Download Digestive Systems

Digestive
System Part II
Digestive Organs- the Stomach
Digestion is regulated by hormones and the Nervous
System

Stomach hormone: Gastrin

produced in the presence of protein-containing food
in the stomach

stimulates the release of gastric juices and muscular
contractions of stomach & intestine
Chemical Digestion
Accessory
Digestive
Organs
Structure of the small intestine
Small Intestine

Small intestine is 20-23’ long:
 1)
duodenum 8-10”
 2) jejunum 8’
 3) ileum 12’
duodenum – most active in digestion
 jejunum & ileum – absorption

Digestion in Small Intestine
Digestion is regulated by hormones and the Nervous System
Duodenal hormones

1) secretin – stimulates pancreas & liver to secrete

2) cholecystokinin (CCK) – triggers release of enzymes from
pancreas and gall bladder (amylase, lipase, etc.)
Activation of protein-digesting enzymes in the small
intestine
Accessory Organs: Liver

largest internal organ = 3 lb chemical
factory

processes food by the Hepatic Portal
Vein delivered from digestive tract

though the liver performs many
functions
Liver Functions
1) Filter blood for wastes to produce urea
2) Maintain a Constant glucose level in bloodstream



Remove excess sugar from blood or release it when needed
Glygogen (Liver)  Glucose (Blood)
Will also metabolize amino acids to make glucose if necessary!!
2) Detoxification blood of drugs & alcohol
3) Production of bile – to emulsify fat in the duodenum
4) Destroy old Red Blood Cells
5) Make blood proteins
6) Regulation of cholesterol & other fats
Chopping up Protein

Cut off the NH2 to
supply glucose
Bile

produced by liver, stored in gall bladder

enters small intestine by duct from gall bladder

fat emulsifier

contains bilirubin (breakdown hemoglobin)
Jaundice occurs when bilirubin isn’t broken down


neutralizes stomach acid, contains sodium
bicarbonate (baking soda)
Jaundice

Yellow tinge to skin or
whites of eyes occurs
when rbc’s bilirubin is
not broken down
properly by the liver
Other Liver Disorders
1.
Viral Hepatitis



2.
often cause jaundice
Hep A often transmitted by infected water, shellfish, etc
Hep B often associated with exposure to contaminated
blood products. This one will destroy the liver over time
Cirrhosis

Long term disease of the liver where liver becomes
fatty. Alcoholism is leading cause of cirrhosis as the
toxin (ethanol) is difficult to break down over time
Cirrhosis of the Liver
The Digestive Enzymes

Enzymes are hydrolytic, meaning they introduce
water to break the molecular bonds of nutrients
(protein, fats, carbs, etc)
In the Mouth
 Starch + H2O ----------------------> Maltose
salivary amylase
Stomach
Protein Digestion
Low pH turns pepsinogen into active enzyme pepsin
Protein + H2O ----------------------> Peptides (AA chains)
pepsin
Small Intestine (duodenum first)
Neutralization, then Absorption
Pancreatic juice (amylase) enters. It contains sodium bicarbonate
which neutralizes acid from the stomach
Starch + H2O
---------------------->
pancreatic amylase
maltose
Protein + H2O
---------------------->
trypsin
peptides
Starch + H2O
---------------------->
bile salts/lipase
glycerol + 3 Fatty Acids
Small Intestine
Further Breakdown …
Peptides are further broken down into Amino Acids
Maltose is broken down into glucose, the simplest sugar
Source: peptidase & maltase secreted by intestine villi
Peptides + H2O
Maltose + H2O
---------------------->
peptidases
---------------------->
maltase
Amino Acids
Glucose
Enzymes of the Digestive System
The Essential Amino Acids

There are 20 amino acids we require

9 cannot be made in our bodies and must be supplied by diet

Sources:

Complete Protein
---> Meat
- supplies all 20 AA’s

Incomplete Protein
---> Vegetable products
- must use combinations to supply all 20 AA’s
- ex. Beans and Rice
- Soy protein is excellent but not complete by itself
Recommended Daily Allowances
120 lb. female needs 44 grams per day
 144 lb. male requires 56 grams per day


Servings
 Cup
of milk
 Roast beef slice (3oz)
 Mmmm…
= 8g
= 25g
The Essential Fatty Acid

Fats were the enemy in the 1990’s

At 9.3 cal/g, reducing fat was identified
as a “fad” method to drop weight

Reducing fat intake, while increasing
exercise is a good idea to maintain
weight, but cutting fat all together is
foolish

Why?  Fats are necessary for the
production of hormones and cell
membranes

Essential Fat  linoleic acid. Without it,
we cannot produce phospholipids for cell
membranes
OBESITY





61% of North Americans are overweight or obese.
Defined as 20% above desirable weight.
Can lead to diabetes, hypertension, hyperlipemia,
cancer, cardiovascular disease, sleep apnea and gout.
Very complex condition.
Never the result of just one factor, but has many causes,
which may include: genetics, environmental/social
lifestyle, food selection, inactivity, and behavioral
conditions.
WEIGHT LOSS

What works?
Moderate calorie
restriction, regular
aerobic exercise,
combined with
strength training,
low fat/high fiber
diet, and
behavioral
changes.
WEIGHT LOSS

Body fat reduction
 Must
include both nutrition and exercise.
 Educate and encourage a healthy weight loss
plan.

Exercise
 Long
duration, low intensity aerobic.
 At least 30 min., but 45 min. is the best.
GOAL FOR WEIGHT LOSS


With a 500 cal decrease per day = 3500 per week =
1lb. of fat.
When combined with increased activity level, provides
1-2 lbs. weight loss per week.

Monitor yourself (food/PT log)

Calorie control:
 Meal
planning (Exchange system/Food guide pyramid)
 Encourage healthy balance of nutrients, portion control,
variety and choices.
Enzyme Problems / Deficiencies

Lactose Intolerance
 75%
of African Americans do not have
sufficient levels of LACTASE to digest
lactose into glucose/galactose sugars
 Result
is painful cramps, diarrhea and
bloating as the milk ferments in the
digestive tract
Vitamin Deficiencies cause Diseases
Vitamin
Niacin
C
- Scurvy
(B3)- Pellagra (Skin Disease)
Vitamin
D - Rickets
Vitamin
A - Night Blindness
Vitamin
K - Blood clotting problems
Ricketts – Vitamin D deficiency
B6 Deficiency

Mild deficiency
 Cheilosis
 Mouth
soreness
 Seborrhea – oily face/ scalp
 Weakness
 Irritability
Severe Angular
Cheilosis
Recommended Sodium Intake

400-3300 mg per day

More salt makes blood hypertonic
Water from surrounding tissues is
pulled in by osmosis


BP increases! This can create
hypertension, leading to heart
attacks, aneurisms and strokes