Exam 4 Flashcards
(115 cards)
1
Q
animals are ______, ________ eukaryotes with ______ that develop from embryonic ________
A
multicellular, heterotrophic, tissues, layers
2
Q
what several characteristics when put together define the animal kingdom
A
Nutritional mode:
- Heterotrophic. No photosynthesis (not a plant)
- internal digestion (not a fungus)
Cell Structure and specialization:
- multicellular eukaryotes
- cells do not have cell walls
- specialized tissues (esp nervous and muscle) that develop from layers
Reproduction:
- Sexual reproduction
- sperm and eggs directly by meiotic division
- often larval stages
3
Q
Early embryonic development in animals
A
- Zygote of an animal undergoes a series of mitotic cell divisions called cleavage
- An 8 cell embryo is formed by three rounds of cell division
- In most animals, cleavage produces a multicellular stage called a blastula.
- Most animals also undergo gastrulation
- the pouch formed by gastrulation (archenteron) opens to the outside via the blastopore
- the endoderm of the archenteron develops into the tissue lining the animals digestive tract
4
Q
what is a blastula
A
a hollow ball of cells that surround a cavity called the blastoceol
5
Q
what is gastrulation
A
a process where one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing layers of the embryonic tissues; the ectoderm and the endoderm
6
Q
larva
A
larva is sexually immature and morphologically and behaviorally distinct from the adult stage. Most animals have at least one larval stage. Larva may even have a different habitat than the adult. They will undergo metamorphosis where they become juveniles that resemble adults but are sexually immature.
7
Q
what are the developmental genes that regulate the expression of other genes that all animals have called
A
hox genes
8
Q
animals are more closely related to what than plants
A
fungi
9
Q
morphological and molecular data indicates that protists called what are the closest living relatives to animals
A
choanoflagellates
10
Q
multicellularity requires cells to do what
A
adhere and signal to each other.
animal genes involved in adherence have sequence similarities in choanoflagellates
11
Q
Timeline of animal development
A
Neoproterozoic era: - chemical evidence - ediacaran biota Paleozoic Era: - cambrian explosion - anthropods to land - vertebrates to land Mesozoic Era: - age of reptiles Cenozoic Era: - age of mammals (current day)
12
Q
Neoproterozoic Era
A
- Chemical evidence of steroids used by sponges has been found in 710 million year old sediments
- Molecular analysis suggests the common ancestor animals likely lived about 770 million years ago
- Ediacaran biota the first macroscopic animals
- Possible predation
13
Q
Paleozoic Era
A
- the cambrian explosion marks a period of rapid animal diversification
- most fossils from cambrian explosion are bilaterians (bilateral)
- land colonization: anthropods and vertebrates
14
Q
Mesozoic era
A
- coral reefs- huge influence on marine habitat
- reptile diversification. Dinosaurs emerged as dominant predators and herbivores
- mammals (tiny nocturnal insect eaters) appeared
- flowering plants and insects diversified
15
Q
cenozoic era
A
- beginning of this era followed mass extinctions of both terrestrial and marine animals
- dinosaurs and marine reptiles extinct
- mammals increased in size and abundance
- the primate diversification
16
Q
how can animals can be characterized by body plans
A
- symmetry: 3 types (radial, bilateral, or asymetric)
- Tissues layers (2 or 3)
- Body cavities (3 types)
- protosome and deuterostome development
17
Q
Body cavities
A
- most triploblastic animals have a body cavity (a few don’t) a fluid or air filled space between the digestive tract and the outer body wall
- Body cavities have many functions:
- The internal fluid cushions the suspended organs
- The fluid can act like a skeleton against which the muscles of soft bodied animals can work
- The cavity enable internal organs to grow and move independently of the outer body wall
- compact (no body cavity), Hemocoel, or coelom
18
Q
protostome and deuterostome development
A
- Bilateral animals can be catergorized as having one of two developmental modes: protostome development or deuterostome development
- these modes differ in cleavage, coelom formation, and fate of the blastopore
19
Q
Cleavage in protostome development vs. Deuterostome development
A
Protostome development: - spiral cleavage - determinate cleavage Deuterostome development - Radial cleavage - indeterminate cleavage
20
Q
radial symmetry
A
body parts are arranged around a single main axis that passes through the center of the animal. Axis divides the body into mirror images
21
Q
bilateral symmetry
A
body parts of the animal are arranged around two axes of orientation, the head-tail axis and the dorsal-ventral axis. Only one imaginary slice divides the animal into two mirror images referred to as the left and right sides
22
Q
fate of blastopore in protostome vs deutersostome development
A
- blastopore is an indentation in the gastrula that leads to the formation of the archenteron
- the blastopore and second opening at the opposite end will form the mouth and anus: in protostomes the blastopore becomes the mouth. In dueterostomes the blastopore becomes the anus
23
Q
what are several data sources used to infer evolutionary relationships among the three dozen extant animal phyla
A
- morphological traits
- whole genomes
- ribosomal RNA (rRNA) genes
- Hox genes
- protien coding nuclear genes
- mitochondrial genes
24
Q
the 5 key ideas about phylogeny of living animals
A
- All animals share a common ancestor: that animals are monophyletic, forming a Metazoa clade, meaning they all have descended from a common ancestor
- Sponges are the sister group to all other animals: sponges are basal animlas that diverged from all other animals early in the history of the group
- Eumetazoa is a clade of animals with tissues:
All animals except for sponges and a few others belong to a clade of eumetazoans. They have tissues such as muscle tissue and nervous tissue - Most animal phyla belong to the clade bilateria:
bilateral symmetry and the presence of three prominent germ layers are shared derived characteristics defining the clade bilateria. - There are 3 major clades of bilaterian animals:
Biliaterians have diversified into 3 main lineages: deuterostomia, lophotrochozoa, and ecdysocoa.
25
sponges (porifera)
basal animals that lack tissues
do not undergo gasturlation
sedentary and radial symmetry
filter feeders: pores --> spongocoel ---> osculum
Flagelluym = flow
choanocytes and amoebocytes
Reproduction: sequential hermaphroditism. Mobile, falgellated larvae
26
Cnidaria
Eumetazoans, animals with true tissues
gastrula --> diploblastic
Radial symmetry, gastrodermi with single opening
Medusa/polyp sensory structure
muscles
Two major clades: Medusozoa and Anthozoa. Medusozoa forms alternate polyp and medusa. Anthozoa is polyp only
27
lophotrochozoan
- Flatworms: freeliving, termatodes, tapeworms
- Rotifers
- Ectoprocts & Brachiopods
- Molluscs: gastropods, bivalves, cephalopods
- Annelids
28
Flatworms
Phylum Platyhelminthes includes flatworms which are dorsoventrally flattened and have no body cavity
Single opening digestive system
free-living and parasitic species
Parasitic flatworms: trematodes, tapeworms
29
Rotifers
- Flow-through alimentary canal ( finally have an anus which is a big step forward because of flow through digestive system)
- specialized organ systems
- body cavity (hemocoel)
- parthenogenesis is common: asexual reproduction unless they are stressed then sexual reproduction begins
30
ectoprocts and brachiopods
ectoprods and brachiopods share several traits:
- a lophophore is used for feeding
- a u-shaped alimentary canal
- the absence of a distinct head
- a coelem and deuterstome development
31
Molluscs
- Phylum Mollusca includes snails and slugs, oysters and clams, and octopuses and squids
- No huge evolutionary step forward, but they are abundant and important in the biotic communities
- mantle, foot, and radula
32
Gastropods
- about 3/4 of molluscs are gastropods
- single shell
- most are marine, but there are also freshwater and terrestrial species
- gastropods move slowly by using cilia or by a rippling motion of the foot
- feeding: grazers, using radula
33
Bivalves
- bivalves are all aquatic
- they have shell divided into two hinged halves drawn together by adductor muscles
- they have no distinct head or radula (they are filter feeders)
- some have eyes and sensory tentacles along the edge of their mantle
- bilaterally symmetric; most have sensory organs along the edge of each opening valve
34
cephalopods
- marine predators
- they immobilize prey using a poison in their saliva
- water is drawn into the mantle cavity and shot out through the excurrent siphon for rapid movement
35
protecting freshwater and terrestrial molluscs
- molluscs have the largest number of documented extinctions among animlas
- freshwater bivalves and terrestrial gastropods are the most severely threatened
36
annelids
- segmented worms that live in marine, freshwater, and damp soil habitats
- they have a coelom (no hemoceol)
- based on phylogenomic analysis, annelids are now divided into two clades
37
Ecdysozoans are the most _____-______ animal group
species-rich
- animals with a cuticle, a tough external coat
- The cuticle is shed during ecdysis, or molting
- primary cavity = hemocoel
- nematodes and arthropods are the largest of eight ecdysozoan phyla
38
nematodes
- Nematodes (roundworms) have cylindrical bodies tapered at the ends and covered by a cuticle
- They range in length from less than 1 mm to more than 1 m
- Many important animal and plant parasites
- C elegans
39
Arthropods
- Zoologists estimate that there are about a billion billion arthropods living on earth
- More than 1 million species have been described
- Two of every three known species are arthropods
- Arthropods are found in nearly all habitats on earth
40
Arthropod origins
- First animals to crawl up on land
- The arthropod body plan = segmented body, hard exoskeleton, and jointed appendages
- They date back to the Cambrian explosion
- Early arthropods ( such as trilobites) showed little variation from segment to segment
- Over time, segments united to form "body regions" specialized for feeding, walking, or swimming
41
General characteristics of arthropods
- segmented boyd with hard exoskeleton of chitin
- appendages are jointed and come in pairs
- arthropod appendages have become modified for walking, feeding, sensory reception, reproduction, and defense
- open circulatory system
Living arthropods consist of three major lineages that diverged early in the phylums evolution:
- Chelicerates (spiders, horseshoe crabs, scorpions, ticks, mites)
- Myriapods (centipedes and millipedes)
- Pancrustaceans (insects and crustaceans)
42
Chelicerates
- named for clawlike feeding appendage called chelicerae
| - arthropod
43
Myriapods
- Mryiapoda includes millipedes and centipedes
- All living myriapods are terrestrial
- They have a pair of antennae and three pairs of appendages modified as mouth parts
44
Pancrustaceans
- Recent evidence indicates that insects are more closely related to crustaceans than myriapods
- So, together, insects and crustaceans form the clade Pancrustacea
45
Crustaceans
- Many crustaceans have highly specialized appendages
- the anterior-most form two pairs of antennae
- three or more pairs are modified as mouth parts
- walking legs are located on the thorax
- smaller, swimming appendages are located on posterior segments ("tail" region)
- Small crustaceans exchange gases through the cuticle; larger crustaceans have gills
- most crustaceans have separate sexes
46
Isopods
- one of the largest groups of crustaceans, live in terrestrial freshwater, and marine habitats
- Pill bugs are common terrestrial isopods that live under moist logs and leaves
47
Decapods
- Decapods (10 'walking' legs) are all relatively large crustaceans including lobsters, crabs, crayfish, and shrimp
- Front pair of legs may be modified as pinchers
- The cuticle is hardened by calcium carbonate
- Most are marine, but crayfishes live in fresh water, and some tropical crabs live on land
48
Planktonic crustaceans
- Small and numerous
- Copepods are among the most abundant animals
- Shrimplike krill are a food source for baleen whales
- Larval stages of many larger crustaceans are planktonic
49
Barnacles
- Mostly sessile crustacenas with a cuticle hardened into a calcium carbonate shell
- Most anchor to submerged surfaces such as rocks, boat hulls, or pilings
- Feeding appendages extend from the shell to strain food from water
50
Insects (the other pancrustacean group)
- Clade Hexapoda (six walking legs) includes insects and their relatives
- Insects live in most terrestrial habitats and in fresh water, but are rare in marine habitats
- They have several complex internal; organ systems
- Oldest insect fossils are 415 million years old (shortly after the arthropod colonization of land)
- Rapid insect diversification followed the evolution of flight
- Flight improved the ability to evade predators, locate food and mates, and disperse to new habitats
- Insect wings are an extension of the cuticle, enabling flight without sacrificing a pair of walking legs
- Most insects have a herbivorous stage
- insect radiations following periods of diversification in their food plants
- Most insects undergo metamorphosis: incomplete or complete
51
Unifying characteristics of Echinoderms and Chordates
- Radial cleavage
- Formation of the anus form the blastopore
- True coelom
- deuterostomes
- BUT these characteristics are also found in other clades, so DNA similarities are used to define taca
- Two groups: Echinoderms (invertebrates) include sea stars and sea urchins. Choradates (have notochord, include all vertebrates, animals that have a backbone)
52
Echinoderms
- Symmetry ???? bilaterally symmetric even though they appear to be radially symmetric
- Sea stars (starfish) and most other echinoderms are slow-moving or sessile marine animals
- The water vascular system, a network of hydraulic canals, branches into tube feet that function in locomotion and feeding
- THey have separate sexese and external fertilization
53
List of Chordates
```
Non-vertabrate chordates:
- Lancets
- Tunicates
Vertebrate Chordates:
- Cyclostomes (round mouth)
- Hagfish (Myxini)
- Lamprey (Petromyzondita)
Gnathostomes (JAWS!)
- Chondrichthyes (sharks)
Osteichthyans (bony fish and lungs)
-Actinopterygii (ray-finned fish)
Lobe-fins
- Actinistia (coelacanths)
```
54
List of Tetrapods (4 limbs w/ digits)
Amphibians:
- Urodela (salamanders), Anura (frogs), Apoda (caecilians)
Amniotes (amniotic egg):
- Reptiles: turtles, archosaurs, lepidosaurs
- Mammals: monotremes (eggs), Marsupials (pouches), Eutherians (placenta): 4 clades
Primates: new world primates, old world primate
Apes: (gibbons. pongo, gorilla, pan, homo)
Humans
55
Derived Characters of Chordates
- All chordates share a set of derived characters, but they may appear only during embryonic development
- Four key Characteristics of chordates:
- Notochord
- Dorsal, hollow nerve cord
- Pharyngeal slits or clefts
- Muscular, post-anal tail
56
Lancelets (cephalochordata)
- Basal chordates
- Small (6") marine suspension feeders, named for the bladelike shape
- NOT FISH, but swim using a simplified form of the mechanism used by fishes
- Adults can reach 6 cm in length and retain key characteristics of the chordate body plan
57
Tunicates (Urochordata)
- Chordate characteristics apparent during the larval stage
| - Adult tunicates (sea squirts) are sessile filter feeders
58
Early Chordate Evolution
- BRAIN
- Lancelets have a slightly swollen tip on the anterior end of the nerve cord, instead of a full-fledged brain
- The brain develops under control of the same Hox genes and patter of expression as vertebrates
59
Early Chordate Evolution
Organs:
- Ancestral chordates likely had genes associated with vertebrate organs including the heart of thyroid
- These genes are found in tunicates and vertebrates, but absent from nonchordate invertebrates
Neural Crest
- Tunicates have embryonic cells with similarities to the nueral crest cells of vertebrates
- The vertebrate neural crest may have evolved from cells similar to those found in tunicates
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Vertebrates are chordates that have a _______
backbone
- Derived Characteristics
- backbone of vertebrae
- Neural crest
- complex genetic code
- Larger brain and skull
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cyclostomes (round mouth)
Hagfish and Lampreys
- molecular analysis supports their placement as a clade of jawless vertebrates
- only living vertebrates lacking jaws
- also retain functional notochord and lack a real backbone, but so have a rudimentary vertebrae.
62
Gnathostomes: JAWS
- Gnathostomes ("jaw mouth") have jaws ( hinged structures) with teeth used to grip and slice food
- More complex genetics (4x hox)
- Larger forebrain with enhanced smell and vision
- lateral line system
63
Chondrichthyes (sharks and rays)
Gnathostomes
- Skeleton composed primarily of cartilage
- Most sharks are preditors with enhanced senses
- Sharks have internal fetilization, but varipus embryonic development strategies
- Oviparous
- Ovoviparous
- Viviparous
64
Ray-Finned Fishes and Lobe-Fins
- Most vertebrates are osteichthyans (bony endoskeleton). Also have lungs or derivatives
- Aquatic oseichthyans are the vertebrates we infromally call "fishes" but ALL 'bony vertebrates' in this classification
65
Ray-Finned Fishes (Actinopterygii)
- >27,000 species of ray-finned fishes. Originated > 400 mybp and have diversified greatly since
- Modifications in body form and fin structure affect maneuvering, defense, and other functions
- Lung turns into swim blasser which functions in buoyancy control
- Use gills for oxygen exchange
- Retain lateral line system
- Most species oviparous with external fertilization
66
Lobe-fins (actinistia)
- lobe-fins arose > 420 mybp
- Their pectoral and pelvic fins have rod-shaped bones surrounded by a thick layer of muscle= primitive appendages
- The lobed fins are used to maneuver across the substrate pf aquatic habitats
- Most now extinct but show a key evolutionary development
67
Tetrapods are gnathostomes that have four ____ with ____
Tetrapods are gnathostomes that have 4 limbs with digits
- Tetrapods evolved by 365 million years again followed by huge diversification
- Life on land selected for numerous modifications to the tetrapod ("four feet") body plan
- Four limbs and feet with digits
- A neck, enabling independent movement of the head
- Fusion of the pelvic girdle to the backbone
- The absence of gills (except some aquatic species)
- Ears for detecting airborne sounds
68
Amphibians
- The term amphibian means "both ways of life" (land and water)
- Three clades
- Salamanders ( Urodela, "tailed ones")
- Frogs (anura, "tail-less ones")
- Caecilians (apoda, "legless ones")
Reproduction tied to water, external fertilization lay eggs
69
Amniotes are tetrapods that have a terrestrially adapted egg
- Amniotic egg
- Amniotic egg four membranes that protect the embryo
- Amniotic egg reduced dependence on water for reproduction
70
Living amniotes include the reptiles
- Reptile clade is diverse and include birds
- Three lineages:
- Turtles
- Lepidosaurs, tuataras, lizards, and snakes
- Archosaurs, crocodilians and birds (+ extinct pretosaurs and dinos)
Shared derived traits:
- scales
- shelled eggs laid on land
- internal fertilization
71
Turtles
- Characterized by the boxlike shell, made of upper and lower shields fused to the vertebrae, clavicles, and ribs
- only about 350 species
72
Lepidosaurs
2 surviving clades:
- Tuatara (weird lizard from New Zealand)
- Squamates: lizards, snakes
73
Crocodilians
- Crocodilians (alligators and crocodiles) belong to an anciet linage (alive when dinosaurs were)
- Only 24 species of living crocodilians are restricted to warm regions of the globe
- Closest living relative to the birds
74
The origin of Birds
- Birds belong to a group of bipedal dinosaurs
- Feathers evolved before powered flight with possible functions including insulation, camouflage, or courtship display.
- Archaeopteryx remains the earliest known bird
- It had feathered wings, but retained ancesteral characters such as teeth, claws, and a long tail
75
Birds
- Birds historically viewed as seperate group... but molecular data shows otherwise
- Birds are "reptiles" that have evolved extensive modifications in their adaptation to flight
Shared derived traits:
- Weight
- Feather of beta-keratin
- endothermic (maintain body temp)
76
Mammals
- Mammals have many distinctive dervied characters:
- Mammary glands, which produce milk
- hair and a fat layer under the skin for insulation
- Efficient kidneys, loop of henle
- Endothermy and a high metabolic rate
- Efficient respiratory and circulatory systems
- A large brain-to-body-size ratio
- Teeth modified for shearing, crushing, or grinding
- Extensive parental care
- Smal mammals coexisted with the dinosaurs
- Mammals radiated after demise of the dinosaurs
- Large predators, herbivores, and flying aquatic mammals arose during this time. 3 major lineages of mammals had emerged by 160 million years ago: Monotremes (eggs), Marsupials (pouch), Eutherians (placenta)
77
Monotremes
- Monotremes are a small group of egg laying mammals found only in Australia and New Guinea
- They include four species of echidnas and one species of platypus
- Females lack nipples and secrete milk from glands on their bellies; the babies suck milk from their fur
78
Marsupials
-Marsupials are born early and develop while nursing in a pouch called the marsupium
- Marsupials share many derived characters with eitherians that are not found among monotremes
- Higher metabolic rates
- Nipples to provide milk
- Birth of live young
- Embryonic development in the uterus
- A placenta for nutrient transfer from mother to
embryo
- Once existed worldwide, but now live only in Austrialia and the Americas
- Geographically isolated marsupials and eutherians can look similar due to convergent evolution
79
Eutherians (placental mammals)
- Compared with marsupials, eutherians have more complex placenta and longer pregnancies
- Young eutherians complete embryonic development within a uterus, joined to the mother by the placenta
- Four clades of eutherians:
- Elephants and Manatees
- Sloths, armadillo, and anteaters
- Rodents, rabbits, primates
- Dogs, rhinos, sheep, whales, bats
80
Primates
```
- The mammalian order primates includes lemurs, tarsiers, monkeys, and apes
Derived Characters:
- Hands and feet adapted for grasping
- Digits with flat nails instead of claws
- fingerprints
- large brain and short jaws
- forward looking eyes
- parental care
- complex social behavior
```
81
Monkeys
- primates and they arose the old world (Africa and asia)
- New world monekys first colonized South America roughly 25 million years ago
- New and Old World monkeys experienced separate adaptive radiations over millions of years of separation (including prehinsile tail)
82
Apes
- Primates that diverged from Old World monkeys about 25-30 million years ago
- Apes include gibbons and four genera of great apes:
- Pongo (orangutans)
- Gorilla (gorillas)
- Pan (chimpanzees and bonobos)
- Homo
83
What are characters that distinguish humans from other apes
- Homo sapiens arose about 200,000 years ago (last 3.8 seconds on a 24 hour clock)
- Our species is young considering a 3.5 billion year history of life on earth
- A number of characters distinguish humans from other apes:
- Upright posture and bipedal locomotion
- Larger brains capable of language, symbolic thought , and artistic expression
- Production and use of tools
- Reduced jawbone and jaw muscles
- shorter digestive tract
84
Animal form and function are correlated at all levels of organization
- Anatomy
- Physiology
- Behavior
85
Evolution of Animal ANATOMY (size and shape)
- Physical laws that govern strength, diffusion, movement, and heat exchange limit the range of animal forms
- Properties of water limit possible shapes for fast swimming animals
- Convergent evolution often results in similar adaptations of diverse organisms facing the same challenge
86
Exchange with the Environment
- Size influences exchange of materials with environment
- To stay alive, materials such as nutrients, waste products, and gases must be exchanged across the plasma membranes of animal cells
- Rate of exchange is proportional to a cells surface area, while amount of material that must be exchanged is proportional to a cell's volume
- A single-celled organism living in water has sufficient surface area to carry out all necessary exchange
- A multicellular organization only works if every cell has access to a suitable aqueous environment
- Multicellular organisms with a sacklike body plan have body walls that are only two cells thick, facilitating diffusion of materials
- in flat animals (like flatworms) most cells are in direct contact with their environment
- More complex organisms are composed of compact masses of cells with a more complex internal organization
- Evolutionary adaptations such as specialized, extensively branched or folded structures enable sufficient exchange with the environment.
87
Hierarchical organization of body plans
- Most animals are composed of cell organized into tissues, groups of cell with a similiar appearance and a common function
- Tissues make up organs, which together make up organ systems
88
What are the four main types of animal tissues
1. Epithelial
2. Connective
3. Muscle
4. Nervous
89
Epithelial Tissue
- Covers the outside of the body and lines the organs and cavities within the body
- Active interface between the organism and the environment (protection, absorption, secretion, etc)
- It contains cells that are closely packed
- The shape of epithelial cells may be cubodial (like dice), Columnar (like bricks on end), or squamous (like floor tiles)
90
Connective Tissue
- Connective tissue hold many tissues and organs tofeth and in place
- It contains sparsely packed cells scattered throughput a more abundant extracellular matrix
- The matrix consists of fibers in a liquid, jellylike, or solid foundation
- Connective tissue contains cells, including:
- Fibroblasts, which secrete fiber proteins
- Macrophages, which engulf foreign particles and cell debris by phagocytosis
91
What are three types of connective tissue fiber
(all are made of protien)
- Collagenous fibers: provide strength and flexibility
- Reticular fibers: joining connective tissue to adjacent tissues
- Elastic fibers: stretch and snap back to their original length
92
In vertebrates what are the 6 major types of connective tissue
1. Loose connective tissues: binds epithelia to underlying tissues and holds organs in place
2. Fibrous connective tissue: is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints
3. Bone: is mineralized and forms the skeleton
4. Adipose tissue: stores fat for insulation and fuel
5. Blood: is composed of blood cells and cell fragments in blood plasma
6. Cartilage: is a strong and flexible support material
93
Muscle Tissue
- Muscle tissue is responsible for nearly all types of body movement
- Muscle cells consist of filaments of the proteins actin and myosin, which together enable muscles to contract
- Muscle tissue in the vertebrate body is divided into three types:
- skeletal muscle, or started muscle, is responsible for voluntary movement
- smooth muscle is responsible for involuntary body activities
- cardiac muscle is responsible for contraction of the heart
94
Nervous tissue
- Functions in the receipt, processing, and transmission or information
- Nervous tissue contains:
- Neurons, nerve cells, transmit nerve impulses
- Glial cells, or flia, which support cells
95
Coordination and Control
- Animals have two major systems for responding to stimuli:
- The Nervous System: fast, short lived, localized
- The Endocrine System: slower, sustained, systemic
96
Feedback control maintains the internal environment in many animals
- Faced with environmental fluctuations, animals manage their internal environment by either regulating or conforming
97
Homeostasis
- Organisms use homeostasis to maintain a "steady state" a relatively constant internal environment regardless of external environment
- In humans, body temperature, blood pH, and glucose concentration are each mainated at a fairly constant level
98
Feedback control in homeostasis
- Negative feedback is a control mechanism that "damps" a stimulus
- It plays a major role in homeostasis in animals
- Homeostasis moderates but doesn't eliminate changes in the internal environment
- Positive feedback amplifies a stimulus and does not play a major role in homeostasis
- Instead, it helps drive a process (such as childbirth) to completion
99
Alterations in Homeostasis
- Set points and normal ranges can change with age or show cyclic variation
- In animals and plants, a circadian rhythm governs physiological changes that occur roughly every 24 hours
- Jet lag is mismatch between circadian clock and actual time of day
- Homeostasis is sometimes altered by acclimatization
- This is a change in an animal's physiology as it adjusts to changes in its external environment. An example is adaptation to changes in altitude
100
Homeostatic processes for thermoregulation involve form, function, and behavior
- Thermoregulation in the process by which animals maintain an internal temperature within a normal range
- Endotherms vs. ectotherms
101
Variation in Body Temperature
- They body temperature of a poikilotherm varies with its environment
- The body temperature of a homeotherm is relatively constant
- The relationship between heat source and body temperature is not fixed
- poikilotherms is not the same as ectotherms
- homeotherm is not the same as endotherm
102
Balancing heat loss and gain
- Organims exchange heat by four physical processes:
1. Radiation (electromagnetic waves)
2. Evaporation (liquid to vapor)
3. Convection (heat transfer to/from fluid (air is fluid))
4. Conduction (heat transfer to/from solid surface)
- Heat regulation in mammals often involved the intergumentary system: skin, hair, and nails
- Five adaptions help animals thermoregulat: 1. insulation, 2. circulatory adaptations, 3. cooling by evaporative heat loss, 4. behavioral responses, 5. Adjusting metabolic heat production
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Insulation
- a major thermoregulatory adaptation in mammals and birds
- It reduces the flow of heat between an animals body and its environment
- skin, feathers, fur, and blubber reduce heat flow between an animal and its environment
- insulation is especially important in marine animals such as whales and walruses
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Circulatory adaptations
- Regulation of blood flow near the body surface significantly affects thermoregulation
- Many endotherms and some ectotherms can alter the amount of blood flowing between the body and the skin
- In vasodilation, blood flow in the skin increases, facilitating heat loss
- In vasoconstriction, blood flow in the skin decreases lowering heat loss
- Countercirculation
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Cooling by evaporative heat loss
- Many mammals and birds live in places where regulating the body temperature requires cooling in addition to warming the body
- When the environmental temperature is above that of the body, evaporation can keep the body temperature from rising
- Sweating moistens the skin, helping to cool an animal down
- Panting increases the cooling effect in birds and many mammals that cant sweat
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Behavioral responses
- Ectotherms, and sometimes endotherms, use behavioral responses to control body temperature
- They amy seek warm places when cold and orient themselves toward heat sources
- When hot, they bathe, move to cooler areas, or change orientation to minimize heat absorption
- Social behavior contributes to thermoregulation in both endotherms and ectotherms
- Endotherms such as emperor penguins may huddle together to conserve heat
- In hot weather, honeybees transport water to the have and fan with their wings, promoting evaportation and convection
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Adjusting metabolic heat production
- Thermogenesis is the adjustment of metabolic heat production to maintain body temperature
- Thermogenesis is increased by muscle activity suck as moving or shivering
- Nonshivering thermogenesis takes place when their hormones cause mitochondria to increase their metabolic activity
- brown fat
- organism size
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Size influences heat exchange
Bergmanns rule:
- within a species, individuals of larger size are found in cooler climate
- Why? surface to mass ratio
- heat loss: function of surface area
- heat produced: function of mass
- if climate change predictions are true there will be a dramatic change in organism size in the coming decades
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Acclimatization in thermoregulation
- Birds and mammals can adjust thier insulation to acclimatize to seasonal temperature changes
- Lipid composition of cell membranes may change with temperature
- When temperatures are subzero, some ectotherms produce "antifreeze" compounds to percent ice formation in their cells
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Bioenergetics
- The overall flow and transformation of energy in an animal
- Units= joule or calorie
- Energy containing food is to make ATP= power for cellular work
- After the needs of staying alive are met, remaining energy can be used in biosynthesis (net production)
- Biosynthesis includes bldy growth and repair, synthesis of storage material such as fat, and production of gametes
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Quantifying Energy Use
- Metabollic rate is the sum of all the energy an animal uses in a unit of time
- Metabolic rate can be determined by:
- an animals heat loss
- Total oxygen consumed, or carbon dioxide
- Mass balance (energy content of food consumed minus energy content from waste products)
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Influences on Metabolic Rate
- Metabolic rates are affected by many factors besides whether an animal is an endotherm or an ectotherm
- Some key factors are:
- body size
- activity
- age, sex, temperature, and nutrition
- BMR is related to body mass
- BMR/Kg mass is MUCH higher for small animals
- Metabolic rate per kg of tissue can be really hard to sustain in smaller animals so they tend to have a shorter lifespan
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Activity and Metabolic rate
- Activity greatly affects metabolic rate for both endotherms and ectotherms
- Minimum= amount needed to stay alive
- Maximum= max possible rate of energy expenditure
- In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity
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Minimum Metabolic Rate
- Basal Metabolic rate (BMR) is the metabolic rate of an endotherm at rest, with an empty stomach, and not experiencing any stress
- BMR is measured under a comfortable temperature range
- Standard Metabolic Rate (SMR) is the metabolic rate of a fasting, non-stressed ectotherm at rest at a specific temperature (usually 20C)
- Ectotherms have much lower metabolic rates than endotherms of a comparable size (2-20%)
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Torpor and Energy conservation
- Torpor is a physiological state of decreased activity and metabolism (below 'normal' BMR)
- Hibernation is long-term torport that is an adaptation to winter cold and food scarcity
- Estivation = summer torport (too hot or too dry)
