Digestion And Absorption,Breathing And Exchange Of Gases, Body Fluids And Circulation, Excretory Products And Their Eli

The human heart normally completes two circulations in one minute. The first circulation is the systemic circulation, where oxygenated blood is pumped from the heart to the rest of the body, and deoxygenated blood returns to the heart. The second circulation is the pulmonary circulation, where deoxygenated blood is pumped from the heart to the lungs to pick up oxygen, and oxygenated blood returns to the heart. Since each circulation involves the blood passing through the heart, there are two double circulations completed in one minute.

The correct answer is Alveoli. Alveoli are tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place. They are surrounded by a network of capillaries, allowing for efficient diffusion of gases between the air and the bloodstream. Tracheoles and bronchioles are parts of the respiratory system, but they do not directly participate in gaseous exchange. Pleura is a membrane that surrounds the lungs, providing protection and lubrication, but it is not involved in the actual exchange of gases.

The pleura is a double-layered membrane that covers the lungs. The outer layer of the pleura is in contact with the thoracic wall, while the inner layer is in contact with the lungs. The fluid between the layers of the pleura reduces friction on the lung surface, allowing for smooth movement during breathing. Therefore, the correct answer is Pleura.

The duration of the cardiac cycle in a normal man is 0.8 seconds. This is the time it takes for the heart to complete one full cycle of contraction and relaxation. During this cycle, the heart fills with blood, contracts to pump blood out to the body, and then relaxes to allow for refilling. This regular rhythm is essential for maintaining proper blood flow and oxygenation throughout the body.

The contraction of the right ventricle pumps deoxygenated blood into the pulmonary artery. The pulmonary artery carries this blood to the lungs, where it will be oxygenated. This oxygenated blood will then return to the heart via the pulmonary veins and be pumped out to the rest of the body through the left ventricle. The coronary artery supplies oxygenated blood to the heart muscle itself, while the dorsal aorta is responsible for carrying oxygenated blood to the rest of the body.

The functioning of the kidneys is efficiently monitored and regulated by hormonal feedback mechanisms involving the hypothalamus, JGA, and to a certain extent, the heart. The hypothalamus releases a hormone called antidiuretic hormone (ADH) in response to low blood volume or increased osmolarity. ADH acts on the kidneys to increase water reabsorption, thus conserving water. The JGA, located in the kidneys, releases renin in response to low blood pressure or decreased blood flow. Renin initiates a series of events that ultimately leads to the production of angiotensin II, a hormone that constricts blood vessels and stimulates the release of aldosterone. Aldosterone acts on the kidneys to increase sodium reabsorption, which in turn increases water reabsorption. The heart also plays a role by releasing atrial natriuretic peptide (ANP) in response to increased blood volume or pressure. ANP acts on the kidneys to increase sodium and water excretion, thus reducing blood volume. Overall, the hypothalamus, JGA, and heart work together to maintain the balance of fluids and electrolytes in the body.

The conducting part of the respiratory system is responsible for filtering, warming, and moistening the air. This is important because the air we breathe may contain dust, allergens, or other particles that need to be filtered out to prevent them from reaching the lungs. Warming and moistening the air helps to protect the delicate lung tissues from damage and irritation. Therefore, the correct answer is "Filter, warm and moisten the air."

Renin is produced in the kidneys. It is an enzyme that plays a crucial role in the regulation of blood pressure and fluid balance in the body. Renin is released by special cells in the kidneys called juxtaglomerular cells, which are located in the walls of the renal arterioles. When blood pressure drops or there is a decrease in blood volume, these cells release renin into the bloodstream. Renin then acts on a protein called angiotensinogen, converting it into angiotensin I, which is further converted to angiotensin II. Angiotensin II is a potent vasoconstrictor and stimulates the release of aldosterone, a hormone that helps regulate blood pressure and electrolyte balance.

ADH, also known as vasopressin, is the correct answer. ADH is a hormone that regulates the reabsorption of water in the kidneys. It is produced by the hypothalamus and released by the pituitary gland in response to changes in blood osmolality or blood volume. ADH acts on the collecting ducts of the kidneys, increasing their permeability to water and allowing for the reabsorption of water back into the bloodstream. This helps to concentrate urine and conserve water in the body.

A healthy human typically breathes 12 to 16 times per minute. This range is considered normal for a person at rest and indicates efficient lung function and oxygen exchange in the body. Breathing too fast or too slow can be a sign of respiratory problems or other health issues.

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Hormones have a widespread influence on various aspects of the digestive system. They can regulate gastric secretions, which are the substances produced by the stomach to aid in digestion. They also affect intestinal secretions, which are the substances produced by the intestines to help with absorption and digestion. Additionally, hormones can control the muscular activities of different parts of the alimentary canal, such as the contraction and relaxation of the muscles in the stomach and intestines. Therefore, all of these options are correct because hormones have an impact on all of these aspects of digestion.

The absorption of digested food is carried out by all the methods mentioned: passive method, active transport, and facilitated transport. Passive method refers to the movement of substances across the cell membrane without the need for energy. Active transport requires energy to move substances against their concentration gradient. Facilitated transport involves the use of carrier proteins to transport substances across the cell membrane. Therefore, all these methods play a role in the absorption of digested food.

During expiration, the intrapulmonary pressure (pressure inside the lungs) is greater than the atmospheric pressure (pressure outside the body). This pressure difference allows air to flow out of the lungs, helping to exhale and remove waste gases from the body.

The secretion of saliva can be stimulated by various factors related to food consumption. The sight of food can trigger the brain to send signals to the salivary glands, leading to the production of saliva. Similarly, the smell of food can also activate the salivary glands, preparing the mouth for digestion. Additionally, the presence of food in the oral cavity, such as when chewing or tasting, can further stimulate saliva secretion. Therefore, all of these factors contribute to the stimulation of saliva secretion.

The thoracic cavity is formed by the vertebral column dorsally, the sternum ventrally, the ribs laterally, and the diaphragm on the lower side. This cavity houses and protects vital organs such as the heart, lungs, and major blood vessels. It is separated from the abdominal cavity by the diaphragm. The thoracic cavity is responsible for the mechanics of breathing, as the diaphragm contracts and relaxes to allow for inhalation and exhalation.

Aldosterone is responsible for the reabsorption of Na+ in the kidneys. It acts on the distal tubules and collecting ducts, increasing the reabsorption of sodium ions and water, while promoting the excretion of potassium ions. This hormone is released by the adrenal glands in response to low blood pressure, low blood volume, or high levels of potassium in the blood. By increasing the reabsorption of sodium, aldosterone helps maintain blood pressure and electrolyte balance in the body.

Vasopressin (ADH) is the correct answer because osmoregulation refers to the regulation of water and electrolyte balance in the body. Vasopressin, also known as antidiuretic hormone (ADH), plays a crucial role in regulating water reabsorption in the kidneys. It acts on the kidneys to increase water reabsorption, thereby reducing urine production and helping to maintain proper fluid balance in the body. Oxytocin and prolectin are not involved in osmoregulation.

The correct answer is Caecum, ileo-caecal. The caecum is a pouch-like structure located at the beginning of the large intestine. It receives undigested substances (faeces) from the small intestine through the ileo-caecal valve. This valve prevents the backflow of faecal matter from the large intestine back into the small intestine.

Purkinje fibers are specialized cardiac muscle fibers that are responsible for conducting electrical impulses through the ventricular myocardium. These fibers play a crucial role in coordinating the contraction of the ventricles, ensuring efficient pumping of blood out of the heart. They are not present in the left or right auricles or the sinoatrial node (SAN), which are involved in other aspects of cardiac function. Therefore, the correct answer is the ventricular myocardium.

The activities of the gastrointestinal tract are under both neural and hormonal control. The nervous system, specifically the enteric nervous system, plays a crucial role in regulating various functions such as peristalsis, secretion, and absorption. The enteric nervous system can function independently or in coordination with the central nervous system. Additionally, hormones released by various organs such as the stomach, pancreas, and intestines also regulate gastrointestinal activities. These hormones, including gastrin, secretin, and cholecystokinin, help regulate digestion, absorption, and the release of digestive enzymes. Therefore, the correct answer is that the activities of the gastrointestinal tract are under neural and hormonal control.

The chodaetendinase prevents the AV valve flaps from everting. This means that it helps to keep the AV valves closed and prevents them from turning inside out. This is important for maintaining proper blood flow through the heart. If the AV valve flaps were to evert, it could lead to regurgitation of blood back into the atria, reducing the efficiency of the heart's pumping action. Therefore, the chodaetendinase plays a crucial role in preventing this from happening.

The correct answer is "The volume of thoracic cavity increases." When the diaphragm contracts upward and the external intercostal muscles relax during inspiration, it allows the lungs to expand and increases the volume of the thoracic cavity. This increase in volume creates a lower pressure inside the lungs, causing air to rush in and fill the expanded space.

Osmoreceptors in the body are sensory receptors that detect changes in the concentration of solutes in the blood and body fluids. These receptors are responsible for regulating the body's fluid balance and maintaining homeostasis. The correct answer states that osmoreceptors are activated by changes in blood volume, body fluid volume, and ionic concentration. This means that osmoreceptors are sensitive to changes in the overall volume of blood and body fluids, as well as changes in the concentration of ions in these fluids.

Glucose and amino acids are absorbed in the intestine by active transport. Active transport is a process that requires energy to move molecules against their concentration gradient, from an area of lower concentration to an area of higher concentration. In the case of glucose and amino acids, they are absorbed against their concentration gradient, meaning they are absorbed from the intestine where their concentration is low into the bloodstream where their concentration is high. This process is essential for the body to obtain these nutrients and ensure proper functioning.

Hormonal control of the secretion of digestive juice is carried out by hormones produced by gastric and intestinal mucosa. This is because the gastric and intestinal mucosa produce hormones that regulate the secretion of digestive juices. Neurotransmitters are involved in the transmission of nerve impulses, but they do not directly control the secretion of digestive juices. The liver and pancreas are involved in the production and release of digestive enzymes, but they are not directly responsible for the hormonal control of digestive juice secretion.

Osmoreceptors are specialized cells in the hypothalamus that detect changes in the osmolarity or concentration of solutes in the blood. When osmoreceptors sense an increase in osmolarity, they stimulate the hypothalamus to secrete antidiuretic hormone (ADH) from the posterior pituitary gland. ADH acts on the kidneys to increase water reabsorption, reducing urine output and helping to maintain water balance in the body. Therefore, when the hypothalamus is stimulated by osmoreceptors, it leads to an increase in ADH secretion.

During the cardiac cycle, approximately 70% of ventricular filling occurs prior to atrial contraction, while the remaining 30% of ventricular filling occurs due to atrial contraction. This means that the majority of blood is passively filling the ventricles before the atria contract to push the remaining blood into the ventricles.

The statement "Very significant digestive activity occurs in the large intestine" is false. The large intestine primarily functions in absorbing water and electrolytes from the remaining indigestible food material, and it also houses bacteria that aid in the fermentation of undigested material. However, the majority of digestion and absorption of nutrients occurs in the small intestine, specifically the duodenum, jejunum, and ileum.

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During inspiration, the diaphragm and external intercostal muscles contract, causing the thoracic cavity to expand and the lungs to expand as well. This creates a negative pressure within the lungs, causing air to be drawn in. Therefore, the statement "Inspiration is a passive and external intercostal muscles and diaphragm play an important role" is true, not false.

The atrioventricular valve prevents the back flow or leakage of blood from the right ventricle to the right atrium. This valve, also known as the tricuspid valve, is located between the right atrium and the right ventricle. It opens to allow blood to flow from the atrium into the ventricle during diastole, and then closes to prevent backflow during systole when the ventricle contracts and pumps blood out to the pulmonary artery. This ensures that blood flows in one direction, from the atrium to the ventricle, and prevents any leakage or regurgitation back into the atrium.

During ventricular systole, the contraction of the ventricles causes the atria to relax (auricular diastole). This relaxation allows the tricuspid and bicuspid valves to close, preventing the backflow of blood into the atria. Simultaneously, the increased pressure within the ventricles forces the semilunar valves (guarding the pulmonary artery and aorta) to open, allowing blood to be pumped out of the heart and into the respective arteries. Therefore, all of these events occur during ventricular systole.

The large intestine is responsible for the absorption of water, minerals, and certain drugs. It also secretes mucus to lubricate feces and temporarily stores feces in the rectum. However, the large intestine does not play a significant role in nutrient absorption. Nutrient absorption primarily occurs in the small intestine.

The correct answer is the conducting part. The conducting part of the respiratory system includes the external nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, and terminal bronchioles. This part is responsible for conducting air from the external environment to the respiratory or exchange part of the system, where gas exchange occurs.

During systole, the atria and ventricles of the heart contract to pump blood. However, they do not contract simultaneously. The atria contract first, pushing blood into the ventricles. Then, after a brief delay, the ventricles contract, pumping the blood out of the heart and into the circulatory system. This sequential contraction allows for efficient and coordinated blood flow through the heart.

The correct answer is "Alveoli and their ducts." The respiratory or exchange part of the respiratory system includes the alveoli and their ducts. Alveoli are tiny air sacs located at the end of the bronchioles in the lungs. They are responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream. The ducts connect the alveoli and help in the transportation of air in and out of the lungs.

The correct sequence for the regulation of kidney function starts with an excess loss of fluid from the body. This loss of fluid is detected by osmoreceptors, which then stimulate the hypothalamus. The hypothalamus, in turn, signals the neurohypophysis (also known as the posterior pituitary gland) to release antidiuretic hormone (ADH). ADH increases the water permeability of the distal convoluted tubules (DCT) and collecting ducts (CT) in the kidneys, leading to the prevention of diuresis (excessive urine production).

During inspiration, the contraction of the external intercostal muscles raises the ribs and sternum (I), which increases the volume of the thorax in the dorso-ventral axis (II). Simultaneously, the diaphragm contracts (IV), further increasing the volume of the thorax in the anterior-posterior axis (VI). As a result, the intrapulmonary pressure decreases (III), creating a pressure gradient that allows air to rush into the lungs (V). Therefore, the correct sequence to initiate inspiration is I, II, IV, VI, III, V.

ADH, also known as antidiuretic hormone or vasopressin, is synthesized by the hypothalamus and released by the neurohypophysis (posterior pituitary gland). It acts on the distal convoluted tubules (DCT) and collecting tubules (CT) in the kidneys to increase water reabsorption and decrease urine production. Therefore, the correct answer is "Hypothalamus, Neurohypophysis, DCT and CT."

The relaxation of muscles is the main cause for the initiation of exhalation. During exhalation, the muscles involved in breathing, such as the intercostal muscles and the diaphragm, relax. This relaxation reduces the volume of the thoracic cavity, leading to an increase in pressure. As a result, air is forced out of the lungs, allowing for exhalation to occur.

During ventricular systole, the correct answer is that oxygenated blood is pumped into the aorta and deoxygenated blood is pumped into the pulmonary artery. This is because the left ventricle contracts, pushing oxygenated blood out of the heart through the aorta to supply oxygen to the rest of the body. At the same time, the right ventricle contracts, sending deoxygenated blood to the lungs through the pulmonary artery for oxygenation.

During forceful breathing, the abdominal muscles and internal intercostal muscles are used. The abdominal muscles, including the rectus abdominis, external obliques, and internal obliques, contract to forcefully exhale air from the lungs. This contraction causes the abdominal wall to push inward, increasing the pressure in the thoracic cavity and aiding in the expulsion of air. The internal intercostal muscles, located between the ribs, also contract during forceful breathing to further increase the pressure in the thoracic cavity and assist in the process of exhaling air.

Expiration is the process of exhaling air out of the lungs. During expiration, the external intercostal muscles relax, allowing the ribcage to return to its normal position. This causes the volume of the thorax to decrease, which leads to an increase in intrapulmonary pressure. Finally, as a result of the increased intrapulmonary pressure, air is expelled from the lungs. Therefore, the correct sequence to initiate expiration is I, III, IV, II.

The correct answer is HCO2. The kidneys play a crucial role in maintaining acid-base balance in the body by controlling the levels of bicarbonate (HCO2) in the blood. Bicarbonate acts as a buffer, helping to neutralize excess acids or bases in the blood. The kidneys can reabsorb or excrete bicarbonate as needed to maintain the proper pH balance in the body. This process helps to regulate the levels of CO2 and H+ ions in the blood, ensuring that the body's acid-base balance is maintained within a normal range.