3.1 Cells and Tissues
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3.1 Cells and Tissues. (Page 199). When a human embryo is only a few hours old, the fate of many cells has ____________________________________. Three factors influence specialization:. The effect of cytoplasm on cell specialization. Cells have identical chromosomes; however.

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When a human embryo is only a few hours old, the fate of many cells has ____________________________________

Three factors influence specialization:

The effect of cytoplasm on cell specialization many cells has

  • Cells have identical chromosomes; however

E.g. having more _____________allows a cell to release more energy as it grows thus affecting development

The effect of environment on cell specialization

  • Temperature and presence of certain chemicals and nutrients

  • Environmental factors can also be responsible for developmental _____________________

  • ___________________, pollution, parasites, diseases can trigger developmental abnormalities

  • In Siamese cats, skin cells that develop in cooler conditions (extremities) produce dark fur

The effect of many cells has neighbouring cells on specialization

  • one of the ____________________ on cell specialization

  • substances produced by neighbouring cells can ___________ across a cell’s membrane

  • substances can change how and when _________________

In chick embryos, neighbouring cells influence eye development (blue area)

Similar cell conditions form similar cells many cells has

As a cell ages, genes are switched on and off by the influence of other cells and _______________________

therefore different situations can produce nerve cells or skeletal cells (for example)

  • Cells that experience similar influences usually become similarly specialized to do the same job

Mature cells stop dividing and live out their lives as a specialized cell (____________________________________)

4 Types many cells has of Tissues

Epithelial tissues many cells has

  • Line the

  • Made of cells with string connections between adjoining cell membranes so they

Skin epithelial:

  • _______________ that act as a semi-permeable barrier between inside and outside the body

Columnar epithelial:

  • columns of cells that line

  • may secrete ________, have cilia and absorb materials

Epithelial tissues many cells has

Muscle tissues many cells has

  • Change their shape by

Skeletal Muscle:

  • cells line up; looks striated

  • attached to bone allowing body to move

  • in

Smooth Muscle:

  • cells are tapered at both ends

  • found in

  • contracts slowly and can be sustained for long time

Cardiac Muscle:

  • nuclei appear between cells, branched unevenly, striated

  • contracts as a unit & only found in

Muscle tissues many cells has

Connective tissues many cells has

  • Strengthens, supports, binds, connects cells and tissues


  • cells surrounded by calcium hardened tissue containing blood vessels


  • large tightly packed cells

  • found under skin and around organs


  • Red & white blood cells, platelets and plasma

Connective tissues many cells has

Nervous tissue many cells has

  • cells called

  • coordinates body actions

  • Varied in their action:

    • some relay signals from brain to muscles & glands

    • others detect info from their environment and trigger responses

Stem Cells many cells has

An unspecialized cell that can produce various types of cells

  • Mammals can naturally only replace small amounts of tissues (bone & skin); not organs



The many cells has Potential of Stem Cells

  • Huge potential in medicine: In 1968 Canadian researchers showed that healthy marrow can restore blood cells in an animal that had undergone radiation therapy

Human embryonic stem cells (1 week old) can become over 300 different types of cells

  • these cells obtained from

  • egg cells fertilized in vitro (in glass)

  • egg cells come from fertility clinics

  • Harvesting stem cells destroys the embryo: