Ch 6b: Muscle Tissue and Nervous Tissue Flashcards
what are the three types of muscle tissue
- skeletal
- cardiac
- smooth
what is the structure of skeletal muscle
long, multi-nucleated cells (fibers); striated ( sarcomeres arranged in bands ); cells run in parallel direction
what is the function of skeletal muscle
voluntary contractions
what is the location of skeletal muscle
attach to bone via tendons; attach to axial and appendicular divisions of the skeleton
what is the structure of cardiac muscle
small, mono-nucleated cells; striated ( sarcomeres arranged in bands ); contain intercalated discs (junction between cells and allows spread of nervous impulse); branching of cells
what is the function of cardiac muscle
involuntary contractions
what is the location of cardiac muscle
heart
what is the structure of smooth muscle
small, mono-nucleated cells; non-striated ( no sarcomeres or bands present ); cells flow into each other
what is the function of smooth muscle
involuntary contractions
what is the location of smooth muscle
walls of blood vessels(circulation of blood); and viscera (except heart)
what are the three parts of a neuron
- dendrite
- cell body (soma)
- axon
dendrite
one or more; pick up nerve impulse (action potential) and send to cell body
cell body (soma)
one; contains the nucleus; translates the incoming impulse (message)
axon
one; longest part of neuron; picks up translated message from the cell body and sends to target (effector organ)
effector organ
can be another neuron; gland; or muscle
glial cells (neuroglia)
these are supporting cells; do not conduct nerve impulses; are found in both the Central Nervous System ( Brain and Spinal Cord ) and the Peripheral Nervous System ( outside of brain & spinal cord )
tissue growth
- Tissues grow because their cells increase in number or size.
- Most embryonic or childhood growth occurs by hyperplasia (tissue growth by multiplication).
- Skeletal muscle and adipose tissue grow through hypertrophy (the enlargement of pre-existing cells).
- Neoplasia (is the development of a tumor, whether benign or malignant, and is composed of abnormal, nonfunctional tissue).
tissue development
- Embryonic Tissue undergoes differentiation
- Epithelia can sometimes exhibit metaplasia
- stem cells
differentiation
(the development of a more specialized form and function); i.e. the differentiation of mesenchyme to muscle
metaplasia
(a change from one type of mature tissue to another); i.e. pre-puberty vaginal epithelia is simple cuboidal, and at puberty changes to stratified squamous
stem cells
Are undifferentiated cells that are not yet performing any specialized function, but have the potential to differentiate into one or more types of mature, functional cells
embryonic stem cells
- Compose the early embryo
- Totipotent stem cells – have the potential to develop into any type of fully differentiated human cell, not only cells of the later embryonic, fetal, or adult body, but also cells of the temporary structures of pregnancy, such as the placenta and amniotic sac; have unlimited developmental plasticity
- Pluripotent stem cells – have the potential to develop into any cell type of the embryo, but not into the accessory organs of pregnancy; have somewhat limited developmental plasticity
adult stem cells
- Occur in small numbers in mature organs and tissues throughout a person’s life.
- An adult stem cell divides mitotically; one of the daughter cells remains a stem cell, and the other one differentiates into a mature specialized cell
3 .Multipotent stem cells – able to develop into two or more different cell lines; some bone marrow stem cells can give rise to all types of blood cells
- Unipotent stem cells – can produce only one mature cell type; cells that give rise to egg and sperm cells
what are the two ways damaged tissue can repair
- regeneration
2. fibrosis
regeneration
the replacement of dead or damaged cells by the same type of cells as before; restores normal function to the organ; most skin injuries heal by regeneration
fibrosis
the replacement of damaged tissue with scar tissue, composed mainly of collagen produced by fibroblasts; scar tissue helps hold the organ together, but it does not restore normal function; scarring of lungs after tuberculosis infection
atrophy
is the shrinkage of a tissue through a loss in cell size or number; it results from normal aging (senile atrophy) and lack of use of an organ (disuse atrophy)
necrosis
is premature, pathological tissue death due to trauma, toxins, or infection;
infarction
is the sudden death of tissue that occurs when its blood supply is cut off;
gangrene
is any tissue necrosis resulting from an insufficient blood supply, usually involving infection
apoptosis (programmed cell death)
is the normal death of cells that have completed their function and best serve the body by dying and getting out of the way; cells shrink and are quickly phagocytized by macrophages; every cell has a built in “suicide program”
what are the two possible suicide program mechanism
- Extracellular suicide signal binds to a receptor protein in the plasma membrane known as Fas
Fas activates intracellular enzymes that destroy the cell; includes an endonuclease which chops up the DNA, and a protease which destroys the cellular proteins - Cells seem to undergo apoptosis automatically if they stop receiving growth factors from other cells
