Brainscape's Knowledge GenomeTM

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


See full index

Cells to Systems > Digestive System > Flashcards

Digestive System Flashcards

1
Q

The gastrointestinal (GI) tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. It includes the following parts:

what are the accessory organs involved in digestion?

A

Mouth
Oesophagus
Stomach
Small intestine
Large intestine

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

where does digestion begin?

A

In the Mouth.

Mastication (chewing) breaks down food and increases
surface area, mixing it with saliva- Forms the food bolus (mass of chewed food mixed with saliva, ready to be swallowed).

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

what is 90% of saliva secreted by?

A

3 pairs of salivary glands:
– Sublingual (lingual =
tongue)
– Submandibular (mandible = jaw)
– Parotid (otid = ear)

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

what is saliva made up of?

How much of it is produced?

what is it under the control of?

what is it secreted by?

what makes saliva hypotonic?

A

99.5% water and 0.5% electrolytes and proteins.

it is Continuously produced so around 1-2L per day.

under the control of the autonomic nervous system

Secreted by the acinar cells:
- Serous – proteins in an isotonic fluid
- Mucous – mucin proteins

Duct cells absorb NaCI to make solution hypotonic (low concentration of solutes-sugar/salts).

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

what are the 5 key functions of Saliva

A

Lubrication
– Mucus facilitates eating and speech

  • Digestion
    – Salivary amylase breaks down carbohydrate
  • Oral hygiene / Antimicrobial
    – Washes away debris
    – Lysozyme lyses bacterial cell walls

*Taste
– Solvent to allow molecules to interact with taste receptors

*Buffering
– Neutralise acids to protect teeth

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

where is the pharynx located and what is its function?

A

Behind mouth and nasal cavity.

Takes food to the oesophagus and air to the
trachea.
Also divides the trachea from the oesophagus- epiglottis folds over as food passes through- swallowing.

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

what is swallowing?

A
  • Complex reflex process
  • Initiated voluntarily
  • Bolus passes to the back of throat and to oesophagus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

oesophagus
what is it?
function?
what does it secrete?

A

Straight tube surrounded by smooth
muscle

Passes food bolus to the stomach using peristalsis (6-10 seconds).

Only secretion is mucus (no absorption)

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

what is peristalsis?

A

a wave of muscle contraction in a coordinated way to help push the food down the oesophagus.

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

where is the Gastroesophageal sphincter located and what is its funtion?

A

between the esophagus and the stomach- its a ring of smooth muscle that prevents the content of the stomach from going back up the oesophagus (When you swallow, the sphincter relaxes to allow food and liquid to pass into the stomach, and then it tightens to keep the stomach contents from coming back up)

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

where is pyloric sphincter located and what is its function?

A

between the stomach and the small intestine- a ring of smooth muscle which controls the amount of
chyme (partially digested food) entering the small intestine.

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

what helps churn food in the stomach?

A

Waves of peristaltic contractions helps mix the food in the stomach- The rhythmic muscle contractions ensures the food is thoroughly mixed with digestive juices, aiding in the breakdown of food into a semi-liquid form called chyme.

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

what does the stomach secrete?

A

Secretes 2 L/day of gastric juice:
– Water
– Mucus
– HCl
– Pepsinogen
– Hormones

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

what are the 3 key functions of the stomach.

A

Mixes and breaks down food into chyme.

Stores food (50ml to 1L) and releases into the
small intestine slowly

Begins protein digestion through secretion of
hydrochloric acid and enzymes (pepsinogen)

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

The stomach is the site of ——– NOT ——–.

A

The stomach is the site of Secretion NOT Absorption.

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

Secretions of the Stomach (Gastric Juice)- Exocrine Secretion:

A
  • Mucous cells – Mucus (protection)
  • Chief cells – Pepsinogen (pre-cursor enzyme, digests proteins)

Parietal cells – Hydrochloric acid and intrinsic factor (HCl
activates pepsinogen, intrinsic factor aids vitamin B12 absorption).

17
Q

Secretions of the Stomach (Gastric Juice)- Endocrine and Paracrine Secretions:

A

Enterochromaffin-like cells (ECL) – Histamine

G cells - Gastrin

D cells - Somatostatin
Control exocrine
secretion

18
Q

Control of Stomach Secretions- Vagal Nerve Stimulation (Ach)

A

– Chief cells (secrete pepsinogen)

– Parietal cells (secretes HCl and intrinsic factor)

– G cells (secretes gastrin)

– ECL cells (secretes histamine)

19
Q

Control of Stomach secretions- Gastrin (endocrine)

A

– Secreted into blood from G cells

– Stimulates parietal cells – increases HCl

– Stimulates chief cells – increases pepsinogen

– Maintains gastric mucosa

20
Q

Control of Stomach Secretions- Histamine (paracrine)

A
  • Released by ECL

– Stimulates parietal cells to increase HCl

21
Q

Control of Stomach Secretion- Somatostatin (paracrine)

A

-Negative feedback in response to low pH
– Inhibits:
* Parietal cells
* G cells
* ECL cells

22
Q

Functions of Stomach acid:

A

Breaks down connective tissue

Activates pepsinogen to pepsin

Denatures protein

Antimicrobial

DOES NOT DIGEST PROTEIN.

23
Q

How is Stomach Acid Secreted.

A
  1. When stimulated, parietal cells insert H+/K+ ATPase into the luminal membrane
    which cause canaliculi to form (increase surface area)
  2. Carbonic anhydrase is abundant and
    causes CO2 to react with H2O to form carbonic acid H2CO3
  3. Carbonic acid dissociates to H+ and HCO3-
  4. H+ is actively pumped into lumen via H+/K+ ATPase.

5.Bicarbonate ions HCO3- exchanged for
Cl- at the basolateral membrane

  1. Cl- passively diffuses out of the luminal
    membrane via chloride channels
  2. HCl formed in the stomach lumen
24
Q

what does the indigestion treatment Omeprazole do?

A

block the proton pump to reduce acid production

25
Q

what are the symptoms of indigestion?

A

Burning sensation in chest

Bad taste in mouth

Cough, hiccups, bad breath, nausea, bloating etc

26
Q

what is acid reflux?

A

Acid reflux can occur when the stomach contents passes through the gastroesophageal
sphincter.

27
Q

what are the two indigestion treatments?

A

Gaviscon
semiticone

28
Q

Gaviscon

A

Gaviscon (sodium alginate, sodium bicarbonate and calcium bicarbonate)

  • Sodium alginate
    – Derived from seaweed
    – Reacts with acid to form a gel – prevents reflux
  • Sodium bicarbonate and calcium bicarbonate
    – Neutralises the acid
    Indigestion Treatments
29
Q

Simeticone

A
  1. Simeticone
    * Treats bloating/trapped wind
    * Silicon surfactant – reduces the surface tension of bubbles
    causing them to coalesce and more easily disperse
    Indigestion Treatments
30
Q

what does the pancreas secrete ?

A

Secretes:
1. Pancreatic juice into the duodenum:
– Alkaline fluid
– Enzymes
(amylase/lipase/peptidases)

  1. Hormones into the bloodstream:
    – Insulin
    – Glucagon
31
Q

what does the biliary system consist of :

A

Liver:
* Processes fats, carbohydrates and proteins once
they are absorbed at duodenum
* Secretes bile
* Detoxification of waste
* Synthesis of plasma proteins

Gall bladder:
* Stores bile before release into the duodenum
* Bile emulsifies fats
Liver and Gallbladder
Common
bile duct
Liver
Duct from
pancreas
Bile salts Cholesterol
Gall
bladder
stomach
duodenum
Sherwood p595

32
Q

what are the 4 layers of the digestive tract.

A

Four layers:
1. Serosa/mesentery
– Secretes fluid
– Supports digestive system

  1. Muscularis externa
    – Smooth muscle (mixing/propulsion)
  2. Submucosa
    – Flexibility/elasticity
  3. Mucosa
    – Lines luminal surface
    – Protective
    – Highly folded in small intestine
33
Q

what are the main components of the small intestine:

CHECK DIAGRAM

A
  • Duodenum
    – 20-25cm
    – Receives chyme, pancreatic
    enzymes and bile
  • Jejunum
    – 2.5m
    – Major area of absorption
  • Ileum
    – 3m
    – Absorption of vitamin B12 and bile
34
Q

what does the small intenstine have on their folds?

what do they secrete?

Are digestive enzymes secreted?

A

Villi / Microvilli / brush border- to increase surface area for absorption.

  • Secretes succus entericus:
    – Water
    – Salts
    – Mucus
  • No digestive enzymes secreted directly into the lumen:
    – Fat broken down by bile
    – Membrane-bound enzymes
    complete carbohydrate and
    protein digestion
    (The cells lining the small intestine have enzymes (e.g. maltase, lactase, etc) attached to them which break down carbohydrates into simple sugars such as glucose. Other enzymes in called peptidases in the site of nutrient absorption, break down proteins into amino acids, making the digestion process very efficient)
35
Q

Large Intestine- what are the 4 parts.

what is the main function of the large intestine?

A

4 parts of the colon:
* Ascending colon
* Transverse colon
* Descending colon
* Sigmoid colon

Main functions:
* Water and salt reabsorption
* Storage of indigestible material

Cells to Systems (11 decks)

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