digestiÓn para bi click4

7/30/2019 DIGESTIN PARA BI CLICK4

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enzimas tiene una menor energa de activacin. Esta menor energa de activacinque corresponde a la temperatura del cuerpo pero slo es posible en presencia deuna enzima

6.1.3 Estado de la fuente, el sustrato, los productos y las condiciones de pHptimo para una amilasa, proteasa uno y lipasa uno. (1)

Ejemplo 1 amilasapancretica:

Condiciones:

Fuente del pncreas PH ptimo 7.5-7.8 El sustrato es almidn

(amilosa) Producto final es eldisacrido maltosa

Accin: la hidrlisis delos enlaces glucosdicos 1-4

Ejemplo 2: La pepsina es una proteasaproducida en el estmago

Condiciones:

El origen es el estmago PH ptimo es de 2 Sustrato es un cadenas

polipeptdicas de aminocidos Producto final es polipptidos

pequeos La accin es la hidrlisis de enlaces

peptdicos dentro de la cadenapolipeptdica (endopeptidasa).

3 Ejemplo: lipasas pancreticas:

El origen es el pncreas

El pH ptimo es 7,2 El sustrato es un lpido de triglicrido El producto es glicerol y cadenas de cidos grasos La accin de las amilasas pancreticas tambin requiere la presencia de sales

biliares que emulsionan el lpido. Esta emulsin tiene dos efectos:

1. Aumenta el rea de superficie del lpido para la digestin de las grasas2. Expone estructura "cabeza" del glicerol a la enzima


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Accin: la hidrlisis de los enlaces ster entre las molculas de glicerol y lascadenas de cidos grasos.

6.1.4 Dibujar y etiquetar un diagrama del sistema digestivo. (1)

6.1.5 Esquema de la funcin del estmago, intestino delgado e intestinogrueso. (2)

1. Estmago:

El estmago almacena los alimentos de unacomida y se inicia la digestin de protenas.

(A) lumen del estmago que almacena elalimento de una comida

(B) Sitio gstrica de moco, que las enzimas y loscidos son secretadas

(C) las clulas secretoras de moco. El mocoprotege la superficie del estmago de auto-digestin

(D) Las clulas parietales que producen HCL que


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mata los microorganismos que entran en el sistema digestivo (alimentos y mocotraqueal). Esto tambin convierte el pepsingeno inactivo a activo pepsina

(E) Las clulas principales: pepsingeno produce una enzima proteasa

2. intestino delgado

En la digestin intestino delgado se completa.

Los productos de la digestin son absorbidosen el torrente sanguneo.

(A) de vellosidades que aumentan el reasuperficial para la absorcin de los productosde la digestin

(B) Las microvellosidades frontera de la clulaepitelial aumenta la superficie son para laabsorcin.

(C) lactferos se conecte al sistema linftico para el transporte de lpidos.

(D) En la pared del intestino delgado son los vasos sanguneos que transportanproductos absorbidos en la circulacin general, hay tambin el msculo para mantener laperistalsis

3. Intestino grueso o colon:

El colon es responsable de la reabsorcin deagua en el intestino.

(A) El lumen del colon

(B) La produccin de moco clulas caliciformes


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(B) las paredes musculares para mantener la peristalsis

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6.1.6 Distinguir entre la

absorcin y asimilacin. (2)

Molculas insolubles se digierenlos alimentos a los productossolubles en el lumen delintestino.

Absorcin:

1. Los productos solublesson primero absorbidos pordiversos mecanismos en lasclulas epiteliales que recubrenel intestino.

2. Estas clulas epitelialesdespus cargar las diversasmolculas absorbidas en lacorriente sangunea.

Asimilacin:

1. Los productos solubles de la digestin son transportados a los diversos tejidos porel sistema circulatorio.

2. Las clulas de los tejidos y luego absorber las molculas para uso dentro de estostejidos

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6.1.7Explain cmo la estructura de la vellosidad se relaciona con su papel enla absorcin y el transporte de los productos de la digestin. (3)

La estructura de las vellosidades aumenta la superficie son para la absorcin demolc

ulasde losalimentosdigeridos.

(A)incrementar lospliegu

es SA: VOL X 3 por racin(B) proyecto Villi en el lumen del intestino aumentando el rea superficial por X 10

(C) Las microvellosidades son pliegues externos de la membrana plasmtica aumenta lasuperficie de otro X10

Esta secuencia de microscopio de luz y las imgenes de micrografa electrnica demostrar la misma secuencia que el diagrama de arriba.

Adaptaciones histolgicosdentro de la vellosidad.

Suministro de sangre enlas vellosidades que absorben los


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productos finales de la digestin de las clulas epiteliales

Los lactferos (verde) que reciben las lipoprotenas antes de transportarlos alsistema circulatorio.

Paredes musculares que mantienen el movimiento del quimo por el peristaltismo.


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6.1.1 Explain why digestion of large food molecules is essential.(3)

Most food molecules are large polymers and insoluble They must first be digested to smaller soluble molecules before they can be

absorbed into the blood

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6.1.2 Explain the need for enzymes in digestion.(3)

Enzymes are biological catalysts that increase the rate of reaction

Digestive enzymes are secreted into the lumen of the gut

Digestive enzyme increase the rate of reaction of the hydrolysis of insoluble foodmolecules to soluble end products

Digestive enzymesincrease the rate of reaction atbody temperature

This image illustrates thereduction in activation energy thatis achieved by the use of anenzyme

Notice that the normalreaction requires a higheractivation energy which wouldcorrespond to a high bodytemperature. This is usually notpossible in living organisms.

The enzyme-catalysed reaction has a lower activation energy. This loweractivation energy would correspond to body temperature but is only possible inthe presence of an enzyme
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6.1.3 State the source, substrate, products and optimum pH conditions for oneamylase, one protease and one lipase.(1)

Example 1 Pancreaticamylase:

Conditions:

Source the Pancreas Optimal pH 7.5-7.8

Substrate is starch(amylose)

End product is thedisaccharide maltose

Action: hydrolysis of 1-4 glycosidic bonds

Example 2: Pepsin is a protease produced in the stomach

Conditions:

Source is the stomach Optimal pH is 2 Substrate is a polypeptide chains of amino acids End product is small polypeptides Action is the hydrolysis of peptide bonds within the polypeptide chain

(endopeptidase).

Example 3: Pancreatic lipases:


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Source is thepancreas

The optimal pHis 7.2

The substrateis a triglyceride lipid

The product isglycerol and fatty acidchains

The action of pancreatic amylasesalso requires thepresence of bile saltsthat emulsify the lipid.This emulsificationhas two effects:

1. Increases the surface area of the lipid for the digestion of fat2. Exposes the glycerol 'head' structure to the enzyme

Action: hydrolysis of ester bonds between the glycerol molecules and the fattyacid chains.

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6.1.4 Draw and label a diagram of the digestive system.(1)


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6.1.5 Outline the function of the stomach, small intestine and large intestine.(2)

1. Stomach:

The stomach stores the food from a meal andbegins protein digestion.

(a) Lumen of the stomach which stores the foodfrom a meal

(b) Gastric pits from which mucus , enzymesand acid are secreted

(c) Mucus secreting cells. Mucus protects thesurface of the stomach from auto-digestion

(d) Parietal cells that produce HCL which killsmicroorganism that enter the digestive system


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(food & tracheal mucus). This also converts inactive pepsinogen to active pepsin

(e) Chief cells: produces pepsinogen a protease enzyme

2. small Intestine

In the small intestine digestion is completed.

The products of digestion are absorbed into theblood stream.

(a) Villus which increase the surface area forabsorption of the products of digestion

(b) Microvilli border of the epithelial cellincreases the surface are for absorption.

(c) Lacteals are connect to the lymphaticsystem for the transport of lipids.

(d) In the wall of the small intestine are the blood vessels to transport absorbedproducts to the general circulation, There are also the muscle to maintain peristalsis

3. Large Intestine or colon:

The colon is responsible for the reabsorption of water from the gut.

(a) The lumen of the colon

(b) The mucus producing goblet cells

(b) Muscular walls to maintain peristalsis


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6.1.6 Distinguish betweenabsorption andassimilation.(2)

Insoluble food molecules aredigested to soluble products inthe lumen of the gut.

Absorption:

1. The soluble products arefirst taken up by variousmechanisms into the epithelialcells that line the gut.

2. These epithelial cellsthen load the various absorbedmolecules into the bloodstream.

Assimilation:

1. The soluble products of digestion are then transported to the various tissues bythe circulatory system.

2. The cells of the tissues then absorb the molecules for use within this tissues

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6.1.7Explain how the structure of the villus is related to its role in absorptionand transport of the products of digestion.(3)

The structure of the villus increases the surface are for the absorption of digested foodmolecules.
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(a)foldsincreaseSA:VOLrationby X3

(b)Villi project into the lumen of the gut increasing the surface area by X 10

(c) Microvilli are outward folds of the plasma membrane increasing the surface areaanother X10

This sequence of light microscope and electron micrograph images show the samesequence as the diagram above.

Histological adaptationswithin the villus.

Blood supply in the villuswhich absorb the end products of digestion from the epithelial cells

The lacteals (green) thatreceive the lipoproteins beforetransporting them to thecirculatory system.

Muscular walls that


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maintain the movement of chyme by peristalsis.

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