Vert Zoo- chapter 10- Excretion & Reproduction

What is the basic principle guiding the function of excretory organs?

To maintain a constant internal environment

What must happen to materials brought into the body according to the excretory principle?

They must be balanced by an equal amount removed

The major functions of the excretory system is to:

(theres 4)

1. Maintain solute concentrations

2. Maintain body volume (water)

3. Removal of metabolic waste

4. Removal of foreign substances

Despite their differences, what can the basic principles of excretion be reduced to?

Ultrafiltration and active transport

What does ultrafiltration rely on to move fluid through a membrane?

Pressure

What type of molecules are withheld during ultrafiltration?

Proteins and other large molecules

Which molecules can pass through the semipermeable membrane in ultrafiltration?

Water and small solutes

What powers active transport in biological membranes?

ATP

Solutes can move into the filtrate

secretion

Solutes can move out of the filtrate

reabsorption

the movement of solutes against their concentration gradients by membrane bound proteins that get energy from ATP.

active transport

pressure forces a fluid through a

semipermeable membrane that withholds

proteins and similar large molecules but allow

water and small molecular solutes (salts, sugars,

amino acids) to pass.

ultrafiltration

excretory organs can be classified into a small number of functional types which are:

Generalized Excretory Organs

Specialized Excretory Organs

what are Generalized Excretory Organs?

Kidneys

what are Specialized Excretory Organs

Gills

rectal glands

salt glands

the liver

What are the three main processes involved in vertebrate kidney function?

Ultrafiltration, reabsorption, tubular secretion

What does the initial ultrafiltrate contain?

All blood solutes except large organic molecules

Why is reabsorption necessary in vertebrate kidneys?

To conserve essential compounds

Which of the following is not listed as an essential compound that must be conserved?

A. Glucose

B. Amino acids

C. Vitamins

D. Proteins

D

What percentage of filtered fluid is typically reabsorbed in a filtration-reabsorption kidney?

More than 99%

What happens to a substance that is filtered but not reabsorbed?

It remains in the urine

Why can organisms eliminate new substances without special mechanisms?

Because filtered substances stay in urine unless reabsorbed

What types of urine can all vertebrates produce?

Hypotonic or isotonic

Which vertebrate groups can produce urine that is hypertonic to body fluids?

Birds and mammals

The general structure of the kidney is the

_________ in all vertebrate groups, with a slight

modification in _______ ______ _____.

1) Same

2)birds and mammals

What are the functional units of the kidney called?

Nephrons

What structure does each nephron begin with?

Malpighian body

What process occurs in the Malpighian body?

Ultrafiltration of blood

What is the name of the capillary bundle inside the Malpighian body?

Glomerulus

What forces fluid out of the glomerular capillaries?

Blood pressure

Where does the glomerular filtrate go after leaving the Malpighian body?

Into a tubule

What two processes modify the fluid in the tubule?

Reabsorption and tubular secretion

What is reabsorbed in the proximal tubule?

Water, salts, and glucose

What is the role of the distal tubule?

To continue transforming filtrate into urine

What do distal tubules eventually form?

Collecting ducts

What separates the proximal and distal tubules in birds and mammals?

Henle's loop

What is the function of Henle's loop?

To concentrate urine beyond blood levels

In which vertebrate groups is Henle's loop found?

Birds and mammals

What type of nephron do most teleost fishes have?

Typical vertebrate nephron

What is the osmotic relationship of freshwater fish to their environment?

Hypertonic to the medium

How do freshwater fish handle excess water?

Eliminate it easily via the kidney

Why do marine teleosts produce very little urine?

They face water shortage

What is the kidney's major role in marine teleosts?

Excretion of ionic salts, Mg, and SO₄

Where do most amphibians live?

In or near fresh water

What happens when amphibians are in water?

They experience osmotic influx and eliminate excess water in urine

How do amphibians compensate for salt loss?

Active uptake through the skin

How is urea eliminated in frog kidneys?

By glomerular filtration and tubular secretion

Why is dual urea elimination beneficial for frogs?

It helps in dry environments

What type of kidney do reptiles have?

Typical vertebrate kidney

What kind of urine do freshwater reptiles produce?

Dilute urine

How do marine and terrestrial reptiles conserve water?

By excreting nitrogenous waste as uric acid

What is true about uric acid in reptile urine?

It is insoluble and precipitates in urine

How is urine expelled in marine and terrestrial reptiles?

As a paste or pellet

Which vertebrate groups can produce hypertonic urine?

Birds and mammals

How pronounced is the ability to concentrate urine in birds?

About 2× blood plasma concentration

What is the maximum urine concentration in mammals compared to blood plasma?

Up to 25×

What mechanism allows ultra-concentrated urine formation?

Geometric arrangement of the renal tubule

What are the gonads in the reproductive system?

Ovary and testis

What do the gonads produce?

Gametes and hormones

What do reproductive hormones facilitate?

Sexual behavior and parental care

What do hormones prepare in the reproductive system?

The ducts to receive gametes and support the zygote

What is the role of the ducts in the reproductive system?

Transport gametes

What do ovaries produce in vertebrate females?

Hormones and mature ova

Through what process are ova produced?

Oogenesis

Where are ovaries suspended from in the body?

Dorsal wall of the coelom by a mesentery

In most vertebrates, how are ovaries arranged?

Paired

Which of the following groups may have unpaired ovaries?

Cyclostomes,

some reptiles,

most birds,

some bats

the platypus

Where are eggs moved after ovulation?

Into the oviduct

What happens during internal fertilization?

Sperm and egg meet almost immediately

What happens during external fertilization?

Ova are driven out of the body for fertilization

n most mammals the walls of the uterus establish a

close vascular association with the embryo through

the _______

placenta

How are testes typically arranged in vertebrates?

Paired and suspended from the dorsal wall of the coelom by mesentery

Where do the testes descend in most mammals?

Into the scrotum, suspended outside the body

What are the two main functions of the testes?

Sperm production and hormonal secretion

What structure transports sperm in tetrapods?

Ductus deferens