LBBBYIO3 (1st Exam)

Dorsal

towards the back or upper side

Ventral

towards the under side

Lateral

towards the sides, right and left.

Anterior/Cephalic/Cranial

towards the head end of the animal

Posterior/Caudal

Towards the tail end

Medial

Towards the middle

Central

near the center of the body or organ

Peripheral

the part nearest the surface.

Proximal

near the main mass of the body, as the thigh.

Distal

away from the main mass of the body, as the toes.

Superficial

on or near the surface.

Deep

some distance below the surface.

Superior

Above

Inferior

Below

Planes and axes

The structures of most animals are arranged symmetrically with reference to certain imaginary planes and axes.

Sagittal plane

divides body into left and right

Parasagittal plane

divides the body into unequal left and right halves

Midsagittal plane

divides the body equally into left and right

Coronal / Frontal plane

divides body into dorsal and ventral parts

Transverse / Cross plane

divides body into anterior and posterior parts

Oblique plane

Any plane that is not perfectly sagittal, frontal, or transverse is described as an ________. Combination of two or all three cardinal planes

Anatomical axis

An imaginary straight line that passes through the body. Provides reference points for describing the orientation and movement of body parts.

Longitudinal (Anteroposterior) axis

runs from head to tail; associated with the transverse plane (movement around this axis includes rotation, like twisting).

Sagittal (Dorsoventral) axis

runs from back to belly; associated with the frontal plane (movement around this axis includes abduction/adduction).

Transverse (Mediolateral) axis

runs from side to side (left → right); associated with the sagittal plane (movement around this axis includes flexion/extension).

Symmetry

refers to the balanced arrangement of body parts on opposite sides of a dividing plane or around a central point

Asymmetry

No pattern in body parts.

Sponges, corals

Examples of asymmetry

Radial Symmetry

body parts arranged around a central axis (e.g., cnidarians)

Jellyfish, sea anemones, adult sea urchins

Examples of radial symmetry

Bilateral

right and left halves that mirror each other

Humans, frogs, insects, cats, dogs, fish

Examples of bilateral symmetries

Biradial

Radial with slight bilateral features

Metamerism (Segmentation)

Repetition of similar structural units (segments or metameres) along the longitudinal axis of the body

metamere, segment, or somite

Each such division of the body is termed a

vertebrae, ribs, spinal nerves, body muscles (myotomes).

Examples of metamerism

Homonomous Metamerism

all segments are structurally similar, showing little or no specialization.

Earthworms/Annelids

Examples of Homonomous Metamerism

Heteronomous Metamerism

Segments are dissimilar and specialized for different functions

vertebrates, Insects, and other arthropods

Examples of heteronomous segmentation

Yes, humans do exhibit segmentation both heteronomous and Homonomous

Do humans exhibit metamerism or segmentation

The vertebral column (Spine) is made up of repeating bone units (vertebrae), ribs and associated muscles also show a segmented pattern, and during early development, humans form somites.

Reasons why humans exhibit metamerism or segmentation

Cephalization

Evolutionary trend toward the concentration of sensory and nervous tissues in the head region.

1. Formation of a head region containing the brain

2. Clustering of sensory organs (eyes, ears, nose, antennae)

3. Development of feeding structures near the mouth

Key features of Cephalization

heteronomous condition

In segmented animals the advance in cephalization is correlated with the progression of the

Heteronomy

appears first in the head region and gradually progresses posteriorly.

bilateral symmetry, internal and markedly heteronomous segmentation, and a high degree of cephalization

The vertebrates are, then, animals characterized by the possession of

Evolution

Change in the characteristics of a species over several generations and relies on the process of natural selection

Natural selection

Individuals having more useful traits survive better and produce more progeny than individuals with less-favorable traits

Convergent evolution

Occurs when organisms that aren’t closely related evolve similar traits as they both adapt to similar environments (Ex. Birds, Bats, and Butterflies are different but have the same characteristics of having wings and flying.

Divergent evolution

occurs when groups from the same common ancestor split into two groups by a geographic barrier (for instance, a body of water or a migration to a new area), causing each group to develop different traits (Ex. Wolf → Fox and Domestic Dog)

Phylogeny

The relationship between all the organisms on Earth that have descended from a common ancestor

Phylogenetic tree

• The relationships are backed by molecular evidence.

• Should have access to DNA or other molecular data

Cladogram

• The relationships are hypothetical

• You can easily make it on your own

Taxonomy

Science of naming, describing, and classifying organisms

Domain (Most inclusive)

Kingdom

Phylum

Class

Order

Family

Genus

Species (Least inclusive)

Taxonomic Ranking system

Carolus Linnaeus

adopted a system of binomial nomenclature

• A scientific name is always italicized or underlined

• A genus name begins with Uppercase, while a species name is lowercase, e.g., Homo sapiens, Boa constrictor

Conventions of Linnaean taxonomy:

Genus, Species

Scientific name structure

italicized or underlined

A scientific name is always

Analogous structures

are features of different species that are SIMILAR in

function, but not necessarily in structure, and do not

derive from a common ancestral feature.

Homologous structures

Similar physical features in organisms that share a common ancestor, but the features serve completely different functions.

the Pharyngeal gill slits

The wall of the pharynx of the embryo or adult is pierced by openings,____________, originally probably a food-catching device. Modified in tetrapods

Notochord

is a rod lying dorsal to the intestine, extending from anterior to posterior end, and serving as a skeletal support. flexible rod for support; replaced by vertebral column in most vertebrates

1. Notochord

2. Pharyngeal gill slits

3. Dorsal hollow nerve cord

4. Post-anal tail

5. Endostyle/Thyroid gland

Characteristics of the chordata

Hollow central nervous system

containing a single continuous cavity, and is situated entirely on the dorsal side of the body.

Dorsal hollow nerve cord

develops into the central nervous system.

Post-anal tail

extends posterior to anus; may regress (human coccyx).

Endostyle/Thyroid gland

secretes mucus for filter-feeding; in vertebrates becomes

thyroid gland.

Gill arches in body fish and into the jaw and inner ear in terrestrial animals

Pharyngeal pouches becomes

Thyroid gland

Endostyle becomes

central nervous system

Dorsal tubular nerve cord becomes

vertebrae/backbone

Notochord becomes

absent in humans and apes

Postanal tail becomes

Shrinks or restricts

If a body part no longer serves a purpose or function then it

Protostome

When the mouth is first formed is called

Deurostome 

When the anus is first formed is called

Phylum Chordata

all members share the four main features (notochord,

dorsal hollow nerve cord, pharyngeal slits, and post-anal

tail) at some stage in their development

Cephalochordata, Urochordata (Tunicata), Vertebrata (Craniata)

3 Subphylum of Chordata

• Sac-like, soft-bodied, filter-feeding through a pharyngeal basket

• The notochord and nerve cord are present only in the larval stage

• Lacks a vertebral column/backbone

Characteristics of Urochordata/Tunicata

• Small, filter-feeding has a fish-like body

• Retains the notochord and nerve cord throughout life

• Lacks a vertebral column/backbone

Characteristics of CEPHALOCHORDATA

• Highly varied, complex body systems

• Notochord present in embryo only (becomes vertebrae), nerve cord develops into brain and spinal cord

• Has a vertebral column/backbone

Characteristics of Vertebrata

• Tunicata

• Cephalochordata

Which of the subphylum chordata are invertebrates

Cirri - finger-like projections

Subphylum Cephalochordata

Oral hood with ___________ that filter food and keep large particles out

Myotomes

Subphylum Cephalochordata

_______ are V-Shaped muscle blocks for swimming

Fins

Subphylum Cephalochordata

________ are dorsal, ventral, and caudal fins for stabilization

Atriopore

Subphylum Cephalochordata

________ are the opening where water exits the body 

Anus

Subphylum Cephalochordata

____ is located near the tail end 

Sessile (Immovable), Motile

Subphylum Urochordata (Tunicata)

Adult are ____, but larvae are ___ and show all chordate features

Tunic made of tunicin (cellulose-like material) 

Subphylum Urochordata (Tunicata)

Body covered by a ____ made of ______

oral (incurrent) and atrial (excurrent)

Subphylum Urochordata (Tunicata)

They have______ and ________ siphons for water flow

Large pharynx with gill slits

Subphylum Urochordata (Tunicata)

______ Used for filter feeding

Larvae

Subphylum Urochordata (Tunicata)

Chordate traits (notochord, post-anal tail, dorsal nerve cord) are present only in _____

Retrogressive metamorphosis

Subphylum Urochordata (Tunicata)

Undergo __________, where the adult is simpler than the larva

Humans have tails when we were embryos. The embryonic tail usually grows into the coccyx or the tailbone

Why people don’t have tails

Vertebrae (Plural form = Vertebra) 

Animals with backbone or spinal column, also called _____

•Have a backbone (vertebral column)

•Have a skull (cranium) to protect the brain

•Internal skeleton (cartilage or bone)

•Well-developed brain and nervous system

•Closed circulatory system with a heart

•Complete digestive system

•Paired fins or limbs (in most)

•Gills or lungs for breathing

•Kidneys for excretion and water balance

•Hormones to control body functions

•Separate sexes (mostly)

•Sense organs concentrated in the head (eyes, ears, etc.)

Main characteristics for vertebrates

Superclass Agnatha (jawless vertebrates)

First vertebrates

•do not have true jaws like other fish

•have a circular, toothed mouth

•have a cartilaginous skeleton rather than made of bone

•lack scales on their bodies

•have long, eel-like bodies

•often parasitic

•include jawless fishes like hagfishes (Class Myxini) and lampreys (Class Petromyzontida)

Characteristics of superclass Agnatha

• Class Myxini

• Class Petromyzontida 

Two classes of Superclass Agnatha (jawless vertebrates)