Exam 1 Flashcards
Hypertrophy
increase in size -changes dramatically after birth (postnatal growth), so the muscle growth is the size increase of muscle fibers postnatally
hyperplasia
increase in number -completed in prenatal growth. Fixed at birth
Bone
a mineralized connective tissue (hydroxyapatite)
Osteoblasts
bone-forming cells deposited in a matrix of collagen; once osteoblasts are trapped in their secretion
three types of bones in most animals
long bones irregular bones flat bones
two types of bone tissue
compact bone spongy bone
Skeletal muscle
attached to bones striated voluntary multi-nuclei
cardiac muscle
found in the heart striated involuntary one or two nuclei
smooth muscle
found in vessels, ducts, skin and internal organs nonstriated involuntary single nucleus
Muscle tissue can be controlled by
nerves, hormones, local chemicals, or itself depending on the type and location
What grows as muscle grows?
Connective tissue, but the percentage of connective tissue decreases because muscle fiber protein deposit at a greater rate
Factors that affect growth
Nutrition, genetic, environment, sex
Explain how nutrition alters growth
muscle fibers develop before birth, so nutrition alters muscle fiber only during prenatal development
Explain how genetics alters growth
Faster growing breeds have more muscle fibers than their slower growing counter parts
Explain how age alters growth
muscle fiber number increases rapidly during secondary muscle development. Age-related changes in muscle fiber number ocur only during early to middle phases of prenatal development and vary w/in species
determinate growth
stops once a genetically pre-determined structure has completely formed
indeterminate growth
animal grows rapidly when young and continue to grow after reaching adulthood although at a slower pace
Explain how environment alters growth
DNA mutations may lead to advantageous genetic material.
Explain how sex alters environment
androgens play a major role in increasing muscle fibers
What is development
the gradual progression in which something transforms into a different stage from a lower to a higher stage of complexity -can be quantitatively and qualitatively measured
Differentiate between growth and development
growth is the permanent increase in size and mass of an organism, while development is the increase in complexity of an organism
What are some factors affecting muscle fiber number?
Animal variation muscle type species nutrition age breed and genetic selection sex genetic “conditions”
What are the transcription factors?
Myogenin MRF-4 MyoD Myf5
Muscle regulatory factor genes
the expression of one or more of these genes will determine whether the cells become myogenic
Why does carcuss weight matter?
its an important end goal and dressing percent can affect it a lot
Explain the different paths a zygote can take
What are the stages of embryonic growth?
Ovum phase
embryonic phase
fetal phase
Ovum phase
the period of time from fertilization of the ovum to implantation
embryonic phase
completed when the developing organism begins to reflect its mature form
Fetal phase
from the point where species identification can be established to birth, a developing organism is considered a fetus (the main growth left to complete at this stage is the increase of existing organs and tissues in size)
What does the Ovum phase include?
Meiosis
fertilization
zona pellucida
oocyte activation
cytokinesis
cleavage
morula
Meiosis
The number of sets of chromosomes in the cell is reduced from two sets (diploid) to one set (haploid)
Fertilization
The fusion of an ovum/oocyte with a sperm. After the ovum reaches the fallopian tubes, sperm penetrates the zona pellucida and fertilize the ovum leading to the formation of a zygote (fertilized egg)
Zona pellucida
a glycoprotein membrane surrounding an ovum. This structure is important for sperm binding and allows to initiate oocyte activation/acrosome reaction
Acrosome reaction
the process that a sperm penetrates the zona pellucida and ultimately the ovum by releasing numerous enzymes
cytokinesis
the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells
- After fusion of ovum and sperm, the pronuclei from both ovum and sperm migrate to the center of the cell and fuse together. At this point, fertilization is complete and cytokinesis events ensues.
Cleavage
- once fertilization is complete, the fertilized egg enters cell division known as the period of cleavage.
- Increase in cell number: during the cleavage, cell numbers increase massively, but no protein synthesis during the cleavage phase. Amount of DNA increase, and cell size decreases, however, overall size of embryo has no change
Morula
- signals the end of the ovum and cleavage phases of development of fertilized egg.
- At this stage, Morula reaches the uterine lumen or cavity and zona pellucida is lost (figure 3.4). In Chicken, the liberation of a chick from a shelled egg is often referred as the process of hatching.
What are the stages of the embryonic phase?
Blastula
morphogenesis
gastrulation
neurulation
somitogenesis
limb bud formation
Blastula
a hollow sphere of cells surrounding an inner fluid-filled cavity called the blastocoele formed during an early stage of embryonic development in animals.
Morphogenesis
- After formation of the blastula, embryo enters the gastrulation phase of development. At this stage, germ layers start to form.
- Morphogenesis is a term used to refer to the collective changes of the internal and external structures in the embryo. These structural changes involve in the development of multiple cell layers.
Invagination
- Yields multiple cell layers by creating a depression in the surface of the embryo. As the depression becomes deeper, the sides of the depression come together forming multiple layers
Involution
- When new layers are formed by the inward rolling of cells along an existing membrane
Ingression
- When cells begin to replicate on the internal aspects of an existing cellular layer and form another layer
Epiboly
- The increase in cell numbers on the outer surface of an embryonic layer
Delamination
- Develops new structures by dividing an existing layer into two separate structures
Gastrulation
- a phase early in the embryonic development of most animals which the single-layered blastula forms three germ layers, known as the ectoderm, mesoderm, and endoderm
- all tissues and organs form from on of the three layers of cells in the gastrula.
- The cavity that forms within the gastrula is known as the primitive gut; it later develops into the animals digestive system
Neurulation
- The process begins when the notochord induces the formation of the central nervous system by signaling the ectoderm germ layer above it to form the thick and flat neural plate. The neural plate folds in upon itself to form the neural tube, which will later differentiate into the spinal chord and the brain, forming the CNS
Somitogenesis
- the process by which somites are produced. Somites lie on either side of the neural tube in vertebrate embryos, including human, head to tail succession
Limb bud formation
- Mesodermal Cells from the lateral plate mesoderm and the myotome migrate to the limb field and proliferate to create the limb bud. Mesodermal cells produce the cartilaginous and skeletal portions of the limb while the myotome cells produce the muscle components.
Fetal phase
from the point where species identification can be established at birth, a developing orgnanism is considered a fetus (the main growth left to complete at this stage is the increase of existing organs and tissues in size)
What organs and tissues are formed from the ectoderm?
nervous system (including the brain, spinal cord, and nerves)
lining of the mouth, nostrils and anus
epidermis of the skin, sweat glands, hair and nails
What organs and tissues are formed from the mesoderm?
Bones and muscle
reproductive and excretory system
blood and blood vessels
inner layer (dermis) of the skin
What organs and tissues are formed from the endoderm?
Lining of the digestive tract
liver and pancreas
lining of the trachia, bronchi, and lungs
thyroid, parathyroid, thymus, and bladder
Where is muscle derived from?
mesoderm
plasma cells
white blood cells that secrete large volumes of antibodies
Where do satellite cells reside?
between the plasma membrane and the basement membrane of a skeletal muscle fiber
Myofibrils form new myofibrils how?
By splitting longitudinally
can be increased by exersise
Length of muscle is increased through stretch-induced hypertrophy
Protein turnover
the increased longitudinal and radial growth of muscle fibers obviously need newly synthesized proteins to build up. Muscle proteins maintain a dynamic state and on equilibrium between synthesis and degradation.
-systematically replacing proteins with a newly synthesized protein
Protein turnover is most rapid for what?
Proteins of the sarcoplasm
Protein turnover is slowest for what?
Stromal proteins and intermediate for myofibrillar proteins
What accounts for the majority of muscle fiber hypertrophy?
myofibril splitting
Work induced hypertrophy or exercise induced hypertrophy
Muscle fiber hypertrophy through splitting can be increased through these
Stretch induced hypertrophy
increasing the length of muscle fibers
Sarcomere addition
the mechanisms that allow muscle, individual muscle cells and myofibrils to increase in length
During the lengthening of myofibrils what must happen?
The cell components of the myofiber must accomidate the growth and muscle proteins must be built up as well
Which factos affect determination?
Primary MRF’s
MyoD, Myf-5, Mrf4
Which factors affect differentiation?
Secondary MRF’s
What is the most important factor for differentiation?
Myogenin
Hypertrophy
When cells increase in size
Hyperplasia
When cells increase in number
Accretation
The gradual buildup of cell size, mass and the connective tissues between cells
What is growth
The physical process of becoming larger or longer. Generally defined as an increase in size, mass, or numbers
-it is quantitatively measurable
What is true growth
The increase in the structure tissues including: bone, muscle, and the connective tissues associated with muscle
-Also known as fat-free growth
AGR
Absolute growth rate: the weight gain per unit of time
-average daily gain
RGR
Relative growth rate: growth in relation to total weight
-growth rate per unit weight plotted against time
What is the difference between RGR and AGR?
For AGR, the daily gain is minimal in the beginning and becomes maximum during puberty, while in RGR the daily gain in the beginning is fastest and slows down over time
What is fertilization?
Once the ovum reaches the fallopian tubes, sperm will penetrate the zona pellucida and fertilizes the ovum
-fertilization is complete when the pronuclei of the ovum and sperm fuse together
myogenesis
the formation of muscular tissue during embryonic development
-begins from stem cells in the embryo
Skeletal muscle develops from
paraxial mesoderm
The heart muscle develops from?
lateral plate mesoderm
Protein synthesis
The process by which cells assemble amino acids into proteins
-involves:
- Transcribing DNA into messenger RNA (mRNA)
- Movement of mRNA out of the nucleus into the cytoplasm
- Translation of mRNA into protein Post-translational processing of the protein Positioning the protein to specific locations
Degradation
proteolysis of the proteins into polypeptides and individual amino acids by various proteinases within the cell
Muscle fiber hypertrophy
the amount of protein synthesized exceeds that degraded
Muscle fiber atrophy
protein degradation exceeds synthesis
What is the most abundant protein in the animal kingdom?
Collagen
Collagenous fibers are…?
Nonelastic and do not tear easily when pulled lengthwise
Elastic fibers are…?
Elastic fibers are long threads of elastin protein. Elastin fiber provide a rubbery quality
Reticular fibers are…?
Very thin and branched
Neurons communicate with each other via..?
electrical and chemical signals
Dendrites
receive signals
Axons
send signals
Two major types of cells
neurons and glial cells
Glial cells do what?
Glial cells are supportive cells, providing nourishment and aid to neuron function
Nerves are what?
Bundles of axons surrounded by Schwann cells and some connective tissue. Indivudual axons may either be sensory or motor in function
Simple epithelium
a single layer of cells
stratified epithelium
more than one layer
pseudostratified
a single layer of cells, but its nuceli positioned like stratified epithelia
How is epithelia classified?
According to the shape of cells (squamous, cuboidal, or columnar) and the number of layers (simple, stratified, and pseudostratified)
What does epithelium do?
Depending on its type and its location, it may serve as protection, absorption, or secretory functions
How do you measure body composition of animals?
Subject evaluation (visual), specific gravity or density
Why do we measure body composition of animals?
Academics: research, allows us to better understand growth process
Economics: measuring composition allows us to market animals at the most ideal composition
Myofibrillogenesis
development of myofibrils
consist of contractile proteins and the primary function of muscle is to contract, so the addition of myofibrils to muscle cells is essential to accomplish this task
What are the two possible models of myofibrillogenesis?
1) The Stress Fiber Model
2) The premyofibril Model
Explain the process of myogenesis?
- premyoblasts- cells capable of mitosis but not yet producing muscle proteins
- myoblasts- cells start to produce muscle proteins
- myotube (primary fiber)- a multinuclear myofiber produced by the fusion of myoblasts
- Secondary fiber- a multinuclear myofiber produced by the fusion of myoblasts on the surface of a myotube
- Myofiber- a muscle fiber matured from either a primary myotube or a secondary myotube
Skeletal muscle is attached to bone by_________ and surrounded by _______.
Skeletal muscle attached to bone by tendons and surrounded by epimysium
Primary bundle consists of muscle fibers surrounded by?
Endomysium
Secondary muscle bundles are surrounded by?
Perimysium
What is striated muscle?
Stipped appearance because of overlapping thin and thick filaments across the entire myofibril
-cardiac and skeletal
What is a sarcomere?
A structural unit of myofibril
