41.3 Excretion Systems

41.3 Excretion Systems

• The acid-base balance is maintained by secreting excess H+ ion.

• In a cross-section of the kidneys, the tubules are placed close together and in contact with each other.
• The different cell types can be exchanged for chemical messengers.
• The juxtaglomerular complex is made up of the macula densa and juxtaglomerular cells.
• The hormones renin and erythropoietin are produced by the JGC.
• The cells in the DCT can communicate with the capillaries in the afferent and efferent arterioles if there is a change in blood volume, blood pressure, or electrolyte balance.

• A nephrologist studies and deals with diseases of the kidneys, such as diabetes and hypertension.
• Alterations in blood pressure, blood volume, and changes in electrolyte balance are the responsibility of a nephrologist.

• Nephrologists work with other physicians who refer patients to them or consult with them about specific diagnoses and treatment plans.
• Patients are referred to a nephrologist if they have symptoms such as blood in the urine or high blood pressure.

• There is a subspecialty of internal medicine called Nephrology.
• Medical school is followed by additional training to become certified in internal medicine.
• An additional two or more years is spent studying the effects of certain disorders on the body.

• By the end of this section, you will be able to explain how vacuoles, present in microorganisms, work to excrete waste.
• The excretory systems that evolved in organisms were vacuoles, flame cells, and Malpighian tubules.

• The presence of a cell is the most important feature of life.
• The simplest functional unit of a life is a cell.

• unicellular, prokaryotic organisms that have some of the least complex life processes in place, such asbacteria, do not contain vacuoles.
• The cells of the organisms interact with the environment by binding with cell membranes.
• Some cells, including some leucocytes in humans, are capable of involution of the cell membrane and endocytosis, which is the formation of vesicles.
• The same vesicles are able to interact with each other.
• vacuoles, which store food or water, should not be confused with contractile vacuoles.

• The amoeba ingests food by endocytosis.
• The lysosome digests the food.
• Exocytosis excretes waste.

• Individual organs evolved to perform the excretory function as multicellular systems evolved.
• Planaria live in freshwater.
• The excretory system has two tubules connected to a duct system.
• The excretory pores that open on the body's surface allow cilia to draw water from the interstitial fluid.
• Reabsorption recovers any valuable metabolites.
• Flatworms have flame cells in them.
• The osmotic balance is maintained by them.

• The excretory system of the (a) planaria has a tubule formed by a tube cell.
• Along the sides of the body, there are pores that lead to branched structures.
• The filtrate is released through the pores.
• The opening of the nephridium draws water from the coelom into a tubule.
• As the filtrate passes down the tubules, the solutes are absorbed by the capillaries.
• Nitrogenous and other waste is stored in a bladder and then released into the side of the body.

• The earthworm has a pair of nephridia on it.
• They are similar to flame cells in that they have a tubule.

• They have a system for reabsorption by a capillary network that is more evolved than the flame cells.

• The number of tubules varies with the species of insect.

• Malpighian tubules work with specialized glands in the rectum.
• The urine is produced by the cells lining the Malpighian tubules that are bathed in hemolymph, a mixture of blood and interstitial fluid that is found in insects and other arthropods.