FIS2602 – EXAM NOTES
RESPIRATION AND EXCRETION
The brain’s respiratory center consists of two major pairs of nuclei located bilaterally in the T
Pons and Medulla Oblongata.
In the thick ascending loop of Henle, the movement of sodium across the luminal membrane T
is primarily mediated by a 1-sodium, 2-chloride, 1-potassium co-transporter
Erythropoietin regulates the production of red blood cells in the bone marrow. T
Flow is proportional to the pressure difference between two points and directly proportional F
to the resistance.
Each kidney contains approximately 1 million nephrons. T
The process by which the kidney synthesize glucose from amino acids and other precursors is F
called glycogenesis.
Boyles law states that there is a direct relationship between the pressure of a gas and the F
volume of its container in a closed system.
Cyanosis refers to the blueish skin induced by excessive amounts of deoxygenated T
hemoglobin in the skin in the capillaries.
The total compliance of both lungs in the normal adult human averages about 200 milliliters of T
air per centimeter of water transpulmonary pressure.
Medulla is the outer layer of the kidney. F
The outer zone of the medulla comprises the loop of Henle, collecting duct, and vasa recta. T
In a situation where the resistance is double the alveolar pressure, the bulk flow will also be
doubled.
An elevated carbon dioxide level shifts the oxygen dissociation curve to the left while its F
decrease shifts to the right.
A patient presented to the hospital with dizziness due to diuretics. Following clinical T
evaluation, it was found that he has fluid abnormalities, as demonstrated by a sodium level of
90 mEq/L. A fifth-year medical student was asked to give a diagnosis, and he concluded that
the patient is likely to suffer from hyponatremia.
Each human kidney has approximately 1 thousand nephrons F
Neurogenic dyspnea occurs when a person's state of mind is impaired despite having normal T
respiratory functioning
The right kidney is slightly lower than the left one. T
A 50-year-old man who took part in a study that evaluates the efficacy of a new therapeutic F
drug has serum creatinine of 2.5 mg/dL, urine creatinine of 90 mg/dL, and the urine output
volume per 2500 mL/day. Then his approximate GFR is 62.5 mL/min.
The elastic forces of the lung tissue are determined mainly by elastin and collagen fibers. T
The balance of hydrostatic and colloid osmotic forces acting across the capillary membrane T
determines the glomerular filtration rate.
Conducting airway zone Defends against microbes, toxic chemicals, and other foreign matter. T
A primary renal tubular site of aldosterone action is on the principal cells of the cortical T
collecting tubule
Hemoglobin is the fraction of the blood composed of red blood cells T
Flow is proportional to the pressure difference between two points and directly proportional F
to the resistance
Hyperventilation exists when there is an increase in the ratio of carbon dioxide production to F
alveolar ventilation
, The smallest compartment of body fluid s also known as transcellular fluid. T
Boyles law states that there is a direct relationship between the pressure of a gas and the F
volume of its container in a closed system.
Tubulo-glomerular feedback mechanism consists of efferent and afferent arteriolar systems F
that act together to control glomerular filtration rate.
The most important muscles that raise the rib cage are the sternocleidomastoid muscles. T
Pulmonary surfactant is secreted by type I alveolar cells. F
Principal cells reabsorb potassium and secrete sodium T
Most nephrons are located in the renal medulla. T
The thin segment of the descending loop of Henle is highly permeable to water. T
Physiological shunt occurs when the ventilation-perfusion ratio equals infinity. F
The respiratory center of the brain consists of two major pairs of nuclei located bilaterally in T
the Pons and Medulla oblongata.
Net diffusion of gas occurs from a low concentration area to a high concentration area. F
The total compliance of both lungs together in the normal adult human averages about 200 T
milliliters of air per centimeter of water transpulmonary pressure.
Question 2
2.1 Briefly discuss diabetes insipidus. (5)
Diabetes insipidus:
It is a disorder of salt and water metabolism.
It is marked with intense thirst and heavy urination.
Diabetes insipidus occurs when body can't regulate fluids.
This condition is caused by hormonal abnormality.
Diabetes insipidus is caused by problems with a hormone called vasopressin or anti diuretic hormone.
Anti-diuretic hormone is produced by specialized nerve cells in the hypothalamus.
Anti-diuretic hormone passes from the hypothalamus to the pituitary gland, where it's stored until needed.
This hormone helps to retain water in the body and produce concentrated urine.
In diabetes insipidus, lack of production of this hormone leads to increased excretion of water and produce less
concentrated urine also called polyuria.
This increased loss of water cause dehydration which leads to intense thirst also called polydipsia.
In rare cases, the kidney does not respond to AVP. This causes a specific form of diabetes insipidus called nephrogenic
diabetes insipidus.
Types of diabetes insipidus:
1.Nephrogenic
2.central
3.gestational
,4.dipsogenic.
2.2 Describe what happens during the spinal reflex component of micturition? (10)
Spinal reflex component of micturition:
• Micturition or urination is the process of emptying urine from the storage organ called urinary bladder.
• The act of micturition is an autonomic reflex at the level of spinal cord.
• The spinal reflex component helps to complete micturition when the act is voluntarily initiated.
• In this process, when the bladder is filled the afferent signals from the stretch and volume receptors are carried
to brain about the extent of filling, initiating several spinal reflexes.
• These serve to inhibit micturition until filling is complete while activating the voluntary external urethral
sphincter via the pudendal nerve.
• At the same time, detrusor activity is inhibited, and the internal urethral sphincter is stimulated via sympathetic
activity.
• Impulses from the filling bladder are carried to the spinal cord via the pelvic and hypogastric nerves, whereas
the pudendal and hypogastric nerves carry impulses from the neck of the bladder and the urethra.
• The pontine micturition center in the brain stem is activated via afferent signals from urinary bladder as it is
filling.
• This center sends inhibitory impulses to the spinal reflex arcs to enable bladder voiding.
Question 3
3.1. Discuss the control of respiration under the following headings:
a) The role of carbon dioxide. (2)
Carbon dioxide is used remove from lungs by process of expiration but before removal it is transported to bloodstream.
Where carbon di oxide converts into carbonic acid. It also helps in pH regulation of blood, regulation of respiratory drive,
acts as dilator fir smooth muscles. Its high level in blood stimulates respiration
b) The role of oxygen. (4)
Respiration is controlled by the presence of oxygen. The peripheral chemoreceptors respond to the changes in the
partial pressure of oxygen. These chemoreceptors are in the aortic bodies and the carotid bodies, and form parts of the
peripheral nervous system. When the partial pressure of oxygen falls, the receptors get stimulated. The chemoreceptors
have a negative-feedback system in regulating the levels of respiratory gases. When there is a massive decrease in the
oxygen partial pressure, the chemoreceptors activate the center for inspiration of air. This increases the rate and depth
of breathing (a situation called hyperventilation) which balances the levels of the different respiratory gases.
c) Voluntary control of respiration. (4)
The respiration process can be voluntarily controlled. This is a very advantageous process as it helps to prevent foreign
substances like water from entering the airways. This mechanism is possible because of the connection of the cerebral
cortex with the respiratory center. However, in case of an abnormal buildup of respiratory gases, the breathing process
continues involuntarily, to balance the gases in the body. This is because of the strong stimulation of the inspiratory
area, where impulses are sent through the phrenic and intercostal nerves to the respiratory muscles to resume the
, involuntary breathing process. The hypothalamus and limbic system stimulate the respiratory center to alter the
breathing rate according to the emotional state.
Question 4
Answer the following insight questions.
4.1. Two women (A and B) from a rural village in Limpopo went to the forest to fetch firewood, during the process
they lost each other. It was very hot, and they spend the whole day trying to look for each other without having food
or water. It is known that should a person spend a whole day without having water especially when it’s hot they
become dehydrated. With the aid of the diagram full discuss the mechanism that leads to dehydration and the impact
thereof on the urine output. (10)
Hormones are biomolecules that work by altering cellular mechanisms either by binding to a cell surface receptor or by
directly changing the expression of certain genes. Hormones can be amino acids, proteins, steroids etc.
4.2. Mr. A. is diagnosed with metabolic acidosis while Mr. B. is diagnosed with metabolic alkalosis. How would the
physiological characteristics, causes, and compensations differ in each of these patients? (10)
Metabolic acidosis:- Metabolic acidosis is a condition in which there is a high acid content in the body fluids.
Causes:-