6.2A Animal Homeostasis I

Homeostasis

Balancing and rebalancing of physiological processes that maintain stability in the normal internal state of the body in response to disturbance.

Osmoregulators

An organism that is able to adjust their internal osmolarity through excretion and absorption of ion.

Osmoconformers

An organism that does not actively adjust their internal osmolarity and have fluids isotonic to their environment.

Euryhaline

An organism that can tolerate a wide range of salinities.

Stenohaline

An organism that can only tolerate a limited range of osmolarity.

Convection

Transfer of heat by flow of air.

Radiation

Transfer of heat by electromagnetic waves and emission of heat.

Conduction

Transfer of heat by contact with another surface.

Evaporation

Transfer of heat by the change of a substance from a liquid to a gas.

Metabolic water

Water produced inside a living organism through their oxidation of energy-rich materials.

Simple Diffusion

A type of diffusion used by Deuterostome echinoderms to excrete waste via water vascular system across the thin layers of their tube feet and papulae.

Direct Diffusion

A type of diffusion used by Protostome cnidarians with high water contents in their body to excrete waste through their epidermis or gastrodermis.

Contractile Vacuole

A cell structure that is not a true excretory organ but is used for water balance and excretion since many wastes dissolve in water.

Protonephridia

An excretory system common to flatworms and rotifers wherein fluid enters through flame cells and is moved to tubule cells where water and solutes are resorbed. Then, wastes are expelled through excretory pores.

Metanephridia

An open system excretory organ common to annelids and mollusks.

Antennal Glands

An organ located in the head of crustaceans, the end sac collects fluid from the blood.

Malpghian Tubules

An organ located at the juncture of the midgut and hindgut that serves as a site of resorption of important solutes and water.

Archinephros

First form of kidney found in embryo of hagfish. It is the ancestral condition of the vertebrate kidney.

Pronephros

Second form of a kidney that is functional in adult hagfish, some bony fish species, embryonic fishes, and amphibians while for embryonic reptiles, mammals and birds, this is a fleeting form of kidney. Humans start with this.

Mesonephros

Third form of a kidney that is short-term in embryonic lampreys, fishes, amphibians, reptiles, birds and mammals.

Metanephros

Fourth possible form of a kidney developed from Mesonephros that is functional for adult reptiles, birds and mammals. Humans have this kidney.

Opisthonephros

Fourth possible form of a kidney developed from Mesonephros that is functional for adult lampreys, fishes, and amphibians.

Kidney

The principal organ that is retroperitoneal (attached to back of body) and regulates volume and composition of internal fluids.

Nephron

The microscopic functional unit of the kidney that performs filtration of fluids (blood) and electrolyte concentration.

Renal Capsule

Part of a kidney that serves as covering, protection which helps encase the kidney. It is made of fibrous tissues for sheathing.

Cortex

Part of a kidney where most nephrons are located and filtration of blood occurs via the renal corpuscles.

Medulla

Part of a kidney that is located in the deepest portion and functions to control salt and water balance of animals via tubules.

Cortical Nephron

Type of nephron located almost entirely in the renal corpuscle in the cortex. (Superficial). Has a shorter loop of Henle.

Juxtamedullary Nephron

Type of nephron located low in the renal cortex near the medulla. (Deep). Has a longer loop of Henle that extend deeply into the renal medulla

Glomerulus

A ball of capillaries surrounded by Bowman's capsule in the nephron and serves as the site of filtration in the vertebrate kidney.

Peritubular Capillaries

A type of blood vessel associated with the cortical components of the nephron which resorbs water and materials from glomerular filtrate, secretes ions and excess water into proximal convoluted tubule.

Vasa Recta

A type of blood vessel associated with the medullary components of the nephrons. Has a descending and ascending portion.

Descending Vasa Recta

Part of the vasa recta which resorbs sodium chloride and urea into the blood while secreting water.

Ascending Vasa Recta

Part of the vasa recta which secretes sodium chloride and urea into the interstitium while resorbing water.

Renin-Angiotensin System

A system that controls loss of water and sodium as well as concentrating the urine. It is associated with blood pressure regulation by modulating blood volume, sodium reabsorption, potassium secretion, water reabsorption, and vascular tone.

Poikilotherm

Pertains to organisms whose body temperature fluctuates in response to environmental temperature.

Homeotherm

Pertains to organisms whose body temperature is regulated independently of changes in environmental temperature.

Ectothermy

Type of body temperature regulation that relies on behavioral adaptation to exploit temperature changes in the environment. Metabolic heat is lost as quickly as it is gained.

Endothermy

Type of body temperature regulation in which metabolic heat generated is retained to maintain a high stable internal temperature.

Thermogenesis

Generation of internal heat through shivering and non-shivering mechanisms.

Torpor

State of decreased physiological activity in an animal like birds to save energy.

Hibernation

Response to extreme cold in which animals depress their metabolism, cardiovascular and respiratory weight which allows them to survive on stored body fat.

Aestivation

Response to extreme heat in which animals burrow themselves underneath the ground to conserve as much moisture.