BIOL121 Worksheet

BIOL121 WORKSHEET
Due: 3 am Tuesday 15th October (Week 11)
Submit: via Turnitin link on BIOL121 LEO page
Weighting: 20% final grade (marked /60)
QUESTION 1
Which type of immunity is expressed in the following scenarios? Choose between:
 Non-specific (first line defence)
 Non-specific (second line defence)
 Specific (antibody-mediated)
 Specific (cell-mediated immunity)(0.5 mark each – total 2 marks)
Scenario Type of immunity
Bacterial septicaemia (bacterial
contamination in systemic
circulation)
 Non-specific (first line defence)
Mucous-coated hairs within the
nose trap and filter microbes
from inhaled air.
 Non-specific (second line defence)
Interferons are released by
virus-infected cells and interfere
with viral replication.
 Specific (antibody-mediated)
A virus multiplies inside the
epithelial cells in your throat.
 Specific (cell-mediated immunity)
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QUESTION 2
Choose TWO of the below scenarios and highlight these rows
bold. State which general property of adaptive immunity the scenario illustrates in
the second column. Select ONE phrase (from the list below) that BEST describes what
is happening at a cellular level to result in this property of adaptive immunity. Write
the letter corresponding to this phrase in the third column. An example is included.
(0.5 mark each – total 2 marks)
Scenario General
property
of
immunity
Explana
tion
Even though your body contains a relatively small
number of lymphocytes, your immune system can
mount a response against almost any antigen it
encounters.
Versatility A
Generally, after an initial infection, subsequent
immune responses to that antigen are faster,
stronger and more sustained.
Memory C
You can suffer from ‘the flu’ multiple times
throughout your lifetime.
Tolerance F
Your immune system can distinguish between
antigens on your own cells, and those of an
invading pathogen.
Specificity B
Possible phrases are listed below. Not all phrases will need to be used and only ONE
phrase is required per row. If you record more than one, you will not be awarded any
marks for your explanation.
A There are millions of different lymphocyte populations, each of which is sensitive to
a different antigen. Lymphocytes proliferate when activated by their specific
antigen.
B Each T or B cell has receptors that respond to only one antigen and ignores all
others.
C Activated lymphocytes produce two groups of cells: one group that attacks the
invader immediately, and another that remains inactive unless it is exposed to the
same antigen at a later date.
D Each T and B cell can recognise many antigens and respond to a wide variety of
possible threats.
E T cells are versatile because they produce copious quantities of antibodies that can
respond to a wide variety of threats.
F Phagocytes have a reduced ability to destroy pathogens during subsequent
infections.
G The immune response ignores self-antigens and targets non-self antigens.
2

H B cells differentiate into T cells to create a long-lived immune
response.
QUESTION 3
Which bone cells would be MOST affected by an absence of parathyroid hormone? In
you answer, you must explain the relationship between these cells and any
subsequent effect upon blood calcium levels.
(3 marks)
Parathyroid hormone is essential during regulation of serum calcium due to its effects
on bones, kidneys and the intestines. They influence the remodelling process of the
bones in the bone tissue leading to resorbtion and rebuilding with time. The PTH is
often released due to low blood serum calcium levels. It indirectly leads to stimulation
of the activity related to osteiocclast in the bone matrix aiming at releasing ionic
calcium into the blood to increase the low calcium serum levels. PTH in the bones
binds to the osteoblasts which are the cells responsible for bone creation. Binding
effect allows increased expression of RANKL and offers inhibition of osteoprotegerin
secretion.
QUESTION 4
Define hypertrophy and use an example to explain how this term relates to skeletal
muscle tissue.
(3 marks).
Hypertrophy relates to the overall increase in the size of skeletal muscles due to its
growth size and the cells components. There are two key factors which contribute to
hypertrophy; these are sarcoplasmic hypertrophy which is associated with increased
glycogen storage and myofibrillar hypertrophy which entails increase in the size of
myofibril. Hypertrophy stimulation is linked to a range of stimuli which increases the
overall muscle cells. They occur as adaptive process which increases the veal ability
to produce force or resist fatigue in states of anaerobic condition.
QUESTION 5
Think about how the renin-angiotensin-aldosterone system acts to maintain normal
blood pressure. Susan has sustained damage to her adrenal glands. Consequently,
her circulating levels of aldosterone are abnormally low. What do you expect the lack
of aldosterone to do to Susan’s blood pressure? Explain your answer.
(3 marks)
Renin-angiotensin-aldosterone is a hormone which plays vital role in the regulation of
blood pressure and maintenance of fluid ad electrolyte balance. When there is
reduced flow of renal blood flow, the juxtaglomerular cells in the kidney allows
conversion of precursor porenin to the rennin and lead to direct secretion to the
circulation . Angiostenin has the role of secreting the secretion oif aldosterone
hormone from the adrenal cortex, it causes the increase of absorption in the renal
tubules leading to higher absorption of sodium and water in the blood system, further,
leading to secretion of potassium for maintenance of electrolyte balance. This action
causes rise in the blood pressure levels of the patient. QUESTION 6
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Tasma is enjoying a night out at the pub with her friends. It is
well established that alcohol inhibits the secretion of ADH. Explain how this will affect
her urine output.
(3 marks)
ADH hormone aids in the control of blood pressure through mechanism of kidneys and
blood vessels. It acts a s conservation mechanism in the body through reducing the
level of water passed out as urine. This action is undertaken to take back the urine
into the kidney parts. In this way water returns to the blood system, increasing the
concentration of urine and reducing water loss. ADH hormone is further released by
nausea, thirst, pain and vomiting which acts to keep the fluid volume during adverse
occurrence in the blood system. During alcohol ingestion, ADH hormone is prevented
from being released leading to increase in urine production and dehydration.
QUESTION 7
Haemophilia is the oldest known hereditary bleeding disorder. Explain why
haemophilia is more commonly seen in males.
(3 marks)
Haemophilia is disorder occasioned by the inability of the body to make blood clots
necessary to stop bleeding. This leads to longer bleeding periods. Haemophilia occurs
in two versions; haemophilia A associated with low clotting factor VIII and haemophilia
B occurring due to low clotting factor IX levels. Both Haemophilia A and B are linked to
the X-linked recessive disorders which is linked to men X chromosomes, thus females
are affected by this. In other cases it affects females having malfunctioned gene on
the X chromosomes.
QUESTION 8
Describe the changes in volume and pressure inside the chest cavity during a normal,
quiet inhalation.
A. Explain why these changes are occurring, and the effect upon airflow.
(4 marks)
During inhalation, the diaphragm contracts and moves downwards, this leads to an
increase in space in the chest cavity and expansion of lungs. The muscles in between
the ribs also help the enlargement of chest cavity. They act by contracting and pulling
the rib cage upward and outward. During the inhalation process, the volumes of the
lungs expands leading to the diaphragm and intercostals muscles contraction, this
expands the thoracic cavity. As result of the increase in the volume levels the
pressure is decreased in the cavity.
Due to the resulting increase in volume, the pressure is reduced, according to boyles
Law, the decreased pressure in the thoracic cavity in relation to the environment
makes the overall cavity pressure to be less than atmospheric pressure. The pressure
gradient observed between the atmosphere and thoracic cavity leads to air rush to
the lungs, leading to inhalation process.
B. Is quiet inhalation an active process? Briefly explain your answer.
(1 mark)
Quiet inhalation is a process of breathing which occurs at rests and does not require
the overall cognitive thoughts of individual. During this process, the diaphragm and
the external intercostals contract, thus leading to an active state of breathing.
QUESTION 9
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