Cellular Form and Function

Cytology was first developed by

Robert Hooke

Theodor Schwann Discovered

All animals are made of cells

Cells only arise from

Other cell

All organisms are composed of

Cells and cell products

The cell is the — structural and functional unit of life

simplest

An organism’s structure and functions are ultimately due to

Cellular Activity

The cells of all species exhibit

Biochemical Unity

Cells can be classified according to

Their shapes and sizes

Squamous cells

Thin, flat, my bulge where nucleus lies

Cuboidal cells

Squarish, roughly as tall as they’re wide

Columnar cells

Taller then they are wide

Polygonal cells

Angular shaped with 4 or more sides

Stellate cells

Starlike Shape

Spheroid and ovoid cells

Round and oval shaped

Discoid cells

Disk Shaped

Fusiform cells

Thick in the middle tapered at the ends

Fibrous cells

Have a threadlike shape

Cell size is limited partly due to

Surface area to volume relationship

Volume increases much faster than surface area as

Cells Enlarge

Waste excretion and nutrient uptake require

Surface Exchange

As cell size increases

The ability of a cell to support its activities decreases

All cells have structural

Similarities

The invention of the transmission electron microscope in the mid-1900s allowed

Viweing of a cells ultrastructure

TEM microscopes allowed for

Increased magnification and resolution.sharper images

The scanning electron microscope produces

3d surface level images

The resolution of the TEM

5 mm

Light microscope’s resolution

200 mm

Eye-resoloution

70-100

Cells Componants

Cellular membrane, cytoskeleton, organelles

Cytoskeleton and organelles are embedded in

Cytosol/intra cellular fluid

Fluid outside cell

Extracellular fluid

Physiological Processes that Occur on the Cell’s Surface

Cell signaling

Boundaries of cell are defined by

Plasma Membrane

Intracellular Face Faces

Cytoplasm

Extracellular Face Faces

Outside of cell

The plasma membrane consists of an oily film of

Lipids with diverse embedded proteins

The bilayer contains — percent of the lipids

75

Phosphatte Heads Face

Watery region on each side of membrane

Phosphate Tails Face

Center of Bilayer

Cholesterol molecules constitute about —% of the membrane liquids

20

Glycolipids make up —% of membrane Lipids

5

Proteins make up around —% of membrane weight

50

Most proteins are conjugated with

glycoproteins, oligosaccharides

eripheral proteins adhere to

One face of the membrane

Peripheral proteins are typically associated with

Transmembrane proteins

Membrane Proteins serve at least 7 functions

Receptors to which signaling molecules can
attach, Ion Channels, Enzymes acting at cellular surface, Key role in second messaging system, Carriers bind to target molecules and take them across the membrane, Some glycoproteins are cell-identity markers, Some proteins are cell-adhesion molecules

Cell-adhesion molecules

Hold cells to one another

Iion channels,

Allow water and dissolved ions to pass through membrane

Some channels are — while others have —

Always open, gates which open and close depending on stimulus

Ligand-regulated gates respond to

Chemical messengers

voltage regulated gates respond

changes in electrical potential

Mechanically Regulated Gates Respond to

physical changes such as stretch and pressure

Pumps are carriers that use

ATP energy

Identity Markers allow

Recognition of Cells as Self

Second messengers are of importance to

Hormone and Neurotransmitter action

A first messenger cannot

Pass through cell membrane and bind to a surface receptor

Receptor is linked to —— inside membrane

G protein

Upon activation by binding of the first messenger to the receptor

G protein relays signal to adenylate cyclase

Adenylate cyclase converts ATP to

Cyclic ATP

Cyclic AMP activates kinases that add

Phosphates to Enzymes

All animal cells have a

Glycocalyx external to the plasma membrane

Glycocalyx Consists of

Moieties of glycolipids and glycoproteins

Human Blood Types are Determined By

Glycolipids

Cells may have surface extensions called

microvilli, cilia, flagella, and pseudopods

microvilli, cilia, flagella, and pseudopods aid in

Absorption, movement, sensory process

Microvilli are extensions of

Plasma membrane that serve to increase a cell’s
surface area

Brush Border

Dense fringe of Microvilli on some cells

Some microvilli have a bundle of

Actin Filaments

Actin Filaments

Extend from microvilli to cell attaching terminal web and contracting microvilli towards cell

Cilia are

Hair like processes;

Nearly Every Human Cell Has a

a single, nonmotile primary cilium

Many cilia are

Sensory

Cilia Serve as antenna monitoring condtions in

Inner ear, retina, and kidney tubes

Motile cilia occur in

respiratory tract, the uterine tubes, spaces in the
brain, and ducts of the testes

Motile cilia in a single tissue exhibit

Coordinated action

Motile Cilia exhibit coordinated action via

power stroke in one direction and a passive recovery stroke that restores it to the upright position

Cilia beat within

A saline layer cells surface

The structural basis for movement is a core called

Axoneme

Axoneme is composed of

microtubules arranged in a 9 + 2 structure

Peripheral Microtubules

Continue into the cell as part of a basal body

Basal Body

Anchors the cilium

Dynein is a motor protein responsible

Cilia Movement

Dynein Uses — to Move

ATP

Flagella are

Whiplike structures longer than cilia but with an identical axoneme

In humans flagella only occur as

Tails of sperm cells

Pseudopods

Cytoplasm-filled extensions of the cell that change in shape
continually

Plasma Membrane is — permeable

Selectively

Materials pass through the plasma membrane via

Passive or active mechanisms

Filtration

A process in which fluid is forced through a selectively permeable membrane

The most important physiological example of filtration is in the

Blood Capillaries

Simple Diffusion

The net movement of particles from a place of high concentration to a place of lower concentration

Substances move — their concentration gradient

Down

Simple Diffusion

How oxygen and CO2 diffuse

When a membrane is present that is permeable to a substance, molecules will move

From one side of the membrane to the other

Diffusion rates are based on five factors

Increase in temperature

Particles with greater molecular weight diffuse more slowly

A steep gradient, increases diffusion rate

An increased membrane surface area increases the rate of diffusion.

greater permeability to a substance means that the substance diffuses at a higher rate

Steep Gradient

Gradient with a large difference from one side of a
membrane to the other

Cells can adjust their permeability to different substances by

Adding or taking away membrane channels

Osmosis

The net flow of water from one side of a selectively permeable membrane to another

In osmosis water flows from the — watery side to the — watery side

More, Less

Significant amounts of water enter many cells through channel proteins called

Aquaporins