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Nutrition in humans Biology Chapter 6 - Coggle Diagram
Nutrition in humans
Biology Chapter 6
Nutrition
Nutrition
is the process by which organisms obtain food and energy for growth,repair and maintenance of the body.
In humans, nutrition consists of the following processes:
Feeding
or
ingestion
Feeding
or
ingestion
Digestion
large food molecules are
broken down
into smaller molecules
Absorption
digested food are absorbed into the
body cells
Assimilation
absorbed food substances are
converted
into new
protoplasm
used to provide
energy.
Egestion
undigested
food is
removed
from the body
The human digestive system
Organs involved in the digestive system.
The human digestive system consists of the
alimentary canal(organs that come direct contact with food)
and the
organs
associated with it
gall bladder,liver,pancreas are not part of the alimentary canal
Mouth
Food enters the body through the mouth, which leads into the buccal cavity
Digestion of food is begun in the mouth by the
teeth
,
salivary glands
and
tongue
.
Teeth -
chewing
action of the teeth
breaks down
large pieces of food into smaller pieces
Salivary glands - secretes
saliva
into the mouth. Saliva flows into the mouth. Saliva flows into the buccal cavity via salivary ducts.
Tongue - helps to mix food with saliva.Taste buds on the tongue help you to taste food.
Pharynx
The pharynx connects the buccal cavity to the
oesophagus
(food-pipe) and
larynx
(voice-box).
The pharynx also leads to the
trachea
(wind-pipe), which in turn leads to the lungs.
Air passes into the
trachea
while food passes into the oesophagus.
Space at the back of the mouth
Epiglottis
The larynx has a slit -like opening called the
glottis
, which is covered by a flap-like tissue known as the
epiglottis.
During breathing, air passes into the
trachea
, the larynx moves downwards and the glottis is open.
When swallowing food,the
larynx
moves
upwards,epiglottis moves glottis and the glottis is open.
Oesophagus
The oesophagus is a long,
muscular tube
that extends to the stomach.
The wall of the oesophagus is made up of 2 layers of muscles:
longitudinal
and
circular
muscles.
The
lumen
is the space inside the gut.
The longitudinal and circular muscles are
antagonistic muscles
When one
contracts,
the other
relaxes
.
The muscular actions results in
peristalsis
Rhythmic,
wave-like contractions
of the gut wall
Functions:
Moves food
along the gut
Mixes
food with
digestive juices
Peristalsis
When the
circular muscles contracts,
longitudinal muscles relax
Lumen is
consticted
Food is
pushed forward
When the
longitudinal muscles contract,
circular muscles relax
Shortens and
widens
the lumen
More
space for food to enter