Anatomy and Physiology: Inflammation, Immune System, Heart and Blood Pressure Regulation

This article covers topics related to anatomy and physiology, including inflammation, immune system, heart, and blood pressure regulation. It explains the four signs of inflammation, the first and second-line defenses of the immune system, and the role of T-cells. It also describes the flow of blood through the heart, the Renin-Angiotensin-Aldosterone System, and the negative feedback loop that regulates blood pressure.

1. Nathan is fixing a fence and scrapes his leg along a length of barbed wire. He manages to
stop the flow of blood by applying pressure and wraps his t-shirt around his leg while he
drives home from the paddock. At home, Nathan gives the wound a good clean but calls the
hospital for information and advice because he has noticed swelling and his leg is a bit sore.
a) Explain the four signs of inflammation and include the purpose (benefit) of each
response. In your answer, make it clear how pain serves a protective function (6 marks).
Inflammation is known as the response triggered as a result of damage cause to a living
tissue. There are commonly four signs associated with inflammation which involves the
following:
Pain: It results from inflammatory chemicals which attempts to stimulate nerve endings
and accordingly causes affected areas to feel more sensitive. Pain can arise in both
muscles and joints and in the event of chronic inflammation, a person feels high level of
stiffness and pain sensitivity making the area sensitive to touch. A severe injury causes
higher pain as compared to less severe injury and accordingly, pain serves as a protective
function. A person usually behaves in certain manner after sensing a noxious stimulus to
minimize injury, thus promote healing for the injury.
Heat: With the flow of more blood to the inflamed areas of the body, that part of the
body became warm. People affected with arthritic condition have inflamed joints which
results in that area becoming warm to touch. In the event of whole body inflammation, a
person feels fever as a result of infection or illness. This is helpful in avoiding big injury or
infection.
Redness: The purpose of the inflamed area becoming red is the blood vessel getting filled
with more blood than usual which triggers the need for treatment.
Swelling: It takes place as a result of fluid accumulating in tissues which may be only
restricted to the affected area or may be affecting the entire body.
b) Name and briefly discuss the first and second-line defenses in place to resist pathogens
entering the body and to stop the spread of the pathogen and potential infection. Name
two phagocytic cells and outline the importance of phagocytosis during the inflammatory
process (5 marks).
The first line of defense in place are the surface barriers. Mucus, tears and skin are the
surface barriers that fight against the infection and thus protects from invading
pathogens. There are beneficial bacteria grown over the human skin, bowel and other
parts of the body like mouth & gut that prevents harmful bacteria to take over. The
second line of defense are the non-specific phagocytes as well as other mechanism lying
internally which are having innate immunity that prevents the entry of pathogens into the
body. They destroy invaders in general manner and not target specific individual.
The name of two phagocytic cells are macrophages and neutrophils. Phagocytosis is
regarded as complex process where cells in most of the organ systems eliminate cell

debris and pathogens. This process is followed by inflammatory pathway activation which
in turn promotes elimination of pathogens as well as inhibits growth in it.
c) The adaptive (specific) immune system is activated when innate defenses are
unsuccessful in capturing and destroying a pathogen, such as bacteria or virus. Briefly
describe the role T-cells have in protecting the body against substances that infect body
cells (3 marks).
Human body is highly exposed to pathogens like viruses, bacteria & fungi. In the absence
of T cells such exposure is life threatening because these cells are helpful wiping out the
cancerous or infected cells. T cells are a part of immune system and plays the role of
coordination and focuses on particular foreign particles. Instead of attacking any antigens
generically, T cells keep in circulation till encountering their specific antigen.
d) Which steps are involved in haemostasis? Briefly describe the importance of the second
step of haemostasis (3 marks).
There are four steps involved in the mechanism of haemostasis which are as follows:
1. Blood vessel constriction
2. Temporary platelet plug formation
3. Coagulation cascade activation
4. Final clot formation.
The second step involve formation of temporary platelet plug which is important in
preventing blood loss with the accumulation of platelets around a breakage. Therefore,
more loss of blood from the body can be prevented alongside preventing any
contaminants from the outside getting into the body.

2. You are working in a hospital where you see numerous patients with respiratory illnesses
every day. Patients who have chronic obstructions in their airways run the risk of retaining
carbon dioxide in the body because they cannot exhale it properly from their lungs. A
healthy respiratory system helps regulate carbon dioxide levels in the body as part of the
acid-base balance. The kidneys also regulate acid base balance in the body and help
maintain stable plasma pH levels.
a) What effect does an increase in plasma carbon dioxide levels have on hydrogen ion
concentration? Does this result in an increase or decrease of plasma pH? (2 marks).
Respiratory acidosis takes place with the occurrence of CO2 not getting out with
breathing which results in overly acidic blood and thus respiratory problem like COPD
arise. With the rise in CO2, the concentration of hydrogen ion in the bloodstream rises
alongside lowering the ph level which in turn sets the state of acidosis. On the other hand,
with the lowering of CO2, the concentration of hydrogen ion in the bloodstream falls
resulting in alkalotic state.
b) What role do the kidneys play in maintaining the acid base balance in the body? (2
marks).
The role of kidney in maintaining the acid base balance in the human is quite major which
involves reabsorption of bicarbonate filtered by the glomeruli along with excreting the
titratable acids & ammonia through the urination process. Therefore, two roles does the
kidney play in maintaining the acid base balance that is, excretion of hydrogen ion into
the urine and reabsorbing bicarbonate from the urine.
c) Explain in detail the respiratory negative feedback loop activated when an increased level
of carbon dioxide is detected in the bloodstream. Include in your answer the names of the
general components of a negative feedback loop and identify by name the specific parts of
the body involved in regulating carbon dioxide levels. Make it clear how a change in
ventilation rectifies the imbalance and what makes the whole process an example of
homeostasis (8 marks).
On detecting the rise in carbon dioxide in the bloodstream, the lungs are signaled
resulting in rise in its activity & exhaling more carbon dioxide which is experience by a
person with the increase in breathing rate. The body respond to the rise in carbon dioxide
through hyperventilation or hypoventilation. A negative feedback loop facilitates self
regulation of the human body like regulation of O2 and CO2 levels in the blood in an
attempt to make sure that sufficient O2 is delivered for meeting the needs of cells for
cellular respiration as well as sufficient amount of CO2 has been removed from the body
for the prevention of harmful effects.
There are four basic components of the negative feedback loop which involves stimulus,
control, censor and effector.
Specific parts of the body involved in regulating carbon dioxide levels are airways, blood

vessels and lungs which works together for moving or cleaning out unwanted gases like
CO2 from the body. Also, the brain performs the function of regulating the amount of
carbon dioxide during exhalation by controlling the depth & speed of breathing known as
ventilation.
With the change in ventilation (speed or depth of breathing) that is, the breathing rate
increases results in the reduction of the amount of CO2 in the blood leading to rise in
blood ph and then comes to normal level. In case of blood ph becoming too alkaline, the
rate of breathing decreases leading to rise in carbon dioxide in the blood. Therefore, the
increase or decrease in breathing rate (ventilation) is helpful in balancing the levels of
CO2 and O2 in the blood and acts as an example of homeostasis which is the process
through which body reacts to the changes for keeping the condition inside the body in
order.

3. You have a young woman on your ward who is awaiting heart surgery. She is keen to
know about the structure and function of the heart and asks you to explain the flow of
blood through the heart from start to finish. She wants to hear anatomical names and learn
about physiological processes ejecting blood from her heart, your response will help keep
her distracted from thinking about her upcoming operation.
a) In your own words, describe the flow of blood through the heart, naming each of the
vessels bringing and taking blood to and from the heart. Include chambers of the heart and
name structures in the correct sequence along the blood’s pathway through the heart –
begin with blood returning to the heart from the body and end with blood being ejected
into the systemic circulation (6 marks). Include the names of the valves and identify which
valves are open and closed during each cardiac cycle. Describe, using terms like diastole and
systole, the changes in ventricular pressure during one cardiac cycle and clearly identify
what causes the heart sounds lub dub (6 marks; 12 marks in total for Question 3).
Bloods are carry all over the body through blood vessels. Oxygen poor blood across the
body enters the right atrium through two large veins that is, inferior vena cava and
superior vena cava. This results in the opening of the tricuspid valve to let the blood travel
from right atrium to right ventricle and the latter on becoming full gets squeezes which
also closes tricuspid valve and opens the pulmonary valve. This led the blood flowing from
the pulmonary artery to the lungs to get the oxygen. Post this, the oxygen rich blood
travels from the lungs towards the left atrium with the help of large veins known as
pulmonary veins. This led the opening of the mitral valve which plays the role of sending
the blood from left atrium to left ventricle and on the latter becoming full gets squeezes
leading to closing of mitral valve and opening of aortic valve. Accordingly, heart sends
blood through aortic valve to aorta which in turn flows to the rest of the body.
The cause of heart sounding like lub is due to closing of mitral and tricuspid valve while
the next sound dub happens when the pulmonary & aortic valve closes with blood
squeezing out of the heart.

4. There are two ways blood pressure is regulated in the body – the nervous system (short-
term control) and hormonal regulation (long-term control).
The nervous system works with the cardiovascular system to bring about rapid changes in
blood pressure. However, for long term control of blood pressure, the kidneys are involved
in maintaining adequate blood volume in the body whilst keeping fluid composition
balanced.
a) Discuss the negative feedback pathway known as the Renin-Angiotensin-Aldosterone
System (RAAS) which helps regulate systemic blood pressure. Include all of the events that
occur from the detection of the stimulus through to the overall response. Clearly identify
the parts of the body involved and explain the actions of the hormones at their target
tissues (6 marks).
Renin-Angiotensin-Aldosterone System (RAAS) is a multi-organ complex endocrine
(hormone) system involved in the regulation of blood pressure by balancing fluid and
electrolyte levels, also regulating vascular resistance and tone. RAAS helps in regulating
sodium and water absorption in the kidney thus directly impacting the systemic blood
pressure.
RAAS becomes active when the blood pressure drops to increase the reabsorption of
water and electrolytes in the kidney; compensating for the drop in the volume of blood
hence increasing blood pressure.
Renin
In the kidney juxtaglomerular cells are abundant in prorenin (an inactive precursor
protein) secreted constantly. Drop in blood pressure activates juxtaglomerular cells,
causing the prorenin to cleave into its active form-renin, which is then secreted into the
bloodstream.
Angiotensin
Renin acts on angiotensin (produced by liver continuously) to cleave a 10 amino acid
peptide from the N-terminus to form angiotensin I. angiotensin-converting-enzyme (ACE)
further cleaves angiotensin I to form angiotensin II – the primary active peptide of RAAS.
ACE is found primarily in vascular endothelia of the lungs and kidneys.
Angiotensin II binds to angiotensin type I as well as type II receptors. Angiotensin is a
potent vasoconstrictor, causing increased blood pressure. Normally, during very high
blood pressure, atrial natriuretic peptide – secreted by cardiac muscle cells – leads to
decrease in blood volume, leading to decreased blood pressure.
The binding of angiotensin II to AT1R can cause a cascade of inflammation, constriction
and the promotion of atherosclerosis. Furthermore, these events can also cause insulin
resistance and thrombosis, whereas the binding to AT2R has opposite effects: vasodilation
reduced platelet aggregation and insulin activity.
Angiotensin II also acts on the brain where it can bind to the hypothalamus to stimulate
thirst to increase water intake. By acting on the pituitary gland, secretion of vasopressin is
also stimulated by angiotensin II. Vasopressin is also known as antidiuretic hormone,

which increases water retention in the body by adding water channels (aquaporin) to the
collecting duct.
Aldosterone
Angiotensin II stimulates the secretion of aldosterone produced by the zona glomerulosa
of the adrenal cortex (adrenal gland) and is involved in the retention of sodium in the
kidney and other glands. The retention of water and sodium increases blood volume and
thus blood pressure.
Please answer the following questions in relation to blood pressure and cardiac output.
You leap into action when an alarm sounds from a room down the hall on the cardiac ward.
Once the patient emergency has subsided, you think back to your days as a student nurse
and remember fondly when you learned about cardiac output equaling heart rate multiplied
by stroke volume (CO = HR x SV).
b) Standing rapidly from a seated position will elicit which neural response in relation to
blood pressure? (1 mark).
The baroreceptor reflex is the neural response that acts upon this scenario. This is an
autonomic response that serves to keep blood pressure steady in the near term, especially
in response to posture changes, such mounting up from a sitting or lying down position,
when gravity might cause blood pressure to drop.
c) What is venous return? How does an increase in venous return affect stroke volume?
What effect does this have on cardiac output? Explain the mechanism clearly and how the
change in cardiac output can influence blood pressure (6 marks).
The term "venous return" describes the blood flow from the periphery back to the right
atrium, and it is always equal to cardiac output, save for brief intervals. Mechanisms
controlling the flow of blood to the heart are important because doctors and researchers
have long noticed that variables predominantly influencing the venous side of the
circulatory can have a significant impact on cardiac output. Increased cardiac output,
peripheral vascular resistance, blood volume, blood viscosity, and vessel wall stiffness all
contribute to a rise in blood pressure. Reduced cardiac output, peripheral vascular
resistance, blood volume, blood viscosity, and vessel wall flexibility all lower blood
pressure. Increased filling of the left ventricle from increased pulmonary venous return to
the left atrium results in an increase in left ventricular stroke volume.

5. A young man named Clyde accompanies his girlfriend, Josie, to the emergency
department. She has a deep laceration on her right arm and has lost a lot of blood. She is
pale, cool and clammy to the touch. You think she may need a blood transfusion if the
intravenous fluids do not restore her blood volume promptly and adequately. Clyde is
adamant you take his blood and give it to Josie; he would do anything to save her. You will
need to explain to him whether his blood type (AB) is a match for her blood type (O).
a) What will you tell Clyde? Be specific with your explanation why he can or cannot donate
his blood to Josie (3 marks).
Clyde cannot donate blood to Josie due to the different blood types that are incompatible with
each other. Blood type of Clyde is AB which neither have A nor B antibody in the plasma whereas
the blood type O is possess the antibody of both A and B. This lack of similarity provides a rationale
behind the inability of the blood transfer. Serious transfusion issues can be caused in the boy of the
recipient if incompatible blood is transferred.
b) Describe the role B-cells have during an immune response when an incompatible blood
type is donated (3 marks).
B cells are produced by stem cells in the bone marrow and are a component of the
immune system. As well-known as B lymphocyte. Enlarge. Blood cell formation. To develop
into a red blood cell, platelet, or white blood cell, a blood stem cell must go through a
number of stages. The immune system will already be equipped with primed B cells
(memory cells), which speed up the synthesis of more IgG. (rather than IgM). The
secondary immunological response is what is meant by this. It is quicker and more
targeted, and production of the targeted antibody may continue to be high for years. To
further enhance how well the antibodies they generate attach to the antigen, B cells may
also experience modifications.
c) Which blood type is considered the universal recipient? Briefly explain why (2 marks).
People with the AB blood type are regarded as universal donors since they may receive
blood from all blood types because they do not have any antibodies. A person with AB type
blood can receive any kind of blood without running the risk of complications since AB type
blood does not have any antibodies against type A or type B blood.
d) Considering the blood loss Josie is experiencing, will vasopressin (AKA anti-diuretic
hormone) be released in this situation? Briefly explain your response (2 marks).
The left atrium and carotid sinus stretch, vasopressin secretion, and water excretion all
rise, helping to return blood volume to normal. So yes, ADH will be released.

6. Robert is a diabetic. He has been told he may end up needing to inject insulin every day if
his plasma glucose levels are not managed correctly. Robert’s family is having trouble
understanding the new diagnosis and have questions about how plasma glucose levels are
regulated in the body normally.
a) In a healthy body, what stimulus causes the release of insulin? What is the role of insulin
in the body? Where are the target cells for insulin? Name and explain one cellular activity
promoted under the influence of insulin (6 marks).
HIGH blood glucose level triggers the release of insulin. Although the pancreas constantly
secretes a little quantity of insulin into the blood, this amount grows when blood glucose
levels rise. Liver muscle and adipose tissues are the targeted cells of insulin. Insulin inhibits
lipolysis and gluconeogenesis from muscle amino acids while promoting glycogen and lipid
synthesis in muscle cells. In muscles when there is a sufficient supply of amino acids, insulin
is anabolic.
b) Which hormone is released in the fasted state? Where is this hormone released from, be
specific? What are the target cells for this hormone? Briefly explain one cellular response
occurring in the target cells during the fasted state and relate the response to the
homeostatic regulation of plasma glucose (4 marks).
During a fast, the pancreas secretes more glucagon when blood glucose levels drop.
Additionally, this action lowers insulin production, which lowers the amount of glucose
stored as glycogen. Insulin affects the liver, muscles, and adipose tissue. 4. During a fast,
glucagon controls how stored nutrients are transported into the circulation. The primary
physiological target of glucagon is the liver. Ketones play a crucial function in prolonged
hunger by taking the place of glucose as the brain's main fuel source and indicating a
decrease in protein catabolism and muscle alanine production. Both glucose homeostasis
and protein conservation are accomplished.
c) In a healthy person, is glucose present in the urine? Very briefly explain your answer (2
marks).
Generally, no glucose is found in the urine of a healthy person. However, there are some
exceptions to it where the glucose is present in the urine but that too in very low level.
d) In terms of absorbing nutrients, such as glucose, where does the absorption of glucose
occur within the gastrointestinal tract (GIT)? What are the cells called that absorb nutrients
in this location of the GIT? Where are brush border enzymes located and how do they
contribute to the absorption of nutrients? (4 marks).

The absorption of glucose in the gastrointestinal tract (GIT) while passing through this
passage by the absorptive cells (Villi). This process takes place in two steps. Firstly, sodium
ions from inside the cells are transported to the interstitial fluid which then lowers the
sodium concentration inside the membrane. Further, sodium ions are transferred from the
intestinal lumen with diffusion to the cells. In this instance, the transport protein serves a
helpful purpose. It transports sodium-glucose ions. This protein pulls glucose into the cell
along with sodium ions from the lumen.
Enzymes for this last stage of digestion are anchored into the apical plasma membrane of
the microvilli that make up the brush border as integral membrane proteins.