Breathing, Circulation & Breathing, Circulation & DigestionDigestion

The importance of The importance of pressure, diffusion pressure, diffusion

and anatomyand anatomy

Lung Structure• Spongy – elastic• Very large surface

area• Bronchi branch to

form smaller bronchioles

• Bronchioles end in grapelike bunches of alveoli – formed of alveolar sacs

• >300 X 106 alveoli per human lung

Surface Area to Volume Ratio

V = ½*½*½*8= 1 cm3

SA = ½ cm*½ cm/side = ¼ cm2/side

6*8 sides: total = 12 cm2.SA:V = 12:1

V = 1 cm* 1cm*1 cm = 1 cm3

SA = 1 cm*1cm/side = 1cm2/side

6 sides: total = 6 cm2.SA:V = 6:1

½ cm½ cm

1 cm1 cm

Common misconception

• The force of air coming into the lungs causes lungs to expand or…

• Without the incoming air, the lungs won’t expand, and if the lungs don’t expand, neither can the chest.

What physical property affects a gas?

• Gases within a given volume exert pressure against surfaces.

• What is pressure?

– Force/Area = N/m2

Snow example

• Snow is a weak supporting structure but spreading weight over a larger surface area can allow it to support you…..snow shoes

Balloon

P = F / AP = F / A

Relationship of Volume to Pressure

Volume increases what happens to the pressure exerted by a gas?

Inhalation

Increased volume lower pressure in the lungs - Atmospheric pressure now greater than lungs

low

higher

Diffusion

Capillary

Lung

O2 High

CO2 Low

O2 Low

CO2 High

Capillary

Tissue

O2 Low

CO2 High

O2 High

CO2 Low

Functions of the circulatory system?

THE CIRCULATORY SYSTEMBesides transporting oxygen and nutrients that sustain body processes, the circulatory system transports waste materials produced by cells.

                                                                                                                                                                                                   

Function of a Digestive System

• Dissasembly process

• Large chunks to smaller molecules

• Ultimately, these small molecules are taken up by circulatory system and distributed to cells

The Four Stages of Food Processing

• Ingestion

– Is another word for eating

• Digestion– Is the breakdown of food to small molecules

• Absorption– Is the uptake of the small nutrient molecules by

the body’s cells

• Elimination– Is the disposal of undigested materials from the

food we eat

• Mechanical digestion

– 1st step in the process of digestion

– Involves physical processes like chewing

– How is this done?• Teeth• Also adds water for chemical reactionsIncreases the surface to volume

ratio of food particles but it does not break the chemical bonds within a food molecule

Role of Saliva

• Salivary glands made up of three glands

• Amylase is responsible for initiation of starch breakdown

• What’s starch?

Esophagus- delivers food to stomach

Nerve endings inNerve endings inthroat/pharnx throat/pharnx cause esophaguscause esophaguswalls to contractwalls to contractwhich move thewhich move thebolus to the bolus to the Stomach.Stomach.

Epiglotis stopsEpiglotis stopsfood fromfood fromentering trachea,entering trachea,acts like a oneacts like a oneway flap.way flap.

Stomach- specialized structure for further chemical digestion

These target and These target and breakdown breakdown proteins and proteins and lipids.lipids.

Gastric juices Gastric juices and enzymes and enzymes mix with food.mix with food.

This mixture This mixture now leaves now leaves stomach thru stomach thru pyloric sphincter pyloric sphincter and enter small and enter small intestine.intestine.

Small intestine – Primary site of absorption of digested molecules

More enzymes are More enzymes are produced in small produced in small intestine as well as……..intestine as well as……..

Hormone secretion that Hormone secretion that regulates release of food regulates release of food from stomach and…….from stomach and…….

The release of secretions The release of secretions from the pancreas and from the pancreas and liver.liver.

Duodenum-upper portion still receives some digestive enzymes

Pancreas- neutralizes acids from stomach by production of bicarbonate ions.

– Is the first part of the small intestine– Receives digestive agents from several organs

LiverLiverBile

GallbladderGallbladderBile

Acid chyme

Pancreatic juicePancreatic juiceDuodenum of Duodenum of

small intestinesmall intestine PancreasPancreas

Liver produces bile that is stored in gallbladder. It is then pumped into doudenum to reduce the size of fat globules in a process called emulsification.

Stomach pH?

Doudenum pH?

• The jejunum and ileum– Are parts of the small intestine– Are specialized for absorption

Blood vessels

Muscle layers

Villi

Nutrient absorption

Intestinal wall

Interior of intestine

Nutrient absorption

Epithelial cells

Blood capillaries

Lymphatic vessel

Villi

Nutrient absorption

Microvilli

Epithelial cells

Colon: Large intestine- absorption of water.

Water reabsorption.Water reabsorption.

Bacteria further Bacteria further breakdown undigested breakdown undigested food.food.

Bacteria add vitamins.Bacteria add vitamins.

Colon: rectum – specialized region for temporary storage

Anus – exit from digestive system- separate exit from the urogenital system

The End