Quizlet 2 Exam

tissue level of organization

stem cells

undifferentiated cells, will in the future specialize, at one point in embryonic development you are just stem cells

tissues are groups of cells already differentiated

the four tissue types

connective, muscular, epithelial, nervous

tissue

stem cells that have differentiated

group of cells that have similar structure and that function together as a unit

epithelial tissue

surface cells, surfaces or linings or covering of organs, very thin, things can travel through, like bronchiole tissue, all your organs are covered in this

avascular, get oxygen and nutrients through diffusion

innervated

regenerative when they have proper nutrients

connective tissue

direct connections for tendons and ligaments, very thick tissue, example of achilles tendon, fat tissue, cartilage (nose, ears, joints), highly vascularized

muscle tissue

well vascularized

body movement

cells tightly packed together

possess myofilaments, actin and myosin

three different types:

skeletal muscle - striated and voluntary, attached to bones of skeleton, form flesh of body, body movement, precise alignment of myofilaments with obvious banded or striated appearance

smooth muscle - non-striated and involuntary, cells have no visible striation, spindle shaped, found mainly in walls of hollow organs other than heart, contracting and relaxing causes movement, digestive and urinary tract organs)

cardiac muscle - striated, involuntary, only in the heart, help propel blood through blood vessels to the rest of body, striated, cells only have one nucleus (uninucleate) and branching cells fit tightly together at unique junctions called intercalated discs

striated

muscle tissue classification, dark band stripes allowing contractile bonds, actin and myosin

The primary function of striated muscles is to generate force and contract in order to support respiration, locomotion, and posture (skeletal muscle) and to pump blood throughout the body (cardiac muscle)

nonstriated

muscle tissue classification

no stripes, Non-striated muscles are smooth and devoid of striations. Found in the hollows of internal organs such as the stomach, intestines, and urine bladder, among other places

voluntary movement

muscle tissue classification

making yourself move the muscle, running, walking, etc

involuntary movement

muscle tissue classification

body just doing it - breathing, blinking

nervous tissue

nervous tissue is found in the brain, spinal cord, and nerves it is responsible for coordinating and controlling many body activities

it stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning

contains, cell body, dendrites, axon, supporting cells

excitable

cardiac and muscle, tissue that can be stimulated and a response can happen

totipotent

(of an __immature__ or stem cell) capable of giving rise to any cell type or (of a __blastomere__) a complete __embryo__

These stem cells are the most powerful that exist. They can differentiate into embryonic, as well as extra-embryonic tissues, such as chorion, yolk sac, amnion, and the allantois. In humans and other placental animals, these tissues form the placenta

really strong and versatile stem cells

endoderm

the innermost of the three basic layers of an embryo that forms the epithelium of the digestive tract and the parts of the body formed from it

inner lining of digestive system

ectoderm

the ectoderm is one of the primary layers of cells that exists in an embryo

the ectoderm cells differentiate into cells that form a number of external structures such as skin, sweat glands, skin sensor receptors, and hair follicles

nervous tissue

mesoderm

the middle of the three primary germ layers of an embryo that is the source of many bodily tissues and structures (such as bone, muscle, connective tissue, and dermis) broadly : tissue derived from this germ layer. mesodermal)

mesoderm, ectoderm, and endoderm

The ectoderm gives rise to the skin and the nervous system. The mesoderm specifies the development of several cell types such as bone, muscle, and connective tissue. Cells in the endoderm layer become the linings of the digestive and respiratory system, and form organs such as the liver and pancreas

these primary germ layers specialize to form the four primary tissues

all three form epithelium

omnipotent

not as strong of stem cells as totipotent, but still very versatile

nervous tissue

main component of nervous system (brain, spinal chord, nerves)

two major cell types:

**neurons** - highly specialized nerve cells that generate and conduct nerve impulses, branching cells with cytoplasmic extensions (respond to stimuli, transmit electrical impulses within body)

**supporting cells** (neuralgia)- nonconducting cells, they support, insulate, and protect delicate neurons

mechanical barriers - 3 defenses at body’s external boundaries

skin, mucosae (cilia of epithelial cells lining respiratory tract), and strong cid produced by stomach glands

what happens when tissues are injured/boundaries penetrated

the inflammation (nonspecific) and immune response (specific) are triggered

Tissue repair basic

requires cells to divide and migrate (initiated by growth factors released by injured cells)

repair occurs in…

regeneration

fibrosis

which one occurs depends on the type of tissue damaged and severity of injury

regeneration (tissue repair)

replaces destroyed tissue with the same kind of tissue

fibrosis

replaced destroyed tissue with scar tissue (dense connective tissue - fibrous connective tissue because fibers are the primary element)

1. inflammation

first step of tissue repair

trauma causes the injured tissue cells and masts to release inflammatory chemicals

these make local blood vessels leaky so that white blood cells, fluid, clotting proteins, and other plasma proteins to seep into the injured area

clotting prevents bacteria and other harmful substances from spreading

surface of clot exposed to air forms scab

2. organization restored blood supply

clot is replaced by ingrowth of fragile capillaries (**granulation tissue**) which restores vascular supply

fibroblasts multiple, produce growth factors and collagen fibers that bridge gap

when healing complete, these fibroblasts revert to resting stage or undergo apoptosis (cell suicide)

macrophages phagocytize dead and dying cells/other debris

surface epithelial cells multiply and begin to migrate over granulation tissue

granulation tissue

special tissue formed in initial part of wound healing, delicate pink tissue that contains capillaries that grow in from nearby areas and lay down on capillary bed, fragile and bleed freely

apoptosis

cell suicide

happens during tissue repair process when the fibroblasts commit apoptosis after healing is complete

3. regeneration and fibrosis effect permanent repair

the fibroses area matures and contracts, pulling ends of wound together

as it regenerates, epithelial thickens under scab, which detaches

fully regenerated epithelium with underlying scar tissue results

scar could be visible as white line depending on severity of wound

what tissues regenerate well?

epithelial

bone

areolar loose connective tissue

dense irregular connective

blood-forming tissue

regenerate moderately well

smooth muscle, dense regular connective tissue

weak ability to regenerate

skeletal muscle

cartilage

no ability to regenerate

nervous tissue in brain and spinal chord, replaced by scar tissue

in the non regenerating tissue…

fibrosis replaces the tissue, but it cannot perform the function of the tissue it replaces, scar tissue is NOT flexible

cancer

cancers are malignant neoplasms

changes normal cell into a killer

cells multiply excessively

**neoplasm** results - abnormal mass of proliferating cells

neoplasms have two classifications:

benign - grow slowly, local, seldom kill hosts

malignant - metastasis and invasiveness

secondary neoplasms

non-encapsulated masses that grow relentlessly, invade surroundings, break away from primary tumor and travel (by blood or lymph) to other organs

metastasis

tumor cell ability to travel to other parts of the body

carcinogens

cause mutations in cells, or changes in DNA that alter the expression of certain genes

defenses against carcinogens:

liver deactivates many, cells have intrinsic DNA repair, immune cells continuously scan for cancer cells

oncogenes

cancer-causing genes

protooncogenes

benign forms of oncogenes in normal cells

code for proteins that are essential in cell division, growth, cellular adhesion, etc

have fragile sites that carcinogens can break to form oncogenes

tumor suppressor gene

inhibit cell growth to try and slow growth of cancer cells

where are cancers most common

skin, colon, lung, breast, and prostate

usually preceded by lumps or structural changes in tissue

WHAT IS THE CONNECTION BETWEEN CANCER AND TISSUE - explain cancer as it relates to tissue

cancer is uncontrolled cell growth

necrosis

death or disintegration of a cell or tissues caused by disease or injury - leads to tissue repair process

vasodilation

relaxation of the smooth muscle of the blood vessels, producing dilation, histamine is the messenger or neurotransmitter that causes vasodilation

histamine

causes blood vessels to dilate, chemical messenger, Causes vasodilation and increased capillary permeability; it is in the stomach and causes acid secretion

atrophy

reduction in size or the wasting away of an organ or cell regulating from disease or lack of use

inactivity in a muscle leading to this wasting away while on the other hand constant load and use makes it stronger and larger

endocrine gland

ductless glands that empty their hormonal products directly into the blood

exocrine gland

glands that have ducts through which their secretions are carried to a particular site

merocrine glands

term used to classify exocrine glands and their secretions secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and then onto a bodily surface or into the lumen

sweat glands abundant on palms, soles of feet, and forehead

holocrine glands

glands that accumulate their secretions within their cells and secretions are only discharged upon rupture or death

releases sebum - made up of lipids to protect and hydrate skin

aprocrine secretions

less numerous type of sweat gland produces a secretion containing water, salt, protein, and fatty acid

armpits, groin, breast

odor

aging and signs of aging in tissue

lost of elasticity, loss of flexibility, dehydration of cells, neurological connections, digestion is slower