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Animal Processes (Osmoregulation & Excretion (Excretion (Excretory…
Animal Processes
Osmoregulation & Excretion
Osmoregulation
Def:
The process by which animals control solute concentrations & balance water gain & loss
Excretion
Def:
The process of releasing metabolic wastes from the body
Excretory processes
#
1) Filtration
The excretory tubule
collects a filtrate
from the blood but
BLOOD CELLS ARE NOT FILTERED THROUGH!!!
Fun:
H2O & solutes
are forced by blood pressure across the
selectively permeable membranes
of a cluster of capillaries and into the
excretory tubule
H2O & metabolic wastes that are small enough go through the filter
Includes:
NaCI, H2O, sugars, & amino acids
2) Reabsorption
The
transport epithelium reclaims
valuable
substances
from the
filtrate & returns them to the body fluids
The body is
reabsorbing minerals
that are needed
Class dis:
Reabsorbing the things that we want to keep
Figure 44.8
Steps of Excretory system function
3) Secretion
Other substances like
toxins & excess ions
are
extracted from the body fluids
&
added to the contents
of the
excretory tubule
Class dis:
Secretion deals with things that didn't get filtered the first time
4) Excretion
The
altered filtrate (urine) leaves
the system & the body
Getting
ride
of the
metabolic waste
From
blood filtrate -> urine
in the nephron
Proximal convoluted tubule
#
Reabsorption
here is critical for the
recapture of ions, H2O, & nutrients
from a volume of filtrate
NaCI
in the filtrate enters the cells by
facilitated diffusion
Epithelial cells
actively transport Na+
into the
interstitial fluid
Which drives
passive
transport of
CI-
As
NaCI
moves from the
filtrate
-> the i
nterstitial fluid
, H2O follows by osmosis
Glucose, amino acids, potassium ions
, & other substances are
actively or passively
transported from filtrate -> the
interstitial fluid
As
filtrate passes
through the
proximal tubule
, materials to be excreted become
concentrated
MAIN IDEA:
Many wastes leave the body fluids
during the non selective filtration process & remain in the filtrate while
H2O & salts are reabsorbed
Descending limb
Reabsorption of H2O
continues as the filtrate moves into the
descending limb
There are almost no channels for salt & other solutes resulting in
low permeability
The
interstitial fluid
must be
hyperosmotic to the filtrate
in order for
H2O
to move out by
osmosis
MAIN IDEA:
The
filtrate loses H2O
&
increases in solute concentration
all the way down the descending limb
Class:
The medulla of the kidney is hypertonic to the filtrate
Ascending limb
NaCI diffuses out
of the permeable tubulei into the interstitial fluid
NaCI
moves
out
of the
filtrate
The epithelium
actively transports NaCI
into the
interstitial fluid
Distal convoluted tubal
#
Regulates K+
&
NaCI concentration
of body fluids
Contributes to PH regulation by controlled
secretion of H+
&
reabsorption of HCO3
Collecting duct
#
Carries
the
filtrate through the medulla
to the renal pelvis
Final processing
of the
filtrate
by the transport epithelium of the
collecting duct forms the urine
Excretory systems
Prontonephridia
Def:
Units of a networks of dead-end tubules
Found:
In flatworms
Made of
a tube of cillia that filtrates & releases urine
Metanephridia
Def:
Excretory organs that collect fluid directly from the coelom
Found:
In earthworms & most annelids
Cilliated funnels
surrounds the
internal opening
of each metanephridium
Malpighian tubules
Def:
Remove nitrogenous wastes that also function in osmoregulation
Found:
In insects & other terrestrial arthropods
They filter
hemolymph
Kidneys
Found:
Chordates & vertebrates
Def:
Functions in both osmoregulation & excretion
Full of
nephrons
Forms of nitrogenous waste
Def:
A nitrogen combined w/other molecules to produce toxic compounds that animals excrete
The
3 forms
of
nitrogenous waste
Ammonia
Can only be tolerated at low concentrations & requires plenty of H2O in order to be excreted
Most common
in aquatic animals
EX:
Most bony fish
Class discussion:
Ammonia is diluted quickly in water: consequently it's seen in many aquatic animals
Class:
You need a nitrogen fish filter in a tank so ammonia can be filtered out & the fish doesn't die
Class:
The filter converts nitrogen into something harmless
Urea
Urea
is less toxic than ammonia & it has a high energy cost
Excreted by
mammals, most amphibians, sharks, & some bony fish
The trade off:
Less toxic than ammonia but more energy required to produce urea. It goes through extra steps to convert ammonia into something less toxic
Uric acid
Uric acid
does not dissolve in water & is relatively nontoxic
Excreted by
birds, many reptiles, insects, & land snails
The trade off:
Uric acid is more energetically expensive than urea, requiring more adenosine triphosphate for synthesis from ammonia
EX:
Birds go through this process to conserve H2O
Circulation & Gas Exchange
Organization of circulatory systems
The circulatory systems
3 parts
Muscular pump (Heart)
Fun:
The heart powers circulation by using metabolic energy - elevate the circulatory fluid's hydrostatic pressure
Circulatory fluid
Fun:
The pressure the fluid exerts on the surrounding vessels
A set of interconnecting vessels
Fun:
The fluid the flows through the vessels & back to the heart
3 Main types of blood vessels
With each type, blood flows in one direction
Capillaries
Fun:
Any of the fine branching blood vessels that form a network between the arterioles and venules
Capillary beds fun:
Infiltrate tissues, passing within a few cell diameters of every cell in the body
Veins
Vanules fun:
A very small vein, especially one collecting blood from the capillaries. Capillaries converge into venules & venules converge into veins
Portal veins fun:
Carry blood between pairs of capillary beds
Hepatic portal veins fun:
Carries blood from capillary beds in the digestive system -> capillary beds in the liver
Fun:
Vessels that carry blood back -> the heart
Difference
between an
artery
&
vein
Arteries:
The
walls
of arteries are
thick & strong
, accommodating blood pumped at
high pressure
by the heart. They are also
elastic
Veins:
B/c veins convey blood back to the heart at a
lower pressure
, they
don't require thick walls
. A vein's wall is around a 1/3 as thick as that of an artery. Unlike arteries, veins
contain valves
, which maintain an unidirectional flow of blood
Arteries
Arterioles fun:
Arteries branch into arterioles within the organs & convey blood -> capillaries
Fun:
Carry blood from the heart -> organs
Heart chambers
The hearts of all vertebrates contain 2 or more muscular chambers
Atria
Fun:
Chambers that
receive blood
entering the heart (singular atrium)
Ventricles
Fun:
Chambers responsible for
pumping blood out
of the heart
Single & Double circulation
Double
Def:
The circulatory system goes through 2 circuits (The pumps for the 2 circuits are combined into a single organ, the heart)
EX:
Amphibians, Reptiles, & mammals
Single
EX:
Bony fishes, rays, & sharks (The heart consists of 2 chambers: an atrium & a ventricle)
Def:
The blood passes through the heart once in each complete circuit through the body
Close vs. opened circulatory systems
Opened
Def:
Blood is not confined in vessels. The circulatory fluid hemolymph is also the interstitial fluid that baths body cells
EX:
Arthropods (Grasshoppers) & some mulluscs (Clams)
Closed
Def:
Blood circulates -> & from <- the heart through a network of vessels. Its distinct from the interstitial fluid
Often called the Cardiovascular system
Mammalian Circulation
Beginning with the pulmonary circuit
1) Contraction of the right ventricle pumps blood to the lungs via 2) the pulmonary arteries
3) As blood flows through capillary beds in the left & right lungs, it loads O2 & unloads CO2
4) Oxygen-rice blood returns from the lungs via the pulmonary veins to the left atrium of the heart
5) The oxygen-rich blood flows into the heart's left ventricle, which pumps the oxygen-rich blood out to the body tissues through the systemic circuit
6) Blood leaves the left ventricle via the aorta, which conveys blood -> arteries leading throughout the body. The first branches leading from the aorta are the coronary arteries (not shown in book), which supply blood -> the heart muscle itself
7) Then branches lead -> capillary beds in the head & arms (forelimbs). The aorta then descends into the abdomen, supplying O2-rich blood -> arteries
8) Which leads to capillary beds in the abdominal organs & leg. Within the capillaries, there is a net diffusion of O2 from the blood -> the tissues & of CO2 (produced by cellular respiration) into the blood. Capillaries rejoin, forming venules, which convey blood -> veins
9) O2-poor blood from the head, neck, & forelimbs is channeled into a large vein, the superior vena cava. Another large vein, 10) the inferior vena cava, drains blood from the trunk & hindlimbs
11) The 2 venae cavae empty their blood into the right atrium, from which the O2-poor blood flows into the right ventricle
Cardiac Cycle
Def:
One complete sequence of pumping & filling
Phases
of the cycle
Systole
The contraction phase
Diastole
The relaxation phase
Cardiac output
Def:
The volume of blood each ventricle pumps per minute
2 Factors determine cardiac output
The rate of contraction -
Heart rate
Number of beats per minute
Stroke volume
The amount of blood pumped by a ventricle in a single contraction
Can be calculated by
2 numbers
Heart rate
Stroke volume
