anatomy & physiology chapter 3. cells zeukaryotic ytrue nucleus (human cells) zprokaryotic...

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