Biology ch.43

Vertebrate skeletal muscles have highly organized, repeating structures (continued) The plasma membrane that surrounds each muscle fiber forms tubes, called ___________________ These structures tunnel deep into the inside of the cell at ___________________ ___________________ released from the T Tubules Each myofibril consists of repeating subunits called ___________________ that are aligned end to end along the length of the myofibril, connected to one another by ___________________

T tubules regular intervals Calcium ions sarcomeres, protein

Vertebrate skeletal muscles have highly organized, repeating structures (continued) Muscle fibers range from ______ to ______micrometers in diameter, and some run the entire length of a muscle, which can be up to 2 feet (60 centimeters ) long Each skeletal muscle fiber contains many ___________________ , located just beneath the cells plasma membrane The largest fibers have several ___________________nuclei Individual muscle fibers contain many parallel cylinders called ___________________ Each myofibril is surrounded by a specialized type of endoplasmic reticulum called a ___________________ (SR), which has membrane-enclosed compartments filled with fluid containing a high concentration of ___________________

10 to 100 nuclei thousand myofibrils sarcoplasmic reticulum calcium ions

Growth and development continue during the last seven months The fetus grows/develops for another ____MONTHS As the brain & spinal cord grow, they generate __________________ As early as MONTH ____ of pregnancy, the fetus can move, respond to stimuli, and even suck its thumb The lungs, stomach, intestine, and kidneys __________________ and become__________________ Fetal urine makes up most of the __________________ during the last 6 MONTHS of pregnancy Although a full-term pregnancy lasts about 38 WEEKS, nearly all fetuses 32 WEEKS or older can survive outside the womb with medical assistance Most infants born as early as 26 WEEKS survive if they are given intensive care

7 behaviors 3 enlarge and become functional amniotic fluid

Cell differentiation, gastrulation, and organogenesis occur during the first two months (cont'd.) After ____ WEEKS, the embryo is recognizably human As 8 WEEKS draws to an end, nearly all of the __________________ have at least begun to develop The gonads appear and develop into testes or ovaries __________________ are secreted—either testosterone from the testes or estrogen from the ovaries At the end of 8 WEEKS, the embryo has taken on a generally human appearance and is now called a __________________ The 8 WEEKS of pregnancy are a time of extremely rapid differentiation and growth for the embryo, and a time of considerable

8 major organs testes or ovaries Sex hormones fetus

___________________communication between cells regulates most embryonic development As development proceeds, cells differentiate in response to chemical ___________________ released by other, usually nearby cells in a process called ___________________ In the early 1900s, embryologists transplanted bits of light-colored amphibian embryos (___________________ ) to locations on dark-colored embryos (___________________ ), and vice versa Used the ___________________ difference to determine whether a structure that developed in the host embryo consisted of cells that came from the donor or host Found: fate of transplanted cells was not ___________________ They also found that the cells of host embryo ___________________ the donor cells to assume the developmental fate of the area of the host into which they were transplanted

Chemical messengers, induction donors, hosts color predetermined induced

Nearly all animals move using the same mechanism ___________________ exert forces on the skeleton, causing the body to change shape The actions of ___________________ on skeletons move animal bodies Pairs of muscles with opposing actions that ___________________or ___________________on its skeleton Across the animal kingdom, there are three different types of skeletons ___________________ ___________________ ___________________

Contracting muscles antagonistic muscles squeeze or pull three hydrostatic skeleton exoskeleton endoskeleton

___________________ Present in arthropods (spiders crustaceans insects Movement typically occurs only at ___________________ in the legs, mouthparts, and body segments, where thin, flexible tissue joins ___________________ of exoskeleton ___________________ attach to the inside of the exoskeleton across each joint Contraction of a ___________________ muscle bends a joint Contraction of an ___________________ muscle straightens a joint Alternating contractions of the antagonistic muscles move joints ___________________ and ___________________ , allowing movement Problem: it cannot significantly expand to allow___________________ Therefore, an arthropod must periodically ___________________ its exoskeleton so that it can grow

Exoskeletons joints, stiff section Antagonistic muscles flexor extensor back and forth growth molt

Cell differentiation, gastrulation, and organogenesis occur during the first two months (cont'd.) __________________ occurs after implantation During WEEK 2, the inner cell mass __________________and __________________, forming two fluid-filled sacs that are separated by a double layer of cells called the __________________ One layer of cells is continuous with th__________________, although in __________________mammals it contains no yolk The second layer of cells is continuous with the __________________ Gastrulation begins near the end of WEEK _______ Cells migrate through a _______ in the amnion side of the embryonic disk Once inside the disk, the migrating cells form mesoderm, endoderm, and the fourth extraembryonic membrane, the _______ The cells remaining on the surface become the ______________

Gastrulation grows and splits, embryonic disk yolk sac, placental amnion 2 slit allantois ectoderm

Antagonistic muscles move joints in the vertebrate skeleton (continued) ___________________joints are located in the ankles elbows knees and fingers Like a hinged door, these joints move in only ___________________ When the flexor muscle contracts, it ___________________the joint When the ___________________muscle contracts, it straightens the joint Contraction of the ___________________ (the flexor) bends the leg at the knee, while contraction of the quadriceps (the extensor straightens it Alternating contractions of flexor and extensor muscles cause the ___________________ bones to swing back and forth at the knee joint

Hinge one plane bends extensor biceps femoris lower leg

___________________ regulate the development of entire segments of the body Homeobox genes are found in animals as diverse as fruit flies, frogs, and humans and comprise a particularly important set of ___________________ Homeobox genes generally code for transcription factors that affect the ___________________ of a particular body region Homeobox genes were discovered in fruit flies, where specific ___________________cause entire parts of the body to be duplicated repacled or omitted EX: ___________________mutant homeobox gene causes the development of an extra body segment, complete with an extra set of wings

Homeobox genes master genes development mutations one

___________________skeleton Present in worms, cnidarians (sea jellies, anemones, and their relatives), and many mollusks (snails octopuses) Basically a ___________________or ___________________ filled with a liquid To squeeze its hydrostatic skeleton the animal uses two sets of antagonistic muscles in its body wall—one ___________________, the other ___________________ If a worm contracts its longitudinal muscles, its body becomes ___________________ If the earthworm contracts its circular muscles, its body becomes

Hydrostatic sac or tube circular, the other longitudinal elongated

"___________________" are rigid structures found inside the bodies of echinoderms (sea stars and their relatives) and chordates ( vertebrates and their relatives) In vertebrates, movement occurs primarily at joints, where two parts of the skeleton are firmly but flexibly attachted to ___________________ Antagonistic muscles, such as the ___________________(a flexor) and the ___________________(an extensor), attach on opposite sides of the outside of a joint; move joints back an forth

Internal skeletons one another biceps, triceps

2. ___________________ connect bone to bone in joints The bones of most ___________________ joints are attached to one another by strong flexible ligaments The parallel orientation of collagen in ligaments gives them tremendous ___________________ 3. ___________________ provides a strong, rigid framework for the body A bone generally includes ___________________ bone surrounded by a hard outer shell of ___________________ ___________________ bone: porous, lightweight, rich in blood vessels ___________________ bone: dense/strong, attachment site for muscle Consists of subunits called ___________________ , surrounding a central canal containing a tiny nerve artery and vein Red bone marrow fills ___________________ and is a source of ___________________

Ligaments movable strength Bone spongy ,compact bone Spongy Compact osteons spongy bone and is a source of RBCs

___________________ in the egg may direct early embryonic differentiation Virtually all the ___________________ in a zygote is present in an egg before it is fertilized; sperm contributes little more than a ___________________ In most animals, specific ___________________ molecules become localized in different places in the egg's cytoplasm Some of these proteins are transcription factors that regulate which ___________________ are turned on/off During the first few cleavage divisions, the ___________________ and its ___________________ cells divide at specific places and in specific orientations The position of maternal molecules in eggs strongly controls ___________________that the egg can be mapped according to the major structures that will be produced

Maternal molecules cytoplasm, nucleus protein genes zygote and its daughter development

Cell differentiation, gastrulation, and _______occur during the first two months (continued) Organogenesis begins during WEEKS 3 to 8 During WEEK 3, the embryo begins to form the s_______ and _______ The heart starts beating around the beginning of WEEK _______ The embryo bulges into the uterine cavity, bathed in fluid contained within the amnion Meanwhile, the umbilical cord forms from the fusion of the yolk stalk and body stalk The yolk stalk connects the yolk sac to the ____________

Organogenesis spinal cord and brain 4 uterine cavity umbilical cord embryonic digestive track

The vertebrate endoskeleton serves multiple functions (continued) ___________________ produces RBCs WBCs and platelets Bones store ___________________ & ___________________, absorbing/releasing as needed The vertebrate skeleton consists of two parts The___________________, which includes the bones of the head, vertebral column and rib cage The ___________________, which includes the pectoral and pelvic girdles, and the appendages attached to them The forelimbs (in humans, the arms and hands) and hind limbs (in humans the legs and feet) The ___________________ links the arms to the axial skeleton and provides attachment sites for muscles of trunk and arms Hip bones form the pelvic girdle, which links the legs to the axial skeleton, helps protect the ___________________

Red bone marrow Ca & P axial skeleton appendicular skeleton pelvic girdle abdominal organs

___________________ have highly organized, repeating structures Skeletal muscle, so named because it ___________________the skeleton, is also known as ___________________ muscle because its cells appear striped under a microscope Most ___________________muscles are attached to the skeleton by tough, ___________________, which consist of ___________________strands bundled into increasingly large groups by ___________________sheaths Nearly all skeletal muscle is under ___________________or ___________________ control Skeletal muscles produce ___________________ranging from quick twitches to powerful sustained tension An individual skeletal muscle consists of repeated ___________________ nested within another

Vertebrate skeletal muscles moves, striated skeletal, fibrous tendons, collagen, conective tissue voluntary or conscious contractions components

All muscle cells are built on the same general principles Filaments of ___________________ and ___________________ attach and slide past one another, causing the muscle cells to contract However, ___________________ and ___________________ muscles differ structurally and functionally from skeletal muscles and from each other

actin , myosin cardiac and smooth muscles

Vertebrate skeletal muscles have highly organized, repeating structures (continued) Thin filaments are formed from two strings of ___________________ , twisted together like Mardi Gras Beads They also contain two smaller proteins called ___________________ and ___________________ Thick filaments are formed from bundles of ___________________ Each myosin protein is shaped like a ___________________with a head attached at an angle to a long shaft The myosin head is ___________________to the shaft and can swivel back and forth Within each thick filament, myosin proteins are bundled together with their shafts in the middle of the bundle and the head ___________________

actin proteins tropinin and tropomyosin myosin proteins hockey stick hinged protruding out

Bone remodeling allows the skeleton to ___________________ and ___________________ itself Each year, _____ % to _____ % of all the bone in your body dissolves and is removed and replaced by the coordinated activity of ___________________ and ___________________ This process, called ___________________ , allows the skeleton to alter its shape in response to the demands placed on it As the body ages, the balance of power shifts to favor osteoclasts, and bone become more fragile, particularly if weight-bearing exercise decreases In middle age, the activity of osteoclasts ___________________ that of osteoblasts and bone density begins to decline This can lead to ___________________ , where a person's bones become more porous and weak

adapt and repair itself 5% to 10% , osteoclasts and osteoblasts bone remodeling exceeds osteoporosis

Indirect development occurs in most ______________ and ______________ ; animals undergo a radical change in body form from juvenile to adult The females typically produce huge numbers of eggs, each containing a small amount of ______________ The yolk ______________ the developing embryo until it hatches into a small, sexually immature feeding stage called a ______________ (plural, larvae) After feeding for a period of time, larvae undergo ______________ and become sexually mature adults Most larvae not only look very different from the adults of the species, but also play different roles in their ______________

amphibians and invertebrates yolk nourishes larva metamorphosis ecosystems

Antagonistic muscles move joints in the vertebrate skeleton (continued) Some other joints, such as those of the hip and shoulder, are ___________________ joints, in which the round end of one bone fits into a h ___________________ of another Ball-and-socket joints allow movement in ___________________ The range of motion in ball-and-socket joints is made possible by at least two pairs of antagonistic muscles oriented at angles to each other to move the joint in ___________________ dimensions

ball-and-socket, hallow depression several directions three

Cell differentiation, gastrulation, and organogenesis occur during the first two months (cont'd.) By DAY 5, the zygote has developed into a hollow ball of cells known as a ___________________(the mammalian version of a blastula A human blastocyst consists of an outer layer of cells surrounding a cluster of cells called the ___________________ The outer cell layer attaches to, and then burrows into, the lining of the uterus (endometrium), a process called ___________________ The outer cell layer of the blastocyst will become the

blastocyst inner cell mass implantation

Gastrulation begins when a dimple called the _____________ forms on one side of the blastula The dimple enlarges, gets deeper, and forms a cavity that will eventually become the _____________ The migrating cells eventually form three tissue layers in the embryo, which is now called _____________

blastopore , digestive tract gastrula

Bone is formed by interactions among three types of cells Osteoblasts — ___________________ cells Osteocytes — ___________________ cells Osteoclasts — ___________________ cells During embryonic development, osteoblasts produce ___________________ within the cartilage skeleton by secreting a ___________________ that becomes infiltrated with ___________________ New osteoblasts form through cell division and continue to produce bone throughout ___________________ As osteoblasts generate new bone, many become ___________________ in the hardened matrix and mature in to ___________________ Osteocytes coordinate the activity of osteoclasts and osteoblasts, which are constantly ___________________

bone forming mature bone bone dissolving bone, collagen matrix, minerals throughout life trapped, osteocytes constantly breaking/replacing

When one of a pair of antagonistic muscle contracts, it moves the ___________________around its joint and simultaneously ___________________the relaxed opposing muscle One muscle flexes, and the other is passively ___________________ Agonist and antagonist act in ___________________directions. When the agonist ___________________ an action, the antagonist ___________________ the action.

bone, stretches extended opposite ,produces, opposes

The vertebrate skeleton is composed of ___________________, ___________________, and ___________________ The skeleton is composed of ___________________ types of connective tissue All consist of living cells embedded in a matrix of ___________________, with various other substances included in the matrix Cartilage contains large amounts of ___________________and often includes ___________________fibers ___________________consist principally of slightly wavy collagen fibers, arranged parallel to one another Bone contains large amounts of ___________________, mostly ___________________ and ___________________, which make it hard and rigid

cartilage, ligaments, and bones three collagen protein glycoproteins , elastic Ligaments minerals, calcium and phosphate

There is little or no cell growth between _____________ After a few cell divisions, a solid ball of cells, the _____________ is formed As cleavage continues, a _____________ opens within the morula, and the cells become the outer covering of a hollow structure called _____________

cell divisions morula cavity blastula

Almost all animals have muscle, a tissue composed of ___________________ that are capable of ___________________ and thereby moving the parts of the body The three types of vertebrate muscle—___________________ , ___________________ , and ___________________ —differ somewhat in function appearance and control

cells, contracting ___________________ , ___________________ , and ___________________

The living cells of cartilage are called ___________________ Cells secrete the ___________________ and ___________________ that make up most of the matrix of cartilage No ___________________ penetrate cartilage To exchange wastes and nutrients, chondrocytes rely on ___________________ of materials through ___________________ Cartilage cells have a very ___________________ metabolic rate, so damaged cartilage repairs

chondrocytes glycoproteins and collagen blood vessels diffusion, collagen matrix low

Organogenesis begins during weeks three to eight (continued) The umbilical cord now connects the embryo to the placenta, which has formed from the merger of the __________________ of the embryo and the lining of the uterus During WEEKS 4 to 5, the embryo develops a __________________and pharyngeal grooves—indentations behind the head that are homologous to the fish embryo's developing __________________ These structures are reminders that we share ancestry with other vertebrates that retain their gills in adulthood; however, in humans they disappear as development continues By WEEK____, the embryo has rudimentary eyes and a rapidly developing brain, and the __________________between its fingers and toes is disappearing

chorion prominent tail, gills 7 webbing

Muscle fibers ___________________through interactions between thin and thick filaments The arrangement of the thin and thick filaments allows them both to ___________________and to ___________________ past one another The ___________________ bind and release, temporarily linking the thick and thin filaments As the thin filaments slide past the thick filaments, the ___________________ shorten, causing the entire muscle fiber to contract and generate movement This contraction process, called the "___________________ ", shortens all the sarcomeres along the muscle fiber simultaneously A skeletal muscle's reserves of ___________________ are used up after only a few seconds of high intensity exercise

contract grip and to slide past one another myosin heads sarcomeres sliding filament mechanism ATP

The cells that move through the blastopore to line the future digestive tract are _____________ Forms the lining of the _____________,_____________,_____________ The cells remaining on the outside of the developing gastrula are called _____________ Forms surface structures such as _____________, _____________, and _____________and the _____________ Cells that migrate between the endoderm and ectoderm form the third layer, called the _____________ Forms middle structures including the ____________and the lining of the ____________(____________ ,____________ and the ____________ system)

endoderm respiratory tract ,liver ,pancreas ectoderm skin, hair, and nails and the nervous system mesoderm skin and the lining of the digestive tract (muscles, skeleton and the circulatory system)

A zygote and almost all the cells of embryos and adults contain all of the genes needed to produce an ___________________ In any given cell, some genes are used (or expressed), while others are not The differentiation of cells during development arises because of these differences in ___________________ Several methods available to control gene expression EX: control which genes are transcribed into mRNA, which then directs the synthesis of the ___________________ Every cell contains proteins, called ___________________, that bind to specific genes, turning transcription on/off Determines the ___________________ and ___________________ of the cell

entire animal gene expression proteins transcription factors structure and function

The number of muscle fibers does not change as the result of ___________________ Muscle fibers can change ___________________ in training The number of ___________________ increases, causing an increase in muscle fiber thickness Increased muscle fiber thickness cause increased muscle ___________________

exercise size myofibrils strength

Bones, tendons, and ligaments remodel in response to ___________________ Exercise like weightlifting primarily affects muscles, but it also affects ___________________, ___________________, and ___________________ Weight-bearing exercise increases the activity of tendon- and ligament-building cells, causing them to produce more ___________________ Tendons and bones ___________________ and ___________________ in proportion to the stresses place upon them Different types of athletic activity lead to changes in different bones in If bones are freed from stress, such as the weightlessness that astronauts experience, ___________________may be lost in the

exercise tendons ligaments and bones collagen proteins thicken and strengthen bone mass

Development in reptiles and mammals depends on ______________ membranes All animal embryos develop in ______________ The embryo does not dehydrate, water surrounding the embryo supplies it with ______________ and carries away its ______________ Keeping embryos ______________is not a problem for fish or amphibians, which reproduce in water For terrestrial vertebrates, providing a watery environment for embryonic development is a challenge Fully ______________ life was not possible until the evolution of the amniotic egg This innovation arose first in ______________and persists today in that group (plus birds) and its descendants, the mammals Inside an ______________egg, the embryo develops in a watery environment even if it is laid on land

extra-embryonic water oxygen, waste moist terrestrial vertebrates reptiles amniotic

. Cartilage provides ___________________ and ___________________ Cartilage plays many roles in the ___________________ In sharks and rays, the entire skeleton is is ___________________ During the embryonic development of other vertebrates, the skeleton, except for the ___________________ and ___________________, is first formed from cartilage, which is later replaced by ___________________ Cartilage also covers the ends of ___________________ at ___________________, supports the flexible portions of the ___________________and external ___________________, and provides the framework for the _____________, ___________________, and___________________ of the respiratory system In addition, cartilage forms the tough, shock-absorbing intervertebral ___________________ between the vertebrae of the backbone

flexible support and connections vertebrate skeleton cartilage skull and collarbone, bone bones at joints, nose ,ears, arynx, trachea, and bronchi of the respiratory system discs

Development in reptiles and mammals depends on extraembryonic membranes (cont'd.) The amniotic egg is characterized by______________extraembryonic membranes ______________ lines the egg's shell and exchanges ______________and ______________between the embryo and the air Amnion encloses the embryo, its own "private pond" ______________surrounds and isolates wastes ______________ contains the yolk In mammals (except for platypuses and echidnas, which lay eggs), the embryo develops within the ______________ until birth Nevertheless, all four extraembryonic membranes still persist and in fact are essential for ______________

four Chorion O2 and CO2 Allantois Yolk sac mothers body, development

The ultimate bone remodeling occurs after a ___________________ Broken bones are r___________________ with a cast/splint The rest of the healing process is up to the body's own repair mechanisms and usually takes about ___________________ Healing begins when large ___________________surrounds the break Bone gradually replaces the cartilage in the ___________________ When ___________________completely replaces the callus, the fracture is healed

fracture realigned/immobilized 6 weeks blood clot callus mature bone

Homeobox genes regulate the development of entire segments of the body (cont'd.) Homeobox genes are arranged on the chromosomes in a ___________________ order & transcribed in cells in the specific location in the body whose development they ___________________ EX: "head" homeobox genes transcribed in the head, "tail" homeobox genes transcribed in the tail in embryo

head-to-tail, control head, embryo

Cardiac muscle powers the ___________________ Cardiac muscle is found only in the ___________________ Has a ___________________ appearance The fibers are ___________________ , smaller than most skeletal muscle cells, and have a single ___________________ in each cell Cardiac muscle fibers are connected to one another by ___________________ , that hold cells together Fibers require a large, continuous supply of ___________________ for producing ATP since they contract your ___________________ Surrounded by an extensive network of ___________________ and contain oxygen storing ___________________ Muscle fibers can initiate their own contractions, without input from

heart heart striated branched, nucleus intercalated discs oxygen, entire life blood vessels, myoglobin

Antagonistic muscles move ___________________ in the v___________________ Not all joints are ___________________; for example, immobile joints called ___________________ join the bones of the skull In movable joints, however, the portion of each bone that forms the joint is coated with a layer of ___________________; its smooth, resilient surface allows the bone surfaces to slide past one another with relatively little friction Joints are held together by ___________________that are strong and flexible but usually not very ___________________ Tendons attach The tendon at one end of each muscle, called the ___________________, is fixed to a bone that remains stationary while the other end, the ___________________, is attached to the bone on the far side of the joint, which is moved by the muscle

joints , vertebrate skeleton movable, sutures cartilage ligaments , elastic origin, insertion

A wide variety of animal species, including some snails and fish, and all mammals and reptiles (including birds), undergo direct development Newborns are typically fairly________________, and need significant amounts of ________________before emerging into the world 2 strategies have evolved to meet this food requirement Birds, most reptiles, and many fish produce eggs that contain ______________ amounts of yolk, food reserve which nourishes the embryo before it hatches Mammals, some snakes, and a few fish have relatively ______________ yolk in their eggs; instead, the embryos are nourished within the mothers body (________________) The young of many ______________ developing animals require additional care and feeding after birth Because of these demands, ______________ offspring are produced

large, nourishment large little placenta directly few

The vertebrate endoskeleton serves The skeleton allows ___________________ Different types of vertebrates have evolved skeletons that permit them to crawl, walk, run, jump, swim, fly, or perform various combinations of these actions The skeleton provides a rigid framework that ___________________ the body and ___________________ The brain and spinal cord are almost completely enclosed within the ___________________and ___________________ The rib cage protects the The pelvic girdle supports and partially In mammals, middle ear bones These bones transmit sound vibrations between the

locomotion supports, protects its internal organs skull and vertebral column

Many of the same molecules produced by the organizer region of an amphibian embryo are also employed in ___________________ development Very similar molecules and pathways induce the development of the limbs of all ___________________ Cell differentiation, gastrulation, and organogenesis occur during the ___________________ months Fertilization of a human egg usually takes place in the ___________________ (day ___________________) The resulting zygote undergoes a few cleavage divisions in the uterine tube, becoming a ___________________on its way to the ___________________

mammalian tetrapods first two uterine tube, zero morula, uterus

The ___________________ controls contraction of skeletal muscles Skeletal muscle contraction is controlled by the nervous system and is mostly ___________________ ___________________ excite skeletal muscle fibers at neuromuscular junctions An action potential in the motor neuron releases the neurotransmitter ___________________ onto the muscle fiber This produces a huge excitatory ___________________ in the muscle fiber A single action potential in a muscle fiber causes all of its sarcomeres to shorten simultaneously, slightly shortening the___________________ When the action potential stops, the muscle fiber stops ___________________

nervous system voluntary Motor neurons acetylcholine postsynaptic potential whole fiber contracting

Development is the process by which a multicellular organism grows and increases in ________________ and ________________ Development is usually considered to begin with a ________________and end with a ________________ Three principle processes contribute to development ________________ multiply Some of their daughter cells differentiate, or specialize in both ________________ and ________________ ; for example, as nerve cells or muscle cells As they differentiate, groups of cells move about and become organized into multicellular structures, such as a ________________or a ________________

organization and complexity fertilized egg,sexually mature adult Individual cells structure, function brain,biceps muscles

Chemical communication between cells regulates most embryonic development (cont'd.) In the 1920s, Spemann and Mangold discovered that a specific cluster of cells of an amphibian embryo, now called the ___________________, determines whether nearby cells will become ectoderm or mesoderm and even where the _________________ and _________________ will form A transplant from the organizer region of a donor embryo induced cells of a host to form parts of a___________________ Differentiation was also demonstrated in the 1950s by the experiments of ___________________ and ___________________

organizer head and nervous system second head King and Briggs

The major body parts develop during ____________ Organogenesis is the development of the body's organs from the____________ embryonic layers Two major processes influence organogenesis A series of "master switch" ____________turn on/off in specific cells, similar to an ignition switch in your car Each master gene controls the activity of many individual genes involved in producing an ____________ or a ____________ Organogenesis chips away extra ____________ just like Michelangelo chiseled away "extra" marble, leaving behind his statue of David In development, the sculpting of body parts often requires the ____________ of excess cells

organogenesis three genes arm or a backbone cells death

The __________________exchanges materials between mother and embryo During the first few days after implantation, the embryo obtains nutrients directly from the __________________of the uterus During the following week or so, the placenta begins to develop from the__________________structures produced by the embryo and the endometrium The outer layer of the blastocyst forms the __________________, which grows finger-like chorionic villi that extend into the endometrium Blood vessels of the umbilical cord connect the embryo's __________________ with a dense network of capillaries in the villi

placenta endometrium interlocking chorion circulatory system

Cell differentiation, gastrulation, and organogenesis occur during the first two months (cont'd.) The complex intermingling of the chorion and the endometrium forms the ___________________ All the cells of the inner cell mass have the potential to develop into any type of ___________________ This remarkable flexibility allows the___________________to produce the embryo and the amnion, allantois, and yolk sac Also the source of human embryonic stem cells Although they still retain the potential to develop into any cell type, the cells of the inner cell mass differentiate through ___________________

placenta tissue inner cell mass induction

Vertebrate skeletal muscles have highly organized, repeating structures (continued) Within each sarcomere lies a precise arrangement of thin and thick ___________________ Each thin filament is anchored to a Z disc at one end Suspended between the thin filaments are thick filaments This arrangement of thin and thick filaments gives the muscle fiber its striped appearance The myofibrils are composed primarily of two proteins, ___________________ in the thin filaments and ___________________ in the thick filaments, which interact with one another to contract the ___________________

protein filaments Z disc actin, myosin muscle fiber

Most of the mechanisms of development are ______________ in all animals ______________ are easy to study development because they can be induced to breed at any time of year They produce numerous large______________ and ______________ The embryos develop in______________, where they can be easily ______________, rather than inside their mothers ______________of the zygote begins development Begins when a fertilized egg (______________), undergoes a series of mitotic cell divisions called _____________ The zygote is a very______________ cell (i.e. frog zygote, may be a million times larger than an average _____________cell)

similar Amphibians eggs and embryos water, observed Cleavage zygote, cleavage large, adult

The nervous system controls contraction of skeletal muscles (continued) The ___________________ of motor units and the ___________________ of action potentials determine the force of muscle contraction A motor neuron typically synapses with several muscle fibers in a single muscle, forming a ___________________ Motor units vary In muscles used for ___________________ such as those that move the eyes or fingers, motor units are small In muscles used for large-scale movements, such as those of the thigh and buttocks, motor units are large The nervous system controls the force of muscle contraction by varying both the number of ___________________ stimulated and the rate of ___________________ in each fiber

size, frequency motor unit fine control, small motor units, action potential production

Smooth muscle produces ___________________ , ___________________ contractions Surrounds ___________________ and most hollow organs, including the ___________________ , ___________________ ,and ___________________ Not ___________________ , thin and thick filaments are scattered Fibers each contain a ___________________ Fibers are directly connected to one another by ___________________ , allowing the cells to contract in synchrony Contraction is either slow and sustained (such as the constriction of arteries that elevates BP during times of stress) or slow and wavelike (such as the waves that move food through the digestive tract) Smooth muscle contraction is involuntary and can be stimulated by ___________________ , ___________________ , signals from the ___________________

slow, involuntary blood vessels,uterus, bladder and, digestive tract striated single nucleus gap junctions stretch, hormones, signals from the autonomic nervous system

Skeletal muscle fibers come in two basic types,___________________ - twitch and ___________________ twitch Slow-twitch fibers contract ___________________ , ___________________ power contract for a very long time contain lots of ___________________ with many ___________________ contain high levels of ___________________ , a red-colored protein similar to hemoglobin that stores oxygen Fast-twitch fibers have different forms of ___________________ , causing them to contract more rapidly ___________________ diameter, hence many myofibrils contract with greater force than slow twitch fibers smaller blood supply, less ___________________ less ___________________ , unable to keep up ___________________

slow- twitch and fast-twitch slowly, less mitochondria with many capillaries myoglobin myosin large less myoglobin, less mitochondria, unable to keep up cellular respiration

Cleavage of the zygote begins development (cont'd.) Steps of cleavage differ by _____________ and are partly determined by the amount of _____________, which hinders cytokinesis (_____________) Eggs with extremely large yolks (i.e. chicken egg), don't _____________ all the way through; but, a hollow_____________ is always produced In birds and other reptiles, the blastula is _____________ on top of the yolk Gastrulation forms _____________ tissue layers The location of _____________ on the surface of the blastula forecasts their ultimate developmental fate in the adult The cells on the surface of the blastula move to their proper destinations during _____________ (literally,"producing the stomach")

species , yolk, cytoplasmic division divide, blastula flattened three cells gastrulation

Vertebrate skeletal muscles have highly organized, repeating structures (continued) Skeletal muscles are encased in connective tissue sheaths, which merge into their attaching ___________________ Inside a muscle's outer sheath, individual muscle cells, called ___________________, are grouped into bundles by further coverings of connective tissue ___________________ and ___________________pass through the muscle in the spaces between the bundles Each individual muscle fiber also has its own thin ___________________wrapping Wrapping provides the ___________________ needed to keep the muscle from bursting apart during contraction

tendons muscle fibers Blood vessels and nerves pass connective tissue strength

Animals undergo one of ________________ types of development as they progress from newborn to adult ________________ development, in which the newborn animal resembles the adult ________________ development, in which the newborn has a very different body structure than the adult

two Direct development Indirect development

Cell differentiation, gastrulation, and organogenesis occur during the first two months (cont'd.) An __________________stem cell can divide many times __________________ stem cells (ESCs) are usually derived from the inner cell mass of of blastocyst Can generate any body cell type when in__________________ __________________stem cells (ASCs) are present in small numbers in parts of the body including muscle, skin, bone marrow, fat, brain and heart Can differentiate into only a few types of cells __________________ stem cells (IPSCs) are produced by inserting a handful of genes or molecules that regulate transcription into adult (non-stem) cells This process transforms them into cells that can differentiate into any cell type

undifferentiated Embryonic stem cells culture Adult stem cells Induced pluripotent

The placenta exchanges materials between mother and embryo (cont'd.) The embryo's and mother's blood remain separated by the walls of the __________________ and their __________________ and do not mix Walls of the capillaries and chorionic villi act as barriers to some materials, including large __________________ & most __________________ Many small molecules move across their villi and capillary walls, including __________________ , __________________ and __________________ Some disease-causing organisms and many harmful chemicals can penetrate the placenta The most protective layer of the placenta is the __________________ covering of the __________________ Regulates the passage of __________________ between the fetal and maternal blood, but toxins cans still get through

villi , capillaries proteins & most cells nutrients, oxygen and carbon dioxide outer , chorionic villi materials

Alcohol is soluble in both __________________and __________________ and easily passes through the placenta, so a woman who drinks alcohol exposes her unborn child to the same concentration of alcohol present in her own blood If a pregnant woman drinks heavily or regularly during pregnancy, her child has a significant risk of developing fetal alcohol syndrome Symptoms include below-average intelligence, irritability, and poor impulse control The damage is __________________and can be __________________

water and lipids irreversible and can be fatal