Renal System - Details

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Refers to blood pH. Should be 7.35-7.45. Kidney’s 1. Reabsorb HCO3 from urine and excrete H+ into urine to act as a buffer.

Acid-base balance in Renal System

Regulation of acid-base balance is achieved by 1. Buffers (absorb or release H+) 2. Respiratory System 3. The renal system.

Acid-Base Regulation

Increase in H+ and decrease in pH

Acidosis

A hormone. Regulates the level of water in the collecting duct and enables water to be reabsorbed in the body (e.g. when dehydrated). In over-hydration, there is less AHD, allowing water to be excreted (as the collecting duct is less impermeable to water).

Arginine vasopressin (AVP) or ADH

Above each kidney. Release Hormones.

Adrenal Glands

Brings blood/plasma into the kidneys

Afferent Arteriole

Steroid hormone. Secreted by adrenal glands. Principle regulator of salt and water balance in body. Production is regulated by the renin-angiotensin system.

Aldosterone

Decrease in H+ and increase in pH

Alkalosis

A precursor to angiotensin II

Angiotensin I

Binds to many receptors in the body to affect several systems. It can increase blood pressure by constricting the blood vessels

Angiotensin II

See AVP

Anti-diuretic hormone (ADH)

‘water channels’ inserted into the epithelium of the collecting duct (instructed by the hormones ADH) that allows water to be reabsorbed into the body (e.g. when dehydrated)

Aquaporins

Or anti-diuretic hormone (ADH) Increases water reabsorption in collecting ducts. Reduces urine volume. Main stimulus= plasma osmolality. When osmatic pressure is raised, ADH/AVP output is increased.

Arginine Vasopressin (AVP)

Released from the heart, acts to reduce blood volume. Main stimulus=changes in blood volume. When blood volume is increased, ANP reduces reabsorption of water.

Atrial Natriuretic Factor (ANP)

Stores urine (brought from the kidneys via the ureter)

Bladder

Collects filtrate from Glomerulus.

Bowman’s Capsule

Follows the distal tubule in the nephron. Lined with principle and intercalated cells. Final adjustments to filtrate are made before it becomes urine; urea and sodium chloride are reabsorbed here.

Collecting Duct

In the kidneys is the process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine.

Countercurrent multiplication

The waste product of creatine, which the muscles use to make energy

Creatinine

Follows the Loop of Henle in the Nephron. Initial adjustment to water and salt content of the filtrate takes place here, under the influence of aldosterone. Lined with simple cuboidal cells. Here, Na+, Cl- and almost all remaining HCO3 are reabsorbed and P+ and H+ are secreted into the tubule. Only small amounts of water are reabsorbed.

Distal Convoluted Tubule

Takes blood/plasma away from the glomerulus and branches into peritubular capillaries that form a network around the tubules of the nephron.

Efferent Arteriole

The ionized or ionizable constituents of a living cell, blood, or other organic matter.

Electrolytes

Hormone responsible for red blood cell formation

EPO

A hormone produced mainly by the kidneys. It is produced and released into the bloodstream if the blood oxygen levels are low (hypoxaemia)

Erythropoietin (EPO)

A blood vessels with tiny pores that allows movement of small particles in and out of the blood. RBC, WBC and large proteins can’t pass through.

Fenestrated Capillaries

The body can increase filtration by increasing the afferent arteriole diameter and decreasing the efferent arteriole diameter

Filtration

-Regulate: Blood volume, blood pH, blood pressure, metabolites and electrolytes. Excrete waste products. Produces urine. Produces the hormone EPO.

Functions of the Kidney

A network of capillaries at the entrance of a nephron. Blood enters from the afferent arteriole. Filters blood into the Bowman’s Capsule.

Glomerulus

The product of the glomerulus that filters into the Bowman’s Capsule. In men, 180L a day is produced (but only 1-2L or urine produced). It either becomes urine or is reabsorbed back into the body. Contains water, glucose, amino acids and inorganic ions (Na+, Cl-, K+, HCO3 etc.) plus urea and creatinine.

Glomerulus filtrate

After the proximal tubule in the nephron. Filtrate moves down the thin descending limb, which is permeable to water but less so to sodium and urea; water leaves by osmosis to the salty medulla. Filtrate moves up thin ascending limb into the thick ascending limb, where Na+ followed by Cl- filters out; water cannot follow as it is impenetrable to water (making the medulla salty). Thin segments of the loop are lined with squamous epithelium. It dips down into the medulla. The bottom of the loop is highly concentrated with salt, as water has left.

Loop of Henle

Filter lymph for harmful products (WBC, lymphocytes etc.). Drain around 3L fluid a day.

Lymph Glands

Removes excess fluid from body tissue and returns it to the blood. Lymph vessels, lymph glands and lymph nodes and adenoids, tonsils, thymus and spleen. Contains a colourless fluid call Lymph. Functions: Defence (against invaders) and Clean-up (removes waste products and damaged cells) Immune cells are highly concentrated in blood and lymphatic tissue. Subsystem of both immune and circulatory system.

Lymphatic System

When metabolisms leads to Acidosis or Alkalosis

Metabolic Acidosis/Alkalosis

S an intermediate or product of metabolism. E.g. polyols or antioxidant.

Metabolites

Functional unit of the kidney. Around 1 million in each kidney. Produces urine to get rid of excess water and toxic waste products. Made up of Renal Corpuscle and Renal Tubule.

Nephron

Are tiny blood vessels, supplied by the efferent arteriole, that travel alongside nephrons allowing reabsorption and secretion between blood and the nephron

Peritubular capillaries

Measures the body's electrolyte-water balance

Plasma Osmolality

In the nephron, follows the Bowman’s Capsule (convoluted means twisted). Lined with simple cuboidal epithelium; substances pass through from the basilateral surface (bottom) to the apical surface (top) out into the interstitial fluid. Substances that leave to be reabsorbed are from the Glomerulus filtrate. 100% of glucose and amino acids are reabsorbed.

Proximal Convoluted Tubule

A chemical compound found in foods. Foods with high content of purines include liver, anchovies, mackerel, dried beans and peas, and beer.

Purines

Substances from the glomerulus filtrate leave the proximal tubule (via osmosis and negative ions being attracted to positive ions, e.g. Cl- follows Na+). 100% of glucose and amino acids, 50% of urea, 65% of Sodium and Chloride ions, 65% of water, 65% of potassium and 90% bicarbonate.

Reabsorption

Brings blood to the kidneys

Renal Artery

Are chambers of the kidney through which urine passes

Renal calyces

Filters blood. Substrates are transported into the nephron, creating filtrate. Two sections: Glomerulus and Bowman’s Capsule

Renal Corpuscle

Outside of the kidneys

Renal Cortex

Highly salty region of the kidney. Absorbs approximately 25% of NaCl from filtrate in Loop of Henle. Inside (‘middle’) of the kidneys.

Renal Medulla

Hollow opening at the centre of the kidneys. The nephrons empty into this region. Connects to the ureter.

Renal Pelvis

Predominantly responsible for maintaining water and salt balance. Acts in response to the hormones Arginine Vasopressin, Aldosterone and Atrial Natriuretic Factor (ANP)

Renal System

Filtration (of substances from the blood); Reabsorption (of useful substances), Secretion (of chemical messages) and Excretion (of wastes).

Renal System Processes

Forms urine by reabsorbing and secreting substances to and from the glomerular filtrate. Four sections: Proximal Tubule, Loop of Henle, Distal Tubule and Collecting Duct.

Renal Tubule

Takes blood away from the kidneys

Renal Vein

An enzyme released when low blood volume. Renin converts angiotensinogen to angiotensin I and then angiotensin II which stimulates aldosterone

Renin

Is a hormone system that regulates blood pressure and fluid and electrolyte balance, as well as systemic vascular resistance

Renin-angiotensin system

When change in respiration leads to Acidosis of Alkalosis

Respiratory Acidosis/Alkalosis

Filtered lymph reaches here.

Thoracic duct

A colourless crystalline compound which is the main nitrogenous breakdown product of protein metabolism in mammals and is excreted in urine. Urea is reabsorbed at the collecting tubule to increase osmolarity in the medulla.

Urea

Sometimes urea can be reabsorbed at the loop of Henle rather than excreted as urine.

Urea Recycling

Chemical created when the body breaks down substances called purines.

Uric Acid

Transport urine from the kidneys to bladder.

Ureter

Length different for men and women. Removes urine from the bladder to the environment.

Urethra

Generally contains water, urea, ureic acid, creatinine, Na+, Cl-, K+ and other inorganic substances. 90-95% water, 5-10% inorganic and organic solids.

Urine

Water gain = water loss

Water Balance

Mainly via fluid ingestion (physiological driver is thirst)

Water Gain/intake

Mainly via urine. Driven by hormonal effects on renal function.

Water loss

1. Arginine vasopressin (AVP) or anti-diuretic hormone (ADH) 2.Aldosterone 3. Atrial natriuretic factor (ANP)

3 hormones in Renal System

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Renal System - Details

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