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The Function of Digestive System || Ingestion, Digestion, Absorption and Excretion @biologyexams4u
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Sep 10, 2023
In this comprehensive video, we delve deep into the intricacies of the digestive system, providing you with a thorough understanding of its essential functions - ingestion, digestion, absorption, and excretion. Dive into a fascinating exploration of the human body's remarkable ability to process and extract nutrients from the food we consume. Happy Learning ✌️ ⌚ Stamps 00:00|| Introduction 01:45|| Ingestion 02:17|| Propulsion and peristalsis 03:05|| Mechanical digestion 03:51|| Chemical Digestion 05:08|| Absorption 06:34|| Defecation 07:36||Summary ============================================================ We really appreciate your support ? Thank you so much :) @biologyexams4u ▶Enroll now. Our free certificate course on Introduction to Recombinant DNA Technology https://alison.com/course/introduction-to-recombinant-dna-technology?utm_source=alison_user&utm_medium=affiliates&utm_campaign=22177687 ?Introduction to Recombinant DNA Technology – Download free E Book
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0:00
We can eat upside down. Food doesn't need gravity to reach the stomach. Peristalsis
0:05
a powerful wave-like muscle movement pushes the food along. Hi friends, in this video we can have
0:12
a deeper look into the functions of digestive system and the six steps or activities that is
0:18
happening in the digestive process within five to ten minutes. What do you mean by digestion
0:24
Digestion is simply the breaking down of food we eat, releasing the nutrients that is
0:29
carbohydrates and proteins are broken down into simple molecules or absorbable forms and that is absorbed into the body and use it for energy growth and cell
0:40
repair. The four major functions of digestion are ingestion of food then
0:46
digestion of food by means of mechanical digestion and chemical digestion that is
0:51
followed by absorption of food primarily takes place through small intestine and
0:56
And finally, the undigested matter is removed by defecation or excretion. Six activities is happening during this digestive process
1:07
The first one is ingestion, ingestion of food into the mouth, then propulsion the movement of food along this elementary c by means of peristalsis
1:19
then mechanical digestion by means of chewing and churning, chemical digestion by means of digestive enzymes and gastric juices, absorption primarily taking
1:31
place in the small intestine and finally the undigested matter is removed from the system
1:37
through the opening called anus and the process is called acidification. Let's have a deeper look
1:43
into each of these activities. First one starting with ingestion. Ingestion is the entry of food
1:51
into the elementary c through the mouth. The food mixes with saliva. Saliva contains enzymes
1:57
like salivary amylase that breaks down carbohydrate and lingual lipase that breaks down some amount
2:04
of lipids. Then chewing also increases the surface area so that the enzymes can act upon better and
2:10
finally producing an appropriately sized bolus and that is pushed into the esophagus The second process is called as the propulsion Propulsion is the movement of food along the elementary c or digestive tract It includes both
2:26
voluntary process like swallowing and also the involuntary process of peristalsis. So this is the peristalsis. So it's a sequential alternating wave
2:36
like movement that is caused by the contraction and relaxation of elementary
2:42
wall smooth muscles which propels the food along the digestive tract. So this is the movement as
2:49
you see this movement pushes the food along the elementary c. It mixes the food with digestive
2:55
juices also helping in further digestion. Peristalsis is the reason so that we can even
3:02
eat food upside down. The next process is a mechanical digestion. The first part of mechanical
3:09
digestion takes place in mouth. The food is broken down into smaller pieces that
3:14
increases the surface area and also the mobility. It is called mastication or
3:19
chewing by means of tongue movements helps in mixing this food with saliva
3:26
that contains salivary enzymes. The second part takes place in stomach. The
3:32
churning of food in the stomach that further break down the food into smaller
3:36
particles and exposes this food to digestive juices and finally producing an acidic soup
3:42
which is called a sky. In mechanical digestion there is no change in the chemical nature of the
3:49
food and the next process is a chemical digestion. In chemical digestion starts in mouth. So chemical
3:56
digestion occurs through a process called hydrolysis or mixing of water and digestive enzymes to break
4:03
down complex molecules into simpler molecules that can be absorbed in the small intestine
4:09
The process is completed in the small intestine. Let us take some example to understand chemical
4:15
digestion. In chemical digestion, the chemical nature of the food is changed from a complex
4:21
molecule to simpler molecules that can be easily absorbed by the body. Polysaccharides, salivary
4:27
amylase in mouth, an enzyme that converts polysaccharides like starch into disaccharides
4:32
like maltose Then lingual lipase in mouth that is involved in digestion of lipids to some extent converts lipids to free fatty acids and diglycerides Then pepsin in stomach which is an enzyme that converts proteins to small peptides Then maltase in small intestine
4:52
that converts disaccharate maltose to two glucose units. Pancreatic nucleases that converts nucleic
5:00
acid RNA or DNA into nucleotides. All these simple molecules can be easily absorbed by the body
5:08
The next process is the absorption. The primary goal of digestion is absorption of nutrients
5:15
or converting these complex biomolecules like carbohydrates, proteins etc. into simpler absorbable molecules that can be absorbed by the epithelial cells of the intestinal
5:28
willy of small intestine. The absorptive capacity of this elementary c is amazing. Close to 10
5:36
liters of food along with drink and secretions is processed in the elementary c and as you see
5:44
only one liter close to one liter reaches the small intestine and the rest is absorbed. So the
5:50
absorption capacity of this elementary c is close to 90%. The major site of absorption or 90
5:57
of absorption takes place in the small intestine. It is made up of this diardinum then followed by
6:03
jejunum and the third part is the ileum. Small intestine has this absorptive cells epithelial
6:12
cells that is lined with bile for increasing the absorptive surface or surface area and absorbs
6:19
the nutrients and then transfers it into the bloodstream. Jejunum is the primary site of
6:25
absorption of carbohydrates and proteins whereas ileum is the primary site major
6:30
site of absorption of pile salts and vitamin B12 and the final process is
6:35
called the defecation. The undigested matter is removed from the body as
6:40
feces. The process is called as defecation. So this large intestine is
6:46
involved in this process. It finishes up absorption of nutrients and water
6:50
synthesizes certain vitamins using the bacterial flora that is present in large intestine It forms store and eliminate feces from the body The parts are this cecum that is followed by this long colon then there is a rectum where the vest material is stored and finally through the opening anus
7:12
this vest material or feces is removed from the body. Only mechanical digestion takes place in
7:17
large intestine as there are no digestive enzymes and some kind of digestion is happening with the
7:23
help of bacterium that is present in small intestine. It's also involved in absorption of
7:30
vitamin B, vitamin K and sodium under the influence of hormone aldosterone. Let me summarize the
7:37
process. Ingestion happens through the mouth where mechanical digestion includes chewing and
7:44
salowing happens and chemical digestion also takes place as in the case of carbohydrates and fats
7:49
by means of salivary amelis and lingualipis. Then the food is pushed into the
7:55
esophagus as bolus. Further mechanical digestion by means of peristaltic movement and mixing. Then in the stomach chemical digestion of proteins and fats
8:06
occurs absorption of lipid soluble substances such as alcohol and aspirin. Then the food moves into the small intestine which is a primary site of
8:15
absorption. 90% of the food is absorbed in the small intestine. Here also mechanical
8:21
digestion occurs by means of this movement or propulsion. Primarily the segmentation process happens in small intestine. Then chemical digestion by
8:30
means of different kinds of enzymes like amylases, lipases, the nucleases to
8:36
degrade nucleic acids and we'll be discussing that in the next video. Then
8:40
absorption of all smaller molecules like peptides, amino acids and glucose takes
8:45
place in small intestine and finally further mechanical digestion and segmentation happens in large intestine. there is no chemical digestion in large
8:54
intestine. the undigested matter is removed through the opening called enous. in large intestine absorption of ions, water, minerals, vitamins etc. takes
9:05
place and this is how our digestive system works. and finally leaving you
9:10
with a video on the absorption and digestion of carbohydrates, proteins, lipids and nucleic
9:17
acids. The link is here. Take care. Stay blessed. Thank you so much for your support. You are with
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