BIOB34 Module 6 Notes

Osmoregulation

Osmoregulation

The process of maintaining the balance of water and solutes in an organism's body.

Hydrostatic pressure

The pressure exerted by a fluid due to the force of gravity.

Equilibrium

A state of balance between two opposing forces or concentrations.

Isotonic solution

A solution in which the concentration of solutes is the same inside and outside the cell, resulting in no net movement of water.

Hypotonic solution

A solution in which the concentration of solutes is lower outside the cell, causing water to move into the cell and potentially causing swelling.

Hypertonic solution

A solution in which the concentration of solutes is higher outside the cell, causing water to move out of the cell and potentially causing the cell to shrink.

Osmotic pressure

The pressure exerted by the movement of water across a semipermeable membrane due to differences in solute concentration.

How is osmoregulation largely accomplished by?

drinking fluids and excreting them

What are some things that happen when you are thirsty?

increase water loss, increased respiratory (evaporative water loss), increase sweating

How is the osmotic gradient defined?

the sum total of the various components that make up the electrolyte composition

Homeostasis

The maintenance of a stable internal environment in an organism.

Na+/K+ ATPase pumps

Proteins that actively transport sodium ions out of cells and potassium ions into cells, maintaining the concentration gradient.

Extracellular fluid matrix

The fluid outside of cells that provides a medium for the exchange of nutrients and waste products.

Ionic constituency

The composition of ions in a fluid.

Freshwater teleost

A type of fish that lives in freshwater and actively takes in salt from the environment to offset water loss.

Desert mammal

An animal adapted to living in desert environments, which concentrates urine to minimize water loss.

Marine bird

A bird that lives in marine environments and has adaptations to offset water loss, such as producing uric acid.

Bolus of air

A mass of air.

What happens during inspiration?

incoming air is warmed and humidified, cooling the nose

What happens during expiration?

outgoing air is cooled and loses water, wetting the nose

Osmoregularity

The regulation of osmotic pressure in the body.

Filtering tissue

Tissue that filters substances.

Sponges

Simple animals that have tissues in relative osmoconformity with their environment.

Osmoconformity

The ability to maintain osmotic balance with the environment.

Diffusing

The process of spreading or moving from an area of high concentration to an area of low concentration.

Glomerulus

A network of capillaries in the kidney.

Bowman's capsule

Part of the cortical nephron that surrounds and interfaces with the glomerulus.

Filtrate

The fluid that accumulates in Bowman's capsule.

Nephron

The functional unit of the kidney.

Cortical nephron

A type of nephron that is mostly contained within the cortex.

Juxtamedullary nephron

A type of nephron that extends into the medulla.

Collecting duct

The part of the nephron where filtrate is dumped and mixed with filtrate from other nephrons.

Ureters

Tubes that carry urine from the kidneys to the bladder.

Bladder

An organ that stores urine.

Beaver

An animal with a reduced medulla and less developed kidney.

Osmotic stress

Stress caused by changes in osmotic pressure.

Cutaneous water loss

Water loss through the skin.

Saudi Arabian sparrow

A sparrow from an arid environment with less cutaneous water loss.

Ohio sparrow

A sparrow from a wet environment with more cutaneous water loss.

Ceramides

Lipids that correlate with less cutaneous water loss.

Cerebrosides

Lipids that correlate with less cutaneous water loss.

anaplerosis

metabolic process that replenishes intermediates in the citric acid cycle. It helps maintain the balance of metabolites and supports energy production; reaction is important for the synthesis of glucose and other molecule

Protein catabolism

The breakdown of proteins.

Protein-for-water hypothesis

The hypothesis that protein catabolism serves the function of liberating bound water.

Tracer

A chemical that birds ingest but cannot effectively absorb, so it is excreted in their urine.

GFR (Glomerular Filtration Rate)

The rate at which urine is produced in the kidneys.

L-glucose

A molecule that behaves similarly to D-glucose but cannot be metabolized, making it a good tracer.

Carbohydrate absorption

The process by which carbohydrates, such as glucose, are absorbed in the lumen of the stomach through cellular mediation.

Sodium-linked process

A process in which the absorption of glucose is linked to the concentration of sodium.

Fructose

A type of sugar that is absorbed differently than glucose, as it is not a sodium-linked process.

Vitamin C

A micronutrient that is absorbed through a sodium-linked process.

Amino acids

Organic compounds that follow a similar mechanism of reabsorption in the kidneys as glucose.

Sodium-glucose co-transporter

A transporter that allows the movement of glucose and sodium across the brush border of the absorptive cells in the kidneys.

SLGT2 (Sodium-linked glucose transporter 2)

A transporter responsible for 90% of glucose reabsorption in the kidneys.

SLGT1 (Sodium-linked glucose transporter 1)

A transporter responsible for 10% of glucose reabsorption in the kidneys.

Type II Diabetes

A condition characterized by uncontrolled high blood sugar levels, which can overwhelm the kidneys' ability to effectively reabsorb glucose.

Hyperglycemia

High levels of glucose in the blood.

Bicarbonate

A buffer that helps regulate blood pH by neutralizing excess protons.

Carbonic anhydrase

An enzyme that catalyzes the conversion of CO2 and H2O into bicarbonate and protons.

Chloride antiporter

A transporter that exchanges chloride ions for bicarbonate ions in the kidneys.

Urine acidification

The process of making urine more acidic by excreting protons.

Ammonia

A nitrogen breakdown product that is actively secreted in urine and can act as a buffer.

Phosphates

Substances that can act as buffers and can attach to protons to effectively buffer pH.

Vasopressin

Also known as antidiuretic hormone (ADH), a peptide hormone that increases water reabsorption from the collecting duct by increasing the number of aquaporins.

Where is vasopressin or ADH produced and released from?

produced in the hypothalamus and released by the posterior pituitary gland

What is the release of ADH stimulated by?

increasing plasma osmolarity which is detected by osmoreceptors in the hypothalamus

What is the release of ADH inhibited by?

increasing blood pressure which is detected by stretch receptors in atria and baroreceptors in carotid and aortic bodies

How does alcohol impact ADH?

inhibits release of ADH by pituitary cells; acting as diuretic

Diuretic

promotes greater volume of dilute urine production

Aquaporins

Transporters that act like pores, allowing water molecules to move across the membrane. Increased aquaporins in the membrane allow for greater movement of water.

Hypertension

Chronic elevated blood pressure caused by factors such as increased plasma sodium concentration and disrupted kidney function.

ACE inhibitors

Antihypertensive drugs that inhibit the angiotensin-converting enzyme, counteracting the effects of increased renin and angiotensin II.

Angiotensin II receptor blockers

Antihypertensive drugs that act on the angiotensin II receptors, blocking downstream effects of angiotensin II.

Renin-Angiotensin-Aldosterone (RAA) Pathway

A pathway involved in regulating blood pressure, where renin converts angiotensinogen to angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme. Angiotensin II causes the synthesis and release of aldosterone, which increases sodium and water retention.

Aldosterone

A steroid hormone that targets cells in the distal tubule and collecting duct, stimulating sodium and water reabsorption from the filtrate and helping to boost blood pressure.

Vasoconstrictor

A substance that causes constriction of blood vessels, leading to an increase in blood pressure.