Chordata Phylum Characteristics
All PHYLUM : CHORDATA
Phylum Chordata 3 main characteristics key vertbral column , Chordata phylum characteristics - presence dorsal tubular nerve cord , divisions intogroup,chordates and non chordates include .
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| Chordata phylum characteristics |
Chordata phylum characteristics established by :
-- Balfour established this phylum.
-- Eucoelomate, bilaterally symmetrical and metamerically segmented.
-- Presence of a post anal tail.
-- Closed blood vascular system.
-- Three fundamental characters are
1. Dorsal tubular nerve cord.
2. Notochord/vertebral column .
3. Pharyngeal gill slits.
Kingdom chordata into 2 groups :
1 . Acrania / Protochordata / Lower Chordata
-- Exclusively marine
-- Coelom enterocoelic, arising from embryonic archenteron.
-- Head, cranium, vertebral column and appendages absent
-- Endostyle present
Subphyla : Chordata phylum characteristics
Divided into 3 subphyla :
-- Hemichordata, Urochordata and Cephalochordata
2 . Craniata / Euchordata / Higher
Chordata
-- Aquatic or terrestrial
-- Coelom schizocoelic, arising by splitting of mesoderm
-- Head, cranium, vertebral column and appendages present
-- absent Endostyle
-- Divided into only one subphylum vertebrata
Explain Hemichordata character
Subphylum: Hemichordata
-- Body divisible into proboscis, collar and trunk.
-- Notochord occurs only in anterior part (= proboscis).
-- Notochord found in Hemichordata is not of true nature hence called stomochord. This is the reason why this subphylum is removed from phylum Chordata and now considered as an independent phylum of non-chordata by Hyman.
-- Larva - tornaria.
-- e.g. Balanoglossus (acorn worm or tongue worm) is a connecting link between nonchordates and chordates.
Subphylum : Urochordata
-- Commonly called tunicates.
-- Notochord is in larva and confined to tail region only.
-- Hermaphroditic but due to protogyny (eggs mature earlier), cross fertilization is the rule, occurs in surrounding sea water.
-- Development indirect through ascidian larva with retrogressive metamorphosis. example -
1 . Herdmania (sea squirt) - It is filter feeder and has Single chambered heart without valve. Memoir of Herdmania was written by S.M.Das.
2 . Pyrosoma - It emits strongest light among marine. (Chordata phylum characteristics)
All vetebrates & chordates
Subphylum : Cephalochordata
-- Notochord occurs from head to tail & persist throughout life.
-- Excretion by solenocytes.
-- Wheel organ or rotatory organ is found to help in food capture .
-- Hatschek's pit is found to secrete mucus .
-- Heart is lacking hence most blood vessels are muscular and contractile in nature.
Chordata examples : Amphioxus (lancelet) - lt is now known as
Branchiostoma .
Imp . All vertebrates are Chordates
Subphylum : Vertebrata
-- Notochord supplemented or replaced by a vertebral column or backbone, which is composed of overlapping vertebrae.
-- Includes 2 divisions :
-- 1. Agnatha (Chordata phylum characteristics)
-- Primitive
-- Paired appendages and jaws absent
-- Internal ear with 1 or 2 semicircular canals
-- Includes 2 classes
Ostracodermi , cyclostomata
-- 2. Gnathostomata (Chordata phylum characteristics)
-- Advanced
-- Paired appendages and jaws present
-- Internal ear with 3 semicircular canals.
-- Included two-superclasses : Pisces and
Tetrapoda
Chordata phylum characteristics class
Class 1 . Ostracodermi
-- All extinct .
-- First jawless, primitive vertebrates .
-- Appeared during Ordovician period.
e.g. Cephalaspis.
Class 2 . Cyclostomata
-- Body eel-like.
-- Mouth suctorial and circular ( hence the name cyclostomata ).
-- Endoskeleton cartilaginous.
-- Parasites and scavengers.
-- Divided into two orders : (Chordata phylum characteristics)
1 . Petromyzontiformes
-- Gill slits 7- pairs
-- Development indirect with ammocoete larva
-- example - Pteromyzon ( lamprey ) .
2 . Myxiniformes
-- Gill slit one pair
-- Development direct
-- e.g. Myxine ( hag fish )
Kingdom Chordata | All Chordates
Differences Pisces and Tetrapoda
1. Pisces
-- Exclusively aquatic.
-- Paired appendages fins.
-- Respiration by gills.
-- Auricle one .
-- Includes 3 classes : Placodermi, Chondrichthyes & Osteichthyes.
2 . Tetrapoda
-- Aquatic and terrestrial .
-- Paired appen dages limbs .
-- Respiration by lungs .
-- Auricles two .
-- Includes 4 classes :
Amphibia, Reptilia, Aves
and Mammalia.
Chordates and vertebrates
-- Placodermi is a class of extinct fishes.
This group was evolved as first jawed vertebrates e.g. Climatius.
-- Vertebrates with 12 pairs Cranial nerves and amnion extra embryonic membrane are grouped under Amniota e.g. Reptilia, Aves and Mammalia .
-- On the other hand fishes and amphibians are grouped under Anamniota because they lack amnion and have 10 pairs of cranial nerves .
All chordata phylum characteristics
Superclass: Pisces
-- Ichthyology study of fishes.
-- First arose during Silurian period
-- Devonian was age of fishes.
-- Heart 2-chambered (1 auricle &1 ventricle). It is actually
venous heart that pumps only impure blood.
-- Kidney mesonephric.
-- Cranial nerves 10 pairs.
-- Lateral line receptor system present.
-- Following are some important differences between its 2
main classes :
Chondrichythes (Chordata phylum characteristics)
-- Mostly marine .
-- Cartilaginous fishes (elasmobranchs)
-- Gill opening 5-pairs, naked without operculum
-- Nostril & mouth Ventral
-- Ampulla of Lorenzini Present as
thermoreceptor .
-- Intestine With scroll valve
-- Air or swim bladder Absent
-- Skin With placoid scales
Examples - Scoliodon (Dog fish
or shark) viviparous
- Stegostoma (tiger fish or zebrashark)
- Torpedo (electric ray)
- Pristis (saw fish)
- Chimaera (rat fish)
Osteichthyes (Chordata phylum characteristics)
-- Both fresh water & marine
-- Bony fishes (teleosts)
-- Gill opening 5-pair, covered by
operculum; single opening on either
side.
-- Nostril dorsal but mouth terminal
-- Ampulla of Lorenzini Absent
-- Intestine Without scroll valve
-- Air or swim bladder Present as a hydrostatic organ .
-- Skin With or without scales
but never placoid
Example :
- Echeneis =Remura
(sucker fish)
- Anabas (climbing fish)
- Anguilla (fresh water eel)
- Exocoetus (flying fish)
- Amia (ganoid fish)
- Synaptura (flat fish)
Chordata is a phylum in the kingdom
Things to Remember
1. Petromyzon is considered as a living fossil .
2. Hippocampus (sea horse) has scales and bony plates. It shows parental care as the male has brood pouch .
3.Latimeria is a coelacanth crossopterygian lobe finned fish. It is a living fossil.
4. Cat fishes are those which are provided with sensory barbels. e.g. Clarias, Wallago.
5. Lung fishes (Dipnoi) show discontinuous distribution.
They form connecting link between fish & amphibia. (Chordata phylum characteristics)
Three living genera are :
-- lung fishes
1. Lepido siren - America
2. Protopterus - Africa
3. Neiceratodus - Australia
6. Gambusia affinis (mosquito fish) is an exotic fish imported from Italy. It controls malaria biologically by feeding upon mosquito larvae.
7. In Torpedo (electric ray), electric organs are highly modified mass of muscles.
8. Isinglass is a product prepared from air bladder of certain fishes, which is used to make clear the wine , jelly etc.
9. Shagreen is prepared from shark skin, which is used in polishing.
10. Cod liver oil extracted from liver of fishes, is rich source of vitamin A (Vitamin D & E also).
11. Certain fishes migrate from one place to another for the purpose of spawning. It may be of two types:
- Anadromous : from sea to fresh water e.g. Hilsa, Salmon .
- Catadromous : from fresh water to sea eg.Anguilla.
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Chordata Biology | About Chordata
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| Chordata phylum characterstics |
About Chordata Phylum Characterstics
Class 1 : AMPHIBIA
-- Live both in water and land hence the name Amphibia
-- First originated during Devonian period.
-- Age of amphibians was Carboniferous period .
-- Cold blooded or poikilothermic or ectothermal i.e. body temperature very according to environment. Winter
sleep is called hibernation and summer sleep is called aestivation.
-- Skull dicondylic i.e. provided with 2- occipital condyles .
-- Jaws with small homodont teeth .
-- Heart 3- chambered (2 auricles &1 ventricle), both renal and hepatic portal systems present , RBC nucleated.
-- Kidney mesonephric; excretion- ureotelic
-- External ears absent; middle ear with a single rod-like ossicle columella auris (and a stapedial plate).
-- Fertilization external; egg mesolecithal (moderate amount of yolk) and development direct (larvae - axolotl or tadpole) .
Order 1. Apoda (Chordata phylum characteristics)
-- Also called Gymnophiona.
-- Commonly called caecilians or blindworms.
-- Limb and tongue absent but scales present.
-- Shows parental care e.g. lchthyophis .
Order 2. Urodela
-- Also called Caudata.
-- Commonly called newts and salamanders.
-- Limbs two pairs with almost same size.
-- Tail present e.g. Ambyostoma (tiger salamander) Necturus (mud puppy) .
Order 3. Aneura (Chordata phylum characteristics)
-- Also called Salientia.
-- Commonly called frogs and toads.
-- Limbs 2-pairs, forelimbs with four fingers are smaller than hindlimbs with five toes.
-- Tail is absent in adult.
example - Rana (frog) , Rhacophorus (flying frog) , Hyla (tree frog) .
Things to Remember
1 . Males of midwife toad (Alytes) carry eggs and show parental care .
2 . Poison gland of toad is modified parotid gland.
3 . Axolotl is an amphibian larva (Ambyostoma) which Shows:
-- Neoteny : retention of larval characters in adults.
-- Paedogenesis : production of young ones by preadult forms .
CLASS II: REPTILIA (Chordata phylum characteristics)
-- Herpetology study of reptiles .
-- Exclusively first terrestrial vertebrates.
-- Poikilothermic, skin dry without glands.
-- Limbs usually 2 pairs, pentadactyle, digit clawed.
-- Kidney metanephric , urinary bladder
crocodiles and snakes; excretion ammonotelic in crocodiles, ureotelic in turtle and alligator and uricotelic
in snakes & lizards .
-- Eggs macrolecithal , telolecithal and cleidoic (i.e.covered with shell).
-- Fertilization internal , extraembryonic membrane amnion present.
-- Skull monocondylic i.e. provided with 1 occipital condyle.
-- Jacobson's organ ( vomeronasal organ) occurs in lizards and snakes and concerned with smell .
-- First appeared during Carboniferous period. Mesozoic era was age of dinosaurs / reptiles.
-- Heart incompletely 4 or 4 chambered
Subclass : Anapsida (Chordata phylum characteristics)
-- Skull roof solid without any temporal fossa.
-- Includes only one living orderChelonia
-- Contains turtle (aquatic), tortoise (terrestrial) and terrapins (edible fresh water) .
-- They have unusual appearance and are actually the 'reptiles in boxes'.
-- Body is covered with dorsal carapace and ventral plastron.
-- Giant tortoise has maximum life span .
Subclass : Diapsida (Chordata phylum characteristics)
-- It is characterized by having 2 occipital condyles and includes three living orders
Order 1. Rhynchocephalia :
-- Lizards like, burrowing and noctumal.
-- Pineal gland as third eye .
-- Quadrate fixed. e.g. Sphenodon (tuatara)- occurs only in New Zealand. This is a living fossil and connecting
link between Amphibia and Reptilia.
Order 2. Squamata (Chordata phylum characteristics)
-- It is characterized by movable quadrate and includes two Suborders :
-- Sauria (=Lacertilia)
-- Includes lizards.
-- Saurology study of lizards .
-- limbs well-developed .
-- eyelid movable nictitating membrane present .
-- Maxillae , palatine and pterygoid fixed .
-- Shows autotomy i.e. voluntary breaking of tail to confuse enemy example .
- Iguana ( herbivorous lizard )
- Ophisaurus ( limbless lizard or glass snake )
- Heloderma ( beaded lizard aur Gila monster )
- Phrynosoma ( horned toad ) viviparous
-- Ophidia (=Serpentina)
-- Includes snakes.
-- Serpentology or Ophidiology study of
snakes .
-- Limbs absent .
-- Eyelid fixed : nictitating membrane absent .
-- These skull bones freely movable to help in biting mechanism .
-- Shows moulting aur ecdysis i.e. shedding of epidermis of skin .
Poisonous snakes :
- Naja ( cobra )
- Bungarus ( Krait )
- Vipera ( viper )
- Hydrophis ( sea snake )
- Crotalus ( rattle snake )
Order 3 . Crocodilia : (Chordata phylum characteristics)
-- Aquatic.
-- Limbs clawed and webbed.
-- Diaphragm present.
-- Heart completely 4 chambered
-- Foramen of panizzae is found in heart to join the systemic arches. e.g
- Alligator
- Crocodylus (marine) - largest
- Gavialis (gharial) found only in India
Thing to Remember : (Chordata phylum characteristics)
1. Poison of snake is called venom. The antivenom is its medicine prepared by Hopkins Institute Mumbai (by
horse ) .
2. Fangs of snakes are modified maxillary teeth. The poison gland of snake is parotid while that of Heloderma (only poisonous lizard) is sublingual salivary glands.
3. The venom is either neurotoxic (affecting the nervous system) or haemotoxic (affecting the circulatory
system). The venom of cobra, krait, sea snake and Helodermma is neurotoxic while that of viper is haemotoxic .
4. Some non-poisonous snakes are Typhlops (blind snake), Eryx (double headed snake) and Python (azgar)-largest snake.
5. Dinosaurs mean 'terrible lizards', first appeared during Triassic period (along with egg laying mammals) and
become extinct in Cretaceous period. The Mesozoic era is called golden age of dinosaurs.
6. Seymouria was stem reptile and represents a connecting link between Amphibia and Reptilia .
7. Rhamphorhynchus (pterosaur) was a flying reptile.
8. Urinary bladder is absent in crocodiles and snákes .
CLASS Ill : AVES (Chordata phylum characteristics)
- Warm blooded or homiotherms .
- Jawbones prolonged into a toothless beak
- Limbs two pairs ; forelimbs modified as wings for flying .
- Skin without glands but tail has preen or uropygial gland .
- Skull monocondylic ; vertebrae heterocoelous or saddle shaped.
- Synsacrum and pygostyle present.
- Sternum large with a keel for the attachment of larger flight muscles (pectoralis major).
- Ribs with uncinate process.
- Heart 4-chambered ; RBC nucleated.
- Bones are hollow or pneumatic.
- Both clavicles and a single interclavicle are fused to form a v-shaped bone called furcula or wishbone or merry thought bone.
- Larynx without vocal cords; a sound box called syrinx is found in them for voice production.
- Kidney metanephric , 3- lobed ; uricotelic, urinary bladder absent .
- Female has a single functional left overy
- Eyes with pecten (help in nutrition).
- Foramen of triosseus occurs in pectoral girdle.
- Crop secretes pigeon's milk during breeding season.
- Ornithology - study of birds
- Oology - study of birds's eggs
- Nidology - study of birds's nests
- Phenology - study of bird migration
- Class Aves includes two subclasses :
Archaeornithes (Chordata phylum characteristics)
- Extinct, Jurassic birds .
- Toothed
- Wings primitive with little power of flight
- e.g. Archaeopteryx lithographica :
1. Fossil was excavated by Andreas Wagner in 1861 from rocks of Bavaria (Germany)
2. Appeared in Jurassic and became extinct during Creataceous .
3. Connecting and missing link between reptiles and birds .
Neornithes (Chordata phylum characteristics)
- Sternum generally keeled .
- Teeth absent .
- Wings usually well developed
- Includes four superorders :
1. Odontognathae (extinct)
2. Ratitae or Palaeognathae
3. Impennae
4. Neognathae or Carcinatae
Chordata and vertebrata | unique invertebrates
Superorder 1. Ratitae
- Flightless and runnina birds (wings vestigial) .
- sternum not keeled .
- Important evidence for organic evolution.
- Show discontinuous distribution
: Bird Distribution
- Ostrich Africa
- Rhea America
- Emu Australia
- Cassowary Australia
- Kiwi Newzealand
- Dodo Mauritius
Super order 2. Impennae
- Aquatic flightless birds.
- Wings paddle-like e.g. Penguins (Aptenodyres) found in Antarctica (southern Hemisphere) .
Super order 3. Neognathae
- Moden small sized birds .
- Wings well developed ; feathers with interlocking mechanism .
- Teeth absent but beak present to serve as mouth and hand .
- Sternum keeled . e.g.
- Pavo cristatus - National bird of India ,
- Columba livia (pigeon) - has 9 air sacs .
Things to Remember
1 . Birds are originated from flying reptiles (pterosaurs) during Jurassic period. Toothed bird Archaeopteryx and marsupials both are originated during this period .
2 . Dodo become extinct in 1681.
3. Largest living bird is Ostrich while smallest is sunbird (humming bird) .
4 . Birdman of India - Dr. Salim Ali .
5 . Birds are master of air - Young .
6 . Huxley told that birds are glorified reptiles .
Chordata and Vertebrata Chordata phylum characteristics
CLASS IV : MAMMALIA
- Mammology - study of mammals .
- Cetology - study of whales .
- Tricology - study of hairs .
- Mammal is originated during Triassic period.
- Coenozoic era is age of mammals
- Skull dicondylic .
- Presence of seven cervical vertebrae.
- Body with hairs ; homiothermic .
- Skin with glands.
- A muscular transverse diaphragm separates the body into thoracic and abdominal cavity .
- Corpus callosum in cerebral hemisphere ; optic lobes 4 .
- Mammary glands present .
- External ear or ear pinna present .
- Testis extra abdominal i.e. within scrotal sac except in elephant , aquatic mammals and prototherians.
- Heart 4-chambered , RBC non nucleated except camel.
- Divided into 2 subclasses :
Prototheria (Chordata phylum characteristics)
- Oviparous (egg laying) .
- No external ear
- Mammary glands without nipples .
- Beak without teeth .
- Testis abdominal .
- Includes only one order
Monotremata (Australia) e.g.
- Echidna or Tachyglossus (spiny ant eater)
- Omithorhynchus ( duck
billed platypus )
Theria (Chordata phylum characteristics)
- Viviparous (give birth to young)
- With external ear .
- Mammary glands with nipples.
- Beak absent but teeth present .
- Testis extra abdominal.
- Includes two infraclasses ;
1. Metatheria
2. Eutheria
Differences between Metatheria & Eutheria
Metatheria (Chordata phylum characteristics)
- Pouched (=marsupial) mammals
- Vagina Double
- It includes only one order Marsupialia (Australia)
eg. Kangaroo (Macropus)
Eutheria (Chordata phylum characteristics)
- Higher ViviparOus mammals without
marsupium
- Vagina double
- Young ones born in relatively advanced stage .
- It has 18 orders including Insectivora , Proboscidea , Rodentia , carnivora , etc .
Things to Remember :(Chordata phylum characteristics)
- Prototherian mammals are living fossils and serve as connecting link between Reptilia and Mammalia .
- Duck billed platypus is a poisonous mammal .
- Order Lagomorpha includes rabbits and hares. The common rabbit is Oryctolagus cuniculus with worldwide distribution. The North Indian hare is Lepus ruficauda- tus . while South Indian hare is Lepus nigricollis
- Bat (Pteropus) is an example of order Chiroptera, which is nocturnal with a radar system (echolocation).
- Order Cetacea is characterized by aquatic, gregorious and skin with blubber e.g. whale. Largest animal is blue whale (Balaenoptera).
- Order Artiodactyla is characterized by occurrence of 4-chambered stomach without incisors and canines in upper jaw. e.g. Hippopotamus (horse of the river) and
camel (ship of the desert).
- Highly developed order is Primates in which first digit (thumb) is opposable and digit with nail e.g. Monkey Ape and Human
Chordata phylum characteristics
LIVESTOCKS
- It refers to domestic animals, which are kept for use or profit e.g.cattle (Bos indicus) & buffaloes (Bubalus bubalus).
- The breeds of cattle are classified as following :
Milch breeds
1. Gir
2. Red Sindhi
3. Sahiwal
4. Deoni
Drought breeds
1. Malvi
2. Nager
3. Hallikar
4. Kangayam
General utility breeds
1. Haryana
2. Ongole
3. Kankrej
4. Tharparkar
Indian breeds of buffaloes are,
1. Murrah, 2. Bhadawari,3. Jaffrabadi, 4. Surti 5. Mehsana 6. Nagpuri or Elichpuri
(Chordata phylum characteristics)
- They yield milk and help in agricultural practices such as ploughing, threshing, harvesting, transporting etc.
- They also provide leather, fertilizers, dung etc. The gobar gas is prepared from dung, after yielding biogas, the residue retains its fertilizing qualities.
- Superovulation is a technique wherein a high quality cow is made to ovulate more ova by hormone injection .Thus more ova are produced instead of one. After artificial insemination 4-10 embryos are collected at a time and time and each embryo is transplanted into a ' carrier cow ' (Surrogate mother) .
- By deep freezing (-196°C) , it ispossible to preserve seven days old foetus for several
years .
- Super ovulation and embryo transplanta- tion techniques have been used in India for cattle improvement.
- The introduction of semen in the vagina of female by artificial means is called artificial insemination which is Comparatively better and economical.
- In order to increase milk yield, Indian cows are crossbred with superior quality of bulls like Jersey (England) , holstein Freisian (Holland) , Brown swiss (Switzerland) etc .
- National Dairy Research Institute is located in Haryana (Kernal) and Kerala .
- Buffaloes are more adapted for wet areas and rivers while cow is adapted for dry condition .
- The period for which the embryo is retained within the uterus is called gestation period which is usually 307 days (=10 months) in buffalo and 284 days (=9 months) in cow .
- Rinderpest , foot and mouth diseases, haemorrhagic septicaemia, anthrax are some diseases in livestocks .
- Stilbesterol tablets are implanted to induce lactation.
- Main protein of milk is casein vitamin thiamin, ascorbic acid and calciferol are found in very minute quantity while iron and copper are almost absent in milk .
PIGGERY (Chordata phylum characteristics)
1. The care and management of pigs (Sus scrofa) is called piggery . It is of great economic value as it is another important
livestock.
2. Pigs are very much susceptible to extremes of heat and cold as they are provided with poor heat regulating mechanism .
3. All the 7 Regional Pig Breeding Stations of our country are involved in improving both indige-nous (deshi) as well as exotic (foreign) pigs.
4. Following are some important breeds of pigs
- Domesticated indigenous pig : 1. Desi 2.
Ghori
- Exotic pigs: 1. Berkshire 2. Large white York shire 3. Landrace
5. Its oestrous cycle is of 20-21 days but the heat period ranges from 40-65 hours .
6.During the heat period, if female pigs mate twice, the number of young ones produced is more than when they mate only once.
7. Pig's fat is used as cooking medium and for the preparation of soap. Its hide forms leather and its bristles are used for making brushes.
8. Different imp terms regarding pig/piggery are as :
- Pork : is the flesh of pig.
- Bacon : is the flesh of pig, obtained from back and sides .
- Ham : is the flesh of pig, obtained from back of thigh.
- Sausages : are prepared by fresh minced pork, free from bone and skin .
- Lard : is the fat of pig squeezed from body tissues.
- Bristles : are the winy and stiff hairs of pigs.
General Chordata phylum characteristics
POULTRY
1. The term poultry is used for a wide variety of birds which can be reared under domestication such as chicken,ducks, pigeon, turkeys etc.
2. Domestic fowl (Gallus domesticus) constitutes the major poultry bird .
3. Birds reared for meat are called broilers e.g.Plymouth Rock .
4. The 2 types of fowls are
a) Indigenous: Aseel, Ghagus, Malay etc.
b) Exotic: White leghon, Plymouth Rock, New Hampshire and Rhode Island Red
5. Ranikhet (=Newcastle disease) is a viral disease, pullorum is a bacterial disease (caused by Salmonella pulorum) while coccidiosis is a protozoan disease (caused by Eimeria).
6. Imperial Veterinary Research Institute and Central Avian Research Institute are located in Izatnagar (U.P.)
7. Central Food Technological Research Insttitute is located in Mysore .
BIOMEDICAL TECHNOLOGY
(Chordata phylum characteristics)
1. Dialysis : it is a process of diffusion across a semi-permeable membrane for removal of unwanted waste materials from the blood .
It is of 2 types :
(a) Haemodialysis : removal of accumulated waste materials from blood by using artificial kidney .
(b) Peritoneal dialysis : permanent fixation of cetheter in the peritoneal cavity of the patient.
2. Polygraphy :
- it is used for recording the qualitative changes in physiological activities of body such as heart activity, pulse rate, relative blood pressure, breathing etc. It is sometimes used for detecting lies. The polygraph is called lie detecting machine.
3. Pacemaker : (Chordata phylum characteristics)
- The SA node located in right auricle is called pacemaker, as it initiates the heart beat. When normal heart beat drops to abnormally low levels, artificial pacemaker is implanted.
- Artificial pacemaker (first used by Chardack in1960) consists of a pulse generator and an electrode .
- The pulse generator contains lithium halide cells , which provide power for about 10 years .
4. CT Scan : (Chordata phylum characteristics)
- The technique of Computed Tomographic Scanning (=CT) or Computed Axial Tomography (CAT) was first developed by Godfrey Hounsfield (Britain) in 1968 (NP 1979) .
- It combines the use of X-rays with computer technology to produce clear image of an area / any part of body. t helps in diagnosis of diseases of brain, spinal cord, chest etc.
5. PET Scan : (Chordata phylum characteristics)
- The technique of Positron Emission Tomographic Scanning was developed by Sokoloff of USA in 1985 .
- It is based on detection of positrons (+vely charged e-) emitted by radio isotopes such as C11 , N13 , O15 etc generated by cyclotron . These isotopes are incorporated in glucose, amino acids, CO2 etc, which are then taken
by person , who has to undergo investigation
- It is helpful in determining the cerebral blood volume . blood flow , metabolic rates, mental illness , colour processing centres in visual cortex etc.(Chordata phylum characteristics)
6 . MRI : The technique of Magnetic Resonance imaging was developed by Bloch and Purcell in USA . It provides high quality 3-dimensional images of any body structure due to natural behaviour of protons of H-atoms, when Subjected to strong magnetic field and radio waves.
It is useful in understanding the activity of brain and spinal cord with no side effect.
7. Sonography : (Chordata phylum characteristics)
This technique is also known as echography or Ultrasound scanning. in which inaudible high frequency sound waves in the range of 1-15 million hertz are used. The ultrasound waves are emitted by transducer , which is placed on the skin over the part of
body to be examined.
The transducers are substances that have the property of being able to convert one form of energy into another. These contain lead zirconate . The ultrasonic waves are produced as a result of piezo - eiectric (=pressure electric) effect.
It is useful in diagnosing the diseases of kidney stones, brain, gall stones, intestinal obstructions, uterus, obstetrics etc.
8 . SQUID / MET : (Chordata phylum characteristics)
The technique of Super Conducting Quantum interference Device /Magneto-Encephalography is used to study weaker magnetic fields of brain and helpful to know the brain in health and disease .
9 . Endascopy :
It is an instrument with a long flexible tube attached with a hand set. The tube of the endoscope is inserted through an opening into the body.(Chordata phylum characteristics)
The endoscopes are named according to their use e.g. gastroscope to examine stomach, laparoscope to examine uterus, ovaries etc and so on. A surgeon is able to cary out minor operations using an endoscope, without
cutting through overlying tissues.
10 . Prosthesis :
It is the Substitution of artificial body parts . It includes internal prosthes is (e.g. lens replacement) and external prosthesis (e.g. limb replacement) .
Jaipur foot (more or less similar to that of natural foot) was designed by Dr. P.K. Sethi of Jaipur .(Chordata phylum characteristics)
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