Transcript unit 3: cells and tissues notes

UNIT 3: CELLS AND
TISSUES
CH. 3, 5
Cell Basics

Cells are the basic unit of structure and
function of living things

Pancreas produces insulin
 Individual
acinar cells produce the protein insulin
and dump into blood stream  action is the result
of individual cells

Bone is collection of osteocytes – bone cells
 Structure
is repeating units of bone cells
Cell Basics - Organelles

Nucleus – controls cellular activity;
contains DNA




a.k.a centrioles
Lysosome – contains digestive
enzymes


Can be attached to ER or free floating
in cytoplasm
Centrosome – microtubules arranged
in “T” formation involved in cell
reproduction


Chromatin – uncoiled strands of DNA
Mitochondria – powerhouse of the
cell; site of aerobic respiration
Ribosomes – site of protein synthesis


Endoplasmic reticulum – folds of
interior membranes





Golgi Appartus – packages, modifies
proteins; gets ready for transport
Vesicle – membrane bound storage
unit
Cytoskeleton – microtubules and
microfilaments that provide a
framework for cell shape

cilia – short, hair-like projections

Phagocytes (WBC)
Peroxisome – contains catalase to
decompose hydrogen peroxide into
water and oxygen
 H2O2  H2O + O2
Smooth – lipid, carb metabolism;
detoxification
Rough – protein synthesis (ribosomes
attached)


Move substance across surface
Respiratory and Female Reproductive
Systems
Flagella – longer, hair/tail like projection

Used for cellular locomotion - sperm
Movement of Materials Into and
Out of the Cell

Diffusion – passive (no energy) process of materials moving from a
high concentration to a lower concentration


Facilitated diffusion – diffusion through a protein


Diffusion of gases (O2/CO2) between blood an air (in lungs; alveoli) and
between blood and tissues (capillaries)
Uses protein channel in cell membrane to get across barrier
Osmosis – diffusion of water


Hypertonic – higher concentration of solutes
Hypotonic – lower concentration of solutes




Water will always flow towards hypertonic env.
A cell with 5% solute concentration is placed in distilled water  gains water
A cell with 5% solute concentration is placed in sea water (15%)  loses
water
Filtration – uses differences in hydrostatic (water) pressure to drive
materials across membrane

Urinary system; capillary beds
Movement of Materials Into and
Out of the Cell

Active Transport – use of energy (ATP) to drive materials from an
area of lower concentration to an area of higher concentration


Ion/proton pumps
Na+/K+ pump – necessary for establishing correct ionic concentrations
on both sides of a cell membrane




3 Na+ out
2 K+ in
Causes a buildup of Na+ out and K+ in
Endocytosis – bulk transport into the cell

Pinocytosis – cell “drinking”


Membrane indents  liquids flow in  membrane seals off  fluid filled
vesicle forms
Phagocytosis – cell “eating”

Membrane extends arms out  surrounds large solid particle  seals off 
forms vesicle


Usually will fuse wit h lysosome to dissolve/digest contents
Exocytosis – opposite of endocytosis; move large materials out
Cell Reproduction

Mitosis – making genetically identical cells


Meiosis – making gametes with half the genetic
information


multicellular growth and repair
Two gametes fuse to form zygote  mitosis reproduces copies
of zygote many times to form trillions of cells of baby
Phases of Mitosis

Interphase – individual cell growth; DNA replication
Prophase
\
Metaphase
\ organizes DNA and separates
Anaphase
/
chromosomes to opposite sides
Telophase
/
of cell

Cytokinesis – division of cytoplasm and cell itself




Cell Reproduction

Control of Cell Cycle – different tissues must reproduce at different
rates


If cells reproduce slower than normal tissue death  holes result
(stomach ulcers, skin lesions)
If cells reproduce to fast, tumors can result



Psoriasis – skin cells reproduce too fast
Controlled by genes
Cancer – loss of a cell’s ability to control the rate at which it divides;
mitosis too fast

Problems with genes:

Tumor Suppressor genes – usually turned on to slow cell division down


Oncogenes – normally turned off




Cancer results when genes are activated
Tumor – a mass of unspecialized cells


Caner results when genes are inactivated
Benign – non-cancerous
Malignant – cancerous
Damages healthy tissue by: 1) nutrients flow to tumor, starve out
healthy tissue; 2) pressure damage (can cut off blood flow)
Metastasis – spread of cancer to other body parts


Usually associated with lymph and vascular systems
Only takes 1 cancer cell to start new tumor (mitosis produces genetically
identical cells)
Types of Tissues
Tissues – different types of cells working together for a
common purpose
Kinds:
1)
2)
Epithelial Tissue – covering for organs, cavities and surfaces
in general
Connective Tissue – supports or binds different organs
together
a)
b)
3)
Muscle tissue – tissue specialized for contractile motion
a)
4)
Can be used to fill spaces as well
Can be very different in make-up: bone and blood are both types
of C. T.
Skeletal, smooth and cardiac
Nervous tissue – tissue specialized for conduction of impulses
Epithelial Tissues

General Characteristics

Acts as a covering



Usually lacks blood vessels (Avascular)




Must be nourished via diffusion from underlying tissues
Must reproduce rapidly; continually being replaced
Cells are tightly packed with little intercellular material between them
Function – covering, barrier, protection


Free surface – opens to outside
Basement membrane – attached to surface that it is covering
Also can be specialized for secretion, absorption and excretion
Important Terms for Classification






Simple – single row of cells
Stratified – many layers
Squamous – short, flat cells
Cuboidal – box-like shape
Columnar – tall, elongated cells
Ciliated – cilia on free surface
Epithelial Tissues

Simple Squamous Ep.



Single row of flattened cells
Thinnest of coverings
Allows substances to pass freely  important for areas that
need diffusion to happen between tissues


Simple Cuboidal Ep.




Alveoli (air sacs) in lungs; capillary blood vessels
Single row of square shaped cells
Central, spherical nuclei
Ovaries, kidney tubules, ducts of salivary glands, pancreas and
liver
Simple Columnar Ep.



Single layer of tall, elongated cells
Nuclei usually at same level, near basement membrane
Digestive System – specialized for secretion and absorption


Microvilli – tiny folds on surface to increase absorptive surface area
Goblet Cells – specialized cells for secreting mucus
Epithelial Tissues

Pseudostratified Columnar Ep.

Appear (pseudo- = fake) to be layered, but actually only a single layer of
columnar cells



Respiratory tract – cells line trachea, bronchi and larger bronchioles




Ciliated – cilia on free surface act to move substances across surface
Contain goblet cells for mucus production
Also found in reproductive tubes to move female sex cells
Stratified Squamous Ep.


Many layers of flattened cells
Cuboidal cells near basement membrane; flattened near free surface



Cells reproduce near basement membrane; flattened as they are pushed away
Epidermis of skin


Nuclei are at different levels in cells
all cells reach basement membrane
Keritinization – older cells accumulate “keratin” – protein that hardens and waterproofs
the cells
Also lines cavities that open directly to outside world: mouth, vagina, anal canal
Stratified Cuboidal Ep.




Two or three layers of cuboidal cells
Generally lines lumen (cavity of a tube)
Larger gland ducts – mammary, sweat, salivary and pancreas
Ovarian follicles (Female Rep. Sys.) and seminiferous tubules (Male Rep. Sys.)
Epithelial Tissues

Stratified Columnar Ep.

Many layers of columnar cells



Male urethra, Vas Deferens, parts of pharynx
Transitional Ep.

Specialized layers to respond to changes in tension



Cells near basement membrane are cuboidal; elongate as they reach free
surface
Must be able to expand when organ expands and tighten when organ
empties
Bladder and passages of urinary system
Glandular Ep.


Cells that are specialized to produce and secrete substances into tubes
(ducts) or body fluids
Exocrine – secrete into ducts that lead to internal or external surfaces



See Classification Types – P141
Simple, compound, tubular, alveolar
Also classified by how they secrete




Merocrine – substance only
Apocrine – substance + part of cell cytoplasm
Holocrine – substance + all of cell interior
Endocrine – secrete directly into body fluids (commonly blood)

Endocrine glands revisited in Ch. 13
Connective Tissue

General Characteristics


Most abundant by weight
Main function – bind structures together


Cells generally farther apart with lots of intercellular material (matrix)



Also provide support and protection; framework; fill spaces; store fat;
produce blood cells; protect against infections; help repair tissue damage
Matrix can vary from solid, to semi-solid, to liquid
Cells usually able to reproduce – how fast depends on blood supply
Cell Types





Resident cells – numbers of cells are relatively constant
Wandering cells – increase in numbers when needed
Fibroblast – cells that produce fibers
Macrophages – specialized for phagocytosis
Mast Cell – produces compounds histamine and heparine


Histamine – associated with inflammatory response
Heparin – helps prevent blood clotting
Connective Tissue

Fiber Types

Collagenous Fibers – tough, dense protein fibers




Made of collagen – long parallel bundles
White fibers
Great tensile strength – resist pulling forces
Dense – many; loose – few and spread out



Elastic Fibers – made of protein elastin




Regular – all fibers in similar direction
Irregular – fibers are arranged in all directions
Weaker than collagenous but can return to original shape
Vocal cords and respiratory passages
Yellow fibers
Reticular Fibers – thin, single strands of collagen fibers

Highly branched for a delicate framework
Connective Tissue

Loose Fibrous C. T.





Adipose C. T.




Delicate thin membranes
Fibroblasts spread out – produce collagenous and elastic fibers
Binds skin to underlying tissue
Highly vascular
Specialized loose C. T. for fat storage
Looks like big marshmallows; filled with fat; nucleus squeezed against side
Beneath skin, between muscles, around kidneys, behind eyeballs
Dense Fibrous C. T.


Mostly fibers; few actual cells
Can be regular  tendons and ligaments



Can be irreguar  dermis of skin
Elastic C. T.




Slow to heal b/c of poor vascularization
Parallel stands or branching networks of elastic fibers
Ligamente flava – attachments between adjacent vertebrae
Larger arteries, airways
Reticular C. T.


Thin, collagenous fibers arranged in 3-D network
Walls of liver, spleen and lymphatic organs
Connective Tissue

Cartilage – rigid connective tissue



Provides support, framework, attachment, protection of
underlying tissues, structural model for developing bones
Composed mainly of collagenous fibers
Chondrocytes – cartilage cells


Perichondrium – covering of cartilage



Ends of bones, soft part of nose, supporting rings of respiratory
system
Bone forms from this during development
Elastic – more flexible than hyaline


Provides blood to cartilage (which is avascular; slow healing)
Hyaline – most common type


Lacunae – spaces that chondrocytes occupy
External ears and larynx
Fibrocartilage – shock absorber with many collagenous fibers

Intervertebral disks
Connective Tissue

Bones (osseous tissue) – solid connective tissue



Solid matrix due to calcium phosphate and calcium carbonate
(mineral salts)
Attachments for muscles, leverage, protection, inorganic salt
storage
Osteons – basic repeating unit of bone





Blood – liquid connective tissue



Cells suspended in liquid plasma
Red blood cells, white blood cells, platelets
Hematopoietic tissue – blood cell forming tissue


Osteonic (Haversion) canal – central tube
Osteocytes – bone cells
Lacunae – space that bone cells occupy
Canaliculi – cytoplasmic extensions that connect osteocytes
Red bone marrow found in spaces of bones
Reticuloendothelial tissue – largely phagocytic tissue

Found in blood, brain, lungs, bone marrow, spleen, liver and
lymph glands
Muscular Tissue


Elongated cells (fibers) specialized for contraction
Skeletal:



Smooth:


Voluntary, striated, movement of body parts
Fibers contain many nuclei and mitochondria; very long
Involuntary, non-striated, movement of walls of internal organs
(digestive, blood vessels, urinary etc.)
Cardiac:


Involuntary, striated, self-exciting, rhythmic beating of heart
Intercalated disks – hold cardiac cells together
Nervous Tissue:


Tissue specialized to transmit electrochemical messages (nervous
impulses) throughout the body
Neurons – functional cell of nervous system




Dendrites – receiving end
Cell body
Axon – impulses travel down axon to terminals
Synapse – space between neurons





Neurotransmitters – chemicals released from axon into synapse
Motor neurons – send messages to effectors (muscles and glands)
Sensory neurons – receive sensory information from external and
internal environment
Interneurons – connect and integrate information from sensory neurons
to motor neurons
Neuroglial cells – accessory cells of nervous system

Support, bind components of nervous system together, phagocytosis,
help supply nutrients