Cellular Composition and Functionality in the Human Digestive System

This report details the structure and function of five different cell types within the human digestive system: red blood cells, Kupffer cells, goblet cells, enterocytes, and chief cells, highlighting their main features and essential roles. It explains how these cells combine to form tissues and organs, enabling the digestive system to function effectively, focusing on the role of epithelial, connective, muscle, and nervous tissues in the GI tract, particularly in the stomach. Furthermore, the report briefly touches on the importance of various organs working together to convert food into energy and absorb essential nutrients. The document also provides a brief overview of macromolecules and dietary requirements.

Fig. 1 Structure of cell and its Organelles
(Source-Byjus.com)
Cell
Organelles Structure & Function
Nucleus
Nucleus is enveloped by a
double membranous nuclear
membrane. Nucleus are
regarded as the “brains” of the
cell as they regulate the cell
activities. It also contains DNA,
RNA, Protein, nucleolus, and
Chromatin network.
Mitochondria
It is a double membranous
structure which is the
powerhouse of the cell.
Ribosomes Make protein
Golgi
Apparatus
It includes sac like Cisternae
and vesicles. It makes,
modifies and manages the
materials.
Lysosome
These are small round single
membrane bound organelles
which contains digestive
enzymes.
Endoplasmic
Reticulum
Two types of networks of
membrane are present, smooth
and rough. These are
responsible for transportation
of materials intercellularly.
Vacuole These are mainly used for
storage pupose.
TASK 1
Task 1a
5 different cell types used
within the digestive
system of the human body
1. Red blood cell 2. Kupffer cell (liver macrophage) 3.
Goblet cell 4. Enterocyte (Absorptive cell) 5. Chief cell
of the stomach
1. Red Blood Cells (RBC)
RBCs possess a unique structure and are disc-
shaped as shown in Fig.2. This shape increases
the surface area-to-volume ratio of the very
small cells. Therefore, during digestion this
feature facilitates the gases (oxygen and
carbon dioxide) in diffusion across the plasma
membrane of the RBCs more readily. These
cells comprise of huge amount of iron-
containing molecule, hemoglobin (hb) attaches
oxygen as oxygen molecules move into blood
vessels in the lungs. Mature RBCs do not have
cell organelles such as nucleus, mitochondria,
or ribosomes. As it does not have cell
organelles it gives space for the millions of hb
molecules present in RBCs. The fundamental
function of RBCs is to carry oxygen to cells of
the body and bring carbon dioxide to the lungs
(Bailey, 2018).
2. Kupffer cell (liver macrophage)
Among the tissue macrophages, Kupffer cells are
the most frequently found. They are specific
macrophages which are present in liver. They
perform specialized function largely because of
their peroxidase activity. It is referred to as
“tolerogenic” phentotype required to avert
unwanted immune response to stimuli. It contains
all the organelles having specific structure and role
in digestion as shown in Fig. 2.
Plasma Membrane- Kupffer cells have plasma
membranes with structures such as microvilli,
pseudopodia, filopodia, and lamellipodia. These
extensions give them star-like to bug-like look.
Cytoplasm- As Kupffer cells are the largest
sinusoidal cells, volume of their cytoplasm is
usually dense and substantial. Cytoplasm has huge
amount of lysosomes as well which helps in
degradation of organelles and elimination of
wastes, vacuoles which stores substances and
wastes, and phagosomes which helps in engulfment
of foreign bodies.
Golgi Bodies- Golgi bodies are present in groups in
close vicinity to the nucleus. Golgi bodies assist in
secretion and intracellular movement of vesicles.
Rough Endoplasmic Reticulum (RER)-There are
present in abundance in Kupffer cells and perform
the function of ribosome (for protein synthesis)
production.
Fig. 2 Kupfell cell (Source-Sciencedirect.com)
Nucleus- Kupffer cells have only one nucleus which
are usually oval-shaped and have uniformly
dispersed euchromatin.
Other Organelles- various organelles such as free
ribosomes, mitochondria (for ATP production), and
microtubules (for the movement of other
organelles) are plainly circulated in the cytoplasm.

Task 1b
Cells are the fundamental unit of living organism. A
variety of cells are present in human body which
are different in their size, shape, morphology and
functions. Like in digestion, RBCs, Chief cells,
Goblet cells are certain cells which are used and
have different shape and functions as mentioned
above. The cells which are similar in structure unite
to perform a common function and are called as
tissues. Every tissue in the GI tract of the human
body have a particular function when the
fundamental cells work together. All the four basic
type of tissues are found in the GI tract that are
epithelial tissue, connective tissue, muscle tissue,
and nervous tissue. Stomach is the organ which is
made up of different tissues but mainly it is made of
epithelial, muscular and connective tissue. Muscular
tissue mixes the contents of the stomach and
pushes it towards the intestine. Connective tissues
are fundamentally responsible for separating
mucosa from the smooth muscle layer of the wall of
the stomach in the stomach. Connective tissue
along with the epithelial tissue compose the
mucosa, that produces gastric acid for the purpose
of digestion. They also absorbs nutrients from the
stomach. Muscular tissue encompasses the inner
and outer surfaces of the stomach to provide
protection from acids. The epithelial tissue secretes
digestive fluids, enzymes and acid.
Various organs such as mouth, esophagus,
stomach, small intestine, large intestine, liver,
pancreas, gall bladder, rectum and anus work
together to achieve the common goal of digestion
and form the digestive System. In this system these
group of organs working together to convert food
into energy and absorbs nutrients, minerals,
vitamins, and water required to sustain the body.
Every organ is has a unique structure.
References
Bailey, R., 2018. Red Blood Cells (Erythrocytes). [Online]
Available at: https://www.thoughtco.com/red-blood-cells-373487
3. Goblet cells
Goblet cells are the glandular and simple
columnar cells which are found in the epithelia of
several organisms. The name of goblet cells
comes from their “goblet-like shape after they
collapse following mucin secretion. Irrespective of
whether they collect mucus or not, goblet cell’s
shape are based on their age. Cells which are
young are spherical but enlarge in size and flatten
with age. Goblets cells demonstrate a very
conspicuous morphology as shown in Fig. 3.These
have nucleus, mitochondria, Golgi body, and the
endoplasmic reticulum at their basal section.
Remaining cell has mucus in the secretory
granules.They comprise the epithelial lining of
various organs, and also responsible for producing
large glycoproteins and carbohydrates. The most
significant function of goblet cells is secretion of
mucus (McDole, et al., 2012).
Fig. 3 Goblet cell (Source- Reseaechgate)
Fig. 4 Enterocyte (Source- Byjus.com)
5. Chief cell of the Stomach
Chief cells of the stomach are epithelial cells
that are present in the gastric unit or gastric
gland. These cells have a wide network of RER
placed around the nucleus. They also contain
several large secretory vesicles filled with
digestive enzymes in the apical cytoplasm
(Goldenring, et al., 2011). These cells are also
called zymogenic cell or peptic cell. Peptic cells
release pepsinogen and chymosin in the
stomach which are essential for the process of
digestion. Pepsinogen is converted into pepsin
by the acid secreted by gastric parietal cells.
Peptic cell also secrete gastric lipase enzymes
that break down the triglycerides into di and
monoglycerides and free fatty acids. Chief cells
of the stomach secrete leptin when they come
in contact of food present in the stomach.
Pepsinogen granules of Chief cell contain
leptin.

[Accessed 14 March 2019].
Goldenring, Nam & Mills, 2011. The origin of pre-neoplastic
metaplasia in the stomach: chief cells emerge from the Mist.
Experimental Cell Research, 317(19), p. 2759–64.
McDole, J. R. et al., 2012. Goblet cells deliver luminal antigen to
CD103+ DCs in the small intestine. Nature, 483(7389), p. 345–
349.