement of faeces into rectum stimulate visceral afferents (distension)

Initiates a parasympathetic spinal reflex (S2-S4)
Contraction of rectum & relaxation of IAS

Message also reaches brain: allows for conscious decision on relaxation of the EAS

Yr 3 Sem 1 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions