Urogenital System
Excerpts from previous naturopathy assignments HLT60512. The Urogenital System
The urogenital system, fluid balance, renal function and micturition
Blood composition, detoxification, blood pressure and hormonal functions are regulated by the urogenital system. The kidneys are continuously processing and removing nitrogenous waste, and balancing Ions such as H+ and Bicarbonate.
Kidneys maintain fluid balance by the filtering blood and releasing antidiuretic hormone (ADH) and renin hormone which plays a role in blood pressure. Erythropoietin hormone is also manufactured and this plays a role in in blood cell production. Calcitriol hormone (The active form of vitamin D) is also released. This plays a vital role in promoting intestinal absorption of calcium, and stimulating osteoclasts to release Ca2+ from bone matrix. The Parathyroid tells the kidneys to release calcitriol when Ca2+ levels drop. (Taylor, 2018).
Nephrons filter blood to urine. When the urine volume reaches 150 to 400 mls, bladder stretch receptors signal the brain and spinal cord to relax the internal urethral sphincter giving the sensation of needing to urinate. This can be delayed until maximum bladder volume occurs. Increasing nerve signals lead to a greater desire to urinate’ (Tim Taylor, 2018).
Fluid Balance
In general, the kidneys have 3 major roles to play, which help keep the blood composition relatively constant.
These are
- excretion of nitrogen containing wastes,
- maintaining water and electrolyte balance of the blood,
- ensuring proper blood pH
(Essentials of Human Anatomy and Physiology)
Fluid, Electrolyte, and Acid-Base Balance Blood composition depends on three major factors:
Diet
Cellular metabolism
Urine output
Renal Function
The kidneys maintain the homeostasis of several important internal conditions by controlling the excretion of substances out of the body.
Ions (Conserve or excrete) potassium, sodium, calcium, magnesium, phosphate, and chloride ions into urine. pH
Hydrogen (H+) and bicarbonate ions affect blood pH. H+ ions are by-products from dietary proteins accumulating in blood over time.
Excretion of excess H+ ions and conservations of bicarbonate ions which are pH buffers.
Osmolarity
The kidneys maintain the body’s osmotic balance by controlling the amount of water that is filtered out of the blood and excreted into urine. Changes in excretion of water are controlled by antidiuretic hormone (ADH).
Blood Pressure
The kidneys monitor the body’s blood pressure to help maintain homeostasis. They can reduce blood volume by reducing the reabsorption of water into the blood and producing watery, dilute urine or produce the enzyme renin to constrict blood vessels and produce concentrated urine when blood pressure becomes too low.
Filtration
Millions of nephrons filter blood to produce urine. Arterioles in the kidneys deliver blood to the glomerulus. The liquid filtrate here flows through tubules lined with filtering cells and capillaries which selectively absorb water and substances. Waste products present in the blood are secreted into the filtrate. By the end of this process the filtrate has become urine containing only water, waste products, and excess ions.
Storage and Excretion of Wastes
Urine is transported through the ureters to the bladder.
Production of Hormones
The kidneys produce and interact with several hormones involved in the control of systems outside of the urinary system.
Calcitriol
Anatomy and Physiology Instructor Tim Taylor states: ‘The active form of vitamin D in the human body is produced by the kidneys from precursor molecules produced by UV radiation striking the skin. Calcitriol works together with parathyroid hormone (PTH) to raise the level of calcium ions in the bloodstream. When the level of calcium ions in the blood drops below a threshold level, the parathyroid glands release PTH, which in turn stimulates the kidneys to release calcitriol. Calcitriol promotes the small intestine to absorb calcium from food and deposit it into the bloodstream. It also stimulates the osteoclasts of the skeletal system to break down bone matrix to release calcium ions into the blood’ (Taylor, 2018).
Erythropoietin
Erythropoietin, also known as EPO, is a hormone that is produced by the kidneys to stimulate the production of red blood cells..
Renin
Renin is an enzyme that the kidneys produce to start the renin-angiotensin system (RAS).
(Tim Taylor, 2018).
Micturition
Tim Taylor states: ‘When the volume of the urinary bladder reaches anywhere from 150 to 400 millilitres, its walls begin to stretch and stretch receptors in its walls send signals to the brain and spinal cord. These signals result in the relaxation of the involuntary internal urethral sphincter and the sensation of needing to urinate. Urination may be delayed as long as the bladder does not exceed its maximum volume, but increasing nerve signals lead to greater discomfort and desire to urinate’ (Tim Taylor, 2018)
Heather Indiana Rose
Copyright 2019