Flashcards in Lecture 1 Deck (49):
List the three subphyla of the phylum Chordata
Cephalochordata, Urochordata, Vertebrata
Describe the major characteristics of cephalochordates
Notochord located in the cranial "head", represented by lancelets (amphioxus)
Describe the major characteristics of urochordates
Represented by sea squirts (ascidians), they develop as larva with dorsal notochords, but lose them upon maturation when they reach their immobile adult phase. Body cavities are only loosely definable.
Describe the major characteristics of vertebrates
Notochord develops into vertebral column - represented by the classes pisces, and tetrapods
List the five classes grouped into the Pisces Supergroup
Agnatha, Acanthodii, Placodermi, Chondrichthyes, and Osteichthyes
Describe the major characteristics of Agnatha
These fish lack jaws or paired appendages. Examples include the hagfish and possibly lampreys.
Describe the major characteristics of acanthodii.
An extinct class which used to include spiny sharklike creatures that were possibly the first vertebrates to have jaws (gnathostomes). They share this characteristic with placoderms
Describe the major characteristics of placoderms
An extinct class of gnathostomes (first jawed fish) who first developed paired fins. Ranged from very small to very large.
Describe the major characteristics of chondrichthyes
Class of fish unable to form bone, but developed skeletal systems made of cartilage. Includes both extinct and extant sharks, and rays.
Describe the major characteristics of osteichthyes
Largest current class of fish species, includes any fish with bone skeletal structures (though some can still retain some cartilage)
Name the four classes of tetrapods
Amphibia, Reptilia, Aves, and Mammalia
Describe the characteristics/examples of amphibia
Includes both extinct and extant amphibians including frogs, toads, and salamanders.
Describe the characteristics/examples of reptilia
Includes extinct and extant lizards, snakes, turtles, crocodiles, and dinosaurs (including flying reptile such as pterosaurs)
Describe the characteristics/examples of aves
Birds, both extinct and extant. Major characteristic is the presence of feathers.
Describe the major characteristics/examples of mammalia
Extinct and extant mammals, had both hair and mammary glands
List the four anatomical features all chordates possess
(Embryological) Dorsal Hollow Nerve Cord, Pharyngeal slits arches and pouches, a notochord, and a post-anal tail.
List four features of the dorsal hollow nerve cord.
1. Represents future brain and spinal cord
2. Hollow tube that runs dorsal to the notochord
3. Retained as adults in vertebrates as the hollow space in brain and spinal canal
4. Can comprise of entire nervous system in some invertebrates
Where is the pharynx located and what is the purpose of pharyngeal pouches
Pharynx is in Cranial portion of the gut tube. The pouches connect exterior of the organism with the interior of the pharynx, and are often retained after maturation as gill slits,
What are pharyngeal arches and where are they found?
The area between pharyngeal pouches are called arches. These each contain a skeletal element, branchiomeric muscles, cranial nerves, and an aortic arch. The first arch is called the Mandibular arch (gills, auditory tubes, middle ear cavities) and the second arch is called the hyoid arch (forms the palate tonsils in mammals)
What were the primitive original purposes of the pharynx in regard to respiration
Though originally for filter feeding by trapping plankton, the pharynx developed external gills from the pharyngeal pouch, which subsequently developed vascularization that allowed oxygen to be extracted from the water flowing through these gill slits.
What is the notochord and what purpose does it serve
The notochord runs ventral to the nerve cord and dorsal to the gut tube and is a hollow tube made of cells resembling (but not matching) cartilage. In embryos it provides hydrostatic support in water (damage during this stage is usually devastating), but it continues to provide axial skeletal support in agnathans.
In mammals, what becomes of the notochord post-embryologically?
Notochord breaks down and forms intervertebral disc nucleus. Also initiates the formation of the central nervous system (brain).
Describe the vertebral column
Only In vertebrates, the vertebral column is a series of irregularly shaped elements (cartilage and/or bone) that protect the nerve cord and provide axial support. Land animals rely on it since it's more rigid and resistant to gravity, though fish still retain some notochord elements due to flexibility required underwater.
What are the three general "sections" of the vertebrate body, and what characteristics do they have?
1. Head - Cephalization - usually the location of sensory organs
2. Body - Contains viscera and central support for the appendages. Can also consist of a slender stalk connecting the head (the neck)
3. Tail - Begins at the caudal opening of the digestive tract - the anus. Often lost post-embryologically or after a certain level of maturation. Can be used for defense/swimming/support/etc...
List the eight characteristics vertebrates share with invertebrates
1. Cephalization 2. Complete Digestive Tract
3. Bilateral Symmetry 4. Metamerism (segments with distinct function?) 5. Triploblasty 6. Eucoelomate body Cavity
7. Closed circulatory system 8. Deuterostomy
List the 8 directional terms associated with anatomy and their 4 correlated axes
Proximal/Distal, Ventral/Dorsal, Left/Right, Anterior/Posterior
Proximodistal Axis, Dorsoventral Axis, Left/Right Axis, Anteroposterior Axis
Name the 3 axes commonly used with quadripedal organisms
Cranial/Caudal (Vertical Axis - Usually parallel to the spine)
Dorsal/Ventral Axis (Saggital, or anterior posterior axis - perpendicular to the spine)
Left/Right Lateral Axis
Define the 3 planes of symmetry and which 2 axes run together to create it.
Saggital - Cranial/Caudal intersects with Anterior/Posterior
Frontal (Coronal) - Cranial/Caudal intersects with Left/Right
Transverse (Cross-Section) - Dorsal/Ventral intersects with Left/Right
List the five movements of bilateral symmetry
Flexion, Extension, Abduction, Adduction, Rotation
Describe the movements for Flexion and Extension
Flexion - Bending movement that takes place in a saggital plane around the left/right axis. Usually brings two body parts closer together. The fetus is developed in a fully flexed position
Extension - Straightens out a bent joint in the same saggital plane around the left/right axis
Describe the movements for abduction, adduction, and rotation
Abduction - Away from the midline, such as raising arms to the side, or extending fingers
Adduction - A reversal of Abduction, where body parts are directed towards the midline. (Bringing arms back to waist)
Rotation - Movement of the body Around the caudal plane in a transverse plane
The vertebrate body plan is generally thought to be comprised into Two distinct tubes. Describe the outer tube.
The somatic tube is what interacts with the external environment and consists of both skin, and skeletal muscle. It is intended to detect changes in the external environment and appropriately respond.
The vertebrate body is thought to be comprised into two distinct tubes. Describe the Inner Tube
The splanchnic, or visceral tube is generally thought to be for metabolism. It involves the gut tube (alimentary tract) and derivitives, such as the liver and pancreas.
In the animal kingdom, the somatic tube and the splanchnic tube are separated by an internal space called the coelom. List and describe the 3 types an organism can have based on their coelum.
- Acoelomates lack a body cavity separating the somatic tube from the visceral tube
- Pseudocoelomates possess a cavity, but it is only partly derived from embryonic mesoderm.
- Eucoelomates includes most animals and chordates; they possess a body cavity that is completely in line with derivatives of embryonic mesoderm.
There are 2 mesodermal derivatives within the coelom of eucoelomates. Name them and their location.
- The lining associated with the somatic tube is referred to as somatic or parietal peritoneum (or pleura or pericardium).
- The lining that is intimately associated with the splanchnic tube is referred to as visceral peritoneum (or pleura or pericardium).
- Places where these two linings meet form double-layered suspensory structures called mesenteries, which help supply pathways for blood vessels to reach to reach visceral organs. (See slide 41 in lecture 1)
Name 8 other characteristics that vertebrates often share with non-vertebrates.
1. Paired Appendages, 2. Internal mesodermal skeleton,
3. Epaxial/Hypaxial Musculature, 4. Subdivided Coelom,
5. Segmentation/metamerism, 6. Triploblasty,
7. Deuterostomy, 8. Cephalization
Describe Paired Appendages and their types
- All modern vertebrates have paired appendages, though some are lost secondarily or modified.
Classified into two categories: Pectoral Appendages, and Pelvic Appendages. Both of which have similar anatomical patterns.
Describe the internal mesodermal skeleton
All vertebrates have an internal mesodermal layer, which forms the mesoderm, one of the three embryonic germ layers. The mesoderm gives rise to many internal structures, including the skeletal system, be that cartilage or bone. (Cartilage often develops into bone embryologically)
Describe the layout of hypaxial and epaxial muscles and which human muscles consist of each.
Epaxial Musculature - lies above the dorsal ribcage and is shaped in block-like structures called myomeres. Useful in fish for locomotion. Not as common of a feature in humans.
Hypaxial Musculature - Often found below the dorsal ribs and lateral to the ventral ribs, this type of musculature is more layered as is the common component of skeletal muscle in the walls of body cavities, and limbs.
The coelom is divided into two different mesodermal subdivisions in most vertebrates, but three in mammals. Name them, and describe what is housed in each
Vertebrates: (Pericardial - heart), (Pleuroperitoneal - lungs, and other viscera)
Mammals: (Pericardial - Heart), (Pleural - Paired cavities of Lungs), (Peritoneal - other viscera)
Describe what separates the subdivisions of the pericardial and pleuroperitoneal cavities in fish, amphibians, reptiles, birds, and mammals.
Transverse Septum (Fibrous wall separates cavities in fish, amphibians, and some reptiles)
Tendinous Oblique Septum (Separates cavities in other reptiles, and birds)
Muscular Diaphragm - Partitions off pleural cavities in mammals
What is the name of the collective mesodermal linings and what sort of properties do they have
The mesodermal linings are collectively referred to as the serous membrane, which produces a thin watery lubricating fluid.
- These layers are known as the Parietal Layers, such as Parietal Pleura, Parietal Pericardium, etc...
- There are also membranes covering the organs within the body cavities called visceral membranes. (Eg. Visceral Pericardium, Visceral Peritoneum, etc...)
The transitional points where the visceral and parietal peritoneum membranes form are called mesenteries. There are 2 main mesenteries: The Dorsal Mesentery connects the dorsal roof to the gut tube, and the Ventral Messentary connects the gut tube to the ventral floor.
- Describe where VM-2 is found.
- Describe where VM-1 is found.
- What is the fate of the ventral mesentery, when, and why?
- What are the organs outside the peritoneum referred to and what's an example?
- In the cranial part of the peritoneal coelom, the ventral mesentery connecting the liver to the floor of the peritoneal cavity forms the falciform ligament (VM-2).
- The part of the ventral mesentery between the liver and the ventral gut tube is the lesser omentum (VM-1).
- Most of the rest of the ventral mesentery is obliterated during embryonic development due to the elongation and coiling of the gut tube.
- Some organs such as the kidneys lie behind the peritoneum and are referred to as retroperitoneal.
- Take note of the diagram on slide 50
- Metamerism refers to segmentation and describes the subdivision of the body into repeating anatomical units on either side of the midline extending from the cranial to the caudal end.
- Metamerism is easy to observe in many invertebrates such as earthworms and insects, but it is also very evident in vertebrates, although not so obvious externally.
- The epaxial musculature is divided into repeating blocks of skeletal muscle (myomeres) lying on either side of the notochord or vertebral column. This is especially evident in fish but can also be seen in tetrapods.
- Metamerism is also evident in the anatomy of the vertebral column, nervous system and kidneys.
List the three germ layers resulting from triploblasty and give an example of the organs found in each layer
Ectoderm - outermost germ layer, and holds the nervous system, and the integument (skin).
Mesoderm - Middle Germ Layer; Holds connective tissue, bones, cartilage, muscle, and other similar structures.
Endoderm - Inner Germ Layer; Houses the Gut tube, and derivatives.
- NOT unique to chordates
- Refers to the origin of the oral opening in relation to the anal opening during embryonic development.
- In deuterostomes, the original embryonic opening (the blastopore) becomes the anus, and the mouth develops as a secondary opening.
- NOT unique to chordates
- Refers to the development of a definite head (cranial end) characterized by an accumulation of sense organs