Human Anatomy, First Edition McKinley & O'Loughlin

1
Human Anatomy, First EditionMcKinley O'Loughlin

• Chapter 2
• The Cell Basic Unit of Structure and Function

2
The Cell

• Cells
• structural and functional units of all living
  organisms.
• building blocks of the human body.
• adult human body contains 75 trillion cells.
• Each cell type performs specific functions.
• 200 cell types in humans
• subcategories of most

3
Common Characteristics of Cells

• Perform the general functions necessary to
  sustain life
• Obtain nutrients and other materials from its
  surrounding fluids.
• Fuel molecules, O2, building blocks, minerals,etc
• Dispose of wastes products
• Urea (from nitrogen), CO2, metabolic waste
• Maintain shape and integrity
• Size and shape are related to function
• Cell division
• Mitosis growth and repair
• Meiosis gamete formation

4
Study of Cells

• Cytology study of cells
• Microscopic anatomy
• Individual cells observable by light microscopy
• Subcellular structures observable by electron
  microscopy.
• TEM
• SEM
• Unit of measure micrometer (um)
• RBC 7-8um

5
(No Transcript)
6
Cells

• Parts of a cell
• Cell Membrane (or plasma membrane)
• Cytoplasm
• Cytosol
• Organelles
• Membranous Organelles
• Non-membranous Organelles
• Inclusions
• Nucleus

7
Plasma (Cell) Membrane

• the outer, limiting barrier
• separates the internal contents of the cell
  from external materials.

8
Cytoplasm

• general term for all cellular contents located
  between the plasma membrane and the nucleus.

9
Nucleus

• control center of the cell
• controls protein synthesis
• directs the functional and structural
  characteristics of the cell.

10
Plasma membrane composition

• Lipids
• Phospholipids
• Head hydrophilic
• Tail hydrophobic
• Form lipid bilayer
• Cholesterol
• Glycolipids
• Carbohydrate component
• Part of glycocalyx

11
(No Transcript)
12
Plasma membrane composition

• Protein
• Integral membrane proteins
• Peripheral membrane proteins
• Some serve as enzymes, ion channels or receptors
• Glycoproteins

13
Plasma membrane functions

• Selectively permeable barrier
• Nutrient in
• Waste out
• Communication
• Intercellular connections
• Physical barrier

14
Transport Mechanisms

• Passive Transport
• Active Transport
• Bulk Transport
• Solution solvent (H2O) solute

15
Passive Transport

• Movement of substances along a concentration
  gradient
• Hi to Low
• ATP is not required
• Types
• Simple Diffusion solutes
• Facilitated Diffusion solutes
• Bulk Filtration solution
• Osmosis solvent

16
Facilitated Diffusion

• Requires the participation of specific transport
  proteins that help specific substances or
  molecules move across the plasma membrane.
• Carrier-mediated

17
Bulk Filtration

• Involves the diffusion of both solvents and
  solutes together across the selectively permeable
  membrane.
• Pressure gradients

18
Osmosis

• Involves the diffusion of a solvent (H2O), across
  a selectively permeable membrane.
• Can cause a volume change

19
Active Transport

• Movement of a substance across a plasma membrane
  against a concentration gradient.
• Materials must be moved from an area of low
  concentration to an area of high concentration.
• requires cellular energy in the form of ATP
  (adenosine triphosphate)
• uses transport proteins (carrier-mediated)
• ATP is continually synthesized by mitochondria

20
Ion Pumps

• Active transport processes that move ions across
  the membrane are called ion pumps.
• ion pumps allow a cell to maintain its internal
  concentrations of small molecules or ions

21
Bulk Transport - Exocytosis

• Used by cells that secrete
• Usually movement of large molecules
• Movement out of the cell.

22
(No Transcript)
23
Bulk Transport - Endocytosis

• process by which the cell acquires materials from
  the extracellular fluid (3 Forms)
• Phagocytosis
• Cell forms pseudopodia
• engulfs a particle
• internalize it into a vacuole
• Pinocytosis
• incorporation of droplets of extracellular fluid
  (solution)
• Taken into the cell in small vesicles
• Receptor-mediated endocytosis
• receptors in the cell membrane
• Bind with specific molecules
• Invagination forms around them to create a
  cytoplasmic vesicle

24
(No Transcript)
25
(No Transcript)
26
Cytoplasm cytosol

• Matrix intracellular material
• Different in different cell
• Mostly water

27
Cytoplasm Organelles

• Complex, organized structures
• Have unique, characteristic shapes.
• Each type performs a different function for the
  cell.
• Are essential for normal cellular structure and
  activities.

28
Membranous Organelles

• Include
• Endoplasmic Reticulum
• Rough Endoplasmic Reticulum (RER)
• Ribosomes
• Make protein for export
• Peroxisomes made here
• Smooth Endoplamic Reticulum (SER)
• Lipids and carbohydrates
• Detoxification

29
(No Transcript)
30
(No Transcript)
31
Membranous Organelles

• Peroxisomes
• Vesicles formed from RER
• Use oxygen to detoxify
• Mediated by specific enzymes
• Most abundant in liver

32
(No Transcript)
33
Membranous Organelles

• Golgi Apparatus
• Modifies, stores and sorts material from RER
• Receiving region (cis-face)
• Shipping region (trans-face)
• Produces Lysosomes
• Autophagy removal of old organelles
• Autolysis destruction of the cell

34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
Mitochondria

• Mitochondria are organelles with a double
  membrane.
• Produce large amounts of ATP.
• Are called the powerhouses of the cell.

38
(No Transcript)
39
Non-Membranous Organelles

• Not made of a membrane.
• Usually made of protein
• Include
• Ribosomes free and fixed
• Cytoskeleton
• Microfilaments
• Intermediate fibers
• microtubules
• Centrosome
• centrioles

40
Ribosomes

• Small, dense granules
• Protein
• RNA
• Site of protein synthesis.
• Each ribosome has a small and a large subunit.
• small subunit is about one-half the size of the
  large subunit.

41
(No Transcript)
42
The Cytoskeleton

• Made of filamentous proteins
• Helps give the cell its shape
• Coordinates cellular movements.
• Three categories
• microfilaments
• intermediate filaments
• microtubules

43
(No Transcript)
44
Non-membranous Organelles

• Centrioles and the centrosome
• Centrosome
• Area close to the nucleus
• Organization site for microtubules
• Centrioles (exist as a pair)
• In the centrosome
• Perpendicular to each other
• 9 sets of microtubule triplets
• Important in cell division (spindle)

45
(No Transcript)
46
Microvilli, Cilia and Flagella

• Appendages extending from the surface of some
  cells.
• Microvilli
• short, cytoplasmic extensions
• For absorption
• Cilia
• usually occur in large numbers
• work together to move materials or fluids along
  the surface of a cell.
• Flagella
• longer than cilia, and usually occur as single
  appendages.
• Move the cell

47
(No Transcript)
48
The Nucleus

• Control center of cellular activities.
• Usually, it is the largest structure within the
  cell
• Appears as a single spherical or oval structure.

49
(No Transcript)
50
The Nucleus

• Enclosed by a double membrane called the nuclear
  envelope.
• The nuclear envelope
• controls the entry and exit of materials between
  the nucleus and the cytoplasm.

51
Nucleolus

• The cell nucleus may contain one or more
  nucleoli.
• Nucleoli
• are responsible for making the small and the
  large subunits of ribosomes.

52
Chromatin and DNA

• DNA is the genetic material housed within the
  nucleus.
• DNA is a polymer of nucleotides (sugar,
  phosphate, nitrogen base)
• Is a double helix.
• Chromatin
• Strands of DNA and histone proteins
• Euchromatin uncoiled active
• Heterochromatin coiled. inactive

53
(No Transcript)
54
Insert Figure 2.18
55
Chromosome

• The chromosome is the most organized level of
  genetic material.
• Each chromosome contains a single, long molecule
  of DNA and associated proteins.
• Chromosomes become visible only when the cell is
  dividing.

56
The Cell Cycle

• The life cycle of the cell is called the cell
  cycle.
• New cells must be made continuously in order for
  an organism to grow and replace its damaged
  cells.

57
(No Transcript)
58
Mitosis and Meiosis

• There are two types of cell division.
• Mitosis is the cell division process that takes
  place in somatic cells.
• Meiosis is the cell division process that takes
  place in gonads to produce gametes.

59
Mitosis

• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

60
The Stages of Mitosis

• Prophase the first and longest stage of mitosis
• Early prophase chromatin threads condense into
  chromosomes
• Chromosomes are made up of two threads called
  chromatids
• Chromatids are held together by the centromere
• Centriole pairs separate from one another
• The mitotic spindle forms

61
The Stages of Mitosis

• Prophase (continued)
• Late prophase centrioles continue moving away
  from each other
• Nuclear membrane fragments

62
Early Prophase and Late Prophase
Figure 2.21
63
The Stages of Mitosis

• Metaphase the second stage of mitosis
• Chromosomes cluster at the middle of the cell
• Centromeres are aligned along the equator
• Anaphase the third and shortest stage of
  mitosis
• Centromeres of chromosomes split

64
Metaphase and Anaphase
Figure 2.21
65
The Stages of Mitosis

• Telophase begins as chromosomal movement stops
• Chromosomes at opposite poles of the cell uncoil
• Resume their thread-like extended-chromatin form
• A new nuclear membrane forms
• Cytokinesis completes the division of the cell
  into two daughter cells

66
Telephase and Cytokinesis
Figure 2.21
67
Tumor

• Normal tissue development exhibits a balance
  between cell division and cell death.
• If this balance is upset and cells multiply
  faster than they die, abnormal growth results in
  a new cell mass that is called a neoplasm, or
  tumor.

68
Cancer

• Benign neoplasms usually grow slowly and are
  confined within a connective tissue capsule.
• Cells within these tumors dedifferentiatethat
  is, they revert to a less specialized state, and
  cause an increase in their own vascular supply to
  support their growth.
• These tumors are usually not lethal, but they
  have the potential to become life-threatening if
  they compress brain tissue, nerves, blood
  vessels, or airways.

69
Cancer

• Cancer is the general term used to describe a
  group of diseases characterized by various types
  of malignant neoplasms.
• unencapsulated
• contain cells that dedifferentiate
• increase their vascular supply
• grow rapidly
• spread easily to other organs by way of the blood
  or lymph (metastasis)

70
Cancer

• Cancer cells lose control of their cell cycle.
• they divide too frequently and grow out of
  control
• cancer cells lose contact inhibition
• they overgrow one another and lack the ability to
  stop growing and dividing when they crowd other
  cells

71
Cancer Cells

• Exhibit dedifferentiation and revert to an
  earlier, less specialized developmental state.
• Produce chemicals that cause local blood vessel
  formation resulting in increased blood vessels in
  the developing tumor (angiogenesis).
• Have the ability to squeeze into any space
  (invasiveness) permitting them to leave their
  place of origin and travel elsewhere in the body.
  
• Acquire the ability to metastasizethat is,
  spread to other organs in the body.