Process of Digestion Hormonal Regulation of Fuel

MetabolismDWI NOVITASARI, S.Kep.,Ns., M.Sc

DIGESTIVE SYSTEM

• The three fundamental processes that take place are: – Secretion: Delivery of enzymes, mucus, ions and the

like into the lumen, and hormones into blood. – Absorption: Transport of water, ions and nutrients

from the lumen, across the epithelium and into blood. – Motility: Contractions of smooth muscle in the wall of

the tube that crush, mix and propel its contents.

FROM MACROMOLECULES INTO MONOMERS

Human Nutritional Needs Food is used for two purposes: as fuel

(to provide energy for cellular metabolism) and as a source of

building blocks (monomers for cellular biosynthesis)

› Basic nutrients: carbohydrates, lipids, proteins, minerals, vitamins

FOOD

BRAINHORMONHORMONHORMONHORMONHORMONHORMONHORMONHORMON

VOLUNTARY

INVOLUNTARY

THE GI SYSTEM

TRACHEA

STOMACH

PANCREAS

SMALL INTESTINE

LARGE INTESTINE

ANUSRECTUM

GALLBLADDER

SUBMANDIBULARSALIVARY GLANDS

SUBLINGUALAND

MOUTH PAROTIDSALIVARY GLAN

Adapted by:Dr. Andreanyta Meliala, PhD.

LIVER

HeartLiver

ABSORPTION

SECRETION

Large intestine

RectumAnusMouth

Food andwater

StomachHepatic

Portal vein

Small intestineSalivary glands

MOTILITY

THE GI DIAGRAM

FECES

enzim asam, dllVitamin

C, D, B2, B12, dllProteinMineral

KarbonhidratLipid

Adapted by:Dr. Andreanyta Meliala, PhD.

Vitamin KAir, Elektrolit

AktifitasBAKTERI

Pembentukan Gas CO2, Metana, dll

FLATUS

Parotid ductParotid gland

Submandibular gland

Sublingual gland

NAMES AND LOCATION OF THE MAJOR SALIVARY GLAND IN THE HUMAN

Adapted by:Dr. Andreanyta Meliala, PhD.

Hard Palate

Tongue

Epiglottis

Upper esophagealsphincter

Soft Palate

Pharynx

Esophagus

Adapted by:Dr. Andreanyta Meliala, PhD.

MOVEMENTS OF FOOD THROUGH THE PHARYNX AND UPPER ESOPHAGUS DURING SWALLOWING

Fundus

Body(secretes mucus

Pepsinogen and HCI)

Esophagus

Duodenum

Pyloricsphincter

Antrium(secretes mucus

Pepsinogen and gastrin)

THE THREE REGIONS OF THE STOMACH :FUNDUS, BODY, AND ATRIUM

Adapted by:Dr. Andreanyta Meliala, PhD.

Adapted by:Dr. Andreanyta Meliala, PhD.

PERISTALTIC WAVESCONTRIBUTE TO THE ANTRAL CONTENTS

Esophagus

LowerEsophagealsphincter

Duodenum

Pyloricsphincter

Stomach Peristalticwave

Intestinal Movements

Segmentation › Mixing mucous and enzyme

Slow peristaltic contractions to encourage absorption

Local contractions (no CNS involvement)

It takes appr. 5 hrs to digest & move chymus from duodenum to ileum

Colon Motility

pattern of motility - Haustration (slow segmentation) - Mass movement (slow peristaltic; 3-4 times/day)DefecationDistension of rectum stimulates sigmoid colon and smooth muscle of rectal wall relaxation of internal sphincter muscle (outonomic nerve) Defecation conducts when external sphincter muscle is relaxed

REGULATION OF GI FUNCTION

Complex regulation with overlappingpathways that involve:

› Neural› Endocrines› Local control mechanism (little brain;

enteric nervous system)

Regulasi sistem GI

Nerve RegulatorsExtrinsic (outside) nervesrelease acetylcholine and another called

adrenaline. Acetylcholine causes the muscle of the digestive

organs to squeeze with more force and increase the "push" of food

Acetylcholine also causes the stomach and pancreas to produce more digestive juice. Adrenaline relaxes the muscle of the stomach and intestine and decreases the flow of blood to these organs.

The intrinsic (inside) nerves are triggered to act when the walls of the organs are stretched by food.

They release many different substances that speed up or delay the movement of food and the production of juices by the digestive organs.

FOOD PROCESSING

Includes: Ingestion Digestion Absorption Elimination

Mechanical Breakdown Biting Chewing Grinding Emulsification

Increases surface area for enzymatic attack

Sekresi lambung: - HCL - pepsinogen - Gastrin

Sekresi di usus halus Kurang lebih 1.8 L Fungsi pelumas Buffer melarutkan enzym dari pankreas

Sekresi Pankreas

Absorbsi

Absorbsi monosakarida

Absorbsi monogliserida dan asam lemak

Absorbsi asam amino

Vitamin Larut lemak (A, D, E, K): lewat bersama lipid Larut air (B, C): masuk bersama airB12 : faktor intrinsik di lambung mengikat B12 dan diabsorbsi di ileum

Air dan mineralMirip reabsobsi di tubulus ginjal dengan aktif transport Na, reabsorbsi air secara pasif mengikuti gradien osmotikNormalnya 95% air masuk usus kecil sebelum masuk kolonCl mengikuti Na dari lumen GI ke dalam darah Kalsium, potassium, magnesium, iodine, bicarbonate, iron

Absorbsi di kolon Reabsorbsi air

› 1500 mL/hr di kolon; 1300 mL reabsorbsi

› Feses terdiri: - 75% air - 5% bakteri - 20% undigested

material, inorganic material,

epitel Reabsobsi garam empedu, vitamin,

bilirubin, toxins

Bile salts› Reabsorbsi, dibawa ke hepar

Vitamin› Bakteri di kolon membentuk 3 vitamin

Vitamin K: fat soluble; diperlukan untuk sintesis faktor pembekuan di hati

Biotin: water soluble; diperlukan untuk metabolisme glukosa

Vitamin B5: water soluble; diperlukan untuk biosintesis hormon steroid dan beberapa neurotransmiter

The blood glucose level involve the combined actions of insulin, glucagon, epinephrine, and cortisol on metabolic processes in many body tissues, but especially in liver, muscle, and adipose tissue.

The pancreas secretes insulin or glucagon in response to changes in blood glucose

GASTRIN

Origin: StomachStimulus: Food in stomachFunction: Stimulates HCl & pepsinogen secretion, increases stomach motility

GASTRIN actions in general: stimulates gastric secretion

& motility1. Stimulates gastric acid secretion2. Stimulates pepsin&intrinsic factor

secretion by the stomach3. Stimulates growth of gastric &

intestinal mucosa (‘thropic action’)4. Increase the tone of musculature of

the LOS,stomach & small intestine5. Stimulates insulin and glucagon

secretion (after a protein meal)6. Stimulates calcitonin secretion

SECRETINOrigin: DuodenumStimulus: AcidFunction: Stimulates pancreatic secretions. Slows stomach motility and acid production

SECRETIN actions1. Stimulates bicarbonate rich-watery alkaline

pancreatic juice by increasing bicarbonate secretion of biliary tract

2. Increases bicarbonate secretion of biliary tract

3. Augments the action of CCK-PZ in producing pancreatic secretion of digestive enzymes

4. Decreases gastric acid secretion5. May cause contraction of the pyloric

sphincter6. Increases insulin secretion; but inhibits

glucagon secretion

Cholecystokininu/ pemecahan lemak

Stressors (anxiety, fear, pain, hemorrhage, infections, low blood glucose, starvation) stimulate hormone cortisol, acts on muscle, liver, and adipose tissue to supply the organism with fuel

In adipose tissue, cortisol leads to an increase in the release of fatty acids from stored TAGs gluconeogenesis in the liver.

Cortisol stimulates the breakdown of muscle proteins and the export of amino acids to the liver for gluconeogenesis.

In the liver, cortisol promotes gluconeogenesis by stimulating synthesis of the key enzyme PEP carboxykinase

Adipose tissue produces leptin that regulates feeding behavior and energy expenditure so as to maintain adequate reserves of fat.

Leptin acts on receptors in the arcuate nucleus of the hypothalamus, causing the release of anorexigenic peptides, including α-MSH, that act in the brain to inhibit eating

Leptin also stimulates sympathetic nervous system action on adipocytes, leading to uncoupling of mitochondrial oxidative phosphorylation, with consequent thermogenesis.

The orexigenic (appetite-stimulating) neurons stimulate eating by producing and releasing:1. neuropeptide Y (NPY)2. α-melanocyte-stimulating hormone (α

MSH)

Ghrelin hormone

Produced in the stomach

Acts on orexigenic neurons in the arcuate nucleus to produce hunger before a

meal

The hormone adiponectin stimulates:

1. fatty acid uptake and oxidation2. inhibits fatty acid synthesis