The gastrointestinal tract breaks down food and absorbs nutrients and water. It consists of the oral cavity, esophagus, stomach, small intestine, large intestine, and anus. The oral cavity breaks food into smaller pieces for further digestion. The stomach acidifies food and the small intestine further breaks down nutrients which are then absorbed. The large intestine absorbs water leaving solid waste to pass through the anus.
Study of the structure/form of the human body. Study location of organs, reasons for location, and shape. Anatomy is the science which deals with the description of the structure of cells, tissues, organs and organisms.
Digestion
Digestion may be defined as physiological process by which complex food particles are broken down into simple form which are suitable for absorption and subsequent utilization.
Digestive system
Digestive system is the system which involves organs that are responsible for the process of digestion.
Gastrointestinal Tract:
The digestive system is composed of a long muscular tube – the gastrointestinal (GI) tract, or alimentary canal – and a set of accessory organs.
Introduction to digestive system
Organs of digestive tract
Mouth and their different enzymes and actions
salivary glands
Oesophagus
Stomach
Small Intestine and funcions
Large Intestine and functions
Anus
Assessary Organs
Liver
Pancreas
Digestive system Physiology
Ingestion
Digestion
Absorption
Assimilation.
Excretion
The digestive system includes the organs of the alimentary canal and accessory structures. The alimentary canal forms a continuous tube that is open to the outside environment at both ends. The organs of the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
The digestive system is made up of the digestive tract and other organs that help the body break down and absorb food. It is a long, twisting tube that starts at the mouth and goes through the oesophagus, stomach, small intestine, large intestine and anus.
Study of the structure/form of the human body. Study location of organs, reasons for location, and shape. Anatomy is the science which deals with the description of the structure of cells, tissues, organs and organisms.
Digestion
Digestion may be defined as physiological process by which complex food particles are broken down into simple form which are suitable for absorption and subsequent utilization.
Digestive system
Digestive system is the system which involves organs that are responsible for the process of digestion.
Gastrointestinal Tract:
The digestive system is composed of a long muscular tube – the gastrointestinal (GI) tract, or alimentary canal – and a set of accessory organs.
Introduction to digestive system
Organs of digestive tract
Mouth and their different enzymes and actions
salivary glands
Oesophagus
Stomach
Small Intestine and funcions
Large Intestine and functions
Anus
Assessary Organs
Liver
Pancreas
Digestive system Physiology
Ingestion
Digestion
Absorption
Assimilation.
Excretion
The digestive system includes the organs of the alimentary canal and accessory structures. The alimentary canal forms a continuous tube that is open to the outside environment at both ends. The organs of the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.
The digestive system is made up of the digestive tract and other organs that help the body break down and absorb food. It is a long, twisting tube that starts at the mouth and goes through the oesophagus, stomach, small intestine, large intestine and anus.
Anatomy and Physiology of Digestive system.
Different Digestive process for absorption of food in GIT.
Different parts GIT Tract where food move from Mouth to the anus.
With this presentation we will learn to develop an understanding of the relationships between the structures and functions of the human digestive system and digestive processes which include the processes of digestion include six activities: ingestion, propulsion, mechanical or physical digestion, chemical digestion, absorption, and defecation
An overview of the GIT with detailed study of the organs, along with their anatomy and physiology. It will find u easier to go through this complex function within our body.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
1. Food to Feces and In Between –
Pathway for Food
Overview of the Gastrointestinal System
Luke MacLeod, Wara Lounsbury, Tejinder Kaur, and James
O’Brien
2. Overview
Large Intestine
Oral Cavity
General Structure
and Functions of the
Digestive System
General
Arrangement of the
Abdominal GI
Organs
Small Intestine Pharynx
Esophogus (The
Swallowing
Process)
Stomach
Rectum/Anus Questions
3. Functions of the Digestive System
Ingestion
Digestion
Secretion
Propulsion
Elimination
Absorption
4. So What Makes up the
Gastrointestinal Tract (GI)?• Oral Cavity
• Pharynx
• Esophagus
• Stomach
• Small Intestine
• Large Intestine
• Anus
Upper
Lower
5. Two Categories: Digestive and
Accessory Digestive
The digestive organs make up the
gastrointestinal (GI) tract
The accessory digestive organs
include the salivary glands, tongue,
pancreas, liver, and gall bladder
6. General Arrangement of Abdominal GI
OrgansTunics of the GI Tract:
• From esophagus to large intestine: 4
layers
Mucosa
Submucosa
Muscularis
Adventitia/serosa
McKinley, M. P., O'Loughlin, V. D., Pennefather-O'Brien, E., & Harris, R. T. (2015).Human anatomy. Page
7. Oral Cavity
• Entrance to the GI tract
• Two distinct regions:
Vestibule
Oral Cavity Proper
• Is comprised of these main components:
Cheeks Tongue Palate
Salivary
Glands
Teeth
8. Muscles of Mastication
There are four muscles that are involved in
mastication:
• Masseter
• Temporalis
• Lateral Pterygoid
• Medial Pterygoid
9. Pharynx
• Comprised of three skeletal muscle pairs:
• Constrictors aid in propulsion
• 3 Sections of Pharynx:
Nasopharynx
Oropharynx
Laryngopharynx
• Works with epiglottis to prevent bolus from entering airway
Superior
(beginning)
Middle
Inferior
(end)
Pharyngeal Constrictors
10. Esophagus
• 25 cm long
• Pathway for bolus from pharynx to stomach
• Connects to the stomach by passing esophageal
hiatus
• Contains 2 sphincters:
Upper esophageal sphincter
Lower esophageal sphincter
• HISTOLOGY:
• Different mucosa: instead of columnar epithelial
cells, has stratified squamous cells
11. The Swallowing Process
• Also called deglutition
• Process of moving ingested materials from the oral cavity to the stomach
• Three phases
• Occurs as a result of coordinated muscular activities that force the bolus
(chewed substance)
• (1) Into the pharynx from the oral cavity
• (2) through the pharynx, and
• (3) into the esophagus on the way to the stomach
Voluntary Pharyngeal Esophageal
12. Stomach
• Muscular J shaped sac occupying the left upper quadrant
of the abdomen
• Continues digestion of bolus into chyme
• Consists of the:
Cardia , fundus, body, and pylorus (pyloric antrum and pyloric
canal)
• Thick muscularis layer is made up of three smooth muscle
layers
Oblique layer, middle circular layer, and an outer longitudinal
layer
Figure 26.12
McKinley, M. P., O'Loughlin, V. D., Pennefather-O'Brien, E., & Harris, R. T. (2015).Human anatomy. Page
13. Cells of the Stomach
• Secrete mucin
• Line stomach lumen
• Protect stomach
Surface Mucous Cells
• Secrete acidic mucin that maintains
stomach pH
Mucous Neck Cells
• Secrete HCl acid to assist in deanimation
of proteins
Parietal Cells
• Secretes inactive pepsin as
pepsinogen into stomach
lumen
• Activates in acidic conditions
Chief Cells
• Release gastrin hormone
• Affects secretion from parietal
and chief cells
Enteroendocrine cells
14. Overview of the Small Intestine
Has 3 segments:
Common features:
• Circular folds: increase surface area so
more nutrients can be absorbed
• Villi: projections of mucosa used for
digestion, made of columnar epithelial cells,
with microvilli, and goblet cells
• Intestinal glands: invaginations of the
mucosa, made of various cells
Duodenum Jejunum Ileum
15. Entering the Small Intestine:
Duodenum Chyme enters the duodenum (25 inches long),
where digestion primarily occurs
• Brunner’s glands, release alkaline mucus to
neutralize acidic chyme, and to activate
digestive enzymes
• At middle of the duodenum (Ampulla of
Vater) pancreatic juice and bile enter the
duodenum via the major duodenal papilla
• Pancreatic juice and bile break down lipids,
proteins and carbohydrates of the chyme
• Joins the jejunum at the duodenojejunal
flexure
16. Entering the Jejunum: Site of
Absorption Chyme enters the jejunum, where absorption primarily occurs along
with digestion, from the duodenum
• Villi are long and finger-like
• Unlike the duodenum, there aren’t any specific glands in the
submucosa
• Smooth muscles contract in localized manner called segmentations
to mix chyme up and increase contact with walls
17. End of the Small Intestine: Ileum
Chyme enters the ileum from the jejunum
• The longest segment: 2 – 4 m long
• Nutrients are absorbed here, as is much of the
water
• Terminal end has lymphatic tissue, known as
Peyer’s patches in the mucosa: they examine
the chyme for pathogens
• Contains Paneth cells: release antimicrobial
substances
• Joins the cecum at the ileocecal sphincter
18. Large Intestine
• Absorbs most the water and ions in the chyme, so it
becomes feces occurs via aldosterone mediated
sodium uptake
• Chyme enters the large intestine at the cecum
• Inferior to the cecum is the verniform appendix
• 4 segments, along with bends: ascending colon right
colic flexure transverse colon left colic flexure
descending colon sigmoid flexure sigmoid
colon
• Fecal matter moves through large intestine by haustra
muscle contractions
19. Histology and Muscles of Large
Intestine HISTOLOGY:
• Lined with simple columnar epithelial cells and goblet
cells, but lacking villi
• Many lymphatic cells are in the lamina propria layer
MUSCLES:
• Teniae coli: longitudinal smooth muscles forming
bundles, cause appearance of sacs (haustra)
20. Rectum/Anus
RECTUM:
• ANATOMY: Stretch receptors, and renal
ampulla
• FUNCTION: Stores fecal matter until excreted
ANAL CANAL:
• Internal (involuntary) and external (voluntary)
sphincters
• Divided by the pectinate line:
21. Questions?
1. What is the benefit of the oral cavity breaking down food into smaller portions
during the initial stages of digestion?
2. Why are there more circular folds in the duodenum than in the ileum?
22. Sources
Biology Forums Gallery. (n.d.). Retrieved October 19, 2016, from http://biology-forums.com/index.php?action=gallery;sa
Digestive System - Physiology. (n.d.). Retrieved October 19, 2016, from https://craniumcommander.wikispaces.com/Digestive System - Physiology
Duodenum. (n.d.). Retrieved October 19, 2016, from http://www.innerbody.com/image_dige02/dige21.html#full-description
Duodenum. (n.d.). Retrieved October 19, 2016, from http://www.siumed.edu/~dking2/erg/GI118b.htm
Duodenum. (2014, July 22). Retrieved October 19, 2016, from http://www.kid-facts.com/2014/07/duodenum.html
Gastric Motility. (n.d.). Retrieved October 19, 2016, from http://www.vivo.colostate.edu/hbooks/pathphys/digestion/stomach/motility.html
How to Survive Days of High Heat, Humidity & Pollution - Allergies & Your Gut. (2016, July 29). Retrieved October 19, 2016, from
http://allergiesandyourgut.com/2016/07/29/survive-days-high-heat-humidity-pollution/
McKinley, M. P., O'Loughlin, V. D., Pennefather-O'Brien, E., & Harris, R. T. (2015).Human anatomy.
Pyloric Sphincter Function. (n.d.). Retrieved October 19, 2016, from http://www.newhealthguide.org/Pyloric-Sphincter-Function.html
Schmidler, C. (n.d.). Anatomy and Function of the Digestive System. Retrieved October 19, 2016, from http://www.healthpages.org/anatomy-
function/anatomy-function-digestive-system/
Small Intestine. (n.d.). Retrieved October 19, 2016, from http://www.webmd.com/digestive-disorders/small-intestine
23. Sources cont.
Tariq, M. I. (2014). Bowel Obstruction. Retrieved October 19, 2016, from http://www.steadyhealth.com/articles/bowel-
obstructionseveral-disorders-are-known-to-cause-this-disorderThe Muscles of Mastication. (n.d.). Retrieved October 19,
2016, from http://visitcore.com/featured-muscles-the-muscles-of-mastication/
Editor's Notes
Explain briefly each process and tie in how each organ contributes to the process throughout the presentation
The digestive system comprises of organs that:
Ingest food
Transport the ingested food
Digest the food into smaller components
Absorb the necessary nutrients into the blood stream and;
Expel the waste products from the body
Mucosa-3 components: superficial epithelium lining; lamina propria, muscularis mucosae (thin layer of smooth muscle)
Submucosa-dense irregular connective tissue, blood and lymph vessels, nerves
Muscularis-2 layers of smooth muscle. Inner circular layer (inner layer of smooth muscle) and outer longitudinal layer (outside layer of smooth muscle)
Adventitia-outer most layer made of areolar connective tissue with elastic fibres and collagen
-retroperitoneal organs contain adventitia because they are somewhat covered by visceral peritoneum
serosa-same make up as adventitia but is covered by a layer of visceral peritoneum
-intraperitoneal organs contain serosa
Teeth: collectively known as the dentition. Teeth are responsible for mastication, the first part of the mechanical digestion process.
Cheeks: The buccinator muscles compress the cheeks against the teeth to hold solid materials in place during chewing.
Tongue: manipulates and mixes ingested materials during chewing and helps compress the materials against the palate to turn them into a bolus. The tongue also performs important functions in swallowing.
Palate: The palate forms the roof of the oral cavity and acts as a barrier to separate it from the nasal cavity. There is a hard plate – helps the tongue manipulate materials before swallowing and the soft plate prevents ingested materials from entering the nasal region
Salivary glands: collectively produce and secrete saliva, a fluid that assists in the initial activities of digestion.
The masseter: elevates and retracts the jaw, the most powerful muscle in the body in terms of ability to exert pressure
Temporalis: elevates and brings the jaw forward
Lateral: bring the jaw forward as well
Medial: elevates the mandible, and assists in closing the mouth
All four of the muscles are skeletal muscles that are innervated by the mandibular nerve, which is a branch of the trigeminal nerve
http://visitcore.com/featured-muscles-the-muscles-of-mastication/
The sequential contraction of the constrictors moves the bolus down the pharynx to the esophagus by narrowing the diameter of the pharynx behind the bolus
While the constrictors are pushing the bolus, the epiglottis shuts over the larynx and trachea (opening to airways)
peristalsis= rhythmic smooth muscle contractions
Why different epithelial cells? No absorption , which is what the simple columnar is useful for, so stratified aquamous for more protection from still mostly intact bolus
Pic: http://blogberlinmd.com/photorii/histology-of-esophagus
The voluntary phase occurs after ingestion. Food and saliva mix in the oral cavity. Chewing forms a bolus that is mixed and manipulated by the tongue and then pushed superiorly against the hard palate.
The appearance of the bolus at the entryway to the oropharynx initiates the pharyngeal phase. During this phase, (1) the soft palate and uvula elevate to block the passageway between the nasopharynx and oropharynx; (2) the bolus enters the oropharynx; and (3) the larynx and laryngeal opening elevate toward the epiglottis, ultimately covering and sealing the glottis to prevent swallowed materials from entering the trachea.
The esophageal phase is involuntary. It is the time (about 5 to 8 seconds) during which the bolus passes through the esophagus and into the stomach.
The stomach follows the esophagus in the GI tract. It is a J-shaped sack which resides in the upper left quadrant of the abdomen. Rugae are gastric folds within the stomach that allow it to expand as food enters, and contract as food leaves. Its purpose is to complete the digestion of the bolus from the oral cavity into chyme.
The stomach itself is made up of four main components: the cardia, the fundus, the body, and finally the pylorus. The cardia is the narrow region anterior to the stomach lumen which connects to the esophagus posteriorly, at the cardiac orifice. The fundus is then the region that lies both lateral and superior to the esophagus. The body of the stomach is the largest region of the stomach, and follows posteriorly to both the cardia and fundus regions. The pylorus is the terminal region of the stomach. It begins to narrow and is divided into two regions: the pyloric antrum and pyloric canal. The pyloric antrum is the wider region of the pylorus, while the pyloric canal is more tapered and connects to the duodenum. This region is known as the pyloric orifice, and to mediate the entry of chyme into the duodenum, there is a pyloric sphincter consisting of circular smooth muscles surrounding the orifice.
There are five cells which are used in the stomach for secretion. The first are surface mucous cells. They line the stomach lumen and continuously secrete mucin in order to protect the stomach lining from the acidic environment. The mucous neck cells are interspersed amongst parietal cells and secrete acidic mucin in order to maintain acidic conditions in the stomach. The parietal cells are the ones that secrete hydrochloric acid into the stomach lumen in order to assist in protein deanimation. Parietal cells can also secrete an intrinsic factor that binds to vitamin B12, assisting in its absorption later on in the small intestine. Chief cells then secrete pepsinogen, which turns into the active enzyme pepsin by the acidic environment of the stomach. This ensures that the enzymes do not start digesting stomach lining immediately after secretion. Finally, the enteroendocrine cells secrete the hormone gastrin which regulates the chief and parietal cells.
Circular folds: are part of the mucosa and submucosa layer, and slow down the flow of chyme to maximize absorption
Villi: they increase the SA for absorption, and are formed out of columar epithelial cells and goblet cells. On the columnar epithelial cells there are microvilli on the apical surface to further increase the SA. The goblet cells release mucous to lubricate the passage of chyme. The villi each have their own capillary network, so nutrients can swiftly enter the bloodstream after absorption, and in the center is a lacteal, which is used for absorbing lipids
Intestinal glands: found in between some of the villi, lined with: columnar epithelial cells, goblet cells, and enteroendocrine cells (releases hormones like secretin, and CCK, that help with digestion and signalling)
Pic: http://www.webmd.com/digestive-disorders/small-intestine
https://craniumcommander.wikispaces.com/Digestive+System+-+Physiology
It’s the shortest segment of the small intestine- only 10-12 inches long, and the superior end attaches to the pyloric sphincter, the inferior end attaches to the jejenum
Journeying through the small intestine, the chyme, which is already partially digested is digested further, breaking down proteins, lipids and carbohydrates, to allow for absorption later in the small intestine. Firstly, Brunner’s glands secrete alkaline mucus to neutralize the acidic chyme, and to create an environment that’s favourable for the activation of the digestive enzymes.
Digestion occurs via the secretion of pancreatic juice (contains digestive enzymes) by pancreatic acinar cells and bile, by the gall bladder. Secretion occurs due to neural and endocrine signals. Neural signalling involves the vagus nerve (parasympathetic nervous system, rest and digest), whereas endocrine involves hormones secreted by the enteroendocrine cells- CCK, gastrin, and secretin. These are secreted and mixed with the chyme at the middle of the duodenum- the Ampulla of Vater.
The smooth muscles contract in a localized manner called segmentations to mix up the chyme and increase contact with the walls of the jejenum
CELLS: composed of villi and microvilli, in order to maximize the surface area for absorption- most of nutrients are absorbed here
Absorption of carbohydrates, lipids and proteins occurs in the microvilli
The villi contains a lacteal, which allows for absorption of digested lipids
ILEUM: chyme enters from the jejenum (2- 4 m long)
Last of the nutrients and water are absorbed here: water flows passively through the cells, and nutrients absorption occurs via the microvilli and villi
Joins the cecum (part of the large intestine) via the ileocecal sphincter, which controls the flow of chyme into the large intestine
Terminal end has lymphatic tissue, known as Peyer’s patches examine the chyme for any pathogens, and Paneth cells release antimicrobial substances
Appendix: is lined by lymphocyte filled lymphatic nodules
The external sphincter is under voluntary control, while the internal is SM, so its involuntary- both must be relaxed in order for fecal matter to be released
answer: smaller food particles allow for an increase in the surface area exposed to the saliva secreted by the salivary glands. This means that more food is exposed to the digestive enzymes at once, increasing the digestive efficiency during mastication and salivation. More specifically, more amylases are able to cleave the sugar compounds through hydrolysis.
Because more absorption occurs in the duodenum than in the ileum, so the circular folds increase the SA for absorption where it most occurs
