anatomy & physiology chapter 3. cells zeukaryotic ytrue nucleus (human cells) zprokaryotic...
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Anatomy & Physiology
Chapter 3
Cells
Eukaryotic true nucleus (human cells)
Prokaryotic before nucleus (bacteria)
Cell composition
Nucleus CytoplasmOrganelles are specialized structures
found within the cytoplasmSeparated by nuclear and cell
membrane
Cell membrane
Thin, flexible, and somewhat elasticSelectively Permeable
allows some in and not othersSignal Transduction
Cell receives and responds to incoming messages
Cell Membrane Structure
Double layer of phospholipid molecules. The water soluble head (phosphate group) forms the surface. The insoluble tail (fatty acid chain) is inside the layers. Lipid molecules are relatively free to move within.
Fig. 3.3 page 51
Cell Membrane
Oil soluble molecules pass easily through the membrane.
Water soluble molecules do not pass easily if at all.
Cell MembraneFibrous proteins
extends outward and inward functions as a receptor specialized to combine with specific kind of molecules.
Globular proteins Called integral proteins imbedded in
the interior. They span the membrane channel allowing small molecules inside (may be a pore)
Cell Membrane
Peripheral protein functions on the surface as an enzyme.
Cytoplasm
Cytoplasm contains network of membranes and organelles suspended in clear liquid called cytosol.
Cytoskeleton consisting of protein rods and tubules make up a supporting network.
Functions as a site for metabolic reaction.
Endoplasmic Reticulum
ER membrane is membrane-bound flattened sacs, elongated canals, and fluid filled vesicles.
ER interconnects and communicates with cell membrane, nuclear envelope, and certain cytoplasmic organelles.
Endoplasmic Reticulum
Plays a role in protein and lipid synthesis.
Transports molecules throughout the cell.
Attachment site for ribosomes
Ribosomes
Found on the ER and floating in the cytoplasm
composed of protein and RNAFunctions in the synthesis of protein
Golgi Apparatus
Composed of a stack of 6 flattened, membranous sacs called cisternae.
Refines, packages, and delivers proteins synthesized by the ribosomes.
Packaging process of theGolgi Apparatus
Protein leaves the ER in a tiny vesicles and arrives at the Golgi.
The sac fuses to the innermost end of the Golgi. Since these proteins were combined with sugar molecules they are referred to as glycoproteins
The glycoprotein is chemically altered as it passes through the layers of the Golgi stacks
Packaging process of the Golgi Apparatus
When the protein reaches the outer layer, it has been packaged in bits of Golgi membrane.
The package travels to the cell membrane and releases it contents to the outside of the cell as a secretion.
Mitochondria
Elongated fluid filled sacMoves slowly through the cytoplasmReproduce by dividingContains small amounts of DNA that is
encoded for making a few proteins and specialized RNA.
Has an outer and inner membrane layer.
Mitochondria
The inner layer is folded into shelflike partitions called cristae.
The enzymes and the mitochondria control many of the chemical reactions that release energy from glucose and other organic molecules.
The energy is transformed into ATPMitochondria is often called the
powerhouse of the cell.
Mitochondria
A typical cell will have about 1700 mitochondria.
High energy demand cells may have thousands more
Lysosomes
The cells garbage disposal.Commonly appear as tiny
membranous sacs that contain powerful enzymes that break down protein, carbohydrates, and nucleic acids as well as foreign particles
They also destroy worn cellular parts.
Peroxisomes
Peroxisomes are similar to a lysosome but are found mostly in the liver and kidneys.
They contain enzymes called peroxidases that catalyzes reactions that produce hydrogen peroxide as a byproduct and catalase which decomposes hydrogen peroxide which is a toxin to cells.
Peroxisomes
The outer membrane of a peroxisome contains some 40 enzymes that perform various duties: synthesis of bile acids breakdown of lipids degradation of rare biochemicals detoxification of alcohol
Centrosomes
Centrosomes consist of two hollow cylinders called centrioles built of tubelike cylinders called microtubules.
They function in cell reproduction.
Cilia & Flagella
Cilia occur in large numbers on the surface of some epithelial cells.
Cilia are tiny hairlike structures attached just beneath the cell membrane to a basal body.
Cilia beat to move fluids along it’s surface.
Flagella function in motion of the cell.
Vesicles
Also called vacuolesThey form as an inward fold in the
cell membrane.They may contain some liquids or
solid material.
Microfilaments & Microtubules
Thin threadlike structures found within the cytoplasm.
Microfilaments
Tiny rods of the protein actin, arranged in a meshworks or bundles.
Aid in cell motility.
Microtubules
Long slender tubes composed of the globular protein tubulin.
Form the cytoskeleton which maintains the shape of the cell.
Aids in movement of flagella and cilia.
Nucleus
Directs the activities of the cell.Enclosed by a double-layered
nuclear envelope.Nuclear envelope consists of an
inner and outer lipid bilayer membrane.
Nuclear pore
Channels consisting of more than 100 different types of proteins.
Pores allow certain dissolved substances to move between the nucleus and the cytoplasm.
Nucleolus
Small, dense body composed largely of RNA and protein.
No surrounding membrane.Site of ribosome production.Cells may have more than one
nucleolus.
Chromatin
Consists of loosely coiled fibers in the nuclear fluid.
Forms chromosomes during cell reproduction.
Composed of DNADNA contains the information for
synthesis of proteins that promote cellular life processes.
Inclusions
Consist of the lifeless chemicals including stored nutrients, lipids, and pigments.
Diffusion
The process by which molecules or ions spontaneously move from regions where they are in higher concentrations toward regions where they are in lower concentrations.
Fig. 3.11 page 58The state of uniform distribution is
called equilibrium.
Diffusion
Oxygen and carbon dioxide are diffused through the air and blood in the lungs, and between the blood and cells of various tissues. The diffusion is caused by a higher concentration seeking to move in an area of lower concentration.
Diffusion
Factors that influence diffusion rate: Distance over which the diffusion will occur. Concentrations weight temperature
Diffusion usually occurs faster when the concentration is higher, weight is lower, & temperature is higher.
Facilitated Diffusion
Most sugars and amino acids are insoluble in lipids or too large to pass through membrane pores. These molecules may enter through the process of facilitated diffusion.
Fig. 3.13 page 60
Osmosis
A type of diffusion that occurs whenever water molecules diffuse from a region of higher concentration to a regions of lower concentration across a selectively permeable membrane.
Fig. 3.14 page 60
Osmosis
When a solution has the same osmotic pressure as the body fluids it is called isotonic.
Osmosis
A solution that has a higher osmotic pressure than the body fluids are called hypertonic. There will be a net movement of water by osmosis out of the cells.
Hypotonic solutions will have a lower osmotic pressure than body fluids. There will be a net movement into the cell.
Active Transport
When a molecule moves from an area of low concentration to an area of high concentration it is called active transport.
Active transport requires energy that is derived from cellular metabolism. It may use as much as 40% of a cell’s energy supply.
Active Transport
Active transport is similar to facilitated diffusion.
Fig 3.16 page 62
Endocytosis & Exocytosis
Molecules or particles too large to pass through the membrane by diffusion are actively transported into (endocytosis) and out of (exocytosis) the cell.
Endocytosis
The three forms of endocytosis are : pinocytosis phagocytosis receptor-mediated endocytosis
Pinocytosis
Cells take in tiny droplets of liquid from their surroundings.
Phagocytosis
Similar to pinocytosis, but the cell takes in solids rather than liquids.
Fig. 3.18 page 63
Exocytosis
Substances made within the cell are packaged into a vesicle, which then fuses with the cell membrane. It is released outside the cell.
Cell Cycle
Each cell goes through a cycle in it’s lifespan
Basically a newly formed cell grows for a time and then divides into two new cells
There is more to it than that, cells do not divide continuously.
The cell cycle is very highly regulated, and includes checkpoints.
Most cells can only divide 40-60 times How would a cell know when to stop?
Telomeres tell it when
Cell cycle
Steps of the cell cycle:1. A cell is newly divided from a
parent cell2. Cell enters G1 phase in which it
begins to grow3. During this period, the cell obtains
many nutrients and materials needed to manufacture new living matter
Cell Cycle
4. Cell enters into the S phase of the cycle
5. DNA is replicated within the above phase
6. The cell enters into the G2 phase of the cycle
7. The cell begins using materials and replicating organelles in this phase
Steps 1-7 called the interphase.
Cell Cycle
8. The cell enters the prophase.9. Chromosomes begin to appear in
the nucleus during the above phase10. The cell enters the metaphase.11. The chromosomes line up in the
middle of the cell12. The cell enters the Anaphase
Cell Cycle
13. Centromeres are pulled apart, moving the chromosomes to their respective sides
14. Cytoplasmic division begins 15. Cell enters Telophase 16. A nuclear envelope begins to form around
each chromosome set Steps 8-16 called mitosis (division of nucleus) 17. Cytokinesis occurs (cytoplasmic division) Pg. 64 Fig. 3.19 Pg. 66 Fig. 3.20
Cell differentiation
All body cells contain the same DNA But they do not all look or do the same
thingDifferentiation – the process by which
cells develop differently in structure How could this be done?
Cells do so by expressing some DNA while repressing others
What DNA would always have to be expressed?
Cell Death
A cell that does not divide or specialize will most likely die
Apoptosis – a form of cell death What would this be used for?
Finger webbing, brain cells, immune system cells
Other types of cell death, such as lysis, but apoptosis is the main one
Tissues
Types of tissuesHow does the organization of the body
go?Atom molecule organelle cell
tissue organ system organismTissues – group of cells that have
specialized structural and functional rolesAll tissues in the same type will have
similar functionsThere are four types of tissues.Epithelial, Connective, Muscle, Nervous
Epithelial tissues
What is epithelial tissue?Tissues that are widespread throughout the
bodyThey are found: covering organs, forms the
inner lining of body cavities, and lines hollow organs Therefore, it always has one surface open
Examples of where it would be?These are very tightly packed cells, so there
is little material in between them
Epithelial tissuesEpithelial tissues lack blood vessels
How do they get nutrients?Nutrients are able to diffuse from the
underlying connective tissuesEpithelial cells divide the fastest of any
tissue Why would that be?
Functions of epithelial tissues: Main: be a protective barrier Secondary: secretion, absorption, and
sensory reception
Epithelial tissuesWhen studying the types of epithelial tissues,
remember: Simple = Single layer, stratified = multiple layers Squamous = flattened, cuboidal = cube, columnar =
column
Simple Squamous Epithelium Single layer, flattened cells Fit tightly together (ex. Floor tiles) Easily damaged Very effective at sites of diffusion
Where would we find these?Lines air sacs in lungs, lines inside of blood
vessels
Pictures
Simple squamous
Epithelial tissues
Simple Cuboidal Epithelium Small cube shaped, single layer
Covers some glands (function = secretion)Simple Columnar EpitheliumColumn shape, single layer
Create a very thick layer function = protection Usually secretes mucus
Pictures
Simple cuboidal simple columnar
Epithelial tissues
Pseudostratified Columnar Epithelium
Single layer but looks like multiple Have cilia Line respiratory system – Why?
Stratified Squamous EpitheliumMany layers, flattened cells, cells
underneath replicate quickly Forms outer layer of skin
Pictures
Pseudostratified Stratified squamous
Epithelial tissues
Stratified Cuboidal EpitheliumTwo or three layers, cube shape
Also covers some glands Provide more protection than single layer
Stratified Columnar EpitheliumSeveral layers, column shaped
Found in reproductive tractThere are other types but we won’t cover
those
Pictures
Stratified cubiodal stratified columnar
Epithelial Tissues
Review:Quick study table : pg 102 table 5.2Pictures of each type on pages 98 – 101When studying the types of epithelial
tissues, remember: Simple = Single layer, stratified = multiple layers Squamous = flattened, cuboidal = cube, columnar
= column
There are 7 types that we talked about
Assignment1. How are Simple Squamous Epithelium
like floor tiles?2. Why would Simple Columnar Epithelium
secrete mucus?3. How does Pseudostratified Columnar
Epithelium having cilia help its function?4. Rename the following types of
epithelium: Single layer cube cells Multilayered flat cells Multilayered cells that are longer than they
are wide
Connective Tissues
What is connective tissue?The most general type of tissuesThis is a group of tissues that is very
diverseThey also serve several functions:Provide support, provide protection, serve
as a framework, fill spaces, store fat, produce blood cells, protect against infections, and help repair tissue damage
Connective TissuesIn general connective tissues:Have a rich blood supply, this gives
them plenty of nutrientsAre farther apart than epithelial cells
Why would this be?Not as necessary for protectionCan divide – but not all of them are
able to.Contain three different types of fibersHave six different types of tissues
Connective Tissues
The three types of connective tissue fibers are:
1. Collagenous Fibers – thick threads of the protein collagen
Flexible but not elasticHave great tensile strength – useful in
areas that hold structures together where would this be?
Ligaments and tendons
Connective Tissue Fibers
2. Elastic Fibers – Thin branching fibers of the protein elastin
Not as strong as collagen but able to stretch.Common in body parts that need the ability
to quickly stretch frequently (ex: vocal cords)
***The under layers of skin contain both of the above types***
3. Reticular Fibers – thin, branching collagenous fibers
Connective Tissue Types
1. Loose Connective TissueForms delicate, thin membranes throughout
the body.The cells of this tissue are a good distance
apart The area between cells contains many
collagenous and elastic fibersWhere would this be found?It lies underneath most layers of epithelium
and attaches the skin to underline tissue
Connective Tissue Types
2. Adipose TissueAnother name for this is … fat tissueFound in many areas around the body
including:Under the skin, around the kidneys, around
heart, behind eyeballs, in abdominal regionWhat would this be used for?Used to cushion some joints and organs, as
well as insulate the body, and store excess fat
Connective Tissue Types3. Dense connective tissueConsists of many tightly packed
collagenous fibers, and a few elastic fibers
Would this tissue be strong or weak?StrongUsed to connect structures togetherWhere would this be found?Ligaments and tendons are the most
common areas
Connective Tissue Types4. CartilageRigid connective tissue, used mainly for
supportFound all over the body (joints, ears, nose, etc.)Does not have a direct blood supplyHow does this affect how cartilage is repaired?3 types of cartilage
Hyaline cartilage – found in nose, trachea, some joints
Elastic cartilage – framework for external ear, larynx Fibrocartilage – toughest, found in spine, and knees
Connective Tissue5. BoneMost rigid connective tissueThis is due to the mineral deposits
between cellsVery well supplied with blood, therefore it
heals much quicker than cartilageWhere is this located?All throughout the body in bonesWhat are the functions?Support, protection, production of blood
cells, storage of minerals
Connective Tissue6. BloodFunctions: transports substances,
exchange of gases, help maintain homeostasis
Found all throughout the body within the blood vessels
Composed of: Red blood cells White blood cells Platelets Plasma
Connective Tissue
ReviewMost general category of tissues, many usesTable 5.4 on page 109Collagen Fibers – used for?Elastic Fibers – used for?Reticular Fibers – used for?Six types of tissues:Loose, Adipose, Dense, Cartilage, Bone,
Blood
Muscle TissueNot as diverse as a groupMuscle tissues are contractileWhat does that mean to you?The cells are elongated and they can
shortenAs each cell shortens, it shortens the
tissue, thus moving the body partThree types of muscle tissuePictures --- Pg. 110 – 111Table 5.5 on pg. 112
Muscle Tissue1. Skeletal Muscle TissueThis is the kind that most people think of.Found in muscles that attach to bonesThese enable use to talk, throw, walk, etc.Controlled by conscious effort (voluntary)Have striationsStriations – alternating light and dark
regions
Muscle Tissue
Muscle Tissue2. Smooth Muscle TissueLacks striations – therefore it looks smoothShorter than skeletal muscleFound in the walls of hollow organsExamples: stomach, intestines, bladder,
etc.Cannot be stimulated by conscious effort
(involuntary) Example: movement of food through the
digestive system
Muscle Tissue
Muscle Tissue3. Cardiac Muscle TissueStriated – but differently than skeletal
muscleFound only in the heart (cardiac = heart)This tissue forms most of the heartVoluntary or involuntary?Cells are connected by intercolated disks
This allows for all cells to fire at once Why would this be important?
Muscle Tissue
Nervous Tissue
Where are they found?Nerves, brain, spinal cordFunctions:Transport messages throughout the
body, to and from the brainStimulate muscles for movementCoordinate other bodily functions