cell

1. PWANI UNIVERSITY
NAME: BRIAN JUMA NYONGESA
REG. NO: SB02/PU/40063/19
SCHOOL: PURE AND APPLIED SCIENCES
COURSE: BSc BIOCHEMISTRY
DEPARTMENT: BIOLOGY
UNIT CODE: SBC B103
UNIT NAME: THE CELL AND ITS EXTERNAL ENVIRONMENT
LECTURER NAME: DR. GHRIS NGENY
ASSIGNMENT: TAKE AWAY CAT TWO EXAM
DATE SUBMITTED:

2. 1. Elucidate the structural morphology of renal tubular cells and their diagnostic
indication when present in urine.
According to Schumann, renal tubular epithelial cells are regrouped under the term: renal
cells. This term implies several renal cells, which include; proximal renal tubular cells, collecting
duct renal tubular cells, necrotic renal tubular cells and renal epithelial cells.
proximal renal tubular cells: They are the large cells with an abundant granular cytoplasm and
with a blunted cell membrane. Their nucleus is round and eccentric. It has elaborate brush
borders. It is constructed from folds of the cellular membrane. In a toxic or ischemic state, the
brush border is eliminated and is found in the urine in the form of granules.
collecting duct renal tubular cells: It has cubic shape but once exfoliated it adopts a rounded
shape. They are large than leukocytes and have lightly granular cytoplasm. The nucleus is round
and well defined and usually centric. They are the most frequently observed renal tubular cells in
cytodiagnostic method (Schumann, 1986).
necrotic renal tubular cells: The necrotic renal tubular cell is an important element
of Schumann cytodiagnostic method. This cell is described, with the PAP stain, as ghost cells,
with the form and size of normal cells, and with poorly stained nuclei. The cytoplasm of these
cells is highly granular. Due to special conditions, the collecting duct renal tubular cells are
unable to resist to the low osmolality of the urine. As water and salts get in the cells, the
cytoplasm starts to disorganize. The cell swells, the cytoplasm takes a granular aspect and the
nucleus shrinks and becomes pycnotic. At the end of the process, the cells are completely
granular. The granules are quite similar to those found in granular casts
Renal epithelial cells: For Schumann, renal epithelial fragments have a high clinical value. The
renal epithelial fragments are quite different from cell clusters. The epithelial fragment is a piece
of tissue. It is not normal to have tissue fragments in urine.
The diagnostic indications of this cells in urine include the following;
1) frequent urination
2) pain when urinating
3) pain in lower tummy

3. 4) back pain
2. Describe the nature of lymph fluid and their functions in the body in comparison
with blood plasma.
Lymph fluid is a clear fluid composed mainly of water, electrolytes, and some small
plasma proteins like lymphocytes and macrophages for body defense. Transported in the
lymphatic pathway form the lymphatic capillaries to the collecting ducts, and at the end disposed
into the venous blood. Reabsorbed by lymphatic capillaries in all body tissues (especially in
extremities) where excessive tissue fluids occur. Because of the lack of a pumping organ in the
lymphatic pathway, lymph movement is largely dependent on skeletal muscle activity (similar to
blood flow in the veins). Lymph movement is normally constant and smooth, except when
obstruction (small blood clot, tumor) occurs which tend to back up the lymph, and results in
edema (fluid accumulation in tissues).
Comparisons of lymph functions and blood plasma
Differences
Lymph: It is an interstitial fluid, present between the cells of a tissue. Exchange of metabolites,
gases and waste products takes place through the fluid.
Functions of Lymph:
1. It maintains balance between blood and tissue fluid.
2. Add lymphocytes for the release of antibodies.
3. Plasma proteins and some other micro molecules synthesized by liver enter the blood
through lymph.
4. Fat is absorbed in the intestine by lymph as chylomicron
5. Some waste products are carried by it into blood.

4. 6. It destroys the invading microorganisms and foreign particles in the lymph nodes.
Plasma contains: Water (About 91%), Plasma proteins (about 7%), Organic substances and
inorganic substances (2%)
Functions of Plasma:
1. Transport: Plasma transport the digested food products like glucose, amino acids, fatty
acids, etc.
2. Prevention of blood loss: Fibrinogen helps in blood clotting and thus prevents blood loss.
During
3. blood clotting the soluble fibrinogen is converted into insoluble fibrin.
4. Retention of fluid in blood
5. Maintenance of blood pH: Plasma proteins act as acid base buffers and thus maintain the
blood pH by neutralizing strong acids and bases.
6. Regulation of body temperature: Plasma helps in the uniform distribution of heat all over
the body, and in conducting heat to skin for dissipation.
SIMILARITIES
1. Both fluids destroy and inactivate the invading microorganisms and foreign particles in
the blood.
3. Describe the structure of viruses, their nature of virulence and how they differ with
other microorganisms.
Viruses vary in their structure. A virus particle consists of DNA or RNA within a protective
protein coat called a capsid. The shape of the capsid may vary from one type of virus to another.
The capsid is made from the proteins that are encoded by viral genes within their genome. The
shape of the capsid serves as one basis for classification of viruses. Virally coded proteins will
self-assemble to form a capsid. Some viruses have an envelope of phospholipids and proteins. The
envelope is made from portions of the host’s cell membrane. It surrounds the capsid and helps
protect the virus from the host’s immune system. The envelope may also have receptor molecules

5. that can bind with host cells. They make it easier for the virus to infect the cells. Examples of
structures include;
Helical Viruses
Helical capsids are made up of a single type of protein subunit stacked around a central axis to
form a helical structure. The helix may have a hollow center, which makes it look like a hollow
tube. This arrangement results in rod-shaped or filamentous virions. These virions can be anything
from short and very rigid, to long and very flexible.
Icosahedral Viruses
Icosahedral capsid symmetry gives viruses a spherical appearance at low magnification, but the
protein subunits are actually arranged in a regular geometrical pattern, similar to a soccer ball; they
are not truly spherical. An icosahedral shape is the most efficient way of creating a hardy structure
from multiple copies of a single protein. This shape is used because it can be built from a single
basic unit protein which is used over and over again. This saves space in the viral genome.
Complex Viruses
Complex viruses possess a capsid which is neither purely helical, nor purely icosahedral, and
which may have extra structures such as protein tails or a complex outer wall. Viral protein
subunits will self-assemble into a capsid, but the complex viruses’ DNA also codes for proteins
which help in building the viral capsid. Many phage viruses are complex-shaped; they have an
icosahedral head bound to a helical tail. The tail may have a base plate with protein tail fibers.
Some complex viruses do not have tail fibers.
Enveloped Viruses
Some viruses are able to surround (envelop) themselves in a portion of the cell membrane of their
host. The virus can use either the outer membrane of the host cell, or an internal membrane such
as the nuclear membrane or endoplasmic reticulum. In this way the virus gains an outer lipid
bilayer known as a viral envelope. This membrane is studded with proteins coded for by both the
viral genome and the host genome. However, the lipid membrane itself and any carbohydrates

6. present come entirely from the host cell. The influenza virus, HIV, and the varicella zoster virus
are enveloped viruses. This type of has an advantage to the virus, in the fact that, they have better
protection from the host's immune system, enzymes and certain chemicals.
Virulence is a pathogen's or microbe's ability to infect or damage a host. Virus virulence factors
allow it to replicate, modify host defenses, and spread within the host, and they are toxic to the
host. They determine whether infection occurs and how severe the resulting viral disease
symptoms are. Viruses often require receptor proteins on host cells to which they specifically
bind. Typically, these host cell proteins are endocytosed and the bound virus then enters the host
cell. Virulent viruses such as HIV, which causes AIDS, have mechanisms for evading host
defenses. HIV infects T-Helper Cells, which leads to a reduction of the adaptive immune
response of the host and eventually leads to an immunocompromised state.
Viruses differ from other microorganisms in the fact that they are incapable of
autonomous reproduction, growth or metabolism. Although some organisms are also incapable
of independent survival and live as obligatory intracellular parasites, they are capable of
independent metabolism and procreation. Although viruses have a few enzymes and molecules
characteristic of living organisms, they have no metabolism of their own; they cannot synthesize
and organize the organic compounds from which they are formed.
Reference
Bull GM, Joekes AM, Lowe KG: Renal function studies in acute tubular necrosis. Clin Sci 9:
379–404, 1950 [PubMed] [Google Scholar]
Jameson, J. Larry & Loscalzo, Joseph (2010). Harrison's Nephrology and Acid-Base Disorders.
McGraw-Hill Professional. p. 3. ISBN 978-0-07-166339-7.
V. Meka. “Panton-Valentine Leukocidin.” http://www.antimicrobe.org/h04c.file...L-S-aureus.asp
Schumann BG. Cytodiagnostic Urinalysis for the Nephrology Pratice. Seminars in nephroloy;
6,308-345,1986
"Lymph - Definition and More from the Free Merriam-Webster Dictionary". www.merriam-
webster.com. Retrieved 2010-05-2