Human Excretion and Kidney Physiology

Molluscs have one or two pairs of renal organs such as sponge-like kidneys.

Mesonephros kidney is the functional kidney of petromyzon, fishes and amphibians.

In echinoderms, specialised amoebocytes found in the coelomic fluid perform excretion.

Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as urine flows along the tubular part of the nephron. So, option 3 is correct.

Kidneys are metanephric in organisms, belonging to class reptilia and aves.

Kidney contains extraglomerular mesangial cells.

Urine flows more slowly through the maternal renal collecting system due to dilatation of the ducts. This dilatation is the result of mechanical obstruction by the enlarging uterus along with the relaxing effects of progesterone on smooth muscle.

When the body temperature begins to rise, a negative feedback response works to counteract and stop the rise in temperature. Thus, sweating is a suitable example of negative feedback.

The kidney is the primary excretory organ that filters blood and removes water, metabolic wastes, and excess substances including fat breakdown products. While skin does excrete water and salts through sweat, the kidney is responsible for comprehensive filtration and excretion of various catabolic wastes from the body.

 The kidneys remove waste products from the blood and produce urine.

Alzheimer's is a neurodegenerative disorder that primarily targets brain cells, causing memory loss and cognitive decline. The heart, liver, and kidney are not the primary organs affected - this disease specifically impacts brain tissue and neural networks.

Role of sodium and potassium ions in the body is to maintain the body osmotic pressure. Whenever there is an increase in sodium and potassium concentration in the blood, the kidney releases most of it in order such that there will be enough water for use by the body. But when there is a decrease in their concentration, there is more release of water to store more sodium which the body needs dearly. This process is known as osmoregulation. 

Approx. 95% of the volume of normal urine is due to water. The other 5% consists of solutes (chemicals that are dissolved in the water). Some of these solutes are the result of normal biochemical activity within the cells of the body. Other solutes may be due to chemicals that originated outside of the body, such as pharmaceutical drugs.

Amount of potassium in urine varies with diet and the amount of aldosterone (a steroid hormone) in the body.

The Urinary System may also be called the Renal System because this group of inter-connected body parts process a liquid substance called urine via specialist organs called the kidneys. The word renal means pertaining to the kidneys, so this group of tissues and organs is either named after the substance it processes (urine; Urinary System), or the organ that does most of the work (kidneys, Renal System).