MCAT Biology Lecture: Digestive System (2/2)

Summary

This educational video delves into the accessory organs of the digestive system, highlighting the pancreas's dual role in hormone secretion and enzyme production, the liver's multifaceted functions in detoxification and nutrient processing, and the gallbladder's role in bile storage. It also covers the absorption process in the small and large intestines, emphasizing the mechanisms of nutrient uptake and the importance of water and electrolyte balance, concluding with the significance of the gut microbiota in human health.

Takeaways

• 😀 The digestive system involves accessory organs such as the pancreas, liver, and gallbladder, which release enzymes and other substances essential for digestion.
• 🌟 The pancreas has both exocrine and endocrine functions, with the endocrine function involving the secretion of hormones like insulin and glucagon that regulate blood sugar levels.
• 🔍 The exocrine pancreas produces digestive enzymes and an alkaline fluid, known as pancreatic juice, which aids in the digestion of carbohydrates, proteins, and fats in the small intestine.
• 🏥 The liver plays a crucial role in nutrient processing, detoxification, and the production of bile, which is essential for the digestion of fats.
• 🛢️ The gallbladder acts as a reservoir for bile, storing and concentrating it for use in the digestive process, particularly in the digestion of fats.
• 🧬 Digestive enzymes include amylase for carbohydrates, lipase for fats, and various proteases for proteins, each with specific sites of production and function.
• 🔄 The absorption of nutrients primarily occurs in the small intestine, with different mechanisms for carbohydrates, proteins, and fats, and the large intestine is responsible for water and electrolyte absorption.
• 💧 Water absorption in the intestine is vital for maintaining homeostasis, with the large intestine fine-tuning the process to prevent issues like diarrhea or constipation.
• 🌱 The large intestine hosts a complex microbial ecosystem that contributes to human health by synthesizing compounds like vitamin K and biotin.
• 🚫 Pathological conditions such as gallstones can disrupt the normal function of the gallbladder and lead to inflammation or obstruction in the bile duct system.
• 📚 The script provides a comprehensive overview of the accessory organs of digestion, their functions, and the processes of absorption and defecation, highlighting the importance of these systems in human physiology.

Q & A

What are the accessory organs of digestion mentioned in the script?

The accessory organs of digestion mentioned in the script include the pancreas, liver, and gallbladder.

What are the two primary functions of the pancreas?

The pancreas serves two primary functions: an exocrine function, which involves the production of digestive enzymes and an alkaline fluid known as pancreatic juice, and an endocrine function, which is primarily mediated through the Islets of Langerhans that secrete hormones like insulin, glucagon, and somatostatin.

How do pancreatic enzymes like trypsinogen become active?

Pancreatic enzymes like trypsinogen are activated by enteropeptidases from the lining of the duodenum, which convert trypsinogen into trypsin. Trypsin then activates other pancreatic zymogens into their active forms.

What is the role of bile in the digestive system?

Bile, produced by the liver and stored in the gallbladder, plays a crucial role in the emulsification and subsequent digestion of fats in the small intestine.

How does the liver contribute to metabolic processes and detoxification?

The liver contributes to metabolic processes by storing and mobilizing glucose and fats, generating glucose from non-carbohydrate sources through gluconeogenesis, and detoxifying endogenous compounds like ammonia and exogenous substances such as alcohol and medications.

What is the primary function of the gallbladder?

The primary function of the gallbladder is to act as a reservoir for bile, which is concentrated before being released into the biliary tree to aid in digestion.

What are the main segments of the small intestine and their roles?

The main segments of the small intestine are the duodenum, jejunum, and ileum. The duodenum is primarily involved in digestion, while the jejunum and ileum are involved in the absorption of nutrients.

How is fat absorption different from the absorption of other nutrients in the small intestine?

Fat absorption differs as small fatty acids are directly absorbed into the intestinal capillaries by diffusion, while larger fats are re-esterified to form triglycerides, packaged into chylomicrons, and enter the lymphatic circulation through lacteals.

What is the role of the large intestine in the digestive process?

The large intestine is fundamentally involved in the absorption of water and electrolytes, as well as serving as a symbiotic habitat for gut microbiota, which contributes to human health in various ways.

How does the script describe the process of absorption in the small intestine?

The script describes the absorption process in the small intestine as involving villi and microvilli that increase the surface area for absorption. Nutrients like glucose, fructose, galactose, and amino acids are absorbed through secondary active transport and facilitated diffusion, while fats are absorbed differently as explained above.

What is the significance of the appendix according to the script?

Contrary to historical views, the script mentions that recent evidence supports the appendix's potential role in mitigating certain bacterial infections and repopulating the large intestine with gut flora following diarrhea episodes.

Outlines

00:00

😀 Accessory Organs of Digestion Overview

The first paragraph introduces the concept of accessory organs in the digestive system, focusing on their roles in enzyme release and their collective contribution to digestion. The pancreas is highlighted for its dual exocrine and endocrine functions, with the endocrine function involving the secretion of hormones like insulin and glucagon by the islets of Langerhans. The exocrine function is characterized by the production of digestive enzymes and pancreatic juice, which aids in the digestion of carbohydrates, proteins, and fats. The activation of these enzymes is also discussed, emphasizing the protective mechanism to prevent self-digestion.

05:03

📚 Liver and Gallbladder Functions in Digestion

The second paragraph delves into the multifaceted functions of the liver, including nutrient processing, detoxification, and bile production. The liver's role in glucose and fat metabolism is explained, with details on glycogen storage and gluconeogenesis. The detoxification process involving endogenous compounds and exogenous substances like alcohol is also covered. Bile's composition and function in fat digestion are highlighted, along with the liver's role in bile transport and storage in the gallbladder. The paragraph also touches on the gallbladder's function as a bile reservoir and the potential pathological conditions associated with it, such as the formation of gallstones.

10:04

🔬 Digestive Enzymes and Their Functions

This paragraph provides a comprehensive overview of the various digestive enzymes, their sites of production, and their functions. It starts with enzymes related to carbohydrate digestion, such as salivary amylase and pancreatic amylase, and moves on to enzymes involved in lipid digestion, including bile and lipase. The paragraph also covers enzymes related to protein digestion, such as pepsin, trypsin, chymotrypsin, and carboxypeptidases, along with their activation processes. The summary of these enzymes is essential for understanding the biochemical processes involved in the breakdown of nutrients.

15:04

🧬 Nutrient Absorption and the Role of the Small and Large Intestine

The fourth paragraph discusses the process of nutrient absorption, primarily in the small intestine, and the role of the large intestine in water and electrolyte absorption. It describes the structural adaptations of the small intestine, such as villi and microvilli, that increase the surface area for absorption. The mechanisms of absorption for different types of nutrients, including carbohydrates, amino acids, fats, and vitamins, are detailed, with a focus on the role of the lymphatic system in fat absorption. The paragraph also explains the large intestine's function in forming feces and the importance of water absorption for maintaining homeostasis.

20:05

🌿 Large Intestine Functions and Gut Microbiota

The final paragraph wraps up the lecture by summarizing the functions of the large intestine, emphasizing its role in water and electrolyte absorption, and as a habitat for gut microbiota. It mentions the structural divisions of the large intestine and the importance of the appendix in gut health. The paragraph also discusses the symbiotic relationship between gut bacteria and human health, including the synthesis of essential compounds like vitamin K and biotin. The lecture concludes with a reminder of the importance of understanding the large intestine's functions for overall digestive health.

Keywords

💡Digestive System

The digestive system is a series of organs responsible for breaking down food into nutrients that can be absorbed by the body. In the video, the focus is on the accessory organs of digestion, which includes the pancreas, liver, and gallbladder, and their roles in the complex process of digestion.

💡Accessory Organs

Accessory organs are those that assist in the digestive process but are not part of the main digestive tract. The script discusses the pancreas, liver, and gallbladder, highlighting their functions in enzyme release and bile production, which are essential for the breakdown and absorption of nutrients.

💡Pancreas

The pancreas is an accessory organ with both exocrine and endocrine functions. It produces digestive enzymes and hormones like insulin and glucagon. The script explains the pancreas's role in producing pancreatic juice, which contains enzymes that aid in the digestion of carbohydrates, proteins, and fats.

💡Liver

The liver is a vital organ with multifaceted roles in metabolism, detoxification, and digestion. It produces bile, stores glycogen, and is involved in the synthesis of essential proteins. The script emphasizes the liver's function in nutrient processing and detoxification, as well as its role in the production and transport of bile.

💡Gallbladder

The gallbladder stores and concentrates bile produced by the liver. When food is ingested, particularly fats, the gallbladder contracts, releasing bile into the digestive system to aid in fat digestion. The script mentions the gallbladder's function and its potential issues, such as the formation of gallstones.

💡Bile

Bile is a fluid produced by the liver and stored in the gallbladder. It plays a crucial role in the digestion of fats by emulsifying them, making them more accessible to digestive enzymes. The script discusses bile's composition and its importance in the mechanical digestion of fats.

💡Enzymes

Enzymes are biological catalysts that speed up chemical reactions in the body. The script describes various digestive enzymes produced by the accessory organs, such as pancreatic amylase, trypsinogen, chymotrypsinogen, and lipase, which are essential for breaking down carbohydrates, proteins, and fats.

💡Zymogens

Zymogens, also known as proenzymes, are inactive precursors of enzymes that become active under specific conditions. The script explains that trypsinogen and chymotrypsinogen are zymogens that are activated in the small intestine to prevent the digestion of the pancreas itself.

💡Glucagon

Glucagon is a hormone produced by the alpha cells of the pancreas. It raises blood sugar levels by promoting the conversion of glycogen to glucose. The script mentions glucagon in the context of the pancreas's endocrine function and its role in metabolism.

💡Insulin

Insulin is a hormone produced by the beta cells of the pancreas. It lowers blood sugar levels by facilitating the uptake of glucose into cells. The script discusses insulin's critical role in regulating the body's metabolism and the storage of glucose.

💡Absorption

Absorption is the process by which nutrients from digested food pass through the walls of the gastrointestinal tract and enter the bloodstream or lymphatic system. The script details the absorption of nutrients in the small and large intestines, highlighting the mechanisms and pathways involved in the uptake of carbohydrates, proteins, fats, and vitamins.

Highlights

Digestion is a complex process requiring the release of enzymes from accessory organs such as the pancreas, liver, and gallbladder.

The pancreas has both exocrine and endocrine functions, with the endocrine function mediated by the islets of Langerhans.

Hormones such as glucagon, insulin, and somatostatin are critical for regulating metabolism and glucose levels in the body.

Exocrine cells of the pancreas produce digestive enzymes and an alkaline fluid known as pancreatic juice.

Pancreatic enzymes include amylase for carbohydrates, proteases for proteins, and lipase for fats.

Liver's primary role is in nutrient processing, including storage and mobilization of glucose and fats.

The liver also plays a significant role in detoxification and the production of bile.

Bile, produced by the liver and stored in the gallbladder, aids in the digestion of fats.

The gallbladder serves as a reservoir for bile, which is concentrated before use in digestion.

Cholesterol or bile rubin stones in the gallbladder can lead to inflammation and digestive issues.

Digestive enzymes and their respective sites of production and function are summarized in a table for easy reference.

Absorption of nutrients primarily occurs in the small intestine, particularly in the jejunum and ileum.

The small intestine is lined with villi and microvilli to increase the surface area for absorption.

Different mechanisms and pathways are used for the absorption of carbohydrates, amino acids, and fats.

Fat-soluble vitamins are absorbed through chylomicrons, while water-soluble vitamins are absorbed directly into plasma.

The large intestine is involved in the absorption of water and electrolytes and forms semi-solid feces.

The appendix, once thought vestigial, may play a role in repopulating gut flora after diarrhea.

The gut microbiota in the large intestine contributes to human health by synthesizing essential compounds.

Transcripts

hello everybody my name is Iman welcome

back to my YouTube channel today we're

continuing our lecture on the digestive

system we are at objective three which

is going to touch on the accessory

organs of digestion now digestion is a

complex process it requires the release

of enzymes not only from the cells

directly lining the alimentary canal but

also from the pancreas liver and

gallbladder and collectively these

organs are called accessory organs of

digestion now we're going to talk about

each one separately starting off with

the pancreas the pancreas serves two

quite different roles in the body it has

an exocrine and an endocrine function

the endocrine function of the pancreas

is primarily mediated through the

eyelids of langerhans each eyelet

contains different types of cells that

secrete hormones you have the alpha

cells that produce glucagon which raises

blood sugar levels you have beta cells

that produce insulin which lowers blood

sugar levels you have the Delta cells

which produce somatostat and which

regulates the secretion of both insulin

and glucagon as well as other digestive

processes

now these hormones all play a critical

role in regulating the body's metabolism

particularly the utilization and storage

of glucose now most of the pancreas

those composed of exocrine tissue

exocrine cells produce digestive enzymes

and an alkaline fluid which is

collectively termed as pancreatic juice

this juice facilitates digestion within

the small intestine and specifically

you'll find a couple of enzymes you'll

find pancreatic amylase which breaks

down carbohydrates you'll have

trypsinogen

chymotrypsinogen and carboxypeptidases a

and b these are precursor forms zymogens

of enzymes that when activated will

break down proteins you'll also see

pancreatic lipase which helps in the

digestion of fats

now

the follow-up question to that is well

how do you how do we activate Simons

well first design against are inactive

forms of enzymes that need to be

activated this is a protective mechanism

to prevent the enzymes from digesting

the pancreas itself uh you'll also have

enteropeptidases from the lining of the

deuteron they activate trypsinogen into

trypsin and trypsin then activates other

pancreatic zymogens into their active

so that's a pancreas now let's talk

about the liver the liver is situated in

the upper right quadrant of the abdomen

it serves as a critical organ with multi

multifaceted functions that are really

vital for a metabolic processes

detoxification and digestive support

actually one of the liver's principle

roles is in nutrient processing this

includes the storage and mobilization of

glucose and fats glucose is stored as

glycogen via glycogen

glycogenesis

glycogenesis and can be converted back

to glucose through glycogenolysis when

needed now additionally the liver can

generate glucose from non-carbohydrate

sources through gluconeogenesis

fats are stored as triacyl glycerols and

they're mobilized for energy when

required now transitioning from the

metabolic roles the liver also has a

significant function in detoxification

so endogenous compounds like ammonia

that's produced from amino acid

metabolism is converted to urea which is

a less less toxic compound that can be

easily excreted by the kidneys the liver

also plays a role in the detoxifying

exogenous substances like alcohol and

also various medications now an

additional crucial function of the liver

is the production of bile all right a

secretion composed of bile salts

pigments and cholesterol bile a bile

salts are

molecules that really play a role in the

emulsification and then subsequent

digestion of fats

bio-rubin is a pot a byproduct of a

hemoglobin breakdown and it serves as a

primary pigment in bile once it's

transported to the liver

biorubin is conjugated and secreted into

bile for elimination any dysfunction in

this process

such as liver damage or bile duct

obstruction can result in jaundice and

this is a condition where you'll have

the yellowing of the skin and eyes

now not only does the liver produce bile

but it also facilitates its transport so

bile ducts connect the liver to the

gallbladder where bile may be stored and

to the duodenum where it aids in

digestion these structural con

connections underpin the liver the

liver's role in the digestive system now

the liver also receives nutrient rich

blood from the abdominal portion of the

digestive tract through the

hepatic portal all right vein enabling

it to process nutrients before they

reach systemic circulation the processed

blood then drains into the inferior vena

cava which leads to the heart now lastly

the liver is responsible for

synthesizing essential proteins such as

albumin and clotting factors now albumin

is really critical for maintaining the

osmotic balance in blood plasma while

clotting factors are really integral in

the coagulation process

all right so that's information on the

liver on to the gallbladder now the

gallbladder it's a small organ situated

beneath the liver has primarily uh

primary functions as a reservoir for

bile which is a digestive fluid that's

produced by the liver bile that's stored

in the gallbladder undergoes

concentration process making it more

potent for its role in digestion now

upon ingestion of food particularly fats

the hormone cck is released promoting

the gallbladder to contract and this

contraction forces the stored bile into

the biliary tree which is a system of

ducts that transport bile all right so

that's one roll of the uh the

gallbladder transitioning to

pathological conditions the gallbladder

is a frequent site for the formation of

cholesterol or a bile Rubin Stones a

condition often

um

that often leads to

um

problems so these stones are problematic

for several reasons actually first they

can result in inflammation of the

gallbladder and that can be pretty

painful

second the stones can actually move into

the bile duct system and they can become

lodged within the biliary tree and

actually this obstruction disturbs that

normal flow of bile and it could very

much impair the digestive process

now the thing with the gallbladder is if

you have that kind of condition they

they can't just remove your gallbladder

through surgery

all right

so those are the accessory organs of

digestion we have the pancreas the liver

and the gallbladder now we've talked a

lot about different nutrients

and their enzymes and then their

respective site of production and

function cytofunction as well as you

know the role of these enzymes so what

we have here in these two pages is a

table that summarizes this so for

nutrients like carbohydrates

all right you could have enzymes like

salivary amylase this is produced in the

salivary glands but it functions in the

mouth all right the site of function is

in the mouth the role of salivary

amylase is to hydrolyze starch to

maltose and dextrin

then we can also have pancreatic amylase

this is produced in the pancreas but the

cytophunction is in the duradum it

hydrolyzes starch to maltose and dextrin

as well all right then we have maltase

this is made in the intestinal glands

but again it's side of function is in

the small intestine it hydrolyzes

maltose to two glucose molecules then we

have isomaltase

this is produced in the

um intestinal glands but the

cytophunction is in the dunam it

hydrolyzes isomaltose to two glucose

molecules then we have sucrase

um it is produced also in the intestinal

glands also functions here all right the

role and function of sucrase is to

hydrolyze sucrose to glucose and

fructose all right and then we have

lactase it's also produced in the

intestinal glands but the cider function

is in the duodenum it hydrolyzes lactase

to glucose and galactose

now what about

the nutrients lipids well we have bile

now bile is not an enzyme but we're

going to have it listed here because

it's involved in mechanical digestion of

fats and it's a good thing to have it in

this table just so you remember that

it's important and it plays a role in

digestion all right it is produced in

the liver it's stored in the gallbladder

and its cytofunction is in the duodenum

its role is to emulsify fats all right

also you have lipase this is produced in

the pancreas but its cytofunction is

again in the due to them and it

hydrolyzes lipids

now if we scroll to the next page if

we're talking about protein so we have a

couple of enzymes here as well

we have pepsin all right

this is produced in the gastric glands

but its cytofunction is in the stomach

what it does is it hydrolyzes specific

peptide bonds and it's activated it's

activated by hydrochloric acid

then we have trypsin all right this is

produced in the pancreas but its cytome

function is in the duodenum it

hydrolyzes specific peptide bonds it

converts chymotrypsinogen to

chymotrypsin and it's activated by

enteropeptidase

all right then we have chymotrypsin

it's made and produced in the pancreas

it's cytofunction is in the duodenum all

right what does it do it hydrolyzes

specific peptide bonds and it's

activated by trypsin

all right then we have the

pro-carboxypeptidase A and B they are

produced in the pancreas but they the

cytop function is again in the dunam it

hydrolyzes terminal peptide bonds at the

carboxyl at the carboxyl end and it's

activated also by enter peptidase

then we have aminopeptidase it is

produced in the intestinal glands but

the cytofunction is again the dunanum

this table is really testing my ability

to say due to them as many times and I

always doubt that I'm pronouncing it

correctly but anyways its role is to

hydrolyze the terminal peptide bond at

the amino end all right then we have

dipeptidase it is made in the intestinal

gland again the site of function is in

the duodenum what this dipeptidases do

is hydrolyzes pairs of amino acids and

then last but not least we have our

enteropeptidase also made in the

intestinal glands also functions in the

dunanum and it converts trypsinogen to

trypsin and

pro-carboxypeptidases a and b to

carboxypeptidases A and B

all right so this is a summary of the

digestive enzymes on the MCAT all right

now we could have another important

table here that we have this is a

summary of the digestion of each major

class of biomolecules so for

triacyl glycerols that get converted to

two monoacyl glycerols fatty acids what

enzymes operate to help

do this in the mouth stomach pancreas

gallbladder or small intestines so what

you can know is you have lipase that

works in the mouth you have lipase that

works in the pancreas and you have

biomycles that work in the gallbladder

for this particular process for

carbohydrates to be broken down into

glucose galactose fructose you have

amylase in the mouth amylase in the

pancreas and then then their respective

sugar enzymes in the small intestine for

proteins to be broken down into amino

acids or die in tripeptides you'll have

pepsin in the stomach you'll have

trypsin

chymotrypsin

carboxypeptidases in the pancreas and

then you'll also have dipeptidase and

aminopeptidase in the small intestines

that will help in the breakdown of

proteins

fantastic with that we move into our

last and final objective which is all

about absorption and defecation now

absorption of nutrients

the absorption of nutrients primarily

occurs in the small intestine especially

in the jujinum and the ilium the large

intestine it largely absorbs water now

like we said earlier the small intestine

it consists of three segments we've

talked a lot about the due to them but

there's also the jujinum and the ilium

now as described previously the dunanum

is primarily involved in digestion while

the other two segments are involved in

the absorption of nutrients now the

small intestine it's lined with veli

which are small finger-like projections

from the epithelial lining as shown in

this figure right here all right each

villus has a micro Villa drastically

increasing the surface area available

for absorption now in addition at the

middle of each villus is both a

capillary bed for the absorption of

water-soluble nutrients and a lactil a

lymphatic channel that takes up fats for

transport into the lymphatic system

now if small intestine is the primary

site for nutrient absorption including

carbohydrates amino acids fats vitamins

and water the absorption process for

these diverse molecules differ both in

mechanisms and in Pathways so simple

carbohydrates like glucose fructose

galactose as well as amino acids are

primarily absorbed through secondary

active transport and facilitated

diffusion these molecules are initially

transported into the epithelial cell

lining

in the small intestine and subsequently

move into the intestinal capillaries now

the blood constantly flowing past these

cells serves to maintain a concentration

gradient so this ensures that there's

always a lower concentration of these

nutrients in the blood compared to

inside the epithelial cells all right

that's and that helps facilitate their

diffusion into the capillaries now from

here these molecules are directed to the

liver via the hepatic portal circulation

for further metabolic processing

now fats present a different case

altogether all right fats present a

different case altogether small fatty

acids are directly absorbed into the

intestinal capillaries by diffusion

bypassing the need for specialized for

specialized Transporters due to their

nonpolar nature in contrast larger fats

glycerol and cholesterol are first

incorporated into the intestinal

epithelial cells and then inside these

cells they're re-esterified to form

triglycerides which are then packaged

into chylomicrons and unlike their

smaller counterparts counterparts these

chylomicrons they enter the lymphatic

circulation through lactils eventually

entering the venous system through the

thoracic duct

now the absorption of vitamins also

varies based on their solubility so fat

soluble vitamins like vitamin A d e and

K they're absorbed through chylomicrons

water soluble vitamins on the other hand

like B complex and vitamin C they're

absorbed directly into the plasma across

the endothelial cells of the small

intestine now it's worth noting that

failure to digest and absorb fats

appropriately which may occur due to

liver gallbladder pancreas or small

intestine pathologies can result in

deficiencies in fat soluble vitamins

um lastly

the small intestine plays a really

crucial role in water absorption water

in the Lumen of the intestine is largely

the result of gastrointestinal

secretions which can total up to seven

liters per day this is significantly

higher than the average daily fluid

intake of about two liters so to

maintain homeostasis this water is

reabsorbed by osmosis as the solutes are

absorbed into the bloodstream

water flows both trans cellularly

through the cell membranes and

paracellularly by passing between the

cells

now

let's also talk about the large

intestine the large intestine serves as

the terminal part of the

gastrointestinal tract it's

fundamentally involved in the absorption

of water and electrolytes like sodium

and chloride ions

morphologically the large intestine is

shorter but it has a larger diameter

compared to the small intestine and it's

struggling it's structurally divided

into three primary sections the cesium

the colon and the rectum now the CCM

acts as a reservoir for chyme or chime

exiting the small intestine through a

valve and it's also the anatomical site

of the appendix now contrary to

historical views that considered the

appendix as vestigial recent evidence

supports its potential role in

mitigating certain bacterial infections

and also repopulating the large

intestine with gut Flora following

diarrhea episodes now notably

appendicitis or the inflammation of the

appendix represents the most common

cause for

surgery to remove the appendix the colon

all right which is another part of the

large intestine is further subdivided

into four segments it has the ascending

the transverse the descending and the

sigmoid colon the primary function of

the colon release to absorb water and

electrolytes from the chime thereby

concentrating the remaining material to

form feces now although the small

intestine is responsible for the

majority of water absorption

the colon kind of fine-tunes this

process imbalances in water absorption

as you know can result in

certain problems like diarrhea or

constipation so it's very important that

water absorption happens appropriately

in the body hence why also the colon

fine tunes this process in addition in

conjunction with the small intestine I

should say now the rectum functions as a

temporary storage site for feces all

right which is it's essentially

compositive indigestible material water

bacteria and certain unabsorbed

digestive secretions water elimination

is

facilitated by two anal spinsters the

internal anal spinster controlled by the

autonomic nervous system and then the

external anal spinster that's under

somatic control this system is similar

to that regulating urination which also

includes an internal since they're under

autonomic control and an external

spinster under somatic control

all right now something that's important

and worth noting is that the microbial

ecosystem of the large intestine is

complex and it consists predominantly of

anaerobic bacteria although aerobic

bacteria also present particularly in

the season the symbiotic relationship

contributes to human health in various

ways so for instance gut bacteria they

synthesize essential biochemical

compounds like vitamin K that's really

necessary for a blood blood clotting and

and it also

synthesizes biotin which is a coenzyme

involved in metabolic reactions so in

summary the large intestine really plays

a lot of important roles in human

physiology ranging from water and

electrolyte absorption to serving as a

symbiotic habitat for gut

microbiota now understanding its

function and mechanisms and the

mechanisms that govern these processes

is very much important which is why we

over all the important things that we

need to know about the large intestine

all right with that we have covered all

the objectives for this chapter in this

video particularly we had covered

objective two three and four

um so let's summarize really quickly

we talked about the accessory organs of

digestion

um these include the pancreas the liver

and the gallbladder and then we moved

into absorption and defecation so we

talked about uh the jujinum and the

ilium of the small intestine and how

they're primarily involved in absorption

and then we also talked about the large

intestine and how it also absorbs water

and salts and it forms semi-solute

semi-solid feces all right with that

we've ended the lecture in the next

video we'll do practice problems that

relate to the digestive system let me

know if you have any questions comments

concerns down below other than that good

luck happy studying and have a beautiful

beautiful day future doctors