Assignment Code: MFN-001/AST-1/TMA-1/22-23

Course Code: MFN-001

Assignment Name: Applied Physiology

Year: 2022-2023

Verification Status: Verified by Professor

Section A -Descriptive Questions(80marks)

There are eight questions in this part. Answer all questions.

1. a) What is a cell? Briefly explain the eukaryotic cell and its organization. (6)

Ans) Cell: The smallest functional unit found in all biological things is called a cell. As with monads, cells can function as autonomous life units. They can also form colonies or tissues, as in higher plants and animals. The cell membrane is the outer membrane or wall that encloses each individual cell. On the surface of each cell are receptors with distinct roles and identifying characteristics. It also has other components, including DNA, that are necessary for it to function as a living being. The cytoplasm and nucleus are parts of the cell. DNA is the genetic substance found in the nucleus. Organelles that perform the tasks required by the cell are found in the cytoplasm.

Eukaryotic cells : Eukaryotic cells are characterised by their structured nucleus and organelles that are encased in membranes. Animals, fungi, protists, and plants are eukaryotic cells examples. They have chromosomes, which organise their genetic material. Eukaryotic cells have the Golgi apparatus, mitochondria, ribosomes, and nucleus. Eukaryotic cells are organised as follows:

Plasma Membrane

1. The plasma membrane separates the cell from the outside environment.

2. It comprises specific embedded proteins, which help in the exchange of substances in and out of the cell.

Cell Wall

1. A cell wall is a rigid structure present outside the plant cell. It is, however, absent in animal cells.

2. It provides shape to the cell and helps in cell-to-cell interaction.

3. It is a protective layer that protects the cell from any injury or pathogen attacks.

4. It is composed of cellulose, hemicellulose, pectins, proteins, etc.

Cytoskeleton

1. The cytoskeleton is present inside the cytoplasm, which consists of microfilaments, microtubules, and fibres to provide perfect shape to the cell, anchor the organelles, and stimulate the cell movement.

Endoplasmic Reticulum

1.  It is a network of small, tubular structures that divides the cell surface into two parts: luminal and extraluminal.  Endoplasmic Reticulum is of two types:

   
   

a) Rough Endoplasmic Reticulum contains ribosomes.

b) Smooth Endoplasmic Reticulum that lacks ribosomes and is therefore smooth.

Nucleus

1. The nucleoplasm enclosed within the nucleus contains DNA and proteins.

2. The nuclear envelop consists of two layers- the outer membrane and the inner membrane. Both the membranes are permeable to ions, molecules, and RNA material.

3. Ribosome production also takes place inside the nucleus.

Golgi Apparatus

1. It is made up of flat disc-shaped structures called cisternae.

2. It is absent in red blood cells of humans and sieve cells of plants.

3. They are arranged parallel and concentrically near the nucleus.

4. It is an important site for the formation of glycoproteins and glycolipids.

Ribosomes

1. These are the main site for protein synthesis and are composed of proteins and ribonucleic acids.

Mitochondria

1. These are also known as “powerhouse of cells” because they produce energy.

2. It consists of an outer membrane and an inner membrane. The inner membrane is divided into folds called cristae.

3. They help in the regulation of cell metabolism.

Lysosomes

1. They are known as “suicidal bags” because they possess hydrolytic enzymes to digest protein, lipids, carbohydrates, and nucleic acids.

Plastids

1. These are double-membraned structures and are found only in plant cells. These are of three types:

   
   

a) Chloroplast that contains chlorophyll and is involved in photosynthesis.

b) Chromoplast that contains a pigment called carotene that provides the plants yellow, red, or orange colours.

c) Leucoplasts that are colourless and store oil, fats, carbohydrates, or proteins.

b) Define Ageing. Elaborate different theories of ageing. (1+3)

Ans) The reduced capacity to maintain homeostasis in the face of difficulties or shocks from the outside or the inside is referred to as ageing physically. As a result, the person becomes more susceptible to these changes and pressures and eventually passes away. The pace of functional decline in different body components is not parallel nor does it follow a perpendicular pattern. Therefore, the ageing process denotes a gradual decline in cells, tissues, and organs as well as their functionality with advancing age.

Theories of Ageing

Natural influences could potentially have an impact on ageing, which is essentially a genetically determined process. Among the numerous theories regarding ageing are:

1. Error catastrophe theory: The insertion of incorrect amino acids causes a random rise in protein synthesis errors as cells age. They stop working as a result. Cell signalling fails as a result.

2. The somatic mutation theory. Cells that randomly mutate become ineffective. An organ's functionality is hampered by an increase in the proportion of inefficient cells. Chromosome abnormality may result from random mutation. This is detrimental.

3. Free-radical theory: The body is put in a difficult situation. O2 is necessary for living, but oxidative reactions can also release a large number of highly reactive, damaged electrons. These could cause oxidative damage to important macromolecules including DNA, proteins, etc.

4. Genetic theory: Different species age at different rates. The species' genetic modifications account for the distinction. Thus, it can be claimed that a function's gradual degradation is genetically predetermined. Progeria (ageing by the age of 10) results from a genetic programming error.

2. a) What are salivary glands? Briefly explain composition and functions of saliva. (5)

Ans) The salivary glands are organs on each side of the face. They make saliva (spit), the lubricating fluid found in the mouth and throat. Saliva has enzymes that begin the process of digesting (breaking down) food. It also has antibodies and other substances that help prevent infections of the mouth and throat.

Composition of Saliva

Saliva is combined secretion from the salivary glands and the small mucus secreting glands of the lining of the oral cavity. It is slightly cloudy due to the presence of cells and mucin. Usually it is slightly acidity (pH 6.02-7.05). It consist of 99.5% of water and 0.5% of solid. Of the solid 0.2% is inorganic salts and 0.3% is organic constituents.

Functions of Saliva

Saliva contributes to the digestion of food and to the maintenance of oral hygiene. Without normal salivary function the frequency of dental caries, gum disease (gingivitis and periodontitis), and other oral problems increases significantly.[citation needed] Saliva limits the growth of bacterial pathogens and is a major factor in sustaining systemic and oral health through the prevention of tooth decay and the removal of sugars and other food sources for microbes.[10]

Lubricant: Saliva coats the oral mucosa mechanically protecting it from trauma during eating, swallowing, and speaking. Mouth soreness is very common in people with reduced saliva (xerostomia) and food (especially dry food) sticks to the inside of the mouth.

Digestion: The digestive functions of saliva include moistening food and helping to create a food bolus. The lubricative function of saliva allows the food bolus to be passed easily from the mouth into the oesophagus. Saliva contains the enzyme amylase, also called ptyalin, which is capable of breaking down starch into simpler sugars such as maltose and dextrin that can be further broken down in the small intestine.

Role in taste: Saliva is very important in the sense of taste. It is the liquid medium in which chemicals are carried to taste receptor cells. People with little saliva often complain of dysgeusia. A rare condition identified to affect taste is that of 'Saliva Hypernatrium', or excessive amounts of sodium in saliva that is not caused by any other condition, causing everything to taste 'salty'.

Other: Saliva maintains the pH of the mouth. Saliva is supersaturated with various ions. Certain salivary proteins prevent precipitation, which would form salts. These ions act as a buffer, keeping the acidity of the mouth within a certain range, typically pH 6.2–7.4. This prevents minerals in the dental hard tissues from dissolving.

b) What are neural mechanisms which control respiration? Elaborate them briefly. (5)

Ans) The medulla and the pons are involved in the regulation of the ventilatory pattern of respiration. Involuntary respiration is any form of respiratory control that is not under direct, conscious control. Breathing is required to sustain life, so involuntary respiration allows it to happen when voluntary respiration is not possible, such as during sleep. Involuntary respiration also has metabolic functions that work even when a person is conscious.

The Respiratory Centers

Involuntary respiration is controlled by the respiratory centers of the upper brainstem (sometimes termed the lower brain, along with the cerebellum). This region of the brain controls many involuntary and metabolic functions besides the respiratory system, including certain aspects of cardiovascular function and involuntary muscle movements (in the cerebellum).

The Medulla

The medulla oblongata is the primary respiratory control center. Its main function is to send signals to the muscles that control respiration to cause breathing to occur.  The medulla also controls the reflexes for nonrespiratory air movements, such as coughing and sneezing reflexes, as well as other reflexes, like swallowing and vomiting.

The Pons

The pons is the other respiratory center and is located underneath the medulla. Its main function is to control the rate or speed of involuntary respiration. It has two main functional regions that perform this role: The apneustic center sends signals for inspiration for long and deep breaths. It controls the intensity of breathing and is inhibited by the stretch receptors of the pulmonary muscles at maximum depth of inspiration, or by signals from the pnuemotaxic center. It increases tidal volume. The pnuemotaxic center sends signals to inhibit inspiration that allows it to finely control the respiratory rate. Its signals limit the activity of the phrenic nerve and inhibits the signals of the apneustic center. It decreases tidal volume.

3. a) Briefly explain phases of cardiac cycle with diagram. (6)

Ans) As previously mentioned, a spontaneous action potential in the sinus node initiates the cardiac cycle's events. The atria and ventricles both experience a sequence of reactions to this stimuli. There are two stages to how these events are "organised":

1. Diastole (when the heart fills with blood)

2. Systole (when the heart pumps the blood)

During these two phases, many different events are observed and we will describe them in the following paragraphs.

Atrial diastole

Atrial diastole is the very first event of the cardiac cycle. It occurs some milliseconds before the electrical signal from the SA node arrives at the atria. The atria function as conduits that facilitate the passage of blood into the ipsilateral ventricle. They also act as primers to pump residual blood into the ventricles. During atrial diastole, blood enters the right atrium through the superior and inferior vena cava and the left atrium via the pulmonary veins. In the early part of this phase, the atrioventricular valves are closed and blood pools in the atria.

There comes a point when the pressure in the atrium is greater than the pressure in the ventricle of the same side. This pressure difference results in the opening of the atrioventricular valves, allowing blood to flow into the ventricle.

Atrial systole

The autonomous sinuatrial node initiates an action potential that is propagated throughout the atrial myocardium. The electrical depolarization results in simultaneous contraction of the atria, thus forcing any residual blood from the upper chambers into the lower chambers of the heart. The atrial contraction causes a further increase in atrial pressures.

Ventricular diastole

During the early stages of ventricular diastole, both the atrioventricular and semilunar valves are closed. During this phase, there is no change in the amount of blood in the ventricle, but there is a precipitous fall in the intraventricular pressure. This is known as isovolumetric relaxation.

Eventually, the ventricular pressure becomes less than the atrial pressure, and the atrioventricular valves open. This results in filling of the ventricles with blood, which is often referred to as the rapid filling of the ventricles. It accounts for most of the blood that is in the ventricle before it contracts. A small volume of blood flows directly into the ventricles from the venae cavae. Towards the end of ventricular diastole, any residual blood in the atria is pumped into the ventricle. The total volume of blood present in the ventricle at the end of diastole is called the end-diastolic volume or preload.

Ventricular systole

Ventricular systole refers to the period of contraction of the ventricles. The electrical impulse arrives at the atrioventricular node (AV node) shortly after the atria are depolarized. There is a small delay at the AV node, which allows the atria to complete contracting before the ventricles are depolarized. The action potential passes to the AV node, down the bundle of His, and subsequently to the left and right bundle branches (conductive fibers that travel through the interventricular septum and branches to supply the ventricles). These fibers carry the electrical impulses through their respective ventricular territories, leading to ventricular contraction.

As the ventricle begins to contract, the pressure exceeds that of the corresponding atrium, resulting in the closure of the atrioventricular valves. At the same time, the pressure is not sufficient to open the semilunar valves. Therefore, the ventricles are in a state of isovolumetric contraction – as there is no change in the overall volume (end-diastolic volume) in the ventricle.

As the ventricular pressure exceeds the pressure in the outflow tract, the semilunar valves open, allowing blood to leave the ventricle. This is the ejection phase of the cardiac cycle. The amount of blood left in the ventricle at the end of systole is known as the end-systolic volume (afterload, between 40 – 50 ml of blood). The amount of blood actually ejected from the ventricle is known as the stroke volume output. The ratio of the stroke volume output to the end-diastolic volume is called the ejection fraction and usually amounts to around 60%.

b) What do you understand by WBCs? Write about their different types in brief. (4)

Ans) Due to their lack of colour, WBCs are also known as leukocytes. They are the human body's army. The WBCs stand to attention and eliminate the invader once a pathogen or infection enters our body. Their main job is to either immediately eliminate the invasive germs or create antibodies (humoral immunity) (cytotoxic immunity).

Granulocytes and agranulocytes are the two types of WBCs that are distinguished by the presence or absence of granules in the cytoplasm.

Granulocytes

Granulocytes are white blood cells that have small granules containing proteins. There are three types of granulocyte cells:

1. Basophils: These represent less than 1%Trusted Source of white blood cells in the body and are typically present in increased numbers after an allergic reaction.

2. Eosinophils: These are responsible for responding to infections that parasites cause. They also play a role in the general immune response, as well as the inflammatory response, in the body.

3. Neutrophils: These represent the majorityTrusted Source of white blood cells in the body. They act as scavengers, helping surround and destroy bacteria and fungi that may be present in the body

Agranulocytes

These are the type of white blood cells without the granules. They have only one lobe and are known as mononuclear leukocytes due to the presence of just one nucleus. They constitute about 35% of the total white blood cells present in the body.

1. Lymphocytes: These are one of the most important types of white blood cells. They provide stability to the human body and prevent it from serious infections.

2. Monocytes: These are present in large numbers and possess an amoeboid shape.

3. Macrophages: These aid in the process of digestion of cellular debris and pathogens. They are uninuclear with lesser lobes.

4. a) Explain how external defence mechanism protects our body from different types of infections. (5)

Ans) Physical and chemical barriers to the entry of infections make up the external defence system.

Physical barriers

Skin: It offers the body a lovely protective covering. Dead keratinized cells can be found in the horny layer, which is the outermost layer. Instead of soft protoplasm, these cells contain hard, insoluble fibrous proteins known as keratin. This layer is both microbial and water resistant. It can stop the spread of bacteria and viruses.

Mucous membranes: The respiratory, vaginal, urinary, and digestive tracts have openings at either one or both ends. They are not in direct contact with any other body parts. The parasites and other bacteria are outside of the body's physiological interior. These tracts' mucous membranes are addressed as an element of their exterior defence.

Chemical barriers

Skin secretions: The sebaceous and soporiferous glands secrete oil and perspiration that is rich in fatty and lactic acids, which causes the skin's surface to become acidic (pH 3-5). These shield the skin against bacterial infection.

Saliva: Microorganisms that are not typical occupants can be found in saliva. Saliva passively flushes dead microorganisms, which are then ingested.

Gut secretions: Bacteria enter the gut from the respiratory tract and saliva, where the hydrochloric acid and proteolytic enzymes of the gastric secretions destroy them. They have the ability to eradicate the microorganisms.

Bile: It is an alkaline liver secretion that inhibits the development of alien microbes on partially digested meals.

Nasal secretions: These have lysosomal functions that can kill dangerous organisms.

Cerumen (wax of ear): Bacteria are captured and killed by it. It has a powerful antibacterial element.

Vaginal bacteria: The vagina generally hosts certain germs. Lactic acid, which they create, decimates the bacteria. This means that a female's best natural defence against diseases is provided by these microorganisms.

b) Write about composition and functions of Gastric Juice and intestinal juice. (5)

b) Following are the composition of gastric juice: The amount of gastric juice secreted while at rest ranges between 10 and 15 ml. Each meal results in an increase in the amount of secretion. The daily secretion ranges from 1500 to 2000 ml. It has a pH of 2.3, which is quite acidic. It has a specific gravity between 1.02 and 1.04. 99.45 percent of the liquid in gastric juice is water, while 0.55 percent is solid. Organic components make up 0.4 percent of the solids, whereas inorganic components make up 0.15 percent of the total gastric juice.

Functions of Gastric Juice

1. The water in the gastric juice further liquefies the food that has been swallowed. The hydrochloric acid turns the stomach's contents acidic and stops salivary amylase from working (ptyalin). Hydrochloric acid converts pepsinogen into active pepsin.

2. The chemical digestion of proteins is started by pepsin. Proteins are changed into peptones by it. Milk is curdled by the newborn enzyme rennin, which turns the soluble caseinogen into the insoluble casein. Pepsin transforms this casein into peptones.

3. Certain germs that are detrimental to human health are prevented from passing through the gastric juice due to the hydrochloric acid inside.

4. The intrinsic factor, which is required for the absorption of vitamin B12, is present in gastric juice. Food-based vitamin B12 mixes with a gastric juice intrinsic factor.

5. Glands in the stomach secrete a lot of mucus. Mucin provides a layer of protection over the gastric mucosa in addition to lubricating the food bolus.

6. Through the stomach juice, some poisons, heavy metals like lead, and certain alkaloids are expelled.

Composition of intestinal juice as follows: Succus entericus is another name for gastrointestinal juice. Juice-related words include succus and entericus. The digestion of protein, fat, and carbohydrates is finished by the digestive juice. Glands located between intestinal villi secrete it.

1. About 1-2 litres of intestinal juice are produced daily overall. It reacts in an alkaline manner (pH 8.0). Water makes up 98.5 percent of the intestinal juice whereas solids make up 1.5 percent of it. There are inorganic components among the solids.

2. organic substances: The proteolytlc enzyme, as well as other enzymes that can divide fats and carbohydrates, are among the juice's organic components.

Functions of intestinal juice:

1. Succus entericus enzymes aid in the digestion of the proteins, lipids, and carbohydrates found in our meals.

2. The succus entericus shields the intestinal epithelium from acid chyme and bile's corrosive effects.

3. When succus entericus is present, the small intestine absorbs nutrients.

4. Water balance control: The body's digestive juice secretion controls water balance.

5. a) Give the functions of following hormones: (6)

(i)Gastrin

Ans)

(ii)ADH

Ans) The anti-diuretic hormone is involved in the:

1. Regulation of the circadian rhythm.

2. It is mainly responsible for homeostasis.

3. Maintains the proper cellular functions.

4. ADH actively monitors the volume of water in the body and controls it.

5. It acts on the kidneys and the blood vessels and functions to control the blood pressure.

6. It allows the water in the urine to be taken back in a specific area in the kidney and thus, reduces the amount of water excreted through the urine thereby conserving the volume of the fluid in the body.

(iii) Insulin

Ans) Functions of the insulin are as follows:

1. Main function of the insulin is regulation of glucose.

2. Modifying the activity of enzymes and the resulting reactions in the body.

3. Building muscle following sickness or injury via the transportation of amino acids to the muscle tissue, which is required to repair muscular damage and increase size and strength. It helps to regulate the uptake of amino acids, DNA replication, and the synthesis of proteins.

4. Managing the synthesis of lipids by uptake into fat cells, which are converted to triglycerides.

5. Managing breakdown of protein and lipids due to changes in fat cells.

6. Uptake of amino acids and potassium into the cells that cannot take place in the absence of insulin.

7. Managing the excretion of sodium and fluid volume in the urine.

8. Enhancing the memory and learning capabilities of the brain.

(iv) Parathormone

Ans) Your parathyroid gland releases parathyroid hormone (PTH) when your body detects low calcium levels in your blood. Parathyroid hormone regulates calcium levels in your blood by affecting the following parts of your body:

1. Bones: Parathyroid hormone stimulates the release of small amounts of calcium from your bones into your bloodstream.

2. Kidneys: Parathyroid hormone enables the production of active vitamin D (calcitriol) in your kidneys. PTH also signals your kidneys to retain calcium in your body rather than flushing it out through your urine.

3. Small intestine: Parathyroid hormone signals your small intestine to absorb more calcium from the food you eat.

Once your parathyroid glands release PTH when you have low blood calcium levels, the PTH is only active in your body for a few minutes. When your blood calcium levels rise, your parathyroid glands stop releasing PTH.

b) Explain types and functions of cranial nerves. (4)

Ans) Types of cranial nerves as follows:

1. Olfactory nerve: Sense of smell.

2. Optic nerve: Ability to see.

3. Oculomotor nerve: Ability to move and blink your eyes.

4. Trochlear nerve: Ability to move your eyes up and down or back and forth.

5. Trigeminal nerve: Sensations in your face and cheeks, taste and jaw movements.

6. Abducens nerve: Ability to move your eyes.

7. Facial nerve: Facial expressions and sense of taste.

8. Auditory/vestibular nerve: Sense of hearing and balance.

9. Glossopharyngeal nerve: Ability to taste and swallow.

10. Vagus nerve: Digestion and heart rate.

11. Accessory nerve (or spinal accessory nerve): Shoulder and neck muscle movement.

12. Hypoglossal nerve: Ability to move your tongue.

Function of cranial nerves as follows:

Your cranial nerves play a role in controlling your sensations and motor skills.

Sensory nerves help you:

1. Feel touch.

2. Hear.

3. See.

4. Smell.

5. Taste.

Motor nerves play a role in controlling your facial muscles or glands. Some cranial nerves have both sensory and motor functions.

6. a) Briefly explain three sections of the human ear. (5)

Ans) The human ear parts are explained below:

External Ear

Auricle (Pinna): The auricle comprises a thin plate of elastic cartilage covered by a layer of skin. It consists of funnel-like curves that collect sound waves and transmits them to the middle ear. The lobule consists of adipose and fibrous tissues supplied with blood capillaries.

External Auditory Meatus: It is a slightly curved canal supported by bone in its interior part and cartilage in the exterior part. The meatus or the canal is lined with stratified epithelium and wax glands.

Tympanic Membrane: This membrane separates the middle ear and the external ear. This part receives and amplifies the sound waves. Its central part is known as the umbo.

Middle Ear

Tympanic Cavity: It is a narrow air-filled cavity separated from the external ear by tympanic membrane and from inner ear by the bony wall. The tympanic cavity has an auditory tube known as the eustachian tube in its anterior wall.

Eustachian Tube: The eustachian tube is a 4cm long tube that equalizes air pressure on either side of the tympanic membrane. It connects the tympanic cavity with the nasopharynx.

Ear Ossicles: These are responsible for transmitting sound waves from the eardrum to the middle ear. There are three ear ossicles in the human ear:

1. Malleus: A hammer-shaped part that is attached to the tympanic membrane through the handle and incus through the head. It is the largest ear ossicle.

2. Incus: An anvil-shaped ear ossicle connected with the stapes.

3. Stapes: It is the smallest ossicle and also the smallest bone in the human body.

Inner Ear

Bony Labyrinth: The bony labyrinth comprises a vestibule, three semi-circular canals, and spirally coiled cochlea. It is filled with perilymph.

Membranous labyrinth: The bony labyrinth surrounds the membranous labyrinth. It comprises sensory receptors responsible for balance and hearing. The membranous labyrinth is filled with endolymph and comprises three semi-circular ducts, cochlear duct, saccule and utricle. The sensory receptors include cristae, an organ of corti, and ampullaris maculae.

b) Briefly explain physiology of lactation. (5)

Ans) Lactation describes the process of milk production and secretion from the breasts; and it also refers to the period of time during which the mother is breastfeeding.

The breasts contain mammary glands responsible for lactation in those assigned female at birth. Mammary glands are made up of 12 to 20 lobes, each of them containing many smaller lobules. These smaller lobules have grape-like clusters of alveoli that contain mammary secretory epithelial cells, the milk producing cells of lactation. These alveoli, lobules and lobes are connected through a network of ducts called the lactiferous ducts, and eventually form a unique lactiferous duct for each lobe which opens independently to the areola to drain the milk produced during lactation. Each lactiferous duct has a dilated portion deep to the areola called the lactiferous sinus in which there’s a small drop of milk that accumulates or remains in a nursing mother, which becomes expelled from the areola when compressed during feeding.

During pregnancy, the placenta releases progesterone, estrogen and human placental lactogen, while the pituitary gland releases prolactin. Now, these hormones work together to promote the development of the breast tissue by increasing the number and size of the alveoli and the development of the lactiferous ducts.

Prolactin also stimulates milk production and during the later stages of pregnancy, the breasts produce an early version of breast milk called colostrum which is a thick yellowish fluid rich in immune cells and antibodies and high in protein. However, during this stage, high levels of progesterone and estrogen inhibit significant milk production to prevent wasting milk before the baby is born.

When the baby is delivered and the placenta is removed, the level of progesterone and estrogen decrease and milk production ramps up. After 2 to 5 days after birth, the breasts start producing larger quantities of transitional milk which is higher in fat and lactulose but contains less antibodies. Finally, after about 2 weeks, the breasts start to produce mature milk which contains more water initially but fat content increases later on.

7. a) Explain female reproductive system in detail. (6)

Ans) The female reproductive system is made up of the internal and external sex organs that function in the reproduction of new offspring. In humans, the female reproductive system is immature at birth and develops to maturity at puberty to be able to produce gametes, and to carry a fetus to full term. The internal sex organs are the vagina, uterus, fallopian tubes, and ovaries. The female reproductive tract includes the vagina, uterus, and fallopian tubes and is prone to infections. The vagina allows for sexual intercourse and childbirth, and is connected to the uterus at the cervix. The uterus or womb accommodates the embryo which develops into the fetus. The uterus also produces secretions which help the transit of sperm to the fallopian tubes, where sperm fertilize ova (egg cells) produced by the ovaries. The external sex organs are also known as the genitals and these are the organs of the vulva including the labia, clitoris, and vaginal opening.

During the menstrual cycle, the ovaries release an ovum, which transits through the fallopian tube into the uterus. If an egg cell meets with sperm on its way to the uterus, a single sperm cell can enter and merge with it, fertilizing it into a zygote.

Fertilization usually occurs in the fallopian tubes and marks the beginning of embryogenesis. The zygote will then divide over enough generations of cells to form a blastocyst, which implants itself in the wall of the uterus. This begins the period of gestation and the embryo will continue to develop until full-term. When the fetus has developed enough to survive outside the uterus, the cervix dilates and contractions of the uterus propel the newborn through the birth canal (the vagina).

b) Describe the following: (2+2)

(i) Hemodialysis

Ans) Hemodialysis, also spelled haemodialysis, or simply dialysis, is a process of purifying the blood of a person whose kidneys are not working normally. This type of dialysis achieves the extracorporeal removal of waste products such as creatinine and urea and free water from the blood when the kidneys are in a state of kidney failure. Hemodialysis is one of three renal replacement therapies (the other two being kidney transplant and peritoneal dialysis). An alternative method for extracorporeal separation of blood components such as plasma or cells is apheresis.

Hemodialysis can be an outpatient or inpatient therapy. Routine hemodialysis is conducted in a dialysis outpatient facility, either a purpose-built room in a hospital or a dedicated, stand-alone clinic. Less frequently hemodialysis is done at home. Dialysis treatments in a clinic are initiated and managed by specialized staff made up of nurses and technicians; dialysis treatments at home can be self-initiated and managed or done jointly with the assistance of a trained helper who is usually a family member.

(ii) Structure of liver

Ans) A person’s liver is in the upper right section of the abdomen and sits below the diaphragm. It typically weighs around 3 poundsTrusted Source, but this can vary between people. The skin is the only organ heavier and larger than the liver.

The liver is roughly triangular and consists of two lobes: a larger right lobe and a smaller left lobe. The falciform ligament separates the lobes. This ligament is a band of tissue that keeps the liver anchored to the diaphragm.

A layer of fibrous tissue called Glisson’s capsule covers the outside of the liver. The peritoneum, a membrane that forms the lining of the abdominal cavity, then covers this.  This helps hold the liver in place and protects it from physical damage.

8. a) Explain the interchange of gases within the lungs. (5)

Ans) Air enters the body through the mouth or nose and quickly moves to the pharynx, or throat. From there, it passes through the larynx, or voice box, and enters the trachea.  The trachea is a strong tube that contains rings of cartilage that prevent it from collapsing.  Within the lungs, the trachea branches into a left and right bronchus. These further divide into smaller and smaller branches called bronchioles.

The smallest bronchioles end in tiny air sacs. These are called alveoli. They inflate when a person inhales and deflate when a person exhales.  During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.  Here you see red blood cells traveling through the capillaries. The walls of the alveoli share a membrane with the capillaries. That's how close they are.  This lets oxygen and carbon dioxide diffuse, or move freely, between the respiratory system and the bloodstream.  Oxygen molecules attach to red blood cells, which travel back to the heart. At the same time, the carbon dioxide molecules in the alveoli are blown out of the body the next time a person exhales.  Gas exchange allows the body to replenish the oxygen and eliminate the carbon dioxide. Doing both is necessary for survival.

Section B – OTQ (Objective Type Questions) (20 marks)

1. Define the following: (5)

i) Plasma

Ans) Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intravascular part of extracellular fluid.

ii) Antigen

Ans) In immunology, an antigen is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response.

iii) Placenta

Ans) The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate maternal and fetal circulations, and is an important endocrine organ producing hormones that regulate both maternal and fetal physiology during pregnancy.

iv) Amniocentesis

Ans) Amniocentesis is a medical procedure used primarily in the prenatal diagnosis of genetic conditions. It has other uses such as in the assessment of infection and fetal lung maturity.

v) Dialysis

Ans) A process for separating substances from a liquid, especially for taking waste substances out of the blood of people with damaged kidneys.

2. Give the functions/role of the following structure/organs in our body: (10)

i) Pancreas

Ans) A healthy pancreas produces chemicals to digest the food we eat.  The exocrine tissues secrete a clear, watery, alkaline juice into the common bile duct and, ultimately, the duodenum. This substance contains several enzymes that break down food into small molecules. The intestines can then absorb these smaller molecules.

ii) WBC

Ans) White blood cells protect your body against infection. As your white blood cells travel through your bloodstream and tissues, they locate the site of an infection and act as an army general to notify other white blood cells of their location to help defend your body from an attack of an unknown organism.

iii) Aorta

Ans) The aorta is the main artery that carries blood away from your heart to the rest of your body. The blood leaves the heart through the aortic valve. Then it travels through the aorta, making a cane-shaped curve that allows other major arteries to deliver oxygen-rich blood to the brain, muscles and other cells.

iv) Trachea

Ans) Trachea's main function is to carry air in and out of your lungs. Because it's a stiff, flexible tube, it provides a reliable pathway for oxygen to enter your body.

v) Nephrons

Ans) Each of your kidneys is made up of about a million filtering units called nephrons. Each nephron includes a filter, called the glomerulus, and a tubule. The nephrons work through a two-step process: the glomerulus filters your blood, and the tubule returns needed substances to your blood and removes wastes.

vi) Synapse

Ans) In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.

vii) Retina

Ans) The retina is a layer of photoreceptors cells and glial cells within the eye that captures incoming photons and transmits them along neuronal pathways as both electrical and chemical signals for the brain to perceive a visual picture.

viii) Stapedius

Ans) In most of the literatures the stapedius muscle is explained as the smallest skeletal muscle in the human body. Its purpose is to stabilise the smallest bone in the body.

ix) Papillae

Ans) Papillae are the little bumps on the top of your tongue that help grip food while your teeth are chewing. They also have another special job – they contain your taste buds, the things that help you taste everything from sour lemons to sweet peaches.

x) Thyroid gland

Ans) The thyroid gland is a vital hormone gland: It plays a major role in the metabolism, growth and development of the human body. It helps to regulate many body functions by constantly releasing a steady amount of thyroid hormones into the bloodstream.

3. Match the following: (5)

Ans)