Long Exam 2 Comparative Vertebrae Anatomy PDF

COMPANA – Comparative Vertebrae Anatomy Lecture LONG EXAM 2 1ST SEMESTER A.Y. 2024 – 2025 | Ms. Rosita Roldan-Gan, MD, FPSP More complex receptors are found in other fishes and tetrapo...

COMPANA – Comparative Vertebrae Anatomy Lecture LONG EXAM 2 1ST SEMESTER A.Y. 2024 – 2025 | Ms. Rosita Roldan-Gan, MD, FPSP More complex receptors are found in other fishes and tetrapods and COMPARATIVE FEATURES OF THE highly used for survival o Neuromasts – capable of sensing vibrations and other sensation from INTEGUMENTARY SYSTEM the environment ROLES OF THE INTEGUMENT RESPIRATION Depends on the types of craniate, often times these are aquatic animals / amphibious animals PROTECTION Supplement gills and lungs of many amphibians (aquatic urodeles) → skin Primary role of the integument being used for respiration Dermal armors protects the internal organs from mechanical injury Plethodontid salamander rely its respiration entirely on the skin (they don’t o Evolutions that portray a more enhanced protection of their organs have gills or lungs) → part of urodele Glands secrete slimy or noxious substances to lubricate our body or Scales and cornified epithelium are not conducive for cutaneous provide deterrent for possible predator respiration Pigments provide protective coloration o Ex. Terrestrial animals and land-locked animals – have thicker skin, it o Coloration is not for beautifying but as protection for the animal has lost its ability to use skin for respiration Serves as barrier to the rays of the sun o Melanin secreted by our skin can block harmful UV rays and give us EXCRETION protection from damaging our cells CO2 excretion in some aquatic amphibians Claws, horns, spiny protuberances and needles give protection → add Sweat glands are supplementary to excrete nitrogenous wastes protection o Animals that tend to dig in the soil → stronger claw Ammonia in fishes is easily diffused via gill epithelium and other tissues o Spiny protuberance → protection from getting eaten exposed to water EXTEROCEPTION THERMOREGULATION How we perceive our external environment Function of the skin of endotherms (birds and mammals) o We need to dissipate or maintain our heat → we are able to this Protective in its most primitive state → protective function because our modifications Naked nerve endings are stimulated when foreign objects contact the skin Fur and feather insulate against cold → allows us to perceive our environment o The only role of cutaneous receptors in agnathans – to perceive a Sweat cools by evaporation of water (in sweat glands) threat outside Dilation of blood vessels within the dermis increases heat loss by radiation ▪ Not very sensitive with the other types of exteroception o Dilating → diameter widens | Constricting → diameter narrows (distinguishing between light touch and deep touch, vibration, etc.) o Regulating flow of the blood to regulate heat Endoderm – warm blooded 1 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Heat is a by-product in the body Cornified epithelium of tetrapod conserve water so that they could live o if goes below 35, the enzymes would not be efficient farther away in water ▪ metabolic processes are slowing down Absorbs water under the influence of posterior pituitary gland in o if super init, may damage na aestivating lungfishes, toads, and other craniates ▪ above 40, the enzymes gets denatured (kumakalas yung mga o Antidiuretic hormone or vasopressin that is secreted by the posterior bonds) pituitary gland that regulates the urine we are producing o adaptations to maintain body temperature: ▪ If we lack water, we produce more antidiuretic hormone making ▪ fur, feathers — added barrier urine more concentrated o sweat carries heat and goes out the body o Aestivating lungfish Ectotherm – cold-blooded ▪ Even though it is outside the water, it doesn’t easily lose water as it o Depends on the environment for heat source is capable of conserving water with the help of hormones o needs a certain warmth in the body so that the metabolic processes will happen and work NOURISHMENT enzymes — to create action (very important) Mucus secreted in some teleosts provide nutrition to hatchlings as they o can only work under certain conditions don’t have milk Mammary glands provide nourishment to the young → Embedded within LOCOMOTION the integument Adhesive pads and claws assist in climbing → lizards and frogs Scutes assist in slithering → snakes, the ventral scales PHEROMONES AND SKIN COLORATION Feathers provide airfoil → improving air dynamic Pheromones are chemical substances that are produced by the skin that Webbed feet for those that wade in water → help them in swimming helps in attracting other animals of the same species across the water and catch their prey o Used as an attractant for potential mates Webbed wings in bats enable them to fly → limited to few animals like the o In humans → the presence of pheromones is still controversial but we bats which enables them to fly use perfume to attract other people | we don’t have pheromones ▪ Studies that were done to investigate the preference of other people MAINTENANCE OF HOMEOSTASIS when it comes to the natural smell of a potential mate Homeostasis → ability of the body to maintain stability in their internal Histo-compability and perception of the smell of another person environment Serves as species identification or serves as alarm o Our body relies on enzymes o Advertise the territory of an alpha male so that he could tell the female o These enzymes work on certain environmental conditions → limited species that he is the alpha male and he is supposed to be the first range of temperature, pH, water balance potential mate choice ▪ In other to ensure that enzymes would work in its optimum, our body Elaborate coloration help during breeding season does certain things to main homeostasis o More colorful, gives a signal that you are a good signal for propagating Reservoirs of calcium and phosphate molecules in fishes their genes o Which is why for us humans, we take advantage this feature where o Evolutionary basis for our idea of what is beautiful → red lips = blood we harvest calcium and phosphate from their scales is rich in oxygen that enables our infant to be more healthy, voluptuous 2 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 body = engorged mammary gland and can give nourishment to the Stratified epithelium which offspring, wide hips = capable of giving birth to a live offspring developed from embryonic ▪ Thin, narrow body and pale skin → deterrent to a potential mate as ectoderm they are not the suitable partner to propagate their species o Ectodermal origin Can be used as protection Rests on a basement membrane made up of delicate GENERAL STRUCTURE AND DEVELOPMENT fibrils and overlies the dermis The integument forms the interface between the animal’s internal o There are several layers of environment and the outside world the epidermis in the Components: basement membrane o Epithelial (for craniates it is usually stratified epithelium), connective o Top-most layer would adipose and smooth muscle tissues determine the ‘middle name’ o Blood vessels (in dermis) of your stratified epithelium o Glands (mucous and sweat secretion) ▪ Often times it is stratified o Sensory receptors squamous epithelium o Nerves because the top-most layer is squamosal or flat o Other structures ▪ But it doesn’t mean it its flat in the entire thickness Stratum basale – more cuboidal as it has the living portion of the cell and require more space for organelles As we go higher in the layers of the stratified squamous epithelium, there will now be the impregnation of keratin in the epidermis and start killing the upper layers of the epidermis Stratum spinosum – looks spiny and it is because of the keratin that starts to embed to the cell Stratum granulosum – looks granular and would notice that the epithelium is starting flatten Thick skin or thin skin would determine if there is stratum lucidum (thick skin has it, thin skin doesn’t) o Light region seen in the microscope o Transition region from thick skin granular going to stratum corneum EPIDERMIS Stratum corneum – outermost layer which is composed of dead cells that embedded with keratin Stratum germinativum or basale consists of 1 to 2 mitotically active, cuboidal cell layers located above the basement membrane → capable of germinating or multiplying 3 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 Cells move toward the body surface to differentiate and eventually Layer of the skin below the epidermis sloughed off Develops from mesenchymal cells Keratin → presence is dependent on the habitat of the animal which are mostly derived from o Water-insoluble, horny protein that may fill the cells and replace other mesodermal dermatome of somites organelles o In the neurulation or development of ▪ Prevents the passage of water the neural tube, lateral to the neural ▪ That’s why the outer layer of epidermis tends to die out tube you would locate the somites ▪ If you have a thicker stratum corneum, that means you have more o Somites – have three regions keratin and that would be helpful in drying out of the skin (dermatome, myotome, sclerotome) o Best developed in terrestrial vertebrates → keratin-filled cells form the that would a designated fate stratum corneum ▪ As the dermis arises from the ▪ Aquatic craniates has lesser keratin dermatome which is the medial portion Fishes and amphibians – thin layer of epidermis Basic component is collagen and elastic fibers embedded in → would have other protective covering proteoglycans and other macromolecules which holds other component Reptiles and mammals – thick layer of epidermis in place and provide tensile strength → since they need to conserve more water o Proteoglycans – molecules that are combination of molecules and carbohydrates and other molecules that hold other components in strength to provide tensile strength Two types of covering: ▪ Ex. when you pinch your skin, it would not fall off 1. Aquatic craniates – thin coat of mucus on the surface of their skin and Other components: it adds protection o Blood vessels, small nerves and pigment cells 2. Terrestrial craniates – water-impervious cornified cells (cells with a lot o Lymphatics of keratins) making it resistant to water and abrasions ▪ Located parallel to the blood vessels Gland cells – epidermal in origin but invade the dermis ▪ Multifunctional system, aside from absorbing the excess water that o Aquatic craniates – predominantly unicellular glands are left behind the veins, they are also passage way for cholesterol, o Terrestrial craniates – mostly multicellular (complex) glands with waste products, and immunity branches ▪ Have a lot of function o Naked and encapsulated exteroceptors DERMIS o Bases of multicellular glands o Bases of hairs or feathers and their erector muscles (changes the orientation of the hair; when you feel cold the erecter pili muscle will contact causing the hair to be more upright or parallel showing goosebumps that is supposed to give a buffer zone from the cold air and our skin – insulation) Dermis is thicker than epidermis in mature skin and consists of two layers: o Stratum laxum – layer that is much closer to the epidermis 4 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Stratum compactum o Composed of epidermal cells in which some parts invade the underlying dermis Superficial bones are dermal derivatives → dermal armor despite being found outside for some Teeth and bony scale are of epidermal and dermal products SKIN DERIVATIVES Teeth, bony, and horny scales, feathers, and hair develop → would have their respective function o Teeth would depend of the diet ▪ Ex. humans who are omnivores would need teeth that is capable of eating cellulose containing food and tearing up meat We have a weak set of teeth as we can chew and grind but we SKIN COLORATION AND ITS FUNCTIONS are not experts on any of them unlike in other animals that have teeth that are designed for herbivore or carnivore diet o Result of epithelial-mesenchymal interactions between the dermis CHROMATOPHORES and epidermis via neural crest cell migration Chromatophore is a general term so any color producing gland is termed ▪ During the development of different tissues, the meeting of two this one surfaces of embryonic layers would now cause an induction or o Depending on the color that the gland produce would give rise to the simulation for other surface to develop shape or mature specific names ▪ Neural crest – when the neural tube separates from the ectoderm, Cells that contain pigments found in all vertebrates except albinos you would have loose cells that are migrating Glands, feather, hair and other keratinized structures 5 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 MELANOPHORES Star-shaped, long, branching cells containing melanin Melanin granules may either be black, brown, or more yellow and reddish o Synthesized and contained within cellular Examples of Albinos organelles called melanosomes (organelles within the cell and the cell is called the Develop from neural crests and are located in the upper part of the dermis melanophore) in fishes, amphibians and reptiles Melanin in birds and mammals transferred to o Which is why the color of amphibians, reptiles, and fishes tend to be feather, hair, and other epidermal derivatives more vivid because their chromatophores are closer to the surface o More diffused in terms of distribution creating the noticeable patterns Melanosomes in anamniotes and reptiles migrate They penetrate and are located in the epidermis of birds and mammals into processes of the melanophores (concentrating o It is much deeper in location which is why from the outside, it looks the color) more diffused o Which is why we are able to see the vivid and distinct patterns OTHER PIGMENT SECRETING CELLS Contain crystalline chemochromes from guanine (nitrogenous base) Iridophores or Generate iridescent colors (rainbow) guanophores because of the diffraction of light within the stacked plates Utilize crystalline purines (often guanine) to reflect light Leucophores Shiny but silver in color Produce reflective white hues Contain yellow pigments composed of Xanthophores crest cells that are being scattered pteridines o capable of ameboid movement Contain reddish pigments composed of Erythrophores o migratory carotenoids o help in the development in the organs of the body Vesicles containing pteridine and carotenoids are sometimes found in the same cell DERMAL CHROMATOPHORE UNIT 6 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 Also used for species recognition, establishment or territories, courtship and other types of communication Also help reptiles thermoregulate → helping them increase body heat FISH INTEGUMENT Body appears: EPIDERMIS o Darker if the melanin is well dispersed within the processes of Integument of fishes is similar in its basic structure melanophore overlying the iridophore Epidermis is relatively thin, and most cells are alive o Yellowish if the pigment is well dispersed in the xanthophore o More layers of living cells compared to land animals Surface cells are covered with microridges that increase the surface TURACOVERDIN AND TURACIN area for exchange between the animal and its environment Pigments specific to certain species o In order to protect the outer area, there is keratin serving as protection Keratin may be deposited in limited areas such as horny teeth of Unique copper uroporphyrin cyclostomes (agnathans) and tubercules that develop in many fishes pigment responsible for the during mating season bright green coloration of several birds of the family Turacoverdin Musophagidae, most notably the turaco The only true green pigment found in birds Naturally occurring red pigment Turacin Found only in the bird family Musophagidae, the turacos IMPORTANT ROLES OF SKIN COLORATION Can be concealing or cryptic helping an animal hide from predators or Within the layer of the epidermis among fishes, there is a layer of enable a predator to stalk a prey unicellular and multicellular glands Can be aposematic where it advertises the presence of dangerous, venomous or distasteful species o Give warning to other animals that they are not prey UNICELLULAR EPIDERMAL GLANDS 7 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 GOBLET CELLS Relatively uncommon in fishes Secrete only mucus Hagfishes have large slime glands Forms a mucous cuticle and a generally slimy surface together with Some teleost have poison glands that produce toxic material and are secretion of surface cells often associated with fin spines o Reduce water exchanges between the fish and its environment and o When you get pricked by the dorsal fin of some fishes, the wound may helps the excretory system maintains a stable internal environment have some toxic materials with it o Water resistant barrier to prevent the fish from bloating or shrinking depending on its environment (freshwater or saltwater) PHOTOPHORES o Maintains homeostasis Look like melanophores but is Protects the body from bacterial invasion and attachment of a light-emitting pigment ectoparasites Light-emitting glands in deep- sea teleost (those that live in GRANULAR CELLS abyss where the rays of the sun cannot reach here) Secrete mucus and additional ingredients mostly of unknown functions o Developed through o Differentiated in their architecture under the microscope, there will be evolution so that they can granules instead of the lightly stained goblet cells see around them Alkaloids which are products of granular cells are not common Upper part of the gland Some contains an alarm substance is released when the fish is injured, consists of modified mucous and the skin is ruptured cells acting as magnifying lens o Acts as a pheromone and triggers a fright reaction in nearby (amplifies the light produce) and lower part contains are light-emitting members of the species cells ▪ If you would notice, the fishes would swim in school and if one of the Cells below are in contact with melanophores and in blood cells which is fish is injured, it can signal to the other fishes that a danger threat the source of raw materials may be nearby o Luciferase (enzyme) + luciferin (substance) = light The light is not intense and usually of many hues o It usually enough to just light their surroundings o Some use it to catch their preys Functions for: o Species and sex identification → for reproduction o Lure for prey in carnivores or is a warning that it is a carnivore o Concealment by countershading ▪ Mimic their environment to help them escape from their predators MULTICELLULAR EPIDERMAL GLANDS 8 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Goblet cells – sting ray o Multicellular glands – male claspers ▪ Modification of the anal fin that is used for copulation Photophores in the dermis are modified epidermal glands that lost connection with the epidermis o Once in a while, especially for deep sea cartilaginous fishes would have the ability to emit some light EPIDERMIS OF BONY FISHES Top layer composed of stratified epidermal cells that do not undergo keratinization o They do not really need keratin as they have scales that function for EPIDERMIS OF AGNATHANS protection of the outermost layer Highly mitotic, multi-layered epidermis with unicellular mucous glands Lowermost layer is the basal layer → mitotically active layers of cells o Which is why agnathans have slimy skin Glands are mostly unicellular (mucous coat on skin) with few multicellular No keratinized or cornified layer and granular glands o Their epidermis is not keratinized which is why their skin is subject ti Photophores for recognition or warning sloughing off Horny denticles on buccal funnel or teeth are the only keratinized structures DERMIS EPIDERMIS OF CARTILAGINOUS FISHES Collagen fibers are generally more regularly arranged than of other Multi-layered than agnathans vertebrates Not as much unicellular glands except in chimeras – but have more Develop in layers that spiral around the body in approximately 45 degrees multicellular glands angle to the longitudinal axis with adjacent layers perpendicular to each Localized glands: other → very organized 9 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 Fiber arrangement strengthens the skin so that body shape is maintained o If we scrape our hand against the during swimming normal orientation of the scales of o The shape of the fishes need to overcome the resistance from the sharks, we may get cut as the water scales are hard. Acts as exotendon transmitting muscular force towards deeper portion Do not grow with the animals of their skin o As they shed off the older scales, more new scales will replace the old one as they grown in size They are of single size Have a soft central area or core (the pulp), a middle layer of dentine and a hard outer layer of enamel o Similar to how the teeth is laid out When the animal grows, space opens up and a new denticles grow to fill Do not overlap as do the scales of bony fishes Most sharks have a complete covering of denticles arranged in a repeating diamond pattern DERMAL SCALES Species that are dorsoventrally flattened such as the skates and rays tend Scales is a modification of the skin and would have roots in the dermal to have fewer denticles portion but it would penetrate the epidermis until it covers the outer layer of the skin COSMOID SCALES Lampreys and hagfish lack scales Scales evolved separately in cartilaginous and bony fishes Found only on the Ceolocanths (Latimeria o Which is why they have different architecture as they did not have the sp.) or as fossils same evolutionary pathway Scales of bony fish with four layers: Types: 1. Dense bone → inner layer o Placoid 2. Spongy bone o Cosmoid 3. Dentine → surrounds the spongy o Ganoid bone o Elasmoid 4. Enamel → outer most layer Ganoid and Elasmoid → scales of bony fishes with only two layers, (1) calcified and (2) fibrous GANOID SCALES o Some of the other types of scales would have four layers Derived from cosmoid scales Has two layers: calcified and fibrous PLACOID SCALES o Much thinner Scales of sharks and rays (cartilaginous fishes) Found on Birchirs, Gars, and Sturgeons Made of bone and resemble teeth → quite tough Hard solid scales 10 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 ELASMOID SCALE Most common form of scale Thin plate that you find in most fishes Two types of elasmoid scales: o Ctenoid – have a set of fine teeth along posterior edge o Cycloid – simply rounded on the outer/posterior edge Sea perches (Epinephelus sp.) have mostly ctenoid scales above the lateral line and cycloid below o The upper portion of the fish would have a different style of scales AMPHIBIAN INTEGUMENT compared to the ventral region Dabs (Limanda sp.) have ctenoid scales on the upper colored surface and EPIDERMIS cycloid scales on the lower white surface → difference in the appearance Skin of amphibian is relatively thin (since they use the skin for respiration) of the scale above and below the lateral line but epidermal cells synthesize keratin As it accumulates, cells die and the stratum corneum is formed o Seldom more than 1 to 2 layers thick to allow cutaneous respiration o Desquamated periodically and is hormonally controlled ▪ Periodically sloughed off o Not sloughed off in toads and they just continue to pile up ▪ Toads have thicker epidermis Highly glandular o Glands aid in survival of land-adapted anurans o Poison gland or mucous gland Cornified appendages are rare o Since they are partly swimmers SCALES OF MODERN FISH EPIDERMAL GLANDS Embedded in the dermis and are covered entirely by the epidermis Mostly multicellular mucus or granular glands (poison glands) o Comparing to Placoid scales are superficial in sharks and rays Tailed aquatic amphibians have the most number of multicellular glands Grow as the fish grow o Secretions keep the skin most when they are on land Scale patterns show how old a fish is and also how many times it has Glands on digits serves as holdfasts in trees or glands thumbpads during spawned and if it has been seriously ill breeding season serves as restraint for females o Pads are made sticky for attachment 11 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 Show more advanced integumental adaptations to the terrestrial environment because they are more far-removed from the water. o Resist desiccation better since they now farther away from the water source Cells are more highly keratinized. Integument is modified into horny scales in snakes and lizards. EPIDERMIS OF REPTILES Represents ultimate adaptation of craniate skin for surviving in an arid (very dry) and hostile environment. With many localized adaptations: horny scales, scutes, beaks, rattles, GRANULAR GLANDS claws, plaques and spiny crests found in the stratum corneum. o Characteristics found in different reptiles Present in toads In snakes, scales on the ventral surface can be further modified into Secrete irritating alkaloids substances which are defensive in nature or scutes, which can be used in locomotion (slithering across the surface). pheromones used during breeding o Makapal ang scales used for crawling. Restricted to a localized area of the body o Tail of a rattlesnake is also a modification of the epidermis. In turtles, epidermis is strongly modified into plates that cover the shell, KERATIN and because they increase in diameter each year, they can be used to Aquatic urodeles have thin desiccation-impending stratum of cornified age the animals. cells o Lines or ring formations can indicate the age. o They do have keratin that will make it harder to dry out especially if they end up in dry environment MOLTING OR SHEDDING Anurans tadpoles have horny tooth-like structures which is shed during Removal of the entire epidermal layer so that they can increase in size. metamorphosis Molting is caused by the release of Prothoracicotropic hormone (PITH), a neuropeptide from the brain. DERMIS o Pag humahaba animal, unti-unting nagsshed yung epidermis. Firmly attached to underlying muscles in apodans and urodeles o Snakes are the only animals that shed wholly. The rest, pira-piraso. Anurans have lymph sinuses separating it from muscles Skin appears slightly dull as separation between old and new skin begins; Dermal chromatophores in other species can elicit color change separating from underlying new skin. o Deeper in location so they are able to form patterns Shedding differs from species to species. Bony scales (osteoderms) present in head of caecilians and a few tropical Turtles shed in pieces. toads at the back of their body Slough skin on their neck and legs as well as old scutes. Lizards also shed their skin in pieces and eat it. REPTILE INTEGUMENT Iguanas shed their skin in pieces on the outside of their bodies except for their eyeballs. 12 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 Snakes shed their skin in one piece except for the giant snakes which ▪ Preening – spreading oil on their feathers coming from their tail may tear their skin. ▪ Oil is used to water-proof feathers. o Oil glands at outer ear canal of domesticated birds. AVIAN OIL GLANDS OR UROPYGIAL GLAND Prominent swelling at rump behind pygostyle. Largest in aquatic birds and in domestic fowl. Oil which is water-repellent is used for preening. Smaller oil glands are found in the outer ear canal and sometimes in the DERMIS vent area. Osteoderm (dermal bone) o Bony deposits forming scales, plates or other structures based in the BIRD FEATHERS dermis. o Rooted in the dermis “Elaborate reptilian scales” Turtles Presence of epidermal scales along legs and feet of birds testifies to their o Carapace, plastron and lateral bridges debt to reptiles. (an evolutionary modification) o Soft-shelled and leatherback turtles lack dermal ossification. Crocodiles and some lizards BIRD FEATHERS; DERMIS o Osteoderms in localized regions of the body (gastralia in ventrolateral Near feather follicles, is richly supplied with blood vessels, sensory nerve abdominal wall) → not in the entire body endings, and smooth muscles. o Some reptiles have plates on the ventral surface of their trunks called o Keeps feathers healthy and attached to skin. gastralia. Dermis in the breast of some birds becomes increasingly vascularized Snakes during brooding season, forming brood patch. o Osteoderm is absent especially in their ventral area because they Provides warmth to incubated eggs. have scutes Minsan may kalbong part, brooding to incubate eggs. o If they have dermal bones in their underbelly, they won’t be able to Naglilimlim where they sit on eggs to incubate until maghatch move. BIRD FEATHERS; EPIDERMIS Comprises of stratum basale and stratum corneum. AVIAN INTEGUMENT Between them is the transitional layer of cells transformed into the keratinized surface of the corneum. EPIDERMIS Scales only present at feet and base of beak. BIRD FEATHER DESIGN Claws are present on toes and 1-2 on digits of wings. Principally of the epidermis and the keratinizing system. o For perching or capturing prey Laid out along distinctive tracts (pterylae) on the surface of the body. Glands are generally lacking except: o Uropygial gland found in the tail is made of pure oil for preening. 13 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 When you pull out feathers, the bird won’t really die because their feathers are nonvascular and non-nervous. But, pulling may stimulate the nerve endings within the dermis. Nonvascular and non-nervous Rachis o Tubular central shaft which carries on either side a vane a series of barbs. o Continues proximally as barbless calamus, which anchors the feather to the body and is often moved by attached dermal muscles. When smooth muscles within the dermis contract, it can also flutter the feathers. DERMIS Supports feather follicles and erector, depressor, retractor and rotator muscles. Feathers are cornified appendages first developed for insulation and is a modified scale. No osteoderms (except in game fowls with a spur of dermal bone at the ankle. Types of Feathers o Contour Feathers, or Pennaceous feathers ▪ Cover the body and usually have symmetrical vanes about a rachis. o Down Feathers, or Pluumulaceous feathers ▪ Lack a distinctive rachis and non-interlocking barbs extend from calamus as a fluffy feather important in insulation. ▪ Softer; babies or chicks have more down feathers. When they become adults, they would have the contour feather But in some areas like the end would have down feathers 14 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Baby hair - Hair na walang medalla, kaya mabilis malagas. Medalla MAMMALS INTEGUMENT helps anchor hair. Undercoat depends on the season. EPIDERMIS Softer hairs (such as fine body hairs) lack a medulla. Stratum germinativum Scalp hair contains medulla and is usually very strong. o Basal layer Modifications of hair Stratum granulosum o Guard hairs (Protect undercoat hair) o Impregnation of keratohyaline o Quills (Hedgehogs and porcupines) Stratum corneum o Vibrissae (Tactile whiskers on snouts) o Highly keratinized o Give rise to scales (armadillos and NAILS pangolins), claws (hoofs and flat nails) For horses, cows, carabaos, they are well-protected by their hooves. and horns. Grow from nail bed located in the epidermis at distal part of phalanges. o Thickest on parts of appendages in Highly cornified in ungulates. contract with surfaces (palms, hooves, In clawed animals, the nail is elongated and thickened for defense or feet) predation. Stratum lucidum o Present in palm and sole o Difference of thick and thin skin ▪ Absent stratum lucidum in thin skin INTEGUMENTAL DERIVATIVES HAIR Distinctive characteristics of mammals; cornified epidermal appendages. Provides insulation and additional protection to the animal. Grow in follicles derived from stratum germinativum of epidermis but are rooted in dermis. Continues to grow until mitosis in root stops. Three layers: 1. Medalla 2. Cortex HORNS AND ANTLERS 3. Cuticle (Outer layer) Some have epidermal covering and some are dermal modifications Protrusions on the head made of hair/keratin. 15 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 Horn Permanent because it has a bone inside then covered by skin. Not shed. Supported by bony structure growing out from skull. Surrounding the bony core is a highly keratinized layer of epidermis which is generally permanent. Antlers Not present throughout the year. They are shed during non-breeding season. Develop a protective covering of skin (velvet), which is lost as antlers mature. Antlers are shed. MUCOUS GLANDS Rhinoceros Horns Hairlike keratin fibers woven together Nabawasan significance dahil sa cornification of skin. without a bony core–similar to baleen in Absent in tetrapods except in mammals. whales that is used for feeding. Lost survival value when skin became covered with cornified cells Hair modification SEBACEOUS GLANDS EPIDERMAL GLANDS Associated with hair Help protect skin and its associated structures. Present when there are hairs and sebum is exuded into hair follicles. Aid in heat regulation. Ceruminous glands secrete cerumen (wax) in the outer ear. Give off scent Meibomian glands assist in lubrication of conjunctiva of the eye → Classification is based on: produce tears. o Structure ▪ Tubular, coiled (twisting), alveolar (grape-like) SUDORIFEROUS OR SWEAT GLANDS ▪ Simple (One branch), Compound (Many branches) Furry animals - Feet of cat and mice, lips of rabbits and side of head of o Substances secreted bats. ▪ Merocrine - Mucus and sweat glands Hippopotamus - Only in the ears. ▪ Apocrine - Mammary and ceruminous glands Absent in pangolins, sirenians, cetaceans and echidnas. ▪ Holocrine - Sebaceous glands Ex. ciliary glands. Turns off function; yung mga may -crine Animals that have a lot of fur tend to overheat when placed in a tropical country. o Sweat glands are limited in a certain area. 16 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 SCENT GLANDS DERMIS Apocrine sweat glands have thicker secretions. Very thick - Hair follicles, erector muscle, numerous glands, connective Contain more odor, sometimes modified into scent glands in some tissue, vascular tissue, nervous tissue. species. Dermal bones of armadillos. Used for scent marking (dogs) or defense (skunks). Antlers and giraffe horns. Superficial fascia separates the dermis from underlying muscles. MAMMARY GLANDS Blubber - Type of contour-shaping adipose tissue found in cetaceans to Compound alveolar glands develop in both sexes along the milk. replace hair. o Males do not traditionally produce milk o Modified hair of whales to keep them warm Modification of integumentary system; epidermal glands rooted in the dermal layer of skin. Number and location (axillary, thoracic, abdominal and inguinal) is SKELETAL SYSTEM dependent on the animal species. o Humans – have one pair ▪ Some instances have more than two nipples VERTEBRAL COLUMN o Mammary line ▪ Existence of many nipples where some disappeared once we are NOTOCHORD born and become only accessory nipples ▪ Where the nipple is aligned One of the important criteria for classifying an animal as a chordate Oxytocin is responsible for milk let-down. Primitive Axial Skeleton → replaced by the vertebral column (deposition o Hormone stored in the posterior pituitary gland. of mineralized tissues) Unsegmented and composed of dense fibrous connective tissues First skeletal element to appear in the embryo of chordates o The mineralization of the notochord VERTEBRAL COLUMN Segmented, more or less flexible, arched rod flanked by axial musculature o Flexible – separated by intervertebral discs o Becomes the adjacent skeletal muscle Function: o Suspends the trunk → hold the trunk in either upright or transverse position 17 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Protects the spinal cord → passes through the foramen Amphicoelus Concave at both ends Parts of a typical vertebrae o Concave on both anterior and posterior side o Centrum/Body → previously the notochord Limited motion is permitted in any direction o Arch → within this is the canal where the spinal cord will pass through Found in fishes, apoda, and some urodela o Processes → protruding CENTRUM Ossification of the notochord → deposition of mineralized tissue replacing the notochord Serve to anchor and support the arches May consist of one or two elements: Opisthocoelus Convex in front and concave in back o Intercentrum – cranial position o Convex anteriorly and concave posteriorly o Pleurocentrum – caudal position Permit motion in any direction In many extinct amphibians and few amniotes have two centra, the Found in salamanders, parrots and ungulates intercentrum and the pleurocentrum o These animals are very flexible and can Some extinct amphibians only have the intercentrum sometimes turn their bodies 360 degrees Amniotes only have the pleurocentrum Procoelus Concave in front and convex in back Permit motion in any direction Found in anurans and modern reptiles Opposite of opisthocoelus Among vertebrates there is great diversity in the structure of the centra o Absent: Aspondyly → none of the two components of the centra o Singular: Monospondyly → have only either intercentrum OR pleurocentrum o Doubled: Disopondyly → have the intercentrum AND pleurocentrum Acoelus Flat ended /amphiplatyan o Both ends are flat TYPES OF CENTRA BASED ON SHAPE Can withstand compression and limit motion Found in mammals The shape of the surfaces at the articulations between vertebrae affect the properties of the column and the way forces are distributed 18 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Which is why mammals are not as flexible as other species Heterocoelus Saddle-shaped o Concave and convex in a 90-degree PROCESSES OR APOPHYSES direction Come in different names Allow vertical and lateral flexion of the joints but Diapophyses (transverse prevent rotation around the axis of spine → processes) → horizontal flexible but cannot rotate o Articulating points for the ribs Found in birds o Serves as attachment for muscles Zygapophyses o Paired processes bearing articular surfaces by which neural arches articulate o Prezygapophyses – in front ▪ More superior (if upright) or anterior/cephalad (if horizontal orientation) ARCHES o Postzygapophyses – in the rear Neural arches ▪ More caudal (if horizontal orientation) o Located at the dorsal portion of the centrum Parapophyses o It (together with interconnecting ligaments) encloses a long vertebral o Lateral projections from the canal which is occupied by the spinal cord centra of a few tetrapods o Protects the neural tube and serve as articulation Hemal arches site for bicipital rib o Located at the ventral portion of the centrum o Not all animals would have o Inverted beneath the centra of tail and houses the caudal vessels this → would only have in ▪ No spinal card but rather we have the arteries and veins that animal with bicipital rib or supplies the tail portion of mostly fishes ribs with two heads o Protect the blood vessels that pass through the foramen or canal PHYLOGENY OF VERTEBRA How they have evolved through evolution 19 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 There are some architectures that are older and closer to the ancestors o Pleurocentra enlarged and became same There are structures that have recently developed size with intercentra o Became alternating with the intercentra Always look for the clues whether if it is asking for the shape of the Giving each neural arch two spool-shaped centrum, term about processes or about the phylogeny because you centra can have a vertebra that have same type of centrum but different phylogeny (not homologous) Rhacitomous Present in earliest land vertebrates The centra retained their geometric relationships but were more robust, articulating Gastrocentrous In amniots and their relatives with one another and restricting the notochord o The notochord will be flanked by the Pleurocentra enlarged and fused intercentrum or pleurocentrum Intercentra reduced to small wedges or are lost o They have both the intercentrum and pleurocentrum flanking the notochors Holospondylous Neural arches and centra ossify together o No clear distinction between these two Stereospondylus The pleurocentra are reduced or lost (no green components legens) Difficult to know if the centrum is derived from The intercentra remains and become spool- the pleurocentrum, intercentrum or both shaped The notochord remains in the form of intervertebral disks Embolomerous Pleurocentra and intercentra become similar 20 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 VERTEBRAL COLUMNS OF REPRESENTATIVE SPECIES Fibroelastic ligament connects the neural spines along the entire vertebral column AGNATHANS Notochord persists → do not have vertebrae or back bone Only skeletal elements are lateral neural cartilages o Limited to the tail region in hagfishes Caudally, they fuse to form a single longitudinally dorsolateral cartilaginous plate perforated by foramina for spinal nerves This is why the hagfish is very flexible because they have a lot of cartilage in the caudal region ACTINOPTERYGIANS Well-ossified amphicoelus vertebrae → has mineralization of the vertebrae Centrum is dumb-bell shaped vacuole where the notochord previously existed CHONDRICHTHYANS Space between successive vertebrae is occupied by porous cartilage- Notochord is present like material throughout the adult vertebral o Since it is concave in each side, in the hollow region there is the column cartilage in between o The only deposition would Centra and neural arches are interconnected by a complex system of be the cartilage collagenous and elastic ligaments o There is no complete Neural spines are often very tall and are sometimes surmounted by deposition of notochord supraneural bones → bones that is easy to detect when we eat bony Centra is composed of fishes chondral and perichordal Variety of processes usually unique to fishes protrude from the arches cartilage and is amphicoelus and centra → the anterior and posterior o Shooting off from the centrum you have different processes that will portion is both concave making the movement limited be point of attachment for the ventral and dorsal rib Two types of vertebrae: o Trunk → vertebra with a neural arch o Caudal → possess haemal arch and haemal spine Neural arches and intercalary plates of Squalus have foramina for the dorsal and ventral roots of spinal nerves and blood vessels 21 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Pleurocentra – small wedges of bone overlying the notochord dorsolaterally o Left and right laminae of bone lateral to the spinal cord the collectively provides a neural arch ▪ Forming the frame for your neural arch Notochord is continuous throughout the body but is constricted at the level of hypocentrum o Notochord into hypocentrum SARCOPTERYGIANS Dipnoans, chondrostei and coelacanth develop no centra o Persistence of the notochord Notochord is present and unconstricted and its thick sheath contains little cartilage or bone Basidorsal, basiventral, interdorsal, and intervertebral cartilages are associated with the notochord o Basidorsal – basic dorsal / at the back o Basiventral – basic ventral / at the front o Interdorsal – in between Rhachitomi The ancestor o Intervertebral – in between Large intercentrum and a small pleurocentra Stereospondyli The older descendants Retained only the intercentrum Embolomeri Increased the size of the pleurocentrum to the size of the intercentrum There is now dual centra seen Amniotes Enlarged pleurocentrum to near or complete exclusion of the intercentrum The intercentrum has been eliminated EVOLUTION OF TETRAPOD VERTEBRAE Rhipidistian and early labyrinthodonts (next gen of rhipidistians) consisted of several bones per segment o Hypocentrum – median, U-shaped anterior bone that cradled the notochord 22 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Since the ribs is illuminated in the cervical vertebra, much of the ribs that persist in tetrapods would appear in the thoracic area Lumbar vertebra o Immediately after the thoracic portion o Absence of ribs o Supports the abdominal cavity and organs within Sacral vertebra o Supports the stress transmitted to the pelvic girdle ▪ Depending now on the type of locomotion of the tetrapod Those who skip or jump, would have flexible or mobile bone Walking or running would have stable architecture Caudal vertebra o Tail vertebra ▪ Long tail – would have vertebral bone ▪ In humans, our caudal tail has become the coccyx which is now just protruding from our caudal area REGIONAL SPECIALIZATION IN TETRAPOD COLUMNS CERVICAL VERTEBRA IN AMPHIBIANS Single cervical vertebra → which is why we do not see frogs turning side to side or up and down Lacks processes and bears facets for articulation with the occipital condyles o The movement on their head to the neck is very limited Permits limited rocking of the skull not available in fishes → have a little Cervical vertebrae bit more mobility than fishes o Development of mobile joint between the first vertebra and the skull → very important since it will determine the mobility and flexibility of the head as it joins the neck of the tetrapod o Shortening or eliminating ribs ▪ Comparing tetrapod to fishes, tetrapod have less and shorter ribs o Increasing mobility of intervertebral joints ▪ Tetrapods can move in more direction Thoracic vertebra o Presence of long ribs in the anterior portion of the trunk 23 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 IN AMNIOTES – ATLAS Allows more motion because of the interplay of the cervical vertebra Atlas is the special structure of the cervical vertebra Ringlike because its centrum is missing Has facets for articulation with the occipital condyles o Base of the skull rests on top of the articulating facets of the atlas Centrum became the odontoid process of the axis – held in place by transverse atlantal ligament o Odontoid process will now be interlocking with the ringlike of the atlas so that it will now allow rotational motion of the joints that is held IN TURTLES together by transverse atlantal ligament Ball-and-socket joints allows the entire head and neck to be completely Reduction or absence of zygapophyses on results to rocking of the skull retracted in the shell and atlas Have only 8 cervical vertebrae o Zygapophyses – limit the extension of the join → no zygapophyses They can still twist their neck and do their ability to hide their head within would mean that flexion would happen their shell incase of presence of danger / predators Sphenodon chondrifies and unites with axis just before hatching o Fusion of the atlas and the axis → less movement Iguana would have greater mobility IN AMNIOTES – PROATLAS Resembles a neural arch and is derived from a pair of bilateral cartilaginous blastemas o There is an additional bone formation on the atlas o Path or canal where the spinal cord will pass through Found in reptiles → crocodilians, Sphenodon and insectivorous spiny hedgehogs o Some modern lizards have a fibrous membrane instead of a bone (mineralized tissue) IN BIRDS Exceptional flexibility due to the configuration of the vertebra (heterocoelus) 24 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 o Can turn their head 360 degrees and flex it at a distance and at an Living reptiles including most birds and angle opossums have 2 transverse processes o Right-left convexity Most mammals have 3 to 5 (ankylosed = o Dorsoventral concavity fused) o Saddle-shaped o Perissodactyls can have up to 8 Increased number of cervical vertebrae which allows them more room for o Edentates can have up to 13 movement o Commonly 12 SYNSACRUM o 25 in swans Special type of vertebra Fusion of the last thoracic, all lumbars and sacral and the first few caudals with the pelvic girdle o Provides rigid brace for the stance of birds as they need the ability to stand and balance with their narrow legs ▪ Which is why you would see them sleeping with one leg o Little flexibility in the avian backbone caudal to the neck → there isn’t much movement on their hips IN MAMMALS Armadillos have a synsacrum of up to 13 fused sacrals and caudal Not as mobile as we have flat surfaces of our centra Almost always have 7 cervical vertebrae o Three-toed sloth (Bradypus) – 9 o Manatees – 6 Length of centra and not the number determines the length of the neck in mammals o Giraffe would not have that much vertebrae but the vertebrae is much longer than usual SACRAL VERTEBRAE Bears stout transverse process strong enough to bear the thrust of the pelvic girdles o Especially for animals that would require strong lower limbs CAUDAL VERTEBRAE Amphibians have only 1 transverse process in the sacral vertebra Early tetrapods usually numbered 50 or more 25 DAVOCOL, Angeli C. Bachelor of Science major in Psychology College of Liberal Arts  LONG EXAM 2 Reduced and dictates how the tail is used in modern mammals AUTOTOMY o Right now the caudals in mammals became shorter or fused Not only the regeneration of tissues but Processes and arches became progressively shorter and rudimentary of bones as well towards the end until such that the last segment is a small cylindrical Responsible for the regeneration of the centra tail of many lizards, salamander, and o The tail is tapering at the end tuatara When caught by the tail, the reptile will shed part of it in attempting to escape o Distracting their predator and allow the lizard to escape U