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hagfish : an eel-like jawless fish that lives on the ocean floor and is a scavenger
https://openstax.org/books/concepts-biology/pages/15-key-terms
hemocoel : the internal body cavity seen in arthropods
https://openstax.org/books/concepts-biology/pages/15-key-terms
heterodont teeth : different types of teeth modified by different purposes
https://openstax.org/books/concepts-biology/pages/15-key-terms
intracellular digestion : the digestion of matter brought into a cell by phagocytosis
https://openstax.org/books/concepts-biology/pages/15-key-terms
lamprey : a jawless fish characterized by a toothed, funnel-like, sucking mouth
https://openstax.org/books/concepts-biology/pages/15-key-terms
lancelet : a member of Cephalochordata; named for its blade-like shape
https://openstax.org/books/concepts-biology/pages/15-key-terms
lateral line : the sense organ that runs the length of a fish’s body, used to detect vibration in the water
https://openstax.org/books/concepts-biology/pages/15-key-terms
Lophotrochozoa : a clade of invertebrate organisms that is a sister group to the Ecdysozoa
https://openstax.org/books/concepts-biology/pages/15-key-terms
madreporite : a pore for regulating entry and exit of water into the water vascular system
https://openstax.org/books/concepts-biology/pages/15-key-terms
mammal : one of the groups of endothermic vertebrates that possess hair and mammary glands
https://openstax.org/books/concepts-biology/pages/15-key-terms
mammary gland : in female mammals, a gland that produces milk for newborns
https://openstax.org/books/concepts-biology/pages/15-key-terms
mantle : a specialized epidermis that encloses all visceral organs and secretes shells in mollusks
https://openstax.org/books/concepts-biology/pages/15-key-terms
marsupial : one of the groups of mammals that includes the kangaroo, koala, bandicoot, Tasmanian devil, and several other species; young develop within a pouch
https://openstax.org/books/concepts-biology/pages/15-key-terms
medusa : a free-floating cnidarian body plan with a mouth on the underside and tentacles hanging down from a bell
https://openstax.org/books/concepts-biology/pages/15-key-terms
mesoglea : the non-living, gel-like matrix present in between ectoderm and endoderm in cnidarians
https://openstax.org/books/concepts-biology/pages/15-key-terms
mesohyl : the collagen-like gel containing suspended cells that perform various functions in sponges
https://openstax.org/books/concepts-biology/pages/15-key-terms
metamerism : having a series of body structures that are similar internally and externally, such as segments
https://openstax.org/books/concepts-biology/pages/15-key-terms
Mollusca : a phylum of protostomes with soft bodies and no segmentation
https://openstax.org/books/concepts-biology/pages/15-key-terms
monoecious : having both sexes in one body, hermaphroditic
https://openstax.org/books/concepts-biology/pages/15-key-terms
monotreme : an egg-laying mammal
https://openstax.org/books/concepts-biology/pages/15-key-terms
Myxini : hagfishes
https://openstax.org/books/concepts-biology/pages/15-key-terms
nacre : a calcareous secretion produced by bivalve mollusks to line the inner side of shells as well as to coat foreign particulate matter
https://openstax.org/books/concepts-biology/pages/15-key-terms
nematocyst : the harpoon-like organelle within a cnidocyte with a pointed projectile and poison to stun and entangle prey
https://openstax.org/books/concepts-biology/pages/15-key-terms
Nematoda : a phylum of worms in Ecdysozoa commonly called roundworms containing both free-living and parasitic forms
https://openstax.org/books/concepts-biology/pages/15-key-terms
notochord : a flexible, rod-shaped structure that is found in the embryonic stage of all chordates and in the adult stage of some chordates
https://openstax.org/books/concepts-biology/pages/15-key-terms
osculum : the large opening in a sponge body through which water leaves
https://openstax.org/books/concepts-biology/pages/15-key-terms
Osteichthyes : bony fishes
https://openstax.org/books/concepts-biology/pages/15-key-terms
ostracoderm : one of the earliest jawless fishes covered in bone
https://openstax.org/books/concepts-biology/pages/15-key-terms
Petromyzontidae : the clade of lampreys
https://openstax.org/books/concepts-biology/pages/15-key-terms
pharyngeal slit : an opening in the pharynx
https://openstax.org/books/concepts-biology/pages/15-key-terms
pneumatic bone : an air-filled bone
https://openstax.org/books/concepts-biology/pages/15-key-terms
polyp : the stalk-like, sessile life form of a cnidarians with mouth and tentacles facing upward, usually sessile but may be able to glide along a surface
https://openstax.org/books/concepts-biology/pages/15-key-terms
Porifera : a phylum of animals with no true tissues, but a porous body with a rudimentary endoskeleton
https://openstax.org/books/concepts-biology/pages/15-key-terms
post-anal tail : a muscular, posterior elongation of the body extending beyond the anus in chordates
https://openstax.org/books/concepts-biology/pages/15-key-terms
Primates : includes lemurs, tarsiers, monkeys, apes, and humans
https://openstax.org/books/concepts-biology/pages/15-key-terms
prosimians : a group of primates that includes bush babies of Africa, lemurs of Madagascar, and lorises, pottos, and tarsiers of southeast Asia
https://openstax.org/books/concepts-biology/pages/15-key-terms
protostome : describing an animal in which the mouth develops first during embryogenesis and a second opening developing into the anus
https://openstax.org/books/concepts-biology/pages/15-key-terms
pseudocoelomate : an animal with a coelom that is not completely lined with tissues derived from the mesoderm as in eucoelomate animals
https://openstax.org/books/concepts-biology/pages/15-key-terms
radial symmetry : a type of symmetry with multiple planes of symmetry all cross at an axis through the center of the organism
https://openstax.org/books/concepts-biology/pages/15-key-terms
radula : a tongue-like scraping organ with chitinous ornamentation found in most mollusks
https://openstax.org/books/concepts-biology/pages/15-key-terms
salamander : a tailed amphibian that belongs to the clade Urodela
https://openstax.org/books/concepts-biology/pages/15-key-terms
Sarcopterygii : lobe-finned fishes
https://openstax.org/books/concepts-biology/pages/15-key-terms
sebaceous gland : in mammals, a skin gland that produce a lipid mixture called sebum
https://openstax.org/books/concepts-biology/pages/15-key-terms
Sphenodontia : the reptilian clade that includes the tuataras
https://openstax.org/books/concepts-biology/pages/15-key-terms
spicule : a short sliver or spike-like structure, in sponges, they are formed of silicon dioxide, calcium carbonate, or protein, and are found in the mesohyl
https://openstax.org/books/concepts-biology/pages/15-key-terms
spiracle : a respiratory openings in insects that allow air into the tracheae
https://openstax.org/books/concepts-biology/pages/15-key-terms
spongocoel : the central cavity within the body of some sponges
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Squamata : the reptilian clade of lizards and snakes
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stereoscopic vision : two overlapping fields of vision from the eyes that produces depth perception
https://openstax.org/books/concepts-biology/pages/15-key-terms
sudoriferous gland : a gland in mammals that produces sweat and scent molecules
https://openstax.org/books/concepts-biology/pages/15-key-terms
swim bladder : in fishes, a gas filled organ that helps to control the buoyancy of the fish
https://openstax.org/books/concepts-biology/pages/15-key-terms
tadpole : the larval stage of a frog
https://openstax.org/books/concepts-biology/pages/15-key-terms
Testudines : turtles
https://openstax.org/books/concepts-biology/pages/15-key-terms
tetrapod : a four-footed animal; includes amphibians, reptiles, birds, and mammals
https://openstax.org/books/concepts-biology/pages/15-key-terms
trachea : in some arthropods, such as insects, a respiratory tube that conducts air from the spiracles to the tissues
https://openstax.org/books/concepts-biology/pages/15-key-terms
triploblast : an animal that develops from three germ layers
https://openstax.org/books/concepts-biology/pages/15-key-terms
tunicate : a sessile chordate that is a member of Urochordata
https://openstax.org/books/concepts-biology/pages/15-key-terms
Urochordata : the clade composed of the tunicates
https://openstax.org/books/concepts-biology/pages/15-key-terms
Urodela : salamanders
https://openstax.org/books/concepts-biology/pages/15-key-terms
vertebral column : a series of separate bones that surround the spinal cord in vertebrates
https://openstax.org/books/concepts-biology/pages/15-key-terms
water vascular system : a system in echinoderms in which water is the circulatory fluid
https://openstax.org/books/concepts-biology/pages/15-key-terms
Homeostasis is a dynamic equilibrium that is maintained in body tissues and organs. It is dynamic because it is constantly adjusting to the changes that the systems encounter. It is an equilibrium because body functions are kept within a normal range, with some fluctuations around a set point. The kidneys are the main ...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
There are many organs that work together to digest food and absorb nutrients. The mouth is the point of ingestion and the location where both mechanical and chemical breakdown of food begins. Saliva contains an enzyme called amylase that breaks down carbohydrates. The food bolus travels through the esophagus by perista...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
Carbohydrates, proteins, and fats are the primary components of food. Some essential nutrients are required for cellular function but cannot be produced by the animal body. These include vitamins, minerals, some fatty acids, and some amino acids. Food intake in more than necessary amounts is stored as glycogen in the l...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
Animal respiratory systems are designed to facilitate gas exchange. In mammals, air is warmed and humidified in the nasal cavity. Air then travels down the pharynx and larynx, through the trachea, and into the lungs. In the lungs, air passes through the branching bronchi, reaching the respiratory bronchioles. The respi...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The mammalian circulatory system is a closed system with double circulation passing through the lungs and the body. It consists of a network of vessels containing blood that circulates because of pressure differences generated by the heart.
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The heart contains two pumps that move blood through the pulmonary and systemic circulations. There is one atrium and one ventricle on the right side and one atrium and one ventricle on the left side. The pumping of the heart is a function of cardiomyocytes, distinctive muscle cells that are striated like skeletal musc...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
Hormones cause cellular changes by binding to receptors on or in target cells. The number of receptors on a target cell can increase or decrease in response to hormone activity.
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
Hormone levels are primarily controlled through negative feedback, in which rising levels of a hormone inhibit its further release.
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The pituitary gland is located at the base of the brain. The anterior pituitary receives signals from the hypothalamus and produces six hormones. The posterior pituitary is an extension of the brain and releases hormones (antidiuretic hormone and oxytocin) produced by the hypothalamus. The thyroid gland is located in t...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The adrenal glands are located on top of the kidneys and consist of the adrenal cortex and adrenal medulla. The adrenal cortex produces the corticosteroids, glucocorticoids and mineralocorticoids. The adrenal medulla is the inner part of the adrenal gland and produces epinephrine and norepinephrine.
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The pancreas lies in the abdomen between the stomach and the small intestine. Clusters of endocrine cells in the pancreas form the islets of Langerhans, which contain alpha cells that release glucagon and beta cells that release insulin. Some organs possess endocrine activity as a secondary function but have another pr...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The human skeleton is an endoskeleton that is composed of the axial and appendicular skeleton. The axial skeleton is composed of the bones of the skull, ossicles of the ear, hyoid bone, vertebral column, and ribcage. The skull consists of eight cranial bones and 14 facial bones. Six bones make up the ossicles of the mi...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The structural classification of joints divides them into fibrous, cartilaginous, and synovial joints. The bones of fibrous joints are held together by fibrous connective tissue. Cartilaginous joints are joints in which the bones are connected by cartilage. Synovial joints are joints that have a space between the adjoi...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The body contains three types of muscle tissue: skeletal muscle, cardiac muscle, and smooth muscle. Muscles are composed of individual cells called muscle fibers. Muscle fibers consist of myofilaments composed of the proteins actin and myosin arranged in units called sarcomeres. Contraction of the muscle occurs by the ...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The nervous system is made up of neurons and glia. Neurons are specialized cells that are capable of sending electrical as well as chemical signals. Most neurons contain dendrites, which receive these signals, and axons that send signals to other neurons or tissues. Glia are non-neuronal cells in the nervous system tha...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
Neurons have a resting potential across their membranes and when they are stimulated by a strong enough signal from another neuron an action potential may carry an electrochemical signal along the neuron to a synapse with another neuron. Neurotransmitters carry signals across synapses to initiate a response in another ...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The vertebrate central nervous system contains the brain and the spinal cord, which are covered and protected by three meninges. The brain contains structurally and functionally defined regions. In mammals, these include the cortex (which can be broken down into four primary functional lobes: frontal, temporal, occipit...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
The peripheral nervous system contains both the autonomic and sensory-somatic nervous systems. The autonomic nervous system provides unconscious control over visceral functions and has two divisions: the sympathetic and parasympathetic nervous systems. The sympathetic nervous system is activated in stressful situations...
https://openstax.org/books/concepts-biology/pages/16-chapter-summary
action potential : a momentary change in the electrical potential of a neuron (or muscle) membrane
https://openstax.org/books/concepts-biology/pages/16-key-terms
adrenal gland : the endocrine gland associated with the kidneys
https://openstax.org/books/concepts-biology/pages/16-key-terms
alveolus : (plural: alveoli) (also, air sacs) the terminal structure of the lung passage where gas exchange occurs
https://openstax.org/books/concepts-biology/pages/16-key-terms
amygdala : a structure within the limbic system that processes fear
https://openstax.org/books/concepts-biology/pages/16-key-terms
amylase : an enzyme found in saliva and secreted by the pancreas that converts carbohydrates to maltose
https://openstax.org/books/concepts-biology/pages/16-key-terms
anus : the exit point of the digestive system for waste material
https://openstax.org/books/concepts-biology/pages/16-key-terms
aorta : the major artery that takes blood away from the heart to the systemic circulatory system
https://openstax.org/books/concepts-biology/pages/16-key-terms
appendicular skeleton : the skeleton composed of the bones of the upper limbs, which function to grasp and manipulate objects, and the lower limbs, which permit locomotion
https://openstax.org/books/concepts-biology/pages/16-key-terms
artery : a blood vessel that takes blood away from the heart
https://openstax.org/books/concepts-biology/pages/16-key-terms
atrium : (plural: atria) a chamber of the heart that receives blood from the veins
https://openstax.org/books/concepts-biology/pages/16-key-terms
auditory ossicles : (also, middle ear bones) the bones that transduce sounds from the air into vibrations in the fluid-filled cochlea
https://openstax.org/books/concepts-biology/pages/16-key-terms
autonomic nervous system : the part of the peripheral nervous system that controls bodily functions
https://openstax.org/books/concepts-biology/pages/16-key-terms
axial skeleton : skeleton that forms the central axis of the body and includes the bones of the skull, the ossicles of the middle ear, the hyoid bone of the throat, the vertebral column, and the thoracic cage (ribcage)
https://openstax.org/books/concepts-biology/pages/16-key-terms
axon : a tube-like structure that propagates a signal from a neuron’s cell body to axon terminals
https://openstax.org/books/concepts-biology/pages/16-key-terms
basal ganglia : an interconnected collections of cells in the brain that are involved in movement and motivation
https://openstax.org/books/concepts-biology/pages/16-key-terms
bicuspid valve : a one-way opening between the atrium and the ventricle in the left side of the heart
https://openstax.org/books/concepts-biology/pages/16-key-terms
bile : a digestive juice produced by the liver; important for digestion of lipids
https://openstax.org/books/concepts-biology/pages/16-key-terms
bolus : a mass of food resulting from chewing action and wetting by saliva
https://openstax.org/books/concepts-biology/pages/16-key-terms
brainstem : a portion of brain that connects with the spinal cord; controls basic nervous system functions like breathing and swallowing
https://openstax.org/books/concepts-biology/pages/16-key-terms
bronchi : (singular: bronchus) smaller branches of cartilaginous tissue that stem off of the trachea; air is funneled through the bronchi to the region where gas exchange occurs in the alveoli
https://openstax.org/books/concepts-biology/pages/16-key-terms
bronchiole : an airway that extends from the main bronchus to the alveolar sac
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