Sauropsids & synapsids (15-16) Flashcards
1
Q
What are 2 distinguishing factors of amniotes?
A
- amniotic egg
- waterproof skin
2
Q
What group do the amniotes contain?
A
Most of tetrapods alive today, except amphibians
3
Q
What animals lay amniotic eggs? (5 groups)
A
- turtles
- lizards
- crocodilians
- birds
- monotremes (egg-laying mammals)
4
Q
What is a monotreme?
A
An egg-laying mammal
5
Q
What is a therian mammal?
A
Marsupials and placentals
6
Q
What parts of therian mammals are homologous to certain membranes in the egg?
A
Embyronic membranes that contribute to the placenta
7
Q
Compare amniote skin to amphibian skin
A
Amniotes have thicker skin and a keratinized epidermis (contributing to their relative skin impermeability)
- amniotes also have greater skin elaborations
8
Q
What is the primary factor in waterproofing amniote skin?
A
The presence of lipids
9
Q
Do amniotes or amphibians have greater skin elaborations?
A
Amniotes, like scales, hair, and feathers all formed from keratin
10
Q
How is amniote skin not suited for gas exchange?
A
They use lungs for gas exchange, so the skin does not have to be moist, and cutaneous water loss is reduced
11
Q
What kind of ventilation do amnniotes use?
A
Costal (rib) ventilation of the lungs
12
Q
What kind of ventilation do amphibians use?
A
Buccal pumping
13
Q
What does costal ventilation allow amniotes to do and how?
A
Allows amniotes to develop a long neck. The pressure difference created by rib movement allows them to draw air down a long thin tube (the trachea)
14
Q
What does a long neck in amniotes allow?
A
Allows elaborations of nerves that supply the forelimb. Nerves leave the spinal cord in the neck and join together in a nerve complex called the brachial plexus
15
Q
Is having a flexible shell ancestral or evolved?
A
- Ancestral (persists in many lizards, snakes, turtles, monotremes)
16
Q
Which groups have rigid calcified shells in some examples?
A
Lizards, turtles, all crocodilians and birds
17
Q
What does the shell protect against?
A
Mechanical damage, microbial invasion, water loss
18
Q
Is the shell porous and what does this allow?
A
Yes. It allows some movement of water vapour, oxygen, and CO2
19
Q
What does the yolk supply?
A
Energy supply
20
Q
What do all vertebrates have that enclose the yolk?
A
Extraembryonic membrane(s)
21
Q
What are the 3 additional membranes that amniotes have?
A
Chorion, amnion, allantois
22
Q
What is the chorion?
A
Outer membrane that surrounds entire contents of the egg (allows gas exchange)
23
Q
What is the amnion?
A
Inner membrane that surrounds just the embryo (protects embryo)
24
Q
What is the allantois?
A
Storage place for nitrogenous wastes in the amniotic egg (gets bigger with age)
25
What is the function of the yolk sac?
Encloses a reserve of nutrients, gets smaller with age
26
What are the parts of an amphibian egg?
- outer layer
- perivitelline chamber
- ovum
- yolk
- inner layers
- vitelline membrane (chorion)
27
What are the parts of a reptile egg?
- shell
- albumin
- yolk
- embryo
- amniotic cavity
- extraembryonic membranes (3)
28
What are the parts of a fish and frog egg that are the same? What is different?
Same: nucleus, cell membrane, yolk granules (surrounded by membrane)
Different: FROG egg has jelly coat (gooey protein solution)
29
Are humans amniotes?
Yes
30
What does the endoderm layer become for humans?
- digestive system
- liver
- pancreas
- lungs (inner layers)
31
What does the mesoderm layer become in humans?
- circulatory system
- lungs (epitheleal layers)
- skeletal system
- muscular system
32
What does the ectoderm layer become?
- hair, nails, skin
| - nervous system
33
How are the maternal and fetal blood components conducted in the placenta?
Conducted through the surface of the chorionic villi, but never mix directly
34
The larval form is lost in amniotes- why?
Because the amniotic egg cannot be laid in water, because the gill-less embryo would drown :(
35
How do marine amniotes (turtles, penguins) lay eggs?
Must come to shore to lay eggs, or be viviparous- inside the body (like sea snakes and marine mammals)
36
What are synapsids?
Mammals
37
What are sauropsids?
turtles, lizards, snakes, crocodilians, birds, tuatara (lizard relatives endemic to New Zealand)
38
What is the commonality between synapsids and sauropsids?
Both are amniotes
39
What are amniotic eggs critical to?
Life on land
40
What is the size of amniotic eggs compared to non-amniotic eggs?
Amniotic are large, so they produce larger hatchlings and then adults
41
What are temporal fenestrations?
Large holes in the head
42
What do temporal fenestrations do?
Functions as attachment for jaw muscles
43
How many arches do synapsids have in their skulls?
A single arch
44
How many arches do sauropsids have in their skulls? What does this make them a subgroup of?
Double arches, they are a subgroup of diapsids (have lizard faces)
45
What features evolved independently in both synapsid and sauropsid lineages? (parallel evolution)
- eliminated conflict between resp. system and locomotion for long distance running
- high oxygen consumption
- insulation to retain heat produced by high O2 consumption
- excretory system that eliminates waste while conserving water
46
Why did both synapsids and sauropsids both need to eliminate conflict between resp. system and locomotion?
For long distance running
47
What type of movement did early tetrapods rely on?
Lateral undulations of the trunk (like salamanders and reptiles today). Use limbs and feet for traction
48
Why does the movement style of the early tetrapods only work for short dashes?
Air flows between lungs, but little goes in and out
49
What is the main features of locomotion important for synapsids and sauropsids?
- allows them to hold trunk rigid and use limbs for propulsion
50
What kind of posture do modern synapsids have?
Upright posture
51
What evolved early in the synapsid tree to expand lungs?
Use of trunk/hypaxial muscles to expand lungs
52
Describe the diaphragm
Sheet of muscle separating the bodt cavity into pulmonary and abdominal cavities. Concave when relaxed and flattened when contracted. Developed later
53
What works with the diaphragm to force air in and out of the lungs?
Bounding gait and inertial back and forth movement of the viscera
54
How did sauropsids solve the problem of decoupling locomotion and respiration?
They rely on bipedal locomotion without movements of the trunk
55
Did early sauropsids have a diaphragm? Why or why not?
No, instead they incorporate pelvic movements and ventral ribs into lung ventilation
56
What group shows the early form of sauropsid ventilation?
Crocodilians
57
Describe the early form of sauropsid ventilation, the inspiration step
To inspire: ribs move forward, diaphragmatic muscle pulls liver posteriorly, contraction of ischiopubic muscle.
- increase volume of thoracic cavity
58
Describe the early form of sauropsid ventilation, the expiration step
Rectus abdominus and transverse abdominus rotate pubis dorsally, forcing viscera anteriorly. Diaphragmatic and intercostal muscles relax
59
What kind of lungs do amphibians have?
Simple lung sacs
60
How does the act of sustained locomotion change the need for lungs?
Increased O2 consumption means you need greater surface area in lungs for gas exchange
61
What kind of pattern and lungs do synapsids develop?
Tree-like pattern of branching in lungs ending in cup-like chambers (alveoli) = alveolar lung
62
What kind of pattern and lungs do sauropsids develop?
Many dif. branching patterns, with cuplike chamber lining the walls of the airways = faveolar lung
63
Describe synapsid lungs (3 main points)
- air passes through trachea branching down levels (23) ending in alveoli for gas exchange
- tidal ventilation (in and out same passages)
- elastic recoil of alveoli helps force air out of lungs
64
What is the surface area of alveoli in humans?
70 square metres
65
How many levels of branching are there in birds and crocodilians?
only 3
66
What direction is air flow in sauropsids?
Unidirectional, not tidal
67
What are the big differences in the resp. systems of birds?
- gas exchange structures are not cups, but capillaries w/ crosscurrent ventilation
- air sacs as reservoirs for air so there is unidirectional flow through lung
- 2 resp. cycles for one unit of air through lungs
68
Why do gas exchange surfaces of birds have little expansion or contraction?
- they can then be thinner for more rapid diffusion of gases
- facilitates respiration at high altitudes
69
Describe the resp of birds
Inhalation: air sacs fill
Exhalation: air sacs empty, lungs fill
70
What is the purpose of parabronchi in birds?
allow for one way flow of air through the lungs
71
Where is high blood pressure wanted and not wanted?
- needed in systemic circuit
- bad for delicate lungs
- would push plasma out of capillaries into air spaces (=pulmonary edema)
72
How do amniotes maintain different blood pressures in the pulmonary and systemic circuits?
- do this by separating ventricle into pulmonary and system sides with a septum
73
What do turtles and lizard's septa look like?
Not a permanent complete septum, but form one during ventricular contraction. This is a derived feature- allows them to shunt in dif conditions
74
Why is substantial energy lost as heat?
synthesis and consumption of ATP is not very efficient
75
Why do cheetahs have to end pursuit within a minute?
Overheating (NOT exhaustion)
76
What do endotherms need to retain heat?
- high metabolic rate and insulation
77
What is the metabolic rate difference in small endotherms vs ectotherms?
Endotherms have 10x higher metabolic rate than ectotherms
78
High metabolism evolved with what?
increased locomotion, and then insulation becomes advantageous
79
What is the function of respiratory turbinates?
To warm and moisten air as it enters lungs, and retrieve water and heat from air as it leaves. Helps to conserve body moisture
80
Where are olfactory turbinates (conchae)?
Out of the direct air stream, which is why we sniff when trying to smell
81
High rate of metabolism means high rate of....
waste production
82
Nitrogenous waste is excreted as...? Why is this a problem?
Urine, but this is mostly water and is valuable to waste
83
What is a toxic waste product or metabolism?
Ammonia
84
What can ammonia be converted to?
Urea! Less toxic but even more soluble in water. It can be accumulated in the body and released in a concentrated solution in the urine
85
Urea production is a ancestral characteristic of amniotes. Which group retains this?
Synapsids- they have a kidney very effective in producing concentrated urine (Ureotelism)
86
What have sauropsids developed to convert waste?
Capacity to convert urea to uric acid through costly pathway
87
How do sauropsids use uric acid?
Uric acid is insoluble and combines w sodium and potassium ions to precipitate out of solution as salt. Sauropsids recover the water released when urate salts precipitate (Uricotelism)
88
What is the basic unit of a synapsid kidney?
Nephron
89
What are the basic parts of a nephron?
- glomerulus (filters blood in a long tube)
| - loop of Henle (derived feature of mammals- able to produce highly concentrated urine)
90
Which group is uricotelic?
All extant sauropsids- but they also may facultatively excrete nitrogenous wastes as ammonia or urea.
91
What would concentrating uric cause?
would cause it to precipitate and block the nephrons (this is why kidneys of reptiles and birds lack loops of Henle
92
When does uric acid precipitate?
When it enters the cloaca or bladder- means urine becomes less concentrated and water can be absorbed back into body
93
How are ions excreted in sauropsids?
as crystallized salt or tears- through salt glands in nasal, sublingual, upper jaw regions. This is a highly efficient way of eliminating salts without losing water
94
What are the strong and weak senses in synapsids?
Highly sensitive to odours, but poor vision (primates are the exception)
95
What are the strong and weak senses in sauropsids?
good vision, poor smell
96
What is the size difference between amniote and amphibian forebrains?
Amniote brains are relatively enlarged
97
Larger animals tend to have what size of brains?
Proportionally smaller brains- bigger bodies don't need more brain tissue
98
What do a greater number of neurons allow for?
More connections and complexity or behaviour
