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a neurotransmitter that enables learning and memory and also triggers muscle contraction


makes up most of the thin filaments in myofibrils that connect sarcomeres

action potential

reversal of the voltage in muscle fibers, neurons, and some excitable cells

The activity of _____ results in a tan after adequate exposure to the sun.


adhering junction

adjoining cells are welded together with a mass of proteins, which is anchored under the plasma membrane by tufts of intermediate filaments of the cytoskeleton

Adipose Tissue

Energy reservoir where excess carbohydrates and lipids are converted to fats. The fats then form an insulating layer and cushion certain body parts and organs such as kidneys and hearts


of or near the head end or toward the front plane of the body


the two upper chambers of the heart- the receiving areas that pool incoming blood.

A beauty-salon permanent begins by applying a chemical to the hair that _____.

breaks the disulfide bonds between adjacent keratin chains


considered a connective tissue because its cellular components arise from stem cells in bone, a connective tissue

bone tissue

hardened connective tissue that is the main tissue of bones. Some bones are sites of blood cell formation

cardiac muscle tissue

occurs only in the heart wall. Contains sarcomeres. Consists of single, branching cells that have a nucleus. At their ends, adhering junctions help keep them from being ripped apart during forceful contractions.


wrist bones


cushions and protects the joints between bones


a connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together

cells need these two elements/molecules to survive

carbon dioxide and oxygen

Cellular communication involves sending signals, receiving signals, and _____

inducing change in a target cell's activity


tells the muscle cells how much energy is needed to perform an action

Circulatory System

Rapidly transports many materials to and from cells; helps stabilize internal pH and temperature

A community of cells that interacts together to perform a specific task is called a/an _____.


connective tissue

Have connecting roles in the body. Structurally or functoinally support, bind, seperate, and in one case, insulate other tissues

cranial cavity

in the skull, encases the brain


series of stages in which specialized tissues, organs, and organ systems form. measured qualitatively

Digestive System

Ingests food and water; mechanically and chemically breaks down food and absorbs small molecules into the internal environment; eliminates food residues


farther from a point of reference

dorsal surface

Along (or toward) the vertebral surface of the body


the part of the small intestine between the stomach and the jejunum


The outer layer of primary tissue. Gives rise to epidermis and the nervous system


first layer of cells to form in the embryo of nearly all animals


carry out suitable responses to the stimulation

endocrine glands

have no ducts. they secrete their products, hormones, directly into interstitial fluid

Endocrine System

Hormonally controls body functioning, works with the nervous system to integrate short-term and long term activities


Inner primary tissue layer. Start of the lining of the digestive tract and organs derived from it


Tissues that cover the internal and external surfaces of the body, the cells of which are held together with specialized structures such as tight junctions. Arise from the ectoderm


sheetlike tissue of cells that are close together, with little extracellular material between them. Absorb or secrete

An epithelium made up primarily of flattened cells is called _____.


Epithelium often overlies connective tissue; a(an) _____ forms the attachment between the two tissues.

basement membrane


concentration and removal of substances that are of no use to the body

exocrine glands

have ducts or tubes that open onto the free epithelial surface. secrete many substances, such as oils, mucus, saliva, tears, milk, digestive enzymes, and earwax

Exocrine glands differ from endocrine glands in that they _____.

have ducts which carry products to a free epithelial surface


Make and secrete structural fiber of collagen and elastin

Fibrous, Irregular Connective Tissue

Matrix is packed with many fibroblasts and collagen fibers that are positioned every which way. Is a component of skin that supports intestinal muscles and also forms protective capsules around organs that do not stretch much

Fibrous, Regular Connective Tissue

Has orderly rows of fibroblasts between parallel, tightly packed, bundles of fibers. Helps keep tissue from being torn apart whrn placed under mechanical stress. Tendons and ligaments are examples

For cells to communicate, a _____ must reversibly bind to a _____.

signal molecule, receptor protein

frontal plane

divides the body into anterior and posterior

gap junction

cylindrical arrays of proteins span the plasma membrane of adjoining cells. they pair up as open channels for signals between cells. Permit ions and small molecules to pass freely from the cytoplasm of one cell to another.


saclike, secretory organs that open to the free epithelial


increase in the number, size, and volume of cells. Measured quantitatively


place where individuals of a species normally live

Hair is primarily composed of _____.

keratin fibers

Hard palate

the bony part of the roof of the mouth

he leaves of the yellow bush lupine conserve water by _____.

trapping moisture lost from stomata in folded leaves

herniated disk

dislocated intervertebral disk

How do the products of endocrine glands reach the appropriate target cells?

products diffuse into the blood and are transported by the circulatory system

How many types of tissue do vertebrates have?


how many vertebrae do humans have?


In a feedback loop, which of the following is the correct pathway from stimulus to response?

receptor, integrator, effector

In a typical feedback loop, an integrator involves the _____ system and an effector involves the _____ system.

nervous, glandular

In cellular communication, a receptor site is activated by _____.

binding to a specific signal molecule

In ligaments, what thing, found in the tissue matrix, facilitates movements around joints?

elastic fibers

In plants, the physical isolation of an injured or infected site is called _____.



central command post that receives and processes information about stimuli

Integumentary system

Protects the body from injury, dehydration, and some pathogens. Controls temperature and excretes wastes

internal environment

made up of extracellular fluid. Changes in its composition and volume affect cell activities

The internal environment consists specifically of fluids in _____.

interstitial fluid and plasma


receive and integrate sensory information. sore the bits that hold meaning and coordinate the body's short term and long term responses to stimuli

interstitial fluid

fills the places between cells and tissues

Interstitial fluid is found _____.

between cells

intervertebral disks

seperate backbones from one another

In which tissues could abundant collagen and elastin be found?

connective tissues

is diffusion easier in thin or thick areas?



areas of contact or near-contact in between bones


organ that removes urea, excess water, and other waste products from the blood and passes them to the ureter


toward the outside of the body


a sheet or band of tough fibrous tissue connecting bones or cartilages or supporting muscles or organs

Loose connective tissue

fibroblasts and fiber are dispersed widely throughout the matrix. Most common in the vertebrae body. Help organs and epithelia stay in place

Lymphatic System

Collects and returns some tissue fluid to the bloodstream; defends the body against infection and tissue damage

Lymph nodes

filters or traps for foreign particles and contain white blood cells


relating to or situated in or extending toward the middle


The middle layer of primary tissue. Start of muscles, bones, and most of the circulatory, urinary, and reproductive systems

A method that animal and plant cells use to achieve homeostasis


most common type of feedback mechanism


motor neurons

relay commands from the brain and spinal cord to muscle cells, and to glands

Mucus, saliva, earwax, milk, and digestive enzymes are considered exocrine products because _____.

each is produced within an exocrine gland and transported by a duct to a free surface

Muscle Tissues

Consist of many cells arranged parallel to one another, in tight or loose arrays. Coordinated contractions of layers or rings of muscles move the whole body or its component parts

Muscular System

Moves the body and its internal parts; maintains posture and generates heat


bundle of contractile filaments that run from one end of a muscle fiber to the other


moor protein that starts at the center of the sarcomere. forms a cross bridge to actin when the local concentration of calcium ions rises and a bindig site for the myosin's head is exposed

ndividuals with a relatively thick layer of _____ tissue may experience less discomfort as the temperature falls.


Negative feedback mechanism

homeostatic control mechanism that reduces the output of the stimulus. fixes changes in the internal environment

Nervous system

Detects external and internal stimuli. Controls and coordinates the responses to stimuli; integrates all organ system activities

nervous tissue

composed of neurons and a variety of cells, collectively called neuroglia, that structurally and functionally support them


Excitable cells that make up the communication line in most nervous systems


Signaling molecules that diffuse to another cell


flexible rodlike structure of mesodermal cells that is the principal logitudinal structural element of chordates and of early empryo vertebrates. Plays an organizational role in nervous systm development


structural unit of at least two tissues, organized in certain proportions and patterns, that carries out one or more common tasks

organ system

A group of two or more organs that interact to perform a set of related tasks

Organ systems of nearly all animal are controlled by what?

neural and endocrine control


bone forming cells. present on the outer surface and internal cavities of the bones of adults


bone cells that break down bone tissue by secreting acids and enzymes into the hardenedmatrix


Osteoblasts that have became imprisoned in small chambers after secreting matrix material around themelves. Most common cells in bony adult tissue

Panting, sweating, and dilation of surface blood vessels in response to overheating are examples of _____.

negative feedback

pectoral girdle

set of bones which connects the upper limb to the axial skeleton on each side

pelvic cavity

Contains the urinary bladder, the reproductive organs, and the last part of the large intestine.

A penetrating injury to the lungs would require entry into the _____ cavity.



toe bones


throat; passageway for food to the esophagus and air to the larynx


vascular tissue responsible for the transport of nutrients and the carbohydrates produced by photosynthesis


study of patterns and processes by which an individual survives and reproduces in the environment


fluid portion of blood


Function in blood clotting

Positive and negative feedback help maintain the internal environment in a state of _____.


positive feedback mechanisms

initiate a chain of events that intensify change from an original condition and after a limited time, the intesification reverses the change. Usually associated with instability in a system


at or near the back of the body

The process of homeostasis that tends to cancel or counteract the effects of the original stimulus is called _____.

negative feedback mechanism

Programmed cell death is controlled by _____.


The protective mechanism in which plants release signal molecules that diffuse to undamaged tissues is called _____.

system-acquired resistance


close to a point of reference

red blood cells

get oxygen to metabolically active tissues and get rid of carbon dioxide wastes

red marrow

major site of blood cell formation that fills the spaces in spongy bone

Reproductive System

Females produce eggs and males produce sperm that fertilize the egg. Hormones of this system also influence other organ systems

Respiratory System

Rapidly delivers oxygen to the tissue fluid that bathes all living cells; removes carbon dioxide wastes of celss


the basic contractile unit of striated muscle; the segment of a myofibril between two adjacent z-lines.

sarcoplasmic reticulum

organelle of the muscle fiber that stores calcium


when a functionally specialized substance (especially one that is not a waste) is released from a gland or cell

sensory neurons

detect specific stimuli, such as light, heat, and pressure

sensory receptors

cells or cell parts that detect stimuli (forms of energy). They then send signals to the brain.

A series of stages in the formation of specialized tissues and organs is called _____.


skeletal muscle tissue

functional partner of bone and cartilage. Helps move and maintain the positions of the body and its parts. Consists of groups of cells fused together

Skeletal System

Supports and protects body parts; provides muscle attachment sites; produces red blood cells; stores calcium and phosphorous

sliding-filament model

The theory explaining how muscle contracts, based on change within a sarcomere, the basic unit of muscle organization, stating that thin (actin) filaments slide across thick (myosin) filaments, shortening the sarcomere; the shortening of all sarcomeres in a myofibril shortens the entire myofibril

smooth muscle tissue

has single, unbranching cells, tapered at both ends. Contracts slower, but longer than skeletal muscle. Found in the stomach, bladder, and uterus

spinal cavity

space inside the spinal column containing the spinal cord


the small openings on the undersides of most leaves through which oxygen and carbon dioxide can move

stratified epithelium

epithelium that has cells that form two or more layers

The structural and physiological characteristics of all plants and animals are specifically adapted to their _____.


surface-to-volume ratio

volume increases in three dimensions. area increases in two directions

Surface-to-volume ratio is most critical to which metabolic process?

rapid gas exchange

Tendons connect bone to _____, while ligaments connect bone to _____.

muscle, bone

thoracic cavity

the cavity in the vertebrate body enclosed by the ribs between the diaphragm and the neck and containing the lungs and heart

tight junction

strands of proteins running parallel with the free surface of the tissue. they block leaking between adjoining cells. Stop most substances from leaking across a tissue


community of cells and intercellular substances that are interacting in one or more tasks

To better coordinate its activity, the heart is formed from cells that are connected to one another with _____ junctions.


transverse plane

splits the top and bottom of a body


complex of three regulatory proteins that is integral to muscle contraction in skeletal and cardiac muscle

these two types of transport help maintain the internal environment and metabolism by adjusting the kinds, amounts, and directional movement of substances

active and passive

Two ways substances can be transported (internally)

active transport and by following concentration gradients

Urinary System

Maintains the volume and composition of the internal environment; excretes excess fluid and blood-borne wastes

Urogenital sinus

point where the vagina joins with the urethra

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