Chapter 3 Cells and Tissues
In the late 1600s, Robert Hooke was looking through a microscope at some plant
tissue - cork. He saw some cube-like structures that reminded him of the long rows
of monk's rooms (or cells) at the monastery, so he named these structures cells.
The living cells that had formed the cork were long since dead. However, the name
stuck and is still used to describe the unit, or building block, of all living things,
plants and animals alike. The human body has trillions of these microscopic building
blocks.
Cells
 Name the four elements that make up the bulk of living matter and list several trace elements.
o Carbon, oxygen, hydrogen, nitrogen = bulk
o Iron, sodium, potassium – smaller amounts
o Calcium, iron, iodine = trace
 Define cell, organelle, and inclusion.
o Cell – The basic structural and functional units of all organisms – enclosed by a limiting
membrane – could be prokaryotic or eukaryotic
o Organelle – metabolic machinery of the cell – each carries out a specific function for the
cell such as nucleus, mitochondria, Golgi apparatus, ER, cytoplasm…
o Inclusion – not functioning units, but are chemical substances that may or may not be
present depending on the type of cell such as fat droplets, glycogen granules, pigments
(melanin), crystals
 Identify on a cell model or diagram the three major cell regions (nucleus, cytoplasm, and plasma
membrane).
o See page 57
 List the structures of the nucleus and explain the function of chromatin and nucleoli.
o Nuclear envelope – double membrane, selectively permeable with nuclear pores
o Nucleoplasm – jelly-like substance inside the nucleus that holds the nucleoli and chromatin
o Nucleoli – sites of ribosome construction and partial assembly – may be more than one
o Chromatin – uncoiled DNA being used for transcription
o Chromosomes – shortened, coiled DNA ready for cell division
 Identify the organelles on a cell model or describe them, and discuss the major function of each.
o Plasma membrane – selectively permeable barrier, communication
 Tight junctions – impermeable junctions to bind cells together into leakproof sheets
 Desmosomes – anchoring junctions that prevent cells subject to mechanical stress
from being pulled apart
 Gap junctions – function mainly to allow communication between cells
o Cytoplasm – hold organelles and dissolved nutrients – site of most cellular activities
o Nucleus – control center containing the DNA
o Mitochondria – makes ATP
o Ribosomes – sites of protein synthesis
o Endoplasmic reticulum
 Rough ER – has ribosomes attached – network of channels for processing and
shipping proteins out of the cell
 Smooth ER – no ribosomes – cholesterol synthesis and breakdown, fat metabolism,
detoxification
o Golgi apparatus – modify and package proteins for shipment
o Lysosomes – contain enzymes for digestion of old cell components and foreign substances
such as bacteria and viruses
Peroxisomes – contain powerful oxidase enzymes that use molecular oxygen to detoxify
harmful or poisonous substances such as alcohol and formaldehyde, also functions to disarm
free radicals (highly reactive chemicals that can damage cell components)
o Cytoskeleton – the cell’s bones and muscles – internal framework that determines cell
shape, supports other organelles, and provides the machinery needed for intracellular
transport and cell movement
 Intermediate filaments – form desmosomes and provide internal guy wires to
resist pulling forces on the cell
 Microfilaments – cell motility and in producing changes in cell shape – made of
actin and myosin
 Microtubules – determine overall shape and distribution of organelles also
important in cell division
o Centrioles – direct formation of the mitotic spindle used to separate the chromosomes
o Cilia and flagella – move substances across the cell surface or for cell movement
 Define selective permeability, diffusion (including simple and facilitated diffusion and osmosis),
active transport, passive transport, solute pumping, exocytosis, endocytosis, phagocytosis, bulkphase endocytosis, hypertonic, hypotonic, and isotonic.
o Selective permeability – allows some substances to pass while excluding others
o Passive transport – does not require ATP energy
 Diffusion – molecules and ions scatter themselves throughout the available space
via kinetic energy (random movement) down their concentration gradient
 Simple – unassisted movement of solutes through the membrane
 Facilitated – uses a protein carrier to assist molecules across the membrane
 Osmosis – movement of water across the membrane
o Active transport – does require ATP to move substances that are either too large or need
to be moves against their concentration gradients
 Solute pumping – uses protein carriers that combine reversibly with the substances
to be transported – usually carries substances against the concentration gradient
 Bulk transport – moves substances that cannot get through the membrane
 Exocytosis – moves substances out of the cell using sacs that fuse with the
membrane and release their contents outside of the cell
 Endocytosis – moves substances into the cell – cell engulfs substances and
wraps membrane around it and the sac pinches off inside the cell
 Phagocytosis – cell eating – white blood cells can bring in bacteria and other
harmful substances and destroy them
 Bulk-phase endocytosis – A.K.A. Pinocytosis – cell drinking – brings in
fluids containing dissolved proteins and fat
o Hypertonic – solution that contains more solutes, dissolved substances, than there are
inside the cell – cells will crenate or shrivel up
o Hypotonic – solution that contains fewer solutes than there are inside the cell – cells will
expand and possibly lyse open
o Isotonic – solution with the same concentration of solutes as inside the cell - cell is normal
 Describe the structure of the plasma membrane, and explain how the various transport processes
account for the directional movements of specific substances across the plasma membrane.
o Flexible double membrane made up of phospholipids arranged tail to tail (hydrophobic tails
(nonpolar) point inward while hydrophilic (polar) heads point outward) in which protein and
cholesterol molecules float
o Proteins scattered in the lipid bilayer are responsible for the specialized functions of the
membrane
o
Glycoproteins can act as enzymes or carriers, form channels or pores, provide
receptor sites for hormones and other chemicals or play a role in cellular recognition
and interactions during development and immune responses
 Describe briefly the process of DNA replication and of mitosis. Explain the importance of mitotic cell
division.
o DNA replication – DNA double helix uncoils and the two strands separate and act as
templates for new complementary strands to be added – end with two DNA strands that are
identical – A=T and C=G
o Mitosis – cell replication for growth and repair of damaged tissues – results in two identical
cells with identical copies of the DNA and organelles
 In relation to protein synthesis, describe the roles of DNA and of the three varieties of RNA.
o DNA template strand is used to produce the mRNA strand during the process of
transcription
o Translation involves the three types of RNA
 mRNA made in the nucleus is a single, uncoiled strand of RNA travels to the
cytoplasm and finds a ribosome
 tRNA carries corresponding amino acids on their tops that match the anticodon on
their bases to the mRNA strand attached to the ribosome and matches up with the
codons on the mRNA strand – amino acids are bonded together with peptide bonds
 rRNA along with proteins make up the ribosomes where protein synthesis takes
place
 Name some cell types and relate their overall shape and internal structure to their special
functions.
o Cells that connect body parts
 Fibroblasts - elongated shape that produces cable-like fibers
 Erythrocytes – streamlined concave disk shape for extra surface area to transport
oxygen
o Cells that cover and line body organs
 Epithelial – hexagonal shape allows for them to be packed together in sheets
o Cells that move organs and body parts
 Skeletal and smooth muscle – elongated and filled with contractile filaments to
shorten to move bones or change the shape of internal organs
o Cells that store nutrients
 Fat cells – spherical shape produced by lipid droplets in the cytoplasm
o Cells that fight disease
 Macrophages – white blood cells – no determined shape – very flexible to squeeze
into tight spots and in-between cells to fight disease
o Cells that gather information and controls body functions
 Nerves – long processes for receiving messages and transmitting them to other
structures
o Cells of reproduction
 Oocyte – largest cell in the body – egg cell
 Sperm – long and streamlined, built for swimming with a flagella
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Body Tissues
 Name the four major tissue types and their chief subcategories. Explain how the four major tissue
types differ structurally and functionally.
o Epithelial – fit closely together to form continuous sheets, membranes have one free
surface, lower surface rests on a basement membrane, no blood supply of their own
(diffusion brings in nutrients), if well nourished can regenerate themselves easily
Simple – one layer of cells
Stratified – more than one layer of cells
Squamous - flat
Cuboidal – cube-like
Columnar – column-like
Glandular – consists of one or more cells that make and secrete a particular product
 Endocrine – lose their connections to the surface (duct) and release their
secretions into the blood – secrete hormones
 Exocrine – retain their ducts and secretions empty through the ducts to the
epithelial surface – sweat and oil glands
o Connective – variations in blood supply depending on the type, extracellular matrix
associated
 Bone – bone cells sitting in cavities called lacunae and surrounded by layers of very
hard matrix containing calcium salts in addition to large numbers of collagen fibers
 Cartilage – less hard and more flexible than bone with abundant collagen fibers
hidden by a rubbery matrix with a glassy, blue-white appearance
 Dense connective tissue – crowded between collagen fibers are rows of fibroblasts
 Tendons – muscle to bone
 Ligaments – bones to bones – more stretchy with more elastic fibers
 Loose connective tissue – softer and have more cells and fewer fibers
 Areolar – soft, pliable, cobweb to cushion and protect body organs – glue
that helps hold internal organs together and in place
 Adipose – fat – areolar tissue in which fat cells predominate – forms the
subcutaneous tissue beneath the skin for insulation and protection of internal
organs as well as serving as an energy reserve
 Reticular – delicate network of interwoven reticular fibers associated with
reticular cells – supports many free blood cells (lymphocytes) in lymphoid
organs
 Blood – vascular tissue – blood cells surrounded by nonliving, fluid matrix called
blood plasma to function in gas exchange
o Muscle – specialized to contract, or shorten, to produce movement
 Skeletal – voluntary, long, cylindrical, multinucleated, striations – move bones
 Cardiac – only in heart – involuntary, branching cells, uninucleate, striations
 Smooth – involuntary, spindle-shaped, uninucleate, no striations
o Nervous – cytoplasm is drawn out into long extensions to conduct an impulse over long
distances – nerves are supported by supporting cells that insulate, support, and protect
 Give the chief locations of the various tissue types in the body.
o See above section
 Describe the process of tissue repair (wound healing).
o Occurs in two major ways – regeneration and fibrosis depending on the type of tissue
damaged and the severity of the injury
 The capillaries become very permeable allowing clotting proteins other substances to
seep into the area
 Granulation tissue forms – made of new capillaries that grow into the damaged area
that freely bleed – tissue also contains phagocytes to remove blood clot and bacteria
– also contains connective tissue cells that synthesis collagen fibers to stitch the gap
together
 The surface epithelium regenerates – as surface epithelium begins to regenerate, it
makes its way across the granulation tissue just beneath the scab, which then
detaches
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Developmental Aspects of Cells and Tissues
 Define neoplasm, and distinguish between benign and malignant neoplasms.
o Neoplasm – mass of cell that forms when cells fail to honor normal controls on cell division
and multiply wildly forming an abnormal mass of proliferating cells
o Benign – local, tend to be surrounded by a capsule, grow slowly, seldom kill the host if
removed before they compress vital organs
o Malignant – nonencapsulated masses that grow more relentlessly and may become killers,
cells resemble immature cells and they invade their surroundings rather than pushing them
aside, tend to spread via blood to other parts of the body (metastasis) to form new masses
 Explain the significance of the fact that some tissue types (muscle and nerve) are largely amitotic
after the growth stages are over.
o Amitotic tissues are severely handicapped by injury because the lost cells cannot be
replaced by the same type of cells
o Damaged heart tissue is not replaced by heart cells but by scar tissue that cannot contract
making the heart weaker
o Once nerves are damaged or lost, a person becomes paralyzed and looses all feeling in that
area serviced by that nerve