Download Digestive - Mrs. Kennedy`s Biology 11 Site!

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Pancreas wikipedia, lookup

Gastric bypass surgery wikipedia, lookup

Bariatric surgery wikipedia, lookup

Human microbiota wikipedia, lookup

Surgical management of fecal incontinence wikipedia, lookup

Hepatotoxicity wikipedia, lookup

Transcript
Animal Digestion
Name, locate and describe the functions
of the parts of the digestive system.
Introduction



Digestion is defined as the breakdown of
nutrients
We consume:
Proteins
Carbohydrates
Fats
Nucleic acids
These are broken down into their simplest
forms
And that’s not all…
We also consume:

Water – is not digested
1.
2.
Hydrates body’s cells
Enables transport and exchange of materials to and
from the cells



3.

Gases
Nutrients
Waste
Regulates body temperature
Vitamins
(living source)
/
/
Minerals
(non-living source)
*These are needed in trace amounts to assist reactions in the cells
From Beginning to End
Mouth
Esophagus
Stomach
Small intestine
Large intestine
Anus
Mouth


Point at which ingestion takes place and
where food is chewed.
Site that begins mechanical and chemical
digestion of food


Mechanical digestion = chewing
Chemical digestion = secretion of saliva
Teeth

provide mechanical
digestion of food by
breaking, cutting,
and tearing.

The increased
surface area :
aids in the
swallowing process.
 Allows more
efficient digestion
by chemicals.

Salivary Glands
Secrete saliva which:



moistens the food (makes it slippery)
stimulates taste
Begins chemical digestion
Saliva contains the enzymes:


salivary amylase
salivary maltase
*Enzymes are organic catalysts that
speed up chemical reactions
without being altered by the reaction.
Saliva includes:

Water: moistens consumed feed and aids in the
taste mechanisms.

Mucin: lubrication aid for swallowing.

Bicarbonate Salts: acts as a buffer to regulate
pH of the stomach.

Enzymes: salivary amylase/maltase initiates
carbohydrate breakdown.
Structures Beyond the Mouth…

Esophagus: hollow, muscular tube
that transports “bolus” from the
mouth to the stomach;



Ingested material is moved by a
series of muscular contractions
referred to as peristaltic waves.
Cardiac Sphincter: valve at the
junction of the stomach and
esophagus.
Stomach: hollow, pear shaped,
muscular digestive organ
Functions of Stomach
(Site of Digestion)
Muscular movements cause
physical breakdown
by grinding food between folds
(called rugae).
Secretes digestive juices for
chemical breakdown:
1) Hydrochloric Acid
2) Pepsin
3) Rennin
Parts of the stomach:

Cardiac sphincterprevents backflow

Esophageal region:
non-glandular area
surrounding the cardiac
sphincter

Cardiac gland region:
contains cells that produce
primarily mucus (protects
stomach lining)

Fundic gland region: contains cells that
provide the gastric secretions needed for the
initial stages of digestion.
Parietal cells: produce hydrochloric acid.
 Chief cells: produce enzymes or precursors of
enzymes



Pyloric gland region: contains cells that
produce mucus and some proteolytic
(protein digesting) enzymes.
Pylorus sphincter: at the beginning of the
small intestine which controls passage of
material (chyme) out of the stomach


Stomach contents approximately a pH of 2
(kills bacteria).
Material arriving at the stomach is called the
bolus

Material leaving the stomach is called
chyme.
Just a Reminder…
Both types of digestion are
occurring in the stomach:
Mechanical and Chemical


The churning of the stomach is considered
mechanical digestion
The enzyme activity is considered
chemical digestion
Chemical > Mechanical
Small Intestine - 3 sections
1.
Duodenum

(first section)
Receives secretions from:
 Pancreas: acts on proteins,
carbohydrates and lipids
 Liver: bile (stored in the
gallbladder) breaks down fat.
 Active site of digestion
2.
Jejunum: (middle section)
3.
Ileum: (last section)
active in nutrient absorption
active in nutrient absorption
Pancreas
Endocrine


Insulin
glucagon
Exocrine


Enzymes
(acini)
Bicarbonate
(ducts)
Small Intestine
Walls of the S.I. are lined
with a series of
fingerlike projections
called villi,
which in turn have
minute projections
called microvilli
that increase the
nutrient absorption
area.
Small intestine cont’d…



Each nutrient has a specific absorption site.
Each villus contains an arteriole and venule,
together with a drainage tube of the
lymphatic system, a lacteal.
The venules ultimately drain into the portal
blood system, which goes directly to the
liver.

The lymph system empties via the thoracic
duct into the vena cava.

S.I. contents are approximately pH 6 to 7.

Sight of digestion and absorption.


Passive absorption = results from diffusion or
movement from high concentrations to low
concentrations.
Active absorption = transport of molecules
across the intestinal lining.
(villi) engulf the molecules and then actively
transport these molecules to either the bloodstream
or the lymph.
 Nutrients are carried to the liver where it is
detoxified.

Large Intestine – 3 sections
1. Cecum (first sections)




size varies considerably in different species;
Non-functional in humans (appendix)
Horses contain an active flora of bacteria similar to the
microbial population in rumen compartment of
ruminants.
 Bacterial breakdown of cellulose and other
carbohydrate material so the horse can utilize
fibrous feeds.
Site of bacterial synthesis of water-soluble
vitamins and protein.
2. Colon


(middle section):
largest part of the large intestine
Primary area of water restoration from
intestinal contents.
3. Rectum

(last section)
the end of the digestive tract before the
unabsorbed material (feces) is excreted out
the anus.
4. Anus:
•
external opening where unabsorbed materials
(feces) are expelled from the body.
Functions of the L.I.





Site of water restoration
Secretion of some mineral elements
 calcium
Storage reservoir of undigested GI contents.
Bacterial fermentation:
 Synthesis of some water-soluble vitamins
and vitamin K.
 Some bacterial breakdown of fibrous
ingredients.
 Synthesis of some protein
Limited absorption of feedstuff from the L.I.
Cross-section of Digestive Tract
Defecation Reflex:
mass movement
 rectal distension
internal sphincter (invol)
 external sphincter (vol)
Bulk flow of liquid in gut

Input



Output


Ingestion ~ 2 litres per day
Secretion (gut) ~ 7 litres/day
Faeces ~100 ml/day
Conclude ~ 9 litres/day absorbed


Small intestine reabsorbs  7.5 L/day of water
Large Intestine reabsorbs 1.4 L/day
Digestive Health: Protection & Problems

Immune defense: M-cells, Peyer's patches,
lymphocytes

Irritable bowel disease – chronic
inflammation

Diarrhea: leads to dehydration (4 million
deaths/yr)

Vomiting (emesis) can lead to alkalosis

Ulcers- H. pylori

"heart-burn"  acid reflux disease
Summary



Processes of digestion: ingestion, digestion,
absorption, secretion, motility, reabsorption
& defecation
Anatomy of digestion: mouth, esophagus,
stomach, small & large intestines, rectum,
anus (pancreas & liver)
Enzyme hydrolysis of carbohydrates, proteins,
lipids and nucleic acids provide the nutrients,
absorbed & conducted to liver for storage and
conversion
Some good websites




http://kidshealth.org/kid/body/digest_noSW.ht
ml
http://www.teachnet.ie/farmnet/Digestive.htm
http://biology.clc.uc.edu/courses/bio105/digesti
v.htm
http://www.williamsclass.com/SeventhScience
Work/HumanBodySystemProject.htm