Chapter 33: Regulation of Temp & Body Fluids

what temp regulation in endotherms would look like (too cold)....

**normal body temp > temp too cold --> thermo-receptors in hypothalamus, skin and other organs detect temp > Hypothalamus initiates heat-promoting mechanisms. (shivering, blood vessels constrict, voluntary changes in behavior [add clothes], etc.) **back to normal body temp

what temp regulation in endotherms would look like (too high)....

**normal body temp > temp too high --> thermo-receptors in hypothalamus, skin and other organs detect temp > sweating, blood vessels dilate, voluntary changes in behavior (move to shade, etc) **back to normal body temp

Urine formation: secretion....

- Blood also secretes some substances straight into the tubule.

Nephron Structure

- Blood is filtered into a nephron at a GLOMERULAR CAPSULE, which surrounds a tuft of capillaries called a GLOMERULUS. Fluid from blood passes through the filter and enters the RENAL TUBULE.

Nephrons are the structural and functional units of the kidney

- Each kidney contains blood vessels and millions of NEPHRONS, which filter and cleanse the blood.

What three processes occur in urine formation?

- Filtration - Reabsorption - Secretion

Urine Formation The chemical composition of urine reflects 3 processes...

- Filtration - Reabsorption - Secretion.

Hormones regulate kidney function

- Hormones, such as antidiuretic hormone (ADH), regulates kidney function. High ADH levels signal the kidneys to decrease water lost in urine - Aldosterone promotes reabsorption of Na+ into the bloodstream from the nephrons. Water follows by osmosis

Protein Digestion

- Inside the digestive tract, enzymes break down proteins into amino acids. Cells absorb the amino acids - During cellular metabolism, amino groups are stripped from amino acids, forming ammonia.

Strategies to obtain and conserve water on land

- Kangaroo rats, for example, get all their water from food.

Urine in the collecting duct loses water by osmosis.

- Note how the solute concentrations in the medulla surrounding the nephron changes through the length of the tubule. These changing concentration gradients help the nephron return water to the body, which further concentrates the urine.

The Renal Tubule Sections of the renal tube have different names....

- Proximal convoluted tubule - Nephron loop - Distal convoluted tubule A collecting duct receives fluids from several neuphrons.

The production and pathway of urine

- The paired kidneys are the major excretory organs of the urinary system. - As the kidneys cleanse blood, urine forms, which travels through ureters to the urinary bladder. - The body releases urine through the urethra.

Endothermy & ectothermy have advantages & disadvantages

- endotherms maintain body temperature even when the environment is cold, allowing them to be active at all times - ectotherms become inactive when environment is cold - ectotherms use far less energy to maintain body temp, so they require less food than endotherms.

Heat Exchange Mechanisms

- radiation (light waves) - conduction (physical contact) - convection (air mass flow)

Body Fluid Homeostasis & Water & Ions

- urine participates in the regulation of the balance between salt and water inside the body - a process called osmoregulation

The collecting duct

A collecting duct receives the fluids that reaches the end of the tubule. The fluid moves toward the urinary bladder.

Which of the following statements correctly describes endotherms? A. they use energy from metabolism to regulate body temperature. B. invertebrates & fishes are examples C. they lack an internal thermoregulating mechanism D. they may not be able to escape predators when body temp is low E. all of the above is true.

A. they use energy from metabolism to regulate body temperature.

Ectotherms

An animals that warms itself mainly by absorbing heat from its surroundings - all invertebrates - amphibians - fishes - nonavian reptiles

Endotherms

Animals (such as birds or mammals) that can regulate their body temperature. - birds - mammals

Urine Formation: reabsorption....

As the fluid travels through the renal tubule, water and some other substances are reabsorbed into the blood

Which statement about osmoregulation in fish is true? A. Freshwater fish drink more water than saltwater fish B. Freshwater fish have more dilute urine than saltwater fish C. Water leaves freshwater fish by osmosis D. Saltwater fish actively pump ions into their bodies

B. Freshwater fish have more dilute urine than saltwater fish

In the kidney, which substance is least likely to be reabsorbed into the blood in high quantities? a. Glucose b. Ions c. Urea d. Water e. Amino acids

C. Urea

Physiological adaptations help maintain body temp homeostasis in endotherms. A wolf has a physiological adaptation to the cold. there is something called

COUNTERCURRENT EXCHANGE.

Urine Formation: filtration.....

Filtration occurs at the glomerular capsule. Water and dissolved substances move out of the blood into the nephron

Nephron function: a summary

- Recall that cleansing the blood of nitrogenous wastes (urea) is a primary function of the urinary system.

Suppose you own a parrot and a snake and both have exactly the same weight. Should your parrot receive the same amount of food (calories) as your snake each day? - yes - no, the parrot needs more - no, the snake needs more

No, the parrot needs more

The principle of surface-to-volume rational in maintaining body temp homeostasis.

Smaller animals lose heat to, or gain heat from, the environment more quickly than larger animals fo the same shape. Babies are more vulnerable than adults in hot or cold environments. This is a math question for a given shape, the surface area to volume ratio (S/V) is larger when the volume is smaller; larger (S/V) means faster heat loss or gain. ex: if A is smaller than b.... Sa/Va > Sb/Vb

The Peritubular Capillaries

The renal tube is surrounded by PERITUBULAR CAPILLARIES. Salts, water, urea, and many others substances move between the blood and the nephron fluid.

Body fluid homeostasis: The functions of the urinary system

The urinary system filters blood, eliminates nitrogenous wastes, and helps maintain the ion concentration of body fluids.

Which of the following would result in concentrated urine? a. ADH levels are high b. Aldosterone levels are low c. Blood volume is high

a. ADH levels are high

Ectotherms regulate body temp externally.....

an ectotherm thermoregulates by moving to areas where it can gain/lose heat. - body temp varies with external conditions

Endotherms regulate body temperature internally....

an endotherm is able to maintain a constant body temp because heat generated in metabolism balances heat lost to the environment.

Thermoregulation

control of body temperature

The nasal cavities of existing endotherms have a higher....

cross-sectional area than those of ectotherms of equal size. - The nasal cavities of 3 dinosaur species were measured and have a size consistent with the idea that they were ectotherms. - The nasal cavities of existing endotherms have a higher cross-sectional area than those of ectotherms of equal size.

Nasal cavities could be an indicator of...

endothermy

Body temp regulation in endotherms

in endotherms, the hypothalamus detects body temp and initiates responses that warm or cool the body.

A thermostat maintains a comfortable room temperature. Likewise, animals have adaptations that allow them to regulate their....

internal environment.

behavioral adaptations help maintain body temp homeostasis....

mammals have behavioral adaptations to adjust body temp. Huddling conserves heat, whereas panting loses excess heat.

Endothermy requires a high...

metabolic rate and a huge demand for oxygen for respiration. Larger nasal cavities may be needed to accommodate additional air flow.

Animal bodies regulate...

temperature, nutrients, and body fluid composition.

countercurrent exchange

the exchange of a substance or heat between two fluids flowing in opposite directions. - vessels carrying warm blood toward the extremities give heat to vessels carrying cold blood toward the body.

In osmoregulation....

water moves from a solution of low salt concentration to a solution of light salt concentration