Chapter 25: Control of Body Temperature and Water Balance

110 days

How many days can male emperor penguins go without nourishment?

Homeostatic control

Animals can survive fluctuations in the external environment; keep internal temp. and water levels

Thermoregulation

is the homeostatic mechanism by which animals maintain an internal temperature within an optimal range despite variation in external temperature

Endotherms

derive body heat mainly from their metabolism

Ectotherms

absorb heat from their surroundings

conduction, convection, radiation, and evaporation

Heat exchange with the environment occurs by

Ability to adjust metabolic heat production
Insulation
Circulatory adaptations
Evaporative cooling
Behavioral responses

Adaptations for thermoregulation include?

thermoregulate

Coordinated waves of movement in huddles help penguins?

a penguin on the periphery of a huddle remains there

One hypothesis is that huddles are static:

a penguin on the periphery can eventually find itself in the center of a huddle

Alternative hypothesis is that huddles are changing:

osmoregulation

Animals balance their levels of water and solutes through?

Osmoconformers

have body fluids with a solute concentration equal to that of the surroundings

Osmoregulators

have internal solute concentrations that are independent from those of the external environment

into the cell

Where does water diffuse in hypotonic?

out of the cell

Where does water diffuse in hypertonic?

Excretion

is the disposal of toxic nitrogenous wastes

Ammonia

(NH3) is poisonous but soluble and is easily disposed of by aquatic animals

Urea and uric acid

are less toxic and easier to store but require significant energy to produce

forming and excreting urine while regulating the amount of water and solutes in body fluids

The urinary system plays a central role in homeostasis?

Nephrons

extract a filtrate from the blood and refine it into urine?

filtration

blood pressure forces water and many small solutes into the nephron.

reabsorption

water and valuable solutes are reclaimed from the filtrate

secretion

excess H+ and toxins are added to the filtrate

excretion

urine leaves the kidney via the ureters, is stored in the urinary bladder, and is expelled through the urethra

kidney

water-conserving organ , water-conserving organ , water conservation occurs because of a solute concentration gradient in the interstitial fluid

urinary system

Hormones regulate the ?

Antidiuretic hormone (ADH)

one hormone that regulates the amount of water excreted by the kidneys

Hypertension, Diabetes, Prolonged use of common drugs, including alcohol

Kidney failure can result from?

dialysis

machine removes wastes from blood and maintains solute concentration

Loss of heat that occurs as molecules of gas are lost from the surface of a liquid

ex. dog cool itself by panting

Define evaporation?

transfer of heat that occurs as air or liquid moves over a surface

ex. an elephant cooling itself with a breeze blowing across it's large ears

Define convection?

transfer of heat between objects that are in direct contact

ex. goose conserving heat in its body core with countercurrent heat exchange in its legs' blood vessels

Define conduction?

transfer of heat via electromagnetic waves such as sunlight

ex. lizard warming itself by basking in the sun

Define radiation?

endothermic thermoregulation

Some insects use their flight muscles to warm up prior to singing and to regulate their nest temperature. This behavior would be considered an example of

animal that gets most of its body heat from its metabolism

The term endotherm refers specifically to a(n)

reduce the loss of heat to the environment

A countercurrent heat exchanger enables an animal to ?

Feathers can trap a layer of insulating air next to the skin.

How do feathers help thermoregulation by birds?

radiation; conduction

The metabolic heat lost by penguins through convection and __________ is offset by heat gained through __________ due to their huddling behavior.

osmoconformer

An aquatic animal that has the same solute concentration as its environment is a(n) _____.

Because they live in a hypotonic solution, their cells take up an excess of water that must be excreted.

Freshwater fish excrete a large amount of very dilute urine. What is the best explanation for this?

forms solids that are relatively water-insoluble and nontoxic

Many birds, insects, and terrestrial reptiles excrete nitrogenous wastes in the form of uric acid, which __________?

ammonia

Which of the following nitrogenous wastes requires the greatest amount of water to excrete?

urea

The primary nitrogen-containing compound excreted by kidneys of mammals is?

renal pelvis ... ureter ...urinary bladder

Urine formed by a kidney collects in the _____ before being drained from the kidney by the _____ and transported to the _____.

renal arteries

The _____ are the major blood vessels transporting blood to the kidneys.

cortex

The outer part of the kidney is the _____.

more concentrated urine

Under the influence of antidiuretic hormone (ADH), _____ is produced.

collecting duct

Antidiuretic hormone (ADH) makes the _____ permeable to water.

Bowman's capsule

Which part of the nephron is most directly involved in the filtration of blood?

filter the blood and capture the filtrate

In each nephron of the kidney, the glomerulus and Bowman's capsule __________?

filtration

The movement of substances out of the glomerulus and into Bowman's capsule is referred to as _____?

urea (and other nitrogenous wastes)

The most abundant solute in urine is _____.

active transport

Glucose is removed from filtrate by _____.

Feathers can trap a layer of insulating air next to the skin.

How do feathers help thermoregulation by birds?

evaporation

Which of the following helps cool animal bodies?

filtration, reabsorption, secretion, excretion

What is the correct sequence of filtrate processing in the nephron?

It is reabsorbed

What happens to glucose in the filtrate as it passes through the proximal tubule?

reabsorption

What is the main function of the loop of Henle?