Breathing and Excretion: Human Respiratory and Urinary Systems

What are the main components of the human urinary system?

The urinary system consists of two kidneys, two ureters, the bladder, and the urethra.

Where are the kidneys located in the human body?

The kidneys are located in the abdominal cavity on either side of the vertebral column, just below the diaphragm.

What is the function of the renal arteries and veins?

The renal arteries transport oxygenated blood to the kidneys, while the renal veins transport deoxygenated blood away from the kidneys.

What is the role of the ureters in the urinary system?

The ureters transport urine from the kidneys to the bladder.

What is the function of the bladder?

The bladder is a muscular sac that stores urine temporarily.

What is the purpose of the urethra?

The urethra transports urine from the bladder to the outside.

Describe the physical characteristics of the kidneys.

The kidneys are dark, reddish-brown, bean-shaped organs protected by a layer of fat and a tough fibrous connective tissue membrane called the renal capsule.

What are the two main regions of the kidney?

The cortex (reddish-brown outer region) and the medulla (lighter-colored inner region containing renal pyramids).

What is the renal pelvis?

The renal pelvis is a funnel-shaped structure that collects urine from the renal pyramids.

What are nephrons and their significance in the kidney?

Nephrons are the structural and functional units of the kidney, with about a million present in each kidney.

What are the two main parts of a nephron?

The Malpighian body and the renal tubule.

What does the Malpighian body consist of?

The Malpighian body consists of the Bowman's capsule and a network of capillaries called the glomerulus.

How does blood flow through the glomerulus?

Blood enters the glomerulus through the afferent arteriole (wider) and leaves through the efferent arteriole (narrower).

What are podocytes and their role in the nephron?

Podocytes are specialized cells in the inner wall of the Bowman's capsule that have projections with small openings for filtration.

What are the components of the renal tubule?

The renal tubule consists of the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule.

What is the process of glomerular filtration?

Glomerular filtration occurs in the Malpighian body, where blood under high pressure forces smaller molecules to filter from the capillaries into the Bowman's capsule.

What is glomerular filtrate?

The fluid that collects in the Bowman's capsule during glomerular filtration.

What occurs during tubular reabsorption?

Useful substances from the glomerular filtrate are reabsorbed back into the bloodstream, including glucose, amino acids, and most water.

How does the loop of Henle contribute to urine formation?

The loop of Henle creates a water potential gradient that allows for further passive reabsorption of water and actively pumps sodium ions out.

What is tubular excretion (secretion)?

Tubular excretion is the process where substances are secreted from the blood in the peritubular capillaries into the renal tubule.

What happens to glucose and amino acids during tubular reabsorption?

All glucose and amino acids are actively reabsorbed into the peritubular capillaries.

What is the significance of the peritubular capillaries in the nephron?

Peritubular capillaries are involved in the reabsorption of useful substances from the glomerular filtrate back into the bloodstream.

How is water balance regulated in the body?

Through a negative feedback mechanism involving the hormone ADH (Antidiuretic Hormone).

What happens when blood is dehydrated?

The hypothalamus is stimulated, sending nerve impulses to the pituitary gland to secrete more ADH, increasing water reabsorption in the kidneys.

What occurs when blood is over-hydrated?

The hypothalamus sends nerve impulses to the pituitary gland to stop or reduce ADH secretion, leading to less water reabsorption in the kidneys.

What hormone regulates salt balance in the body?

Aldosterone.

What triggers the secretion of aldosterone?

A decrease in the salt level in the blood detected by receptor cells in the kidney's arterioles.

What is the role of aldosterone in salt balance?

It increases the reabsorption of sodium ions from the renal tubules into the surrounding blood vessels, raising blood salt levels.

What nutrients are absorbed by the villi in the small intestine?

Glucose, amino acids, fatty acids, glycerol, vitamins, mineral salts, and water.

What is the function of the hepatic portal vein?

It transports absorbed nutrients from the small intestine to the liver.

What happens to excess glucose in the liver?

It is converted into excess glycogen and stored.

What occurs to excess amino acids in the liver?

They undergo deamination to form urea, which is transported to the kidneys for excretion.

What is assimilation in the context of nutrient absorption?

The process by which body cells absorb the required nutrients after they leave the liver.

How are blood glucose levels controlled?

Through a negative feedback mechanism involving the hormones insulin and glucagon produced by the pancreas.

What happens to blood glucose levels after eating?

Blood glucose levels rise, stimulating the Islets of Langerhans in the pancreas to secrete insulin.

What is the role of insulin in blood glucose regulation?

It causes body cells and the liver to take up glucose from the blood and converts excess glucose into glycogen for storage.

What does glucagon do when blood glucose is low?

It stimulates the liver to convert stored glycogen back into glucose, raising blood glucose levels.

What are the requirements of an efficient gas exchange organ?

A large surface area, a thin surface for rapid diffusion, a moist surface for gas dissolution, a well-ventilated surface, and a well-protected surface.

Why is a moist surface important for gas exchange?

It prevents cells from drying out and ensures that gases can dissolve.

What is the significance of a well-ventilated surface in gas exchange?

It ensures a constant supply of oxygen and removal of carbon dioxide.

What is the importance of having a thin surface in gas exchange organs?

It ensures rapid diffusion of gases.

Why is a large surface area necessary for gas exchange?

To provide sufficient oxygen and remove carbon dioxide effectively.

What is the primary function of the alveoli in the lungs?

To facilitate gaseous exchange by providing a large surface area for oxygen and carbon dioxide diffusion.

How does oxygen move from the alveoli into the blood?

Oxygen diffuses from the alveoli through the thin, moist walls into the blood in the surrounding capillaries.

What is the concentration of carbon dioxide in the blood compared to the air in the alveoli?

The blood has a higher carbon dioxide concentration than the air in the alveoli.

What process occurs when oxygenated blood reaches body tissues?

Oxygen diffuses from the blood capillaries into the tissue fluid and then into the cells.

How does carbon dioxide move from the cells back into the blood?

Carbon dioxide diffuses from the cells into the tissue fluid and then into the blood capillaries.

What is the main way oxygen is transported in the blood?

Most oxygen combines with haemoglobin in red blood cells to form oxyhaemoglobin.

How is most carbon dioxide transported in the blood?

Most carbon dioxide is transported as bicarbonate ions.

What are the two phases of ventilation in the lungs?

Inspiration (inhalation) and expiration (exhalation).

What happens to the diaphragm during inspiration?

The diaphragm contracts and becomes flatter, increasing the volume of the thoracic cavity.

What is the role of the external intercostal muscles during expiration?

They relax, moving the ribs down and inwards, decreasing the volume of the thoracic cavity.

Where are the kidneys located in the body?

In the abdominal cavity on either side of the vertebral column, just below the diaphragm.

What is the primary function of the bladder?

To store urine temporarily.

What is the structure that collects urine in the kidney?

The renal pelvis.

What are nephrons?

Microscopic units in the kidneys that are the structural and functional units responsible for urine formation.

How does the structure of the kidneys protect them?

They are protected by a layer of fat and a tough fibrous connective tissue membrane called the renal capsule.

What is the significance of the large surface area of the alveoli?

It enhances the efficiency of gas exchange between air and blood.

What is the process of gas exchange in the alveoli called?

Gaseous exchange.

What happens to the pressure in the lungs during inhalation?

The pressure in the lungs decreases below atmospheric pressure, allowing air to flow in.

What happens to the pressure in the lungs during exhalation?

The pressure in the lungs increases above atmospheric pressure, forcing air out.

What is the pathway of blood entering and leaving the glomerulus?

Blood enters through the afferent arteriole (wider) and leaves through the efferent arteriole (narrower).

What specialized cells line the inner wall of the Bowman's capsule?

Podocytes, which have projections with small openings for filtration.

What type of epithelium lines the renal tubule?

A single layer of cuboidal epithelium.

What do the distal convoluted tubules open into?

They open into a collecting duct.

What is the duct of Bellini and what does it form?

The duct of Bellini is formed by the combination of collecting ducts and it forms the pyramids.

What are the three main processes of urine formation?

Glomerular filtration, tubular reabsorption, and tubular excretion.

Where does glomerular filtration occur?

In the Malpighian body.

What forces smaller molecules to filter from the blood into the Bowman's capsule?

High pressure from the wider afferent arteriole compared to the narrower efferent arteriole.

What substances are actively reabsorbed during tubular reabsorption?

Glucose, amino acids, and fat-soluble vitamins.

How is most water reabsorbed during tubular reabsorption?

Most water is passively reabsorbed through osmosis.

What creates a water potential gradient in the loop of Henle?

Increased sodium concentration in the medulla.

What happens to sodium ions in the ascending loop of Henle?

Sodium ions are actively pumped out.

What is tubular excretion?

The process of substances being secreted from the blood in the peritubular capillaries into the renal tubule.

Where does tubular excretion occur?

In the proximal and distal convoluted tubules.

What happens when the blood is dehydrated?

The hypothalamus stimulates the pituitary gland to secrete more ADH, increasing water reabsorption.

What occurs when the blood is over-hydrated?

The hypothalamus sends signals to stop or reduce ADH secretion, decreasing water reabsorption.

What effect does aldosterone have on sodium ions?

It increases the reabsorption of sodium ions from the renal tubules into the surrounding blood vessels.

What is the result of aldosterone secretion on blood salt levels?

The salt level in the blood vessels increases and returns to normal.

What are the final products of digestion that are absorbed by the villi in the small intestine?

Glucose, amino acids, fatty acids, glycerol, vitamins, mineral salts, and water.

What is the role of the hepatic portal vein in nutrient absorption?

It transports absorbed nutrients from the small intestine to the liver.

How does the liver process excess glucose?

It converts excess glucose into glycogen for storage.

What happens to excess amino acids in the liver?

They undergo deamination to form urea, which is excreted by the kidneys.

What is the process called when body cells absorb required nutrients?

Assimilation.

What hormones control blood glucose levels?

Insulin and glucagon.

What triggers the secretion of insulin from the pancreas?

High blood glucose levels, such as after eating.

What is the effect of insulin on blood glucose levels?

It causes body cells and the liver to take up glucose, lowering blood glucose levels.

What hormone is secreted when blood glucose levels are low?

Glucagon.

What does glucagon do to blood glucose levels?

It causes the liver to convert stored glycogen back into glucose, raising blood glucose levels.

How does oxygen move from the alveoli to the blood?

It diffuses through the thin, moist walls of the alveoli and capillaries into the blood.

What happens to carbon dioxide during gas exchange in the alveoli?

It diffuses from the blood into the alveoli to be exhaled.

What occurs during the gaseous exchange in body tissues?

Oxygen diffuses from blood into tissue fluid and then into cells, while carbon dioxide diffuses from cells into blood.

How is most oxygen transported in the blood?

It combines with hemoglobin in red blood cells to form oxyhemoglobin.

How is most carbon dioxide transported back to the lungs?

As bicarbonate ions, with some combining with hemoglobin and a small portion dissolving in plasma.

What occurs during inspiration?

It is an active phase requiring energy, where external intercostal muscles contract and the diaphragm flattens, increasing thoracic cavity volume.

What occurs during expiration?

It is a passive phase requiring no energy, where external intercostal muscles relax and the diaphragm becomes dome-shaped, decreasing thoracic cavity volume.

What is the effect of inspiration on lung pressure?

It decreases pressure in the lungs below atmospheric pressure.

What is the effect of expiration on lung pressure?

It increases pressure in the lungs above atmospheric pressure.

What is required for efficient gas exchange in a respiratory organ?

A large surface area, a thin surface, a moist surface, a well-ventilated surface, a well-protected surface, and a transport system (the blood).

What are the characteristics of alveoli that facilitate gas exchange?

Alveoli are tiny air sacs with a large surface area.