Anatomy
The study of body structure
Physiology
The study of body function
Natural Selection
the process through which populations of living organisms adapt and change
Evolution
the change in the characteristics of a species over several generations and relies on the process of natural selection
Prokaryotic
organisms are made up of cells that lack a cell nucleus or any membrane-encased organelles
Eukaryotic
organisms cells contain a nucleus and other membrane-bound organelles - includes all animals, plants, fungi, and protists, as well as most algae
Multicellular
organisms use many different cells to function
Unicellular
organisms are made up of only one cell that carries out all of the functions needed by the organism
Heterotrophic
organisms need to 'consume' other living organisms or organic material, in order to attain nutrition. The term stems from the Greek words hetero for "other" and trophy for "nourishment
Autotrophic
organisms 'produce' their own nutrition through the use of inorganic materials, e.g. light, water, chemicals
Protists
a diverse collection of organisms that do not fit into animal, plant, bacteria or fungi groups
Tissue
a group of cells that have a similar structure and that function together as a unit
Embryonic layer
any of three primary cell layers, formed in the earliest stages of embryonic development, consisting of the endoderm (inner layer), the ectoderm (outer layer), and the mesoderm (middle layer)
Sexual reproduction
is the dominant strategy of reproduction in animals, where the diploid stage usually dominates the life cycle, the haploid stage is created through meiotic division
Haploid stage
a single set of chromosomes in an organism's cells
Diploid stage
a double set of chromosomes in the organism's cells
Zygote
forms when the genetic material of two separate haploid cells come together as two sets of chromosomes in a single diploid cell
Meiosis
a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in the gametes
A gamete
the reproductive cell of an animal or plant
Mitosis
a type of cell division where the cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division.
Morphology
focuses on the form of living organisms
Extant
survived to present-day - living
Extinct
no longer living
Taxa
scientifically classified group
Nomenclature
a biological classification system for naming organisms
Binomial nomenclature
is a system in which each species receives a name with two (bi) terms - the genus it belongs to and the species it self
Phylogeny
the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms
Hypothesis
a proposed explanation, made on the basis of limited evidence as a starting point for further investigation
Sister Group
Two descendants that split from the same node in a phylogeny - Sister groups have a common ancestor
Polytomy group
A branch in a phylogeny with more than two lineages. It illustrates where scientists have not definitively determined all of the relationships.
8 hierarchical groups
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Body Plans
a set of morphological and developmental traits
radial symmetry
body plan in which body parts repeat around the center of the body. They have no left and right sides. A section taken anywhere through the central axis results in a mirror image.
bilateral symmetry
Body plan in which only a single, imaginary line can divide the body into two equal halves. It has clear left and right sides. Only a section taken in one specific place would produce a mirror image. These animals have two axes of orientation - Dorsal (top) and Ventral (bottom)
triploblastic
has three germ layers: the ectoderm, endoderm, and mesoderm. occurs in some radially symmetric animals
diploblastic
having two germ layers; ectoderm and endoderm. occurs in vertebrates and bilaterally symmetric animals
Body Cavities
a fluid or air-filled space between the digestive tract and the outer body wall, which forms from the mesoderm
acoelomates
no body cavity
coelom
body cavity lined with mesoderm
pseudocoelomates
An animal whose body cavity is lined by tissue derived from mesoderm and endoderm.
Dichotomous key
consist of a series of statements with two choices in each step that will lead users to the correct identification
Taxonomy
is a strategy of classification, usually, a hierarchical classification, in which things are organized into groups or types
Symmetry
Radial, bilateral or asymmetrical
Cephalisation
distinct head
Skeleton
internal, external, hydrostatic - other
Segmentation
body divided into distinct segments
Appendages
a projecting part of an animal, with a distinct appearance or function.
Mouth
the opening through which many animals take in food and issue vocal sounds
Anus
gastrointestinal tract ends and exits the body
Predation
the preying of one animal on others
Analogous structures
structures that are similar in different species because of convergent evolution - not homology
Homologous structures
are structures in different species that are similar because of common ancestry
Convergent evolution
evolution of similar features in independent evolutionary lineages
Divergent evolution
the evolutionary pattern in which species sharing a common ancestry become more distinct due to differential selection pressure which gradually leads to speciation over an evolutionary time period.
Epithelial tissue
sheets of tightly packed cells that line organs, body cavities and external surfaces
Connective tissue
binds and supports other tissues, having a sparse population of cells scattered through an extracellular matrix
Muscular tissue
long cells that can contract on their own or when stimulated by nerve impulses
Nervous tissue
neurons and supportive cells
Epithelial Tissue Features
simple or stratified, ciliated or non-ciliated, squamous, cuboidal, columnar, stratified or pseudostratified, and polarised
polarised
they have an apical surface that is open to the internal environment and a basal surface that is housed inside the organ
Connective tissue Features
Consists of cells scattered through an extracellular matrix, holding many tissues and organs together and in place. Matrix contains fibroblasts and macrophages. 3 Kinds of tissue fibres, collagenous, reticular and elastic.
Nervous tissue Features
Contains neurons that transit nerve impulses and glial cells.
Muscular tissue Features
striated or nonstriated, voluntary or involuntary. Contains actin and myosin to enable muscle contraction. Has 3 types.
Neurons
The basic units of the nervous system; cells that receive, integrate, and transmit information in the nervous system. They operate through electrical impulses, communicate with other neurons through chemical signals, and form neural networks.
Glia
help nourish, insulate, and replenish neurons
Skeletal muscle
Attached to bones by tendons and is responsible for voluntary movements. Consists of muscle fibres and has multiple nuclei in each one. Arranged in sarcomeres along the fibres that give the striated appearance.
Smooth Muscle
Involuntary muscle that lacks striations and is found in the walls of the digestive tract, urinary bladder, arteries and other internal organs. The cells are spindle shaped.
Cardiac Muscle
Involuntary and striated muscle that forms the contractile wall of the heart. It has branched fibres that interconnect via intercalated disks to help relay signals from cell to cell and help synchronise heart contraction.
Loose connective Tissue
may be either reticular and areolar (mainly fibrous), or adipose (fat). It binds epithelia to underlying tissues and holds organs in place. It has all 3 fibres which are in loose weaves.
Fibrous Connective Tissue
Dense tissue with collagenous fibres that is found in tendons and ligaments.
Adipose tissue
a specialised loose connective tissue that stores fat in adipose cells distributed throughout its matrix. The tissue pads and insulates the body and stores fuel as fat molecules. Each cell contains a large fat droplet that swells when fat is stored and shrinks when the body uses that fast as fuel.
Vascular Connective Tissue (blood)
Has a plasma matrix that consists of water, salts and dissolved proteins. Erythrocytes, leucocytes and platelets are suspended in plasma.
Erythrocytes
red blood cells, carry oxygen
leucocytes
white blood cells, function as defence
platelets
cell fragments that play an important part in forming blood clots
Cartilage
A connective tissue that contains collagenous fibres embedded in chondroitin sulfate. Chondrocytes secrete the collage and chondroitin sulfate to make a strong yet flexible material. Replaced by bone in embryo development.
Bone
Mineralized connective tissue. Osteoblasts deposit a matrix of collagen. Consists of osteons which each have concentric layers of the mineralised matrix deposited around a central canal containing blood vessels and nerves
Collagenous fibres
type of connective tissue fibre that provides strength and flexibility
reticular fibres
type of connective tissue fibre that joins connective tissue to adjacent tissues
elastic fibres
type of connective tissue fibre that makes tissue elastic
fibroblasts
cells that secrete fibre proteins
macrophages
cells that engulf foreign particles and any cell debris by phagocytosis
Cuboidal epithelium
cube shaped cells that specialised for secretion. makes up the epithelium of kidney tubules and many glands (thyroid and salivary)
simple columnar epithelium
large brick shaped cells found where secretion or active absorption is important.
simple squamous epithelium
single layer of platelike cells that function in the exchange of materials by diffusion. It is thin and leaky, lines blood vessels and the air sacs of the lungs, where diffusion of nutrients and gases is essential.
pseudostratified columnar epithelium
consists of a single layer of cells varying in height and the position of their nuclei. Can form a mucous membrane that lines portions of the respiratory tract. The beating cilia sweep the film of mucus along the surface
stratified squamous epithelium
multi-layered and regenerates rapidly. New cells formed by division near the basal surface pushes outwards, replacing cells that are sloughed off. Commonly found on surfaces subject to abrasion.
The Endocrine system
releases signalling molecules called hormones into the bloodstream, which are carried to all locations in the body. Only cells with the correct receptor will respond to hormones. Release of hormones is done in seconds, with effects lasting minutes or hours. Involved in growth, development, reproduction, metabolism and digestion.
The Nervous system
transmits signals via neuron pathways made up of axons. Signals are fast, taking a fraction of a second to reach the target. Signals travelling along an axon is done as a change in 'voltage'. Signals from one axon to another are done by short range chemical signals. Involved in rapid movement and reflexes.