Midterm 1 - UNIT 03

Question 1

THE HUMAN BODY
DIGESTIVE SYSTEM
2 main groups:

Answer 1

1) Alimentary Canal
- Gastrointestinal tract (AKA)
- Continual digestive tube through the whole body

2) Accessory digestive organs
- teeth, tongue, pancreas, liver, gallbladder,

Question 2

1) GI TRACT
Function:
A-
B-

Answer 2

A- Digestion: breaks food into sm fragments

B- Absorption: moves digested fragments from GI –> blood

Question 3

Anatomy
Anatomical Structures
(1-6) and what they include briefly

Answer 3

1 Mouth : lips, cheek, palate, tongue, teeth, salivary glands
2 Pharynx
3 Esophagus
4 Stomach : cardiac orifice, fundas, body, pyloric canal, pylorus, pyloric sphincter, omentum)
5 Small Intestine : duodenum, jejunum, ileum
6 Large Intestine : cecum, ascending/transverse/
descending colon/ sigmoid colon, rectum, anal canal

Question 4

Alimentary canal is considered to be…

AKA

Answer 4

… ‘outside’ of the body - still in external environment
AKA - nutrients not absorbed into cardiovascular system— mouth and anus are open to external body
only through absorption does the nutrients enter the body

Question 5

Digestive System Activities

1-6 - ordered proximal –> distal

Answer 5

1 Ingestion

2 Propulsion

a) Swallowing
b) Peristalsis

3 Mechanical Digestion
a) Segmentation

4 Chemical Digestion

5 Absorption

6 Defecation

Question 6

Digestive System Activities CONT’
in detail describe each activity
1-6

Answer 6

1- Ingestion: physically taking in the food into the dig system

2- Propulsion: moving food forward through the AI Canal

a) Swallowing: voluntary activity - moving food down the esophagus
b) Peristalsis: involuntary movement of smooth muscle, food (chyme) through the esophagus, stomach, intestine

Involves; alternative ‘waves’ of contractions and relaxation of smooth muscle - alters intestinal tube diameter

Question 7

CONT’
in detail describe each activity
3

Answer 7

3- Mechanical Digestion: physical prep of food for absorption
- chewing, mixing food w enzymes (tongue), chuming of food in stomach

a) Segmentation: mixing of food in intestine w digestive juices – smooth muscle contraction/relaxation holds in 1 place instead of forward movement like peristalsis

Question 8

CONT’
in detail describe each activity
4-6

Answer 8

4- Chemical Digestion:
involves the secretion of enzymes into AI Canal ( begins in mouth- salivary glands release amylase)

• chemically breaks food into ‘manageable’ molecules
• enzymes secreted by glands

5- Absorption: movement of digested end products from GI lumen –> bloodstream (or lymph)

• MAJOR absorptive organ = sm intestine

6- Defecation: elimination of indigestible substances through the rectal canal & anus (indigestible fibre)

Question 9

ALIMENTARY CANAL structure
consistent all through esophagus - anal canal

: 4 tunics (layers)

Answer 9

1) Mucosa (most interior part of GI)
2) Submucosa
3) Muscularis externa (thick)
4) Serosa (most superficial)

Question 10

4 tunics in detail:
1)
3 major functions:
3 layers:

Answer 10

1) Mucosa: Moist epithelial layer lines the lumen of the AI Canal = cells that can absorb nutrients

1 - Secretion of mucus; enable smoother movement of food
2- Absorption of end products of digestion
3 - Protection against infectious disease - film/barrier

1- Epithelium: mucus secretions- helps movement and protects organs from digesting themselves

• stomach and sm intestine mucosa contain - enzyme/hormone - secreting cells - makes them endocrine digestive organs

2- Lamina Propria: loose connective tissue - nourishes epithelium & facilitates the nutrient absorption
* contains lymph nodes

3 - Muscularis mucosae: smooth muscle cells that produce localized movements of mucosa

Question 11

4 tunics in detail:
2)
3)
4)
- what is a retroperitoneal organ:

Answer 11

2) Submucosa: dense connective tissue contains elastic fibres - for stretch - blood & lymph vessels/nodes, nerves
3) Muscularis Externa: relatively thick- responsible for segmentation (circular muscle) & peristalsis (longitudinal muscle)

4) Serosa: protective visceral peritoneum (mem)
- replaced by fibrous adventita in esophagus

Retro = what sits outside of peritoneum - have both a adventita and serosa

Question 12

Lacteals =

Water soluble items go…

Microvilli =

Answer 12

= smallest vessel of the lymph system - absorbs fat soluble nutrients (fat sol vitamins, FA, Cholesterol)

… (B and C Vit, protein, water) absorbed directly into capillaries

= on vili - increase surface are for max absorption

Question 13

Nervous System Control

Nervous system specific to digestive system = 
- composed of:
1 =
- regulates:
present in:
2 = 
- that controls:
HOW:
present in:
linked to CNS by:

Answer 13

= Enteric NS
: 2 major intrinsic nerve plexuses

1) Submucosal nerve plexus (meissner’s plexus) -
: regulates glands and smooth muscle in the mucosa
: sm and lg intestine

2) Myenteric Nerve Plexus (Auerbach’s plexus) -
: major nerve supply that controls GI tract mobility and motility
: controls segmentation and peristalsis
H: they both involve local reflex arcs - physical presence of chyme stretches tissue - initiates reflex (aka nerves)

: all throughout AI Canal
: VIA long autonomic reflex arcs

Question 14

Digestive System Blood flow
Arteries:
- super mesenteric artery-
- inferior mesenteric artery-

this circulation also serves:

AT REST ______ of all ______ goes to digestive system =

Answer 14

: branch off abdominal aorta

• delivers oxy blood to sm intestine
• delivers oxy blood to lg intestine

: gut, spleen, pancreas, liver
= 1/4 of all cardiac output –> dig sys
- increases after a meal- presence of food needs more blood

Question 15

Splanchnic circulation =
Function:
1
2
3

Answer 15

= part of the cardio vascular system that communicates with digestive system

1 metabolic support to intestinal cells
2 secretion of chemicals into GI lumen
3 absorption of macro and micro nutrients

Question 16

Hepatic Portal Vein =

Hepatic Vein =

Answer 16

= Blood leaves the digestive organs & before returning to circulation it makes a pass into the liver
Non fat, water soluble nutrients goes here

= Returns nutrients to general circulation - blood flow AWAY from liver –> into vena cava

Question 17

MOUTH
Palate:
1
2

Answer 17

: forms the roof of mouth
1 Hard - boney/ forms a rigid structure for food

2 soft palate - skeletal muscle mainly/ closes nasopharynx during swallowing

Question 18

Tongue- \_\_\_\_\_\_ control
composed of:
function:
1
2
3
4

Answer 18

• voluntary control
  : bundles of muscle fibres

1 grips food during chewing
2 repositions the teeth
3 forms a bolus & initiates swallowing
4 sensory organ (taste)

Question 19

they are _____ glands:

Salivary Glands = 
Function:
1
2
3
4

salivary amylase =

Answer 19

= produces saliva
1 cleanses the mouth
2 dissolves food chemicals for tasting
3 moistens food
4 initiates breakdown of food via enzymes

: exocrine glands
= contain ducts that open into oral cavity

= breakdown of polysaccharides

Question 20

ESOPHAGUS

connection between esophagus and stomach =

Answer 20

= Hollow tube surround by muscle, moves food toward the stomach, pierces through the esophageal hiatus (‘opening’)

= cardiac orifice
opening into the stomach, surrounded by cardiac (gastro-esophageal sphincter - protects esophagus from acids