Transcript MAMMALOGY AS A SCIENCE

VERTEBRATE ZOOLOGY
(VZ Lecture15 – Fall 2012 Althoff - reference PJH Chapter 11)
Synapsids & Sauropsids
Beyond Amphibians….
• Two distinct lineages have emerged from the
early division of amniotes:
____________ (Sauropsida)
turtles, lepidosaurs, and birds
(snakes, lizards, tuatara,
crocodiles)
_____________ (Synapida)
mammals
Sauropsids and Synapsids
• Major advances, over vertebrates already
reviewed, include…
Sustained locomotion
Sustained locomotion in conjunction with
improved external respiration
Improved cardiovascular system
Improved use of “metabolic energy”
Improved handling of metabolic waste resulting
in retention of water
Great examine question here…”What were major
improvements over vertebrates already examined
this semester? Here’s your list !!! …for starters 
Sustained locomotion
• Amphibians cannot go fast for long…
• To sustain running, muscles require steady
•
•
supply of O2
Lateral undulations of the trunk, as salamanders
& lizards exhibit when running—with don’t lend
themselves to maximum utilization of lung
capacity because bending the trunk for
locomotion and compressing the rib cage
bilaterally to ventilate the lungs cannot happen
_____________________.
Synapsids and most sauropsids have developed
modes of locomotion that allow the trunk to be
held rigid and limbs to provide major propulsion
TRUNK NOT RIGID
+
+
+
Fig. 11-1, p266 PJH
TRUNK RIGID _______________
_____________________________
Sustained Locomotion & Synapsids
• “Resolution” in the conflict between locomotion
•
and external respiration…
_______________, a derived feature, was a
major improvement in overcoming limited ability of
trunk muscles to reduce pressure that draws air
into the lungs
a) sheet of muscle that separates body
cavity in anterior portion (pulmonary
cavity) and posterior portion (abdominal
cavity)
b) is convex when relaxed and flattens when
contacted…flattening increases the
volume of the pulmonary cavity, creating
much more negative pressure
…and
• The diaphragm, in conjunction with the
simultaneous contraction of the hypaxial muscles
pulls the ribs forward and outward.
• Very important:
the movements of the diaphragm
____________ conflict with locomotion
Better!!!!
• This is how it “worked out” for the synapsids
Sustained Locomotion & Sauropsids
• “Resolution” in the conflict between locomotion
•
•
•
and external respiration handled a little differently
for this group…
For some “later’ dinosaurs and birds, ________
locomotion involves only the hind limbs without
movements of the trunk.
Sauropsids lack a diaphragm
Crocodile “design” results in them hyperventilating
to achieve. This is achieved by:
1) movement of the ribs
2) movement of the liver
3) rotation of the pubic bones
2-
INSPIRATION
 FRONT
31EXPIRATION
2
 FRONT
3
1
Fig. 11-3, p269 PJH
Some Sauropsids…
• For lizards, when they move respiration almost
•
ceases.
This limits both the speed and distance they can
travel…..
Thus, “____________” locomotion and
respiration allowed more advanced
tetrapods to move farther and faster
Some Sauropsids…
Diaphragm
appeared
disappeared
Gastralia appeared
(ventral ribs)
Fig. 11-5, p271 PJH
Improvements in Lung Design
• Went from “simple” lungs  complex lungs
•
MAIN RESULTS: significantly increased
_____________ for gas
exchange
Two basic “new” designs:
___________ Lungs  synapsid
___________ Lungs  sauropsid
Ancestral lung (amphibian)
Alveolar lung
“________”
Faveolar lung
Fig. 11-6, p272 PJH
“________” flow
FIRST CYCLE
expiration
inspiration
SECOND CYCLE
expiration
inspiration

Improvements in Cardiovascular Design
• Chicken-and-egg scenario here, sort of…
• With increased lung capacity (i.e., better
•
ventilation systems, higher surface-to-volume
ratio achieved in aveloar and faveolar lungs), now
more potential for gas exchange during external
respiration…but also need concurrent
improvement in cardiovascular design, mainly in
the form of a….
Powerful HEART that can produce enough
pressure to move blood quickly—mainly to the
systemic circuit (not necessary for the pulmonary
circuit) but…..
Stronger Heart, Permanent Septum
• Birds and mammals:
•
•
•
permanent septum 
Presence of __________ that provided complete
separation forming ventricles (atria already separated
in amphibians)
This change was derived in separate lineages
with slight differences.
For turtles and lizards, there is not a permanent
septum, but there is a muscular ridge in the
interior of the ventricle helps separate systemic
and pulmonary flows…and with this design they
can shunt blood between the two circuits in
response to changing conditions
Fig. 11-11 on pg283 (PJH) provides overview of
early amniote, mammal-like reptile, mammal,
crocodile, and bird cardiovascular combinations
Endothermy
• Increased locomotion (activity), increased
•
•
respiration (activity), increased
cardiovascular output (activity)—besides
increasing endurance of synapsids and
sauropsids—also produced lots of ______.
Heat was byproduct of cellular respiration
(i.e., burning ATP molecules).
Use of this “wasted energy” (i.e., heat) that
resulted in higher metabolic rates was
retained with the addition of a layer of
______________ (fur or feathers)
Rate of Reaction
(product per unit of time
What effects
enzymes?
Temperature 0C
Endothermy…some other changes
• Besides the insulation “factor”….
• Air that was inhaled would be dry and
cooler than the internal body
temperatures…so ___________________
needed to warm and moisten air. For
mammals the nasal passages have
turbinates covered with moist tissues. The
____________________ serve the ‘nasal’
passage (respiration). The nasoturbinates
serve the “olfactory” passage (smell).
Nasoturbinates
Maxilloturbinates
nasal passage
Fig. 11-12, p283 PJH
Conserving H2O & Getting Rid of
Metabolic Waste
• A cost of a higher metabolic rate (to realize
•
locomotor endurance and thermoregulation)
is __________ metabolic waste
Higher metabolic waste = high rates of
nitrongeous waste...different approaches for
handling have evolved
a) ammonia – most toxic
b) convert ammonia to urea—less toxic
c) some processes produce uric acid
 precipitated out as salts
Urine or Uric Acid?
• Sauropsids  produce _______….water is
•
recovered when uric acid is precipitated out
Synapsids  produce highly concentrated
______…urine formation process
conserves water and is accomplished in the
highly developed kidneys
Human Kidney- NEPHRON
•
•
•
•
Functional unit of the kidney
1,000,000 per kidney
Actually produces urine
Transerves the renal cortex and renal
medulla
• Very detailed structurally speaking
KIDNEY is “the”
functional unit
of the urinary system
Kidney MACROanatomy
• Blood supply
• Cortex
• Medulla
• Renal Pelvis
Kidney MICROanatomy
• Nephron
Nephron Detail
Afferent arteriole
Efferent arteriole
GLOMERULUS
Glomerular capsule
Proximal convoluted
tubule (PCT)
Loop of the Nephron
Distal convoluted
tubule (DCT)
Collecting duct
GLOMERULAR
FILTRATION
URINE
FORMATION
GLOMERULAR
FILTRATION
TUBULAR
ABSORPTION
TUBULAR
SECRETION
And….then there
is urine
Glomerular FILTRATION
• Blood is “filtered” (but typically only things
_____________…not formed elements of blood)
• Filtrate is one-way….balance of blood moves on
through blood vessel
• Blood in urine “happens” here….before it gets to
the bladder…. BAD!!!!
Tubular REABSORPTION
• _______ taken out of urine (was part of blood
that “filtered out” (60-70%)
• ________ (salts) taken out (think….osmosis
process here) (60-70%)
• Urine becomes more and more
_______________
Tubular SECRETION
• ________ secreted from blood  DCT (distal
convulated tubule)
• ________ etc. Secreted from blood  DCT
(active transport!!!)
• NaCl could be reabsorbed here ??? (if low in
concentration)
• _______ still being taken out of urine, becomes
more and more concentrated
1
3
2
4
Processes and materials “moved”
Osmosis
• H2O
Diffusion
• Urea
• NaCl
Active Transport
• NaCl
• Nutrients
•
•
•
•
Drugs
K+
H+
NH3
The KING of minimizing H20 loss
from the process of urine formation!
________________________ (Dipodomys sp.)