02/02/21
Gross Anatomy of The Digestive System
Organ Systems
• In terms of functionality, the human body is comprised of 11 body systems, also known
as organ systems.
• Each system serves the body in a unique way, which is not covered by any of the other
systems.
• Each of the body systems are built from tissues which underpin their functional
specialisation.
• Methods for the imagining of various systems and their specific tissues also differ.
• The digestive system forms on of the major systems of the body.
• It has a unique function from the other systems.
• The anatomical apparatus which compose the system allow it to fulfil its fundamental
functions.
Purpose of The Digestive System
• Effectively, to extract energy sources from food and supply them to the body.
• Energy enables the survival of an individual…
- Maintains optimum temperature of the deep body.
* Enzymatic processes of the body depend on optimal body temperatures.
- Allows for the repair and renewal of body tissues.
- Gives rise to growth, development and maturation of the young.
- Lets the individual reproduce and replicate.
- Lets the species replicate.
* Promotes survival of the species.
Reasons for Evolving a System to Cater for Body’s Energy Needs
• Need for energy is a problem shared by all living organisms.
• At all times, energy sources are in short supply and we overcame this problem by
evolving a digestive system…
- Food sources are usually in short supply.
- Animals will also compete for these limited common food sources.
- Most foods only become available intermittently.
- Sometimes, food will only be available due to chance.
- Most foods become available depending on the season.
• Various animal species have evolved different ways of overcoming these problems.
• Humans (and other multicellular organisms) developed very complex tissue systems,
featuring numerous different cells. As a result, they require high levels of energy and the
pressure on obtaining sufficient energy sources increases for their body to function
normally.
• Therefore, these pressures do not only exist in the external environment, but also our
internal.
• Whereas, energy demands of unicellular organisms are much easier to manage and
obtain which increases their chances of surviving.
, 02/02/21
Overview of The Digestive System
• Human body contains numerous cells, many of which are highly specialised and can be
very energy demanding. For this reason, obtaining sufficient energy sources and
managing them is more complex/difficult.
• The energy source which the digestive system manages and processed is obtained
from food. Other energy sources, such as oxygen/glucagon for example, are managed
and processed by other systems.
• Digestion overview…
- Mouth is required for intake of the food.
- Digestive tubes act as as repository, where some mechanical processes (e.g.
peristalsis) break the food down.
- Enzymatic (chemical) processes will break food down into smaller, easily absorbed
molecules.
- Absorptive surfaces within the digestive system act to extract the nutrition from the
slurry of digested foods.
- Excretory mechanisms will then remove non-digested/non-essential components
from the body.
• Compared to some modern day machines such as cars, the digestive system is not
efficient at extracting energy from food sources.
Key Processes of The Digestive System
• Ingestion…
- Taking food in, normally via the mouth.
- Chewing is a mechanical processes thereby which foods are broken down to smaller,
more manageable particles for the enzymes to work more efficiently.
• Digestion…
- The complex food is further broken down by the chemical, enzymatic processes into
smaller, soluble food molecules.
- Some mechanical processes, such as peristalsis, may assist in this further
breakdown of food.
• Absorption…
- Digested food molecules are then absorbed into the body via absorptive surfaces.
• Assimilation…
- Absorbed food is used to provide energy or form new protoplasms, either via
metabolic or catabolic processes.
• Egestion…
- Removal of undigested food.
Key Anatomical Stages of the Digestive System Muscular Tube
• Mouth…
- Ingestion of food.
- Some chemical digestion.
- Some technical digestion.
• Oesophagus.
• Stomach…
- Further chemical digestion.
- Further mechanical digestion.
• Small intestine…
- Chemical digestion.
- Absorption.
• Large Intestine…
Gross Anatomy of The Digestive System
Organ Systems
• In terms of functionality, the human body is comprised of 11 body systems, also known
as organ systems.
• Each system serves the body in a unique way, which is not covered by any of the other
systems.
• Each of the body systems are built from tissues which underpin their functional
specialisation.
• Methods for the imagining of various systems and their specific tissues also differ.
• The digestive system forms on of the major systems of the body.
• It has a unique function from the other systems.
• The anatomical apparatus which compose the system allow it to fulfil its fundamental
functions.
Purpose of The Digestive System
• Effectively, to extract energy sources from food and supply them to the body.
• Energy enables the survival of an individual…
- Maintains optimum temperature of the deep body.
* Enzymatic processes of the body depend on optimal body temperatures.
- Allows for the repair and renewal of body tissues.
- Gives rise to growth, development and maturation of the young.
- Lets the individual reproduce and replicate.
- Lets the species replicate.
* Promotes survival of the species.
Reasons for Evolving a System to Cater for Body’s Energy Needs
• Need for energy is a problem shared by all living organisms.
• At all times, energy sources are in short supply and we overcame this problem by
evolving a digestive system…
- Food sources are usually in short supply.
- Animals will also compete for these limited common food sources.
- Most foods only become available intermittently.
- Sometimes, food will only be available due to chance.
- Most foods become available depending on the season.
• Various animal species have evolved different ways of overcoming these problems.
• Humans (and other multicellular organisms) developed very complex tissue systems,
featuring numerous different cells. As a result, they require high levels of energy and the
pressure on obtaining sufficient energy sources increases for their body to function
normally.
• Therefore, these pressures do not only exist in the external environment, but also our
internal.
• Whereas, energy demands of unicellular organisms are much easier to manage and
obtain which increases their chances of surviving.
, 02/02/21
Overview of The Digestive System
• Human body contains numerous cells, many of which are highly specialised and can be
very energy demanding. For this reason, obtaining sufficient energy sources and
managing them is more complex/difficult.
• The energy source which the digestive system manages and processed is obtained
from food. Other energy sources, such as oxygen/glucagon for example, are managed
and processed by other systems.
• Digestion overview…
- Mouth is required for intake of the food.
- Digestive tubes act as as repository, where some mechanical processes (e.g.
peristalsis) break the food down.
- Enzymatic (chemical) processes will break food down into smaller, easily absorbed
molecules.
- Absorptive surfaces within the digestive system act to extract the nutrition from the
slurry of digested foods.
- Excretory mechanisms will then remove non-digested/non-essential components
from the body.
• Compared to some modern day machines such as cars, the digestive system is not
efficient at extracting energy from food sources.
Key Processes of The Digestive System
• Ingestion…
- Taking food in, normally via the mouth.
- Chewing is a mechanical processes thereby which foods are broken down to smaller,
more manageable particles for the enzymes to work more efficiently.
• Digestion…
- The complex food is further broken down by the chemical, enzymatic processes into
smaller, soluble food molecules.
- Some mechanical processes, such as peristalsis, may assist in this further
breakdown of food.
• Absorption…
- Digested food molecules are then absorbed into the body via absorptive surfaces.
• Assimilation…
- Absorbed food is used to provide energy or form new protoplasms, either via
metabolic or catabolic processes.
• Egestion…
- Removal of undigested food.
Key Anatomical Stages of the Digestive System Muscular Tube
• Mouth…
- Ingestion of food.
- Some chemical digestion.
- Some technical digestion.
• Oesophagus.
• Stomach…
- Further chemical digestion.
- Further mechanical digestion.
• Small intestine…
- Chemical digestion.
- Absorption.
• Large Intestine…
