This document provides an overview of cell and tissue structure and function. It begins by outlining the objectives and defining cells and tissues. It then describes the anatomy and organelles of the cell, including the nucleus, plasma membrane, cytoplasm, and cytoplasmic organelles. It discusses cellular transport mechanisms and cell division processes like mitosis and meiosis. Mitosis and the four stages (prophase, metaphase, anaphase, telophase) are summarized. Meiosis is also briefly outlined, noting the production of haploid gametes and the two rounds of cell division. The document thus covers the key components and processes within and between cells.

1. UNIT-3:
CELL AND TISSUE.
RN. SOHAIB ALI SHAH.
Faculty
.
Zia Nursing College Mardan.
Lecture: 3.
Year-I, Semester-I.
BS Nursing.

2. Objectives
At the end of this unit, learners will be able to:
– Describe the structure and function of cell
– Discuss the process of cell division: Mitosis and
Meiosis
– Briefly discuss the importance of Mitosis and Meiosis
– Classify the tissue of the body on the basis of
structure, location and function into the following four
major types:
• Epithelial tissue
• Connective tissue
• Muscle tissue
• Nervous tissue

3. Cells and Tissues
• Cell is the structural and functional unit of all
living things
• Carry out all chemical activities needed to
sustain life
• Tissues are groups of cells that are similar in
structure and function

4. Anatomy of the Cell
• All cells share general structures
• Cells are organized into four main regions
– Nucleus
– Cytoplasm
– Nuclear membrane
– Plasma membrane

5. The Nucleus
• Control center of the cell
– Contains genetic material
(DNA)
• Three regions
– Nuclear membrane
– Nucleolus
– Chromatin

6. Nuclear Membrane: Barrier of nucleus
• Consists of a double phospholipid membrane
• Contain nuclear pores that allow for exchange of
material with the rest of the cell
Nucleolus: Nucleus contains one or more nucleoli
• Sites of ribosome production
– Ribosomes then migrate to the cytoplasm through
nuclear pores

7. Cont..
Chromatin:
• Composed of DNA and protein
• Scattered throughout the nucleus
• Chromatin condenses to form chromosomes
when the cell divides

8. Plasma Membrane
• Barrier for cell contents
• Double phospholipid layer
– Hydrophilic heads
– Hydrophobic tails
• Also contains protein, cholesterol, and
glycoproteins

9. Plasma Membrane

11. Plasma Membrane Specializations
• Microvilli
– Finger-like projections
that increase surface
area for absorption

12. Cytoplasm
• Material outside the nucleus and inside the plasma
membrane
– Cytosol
• Fluid that suspends other elements
– Organelles
• Metabolic machinery of the cell

13. Cytoplasmic Organelles
Figure 3.4

14. Cytoplasmic Organelles
• Ribosomes:
–Made of protein and RNA
–Sites of protein synthesis
–Found at two locations
• Free in the cytoplasm
• Attached to rough endoplasmic reticulum

15. Cytoplasmic Organelles
Endoplasmic reticulum (ER):
Fluid-filled tubules for carrying substances
 Rough Endoplasmic Reticulum: Studded/ spotted
with ribosomes
 Site of synthesis of protein
 Smooth Endoplasmic Reticulum:
 Functions in cholesterol synthesis and breakdown, fat
metabolism, and detoxification of drugs

16. Cytoplasmic Organelles
Golgi apparatus:
 Modifies and packages proteins
 Produces different types of packages
• Secretory vesicles
• Lysosomes

17. Golgi Apparatus

18. Cytoplasmic Organelles
Lysosomes
– Contain enzymes that digest unusable materials within the cell.
– In WBC it digest foreign material such as microbes.
Peroxisomes
– Peroxisome, membrane-bound organelle
• Detoxify harmful substances
• Produce bile acid in liver cells
• Convert hydrogen peroxide into water and oxygen.

19. Cytoplasmic Organelles
• Mitochondria:
– “Powerhouses” of the cell
– Change shape continuously
– Carry out reactions where oxygen is used to break
down food
– Provides ATP for cellular energy

20. Cytoplasmic Organelles
• Cytoskeleton
– Network of protein fibres or structures that extend
throughout the cytoplasm
– Provides the cell with an internal framework or support
– Three different types
• Microfilaments = made of actin, anchored to inside of cell
membrane & give the cell support and shape.
• Intermediate filaments = mechanical support for
the plasma membrane
• Microtubules = Rigid proteins that give the cell mechanical
support & movement

21. Cytoplasmic Organelles
• Centrioles:
– Rod-shaped bodies made of microtubules
– Plays an important role in cell division

22. Cellular Projections
• Not found in all cells
• Used for movement
– Cilia: moves materials across the cell surface i.e It moves the
mucus upwards in the respiratory tract
– Flagellum: is whip like projection that form tails of
spermatozoa which propel them through female reproductive
tract
– Microvilli: It is found in intestine which increase surface area
for absorption of nutrients in small intestine

23. Cellular Physiology: Membrane Transport
• Membrane Transport – movement of substance
into and out of the cell
• Transport is by two basic methods
– Passive transport
• No energy is required
– Active transport
• The cell must provide metabolic energy

24. Passive Transport Processes
The movement of water and dissolved
substances from the area of its higher pressure
to the area of its lower pressure is called
filtration.
e.g. formation of urine in the renal tubules.

25. Passive Transport Processes
• Diffusion
The movement of molecules of a substance
from the area of its higher concentration to the
area of its lower concentration is called
diffusion.
For example, Exchange of gases in the lungs or
body tissues.

26. Passive Transport Processes
• Osmosis:
The movement of water molecules from its
higher concentration to its lower concentration
through a semi permeable membrane.
e.g. Absorption of water by small intestine.

27. Passive Transport Processes
• Facilitated Diffusion: The movement of
molecules from the area of its greater (higher)
concentration to the area of its lesser (lower)
concentration with the help of channels or
carriers. Eg, Intake of glucose by cells.
• Filtration: The movement of water and dissolved
substances from the area of its higher pressure
to the area of its lower pressure is called
filtration.
e.g. formation of urine in the renal tubules.

28. Active Transport Processes
• Transport substances that are unable to pass by diffusion
– They may be too large
– They may not be able to dissolve in the fat core of
the membrane
– They may have to move against a concentration
gradient

29. Active Transport Processes
• Active Transport: The movement of molecules
from its lower concentration to the higher
concentration with the help of consumption
of cellular energy (in the form of ATP).
e.g. Sodium Potassium Pump (Na-K pump).

30. CELL DIVSION

31. CELL DIVSION
Cell division is the process by which a parent cell
divides into two or more daughter cells.
Types:
Somatic cell division (Mitosis)
Reproductive cell division (Meiosis)

32. Why Cell divide?
Growth
Multicellular organisms need to grow and develop,
to do this requires more cells.
Replace
Somatic cells die or damaged, they must be
replaced.
Reproduction
Make cells for reproduction.

33. Cell Cycle
Divided into three main stages:
– Interphase – cell grows into its mature size,
makes a copy of its DNA, and prepares for
division.
– Mitosis – one copy of the DNA is distributed into
each of its daughter cells
– Cytokinesis – the cytoplasm divides and
organelles are distributed into the two new cells

34. Interphase (3 parts)
Interphase is longest part of cell cycle & is divided
into 3 phases.
• G1 (Growth Phase):
– Interval b/w mitotic phase & S phase
– Cell replicates most of its organelles & cytosolic
components but not DNA.
– Replication of centrosomes begins.
– Cells that remain in G1 phase for longer time & never
divide again are said to be in the G0 phase.
• S (DNA Copying) :
– Interval b/w G1& G2 phase
– Cell makes a copy of its DNA (replication), because
of this the two identical cells formed during cell
division later will have the same genetic materials.

35. Interphase (3 parts)
• G2 (Preparation):
– Interval b/w S & mitotic phase
– Cell prepares to divide
– Replication of centrosomes completed
– Cell produces structures needed for cell division

36. Mitosis
• During mitosis, the cells’ copied genetic
material separates and the cell prepares to split
into two cells
• This allows the cell’s genetic material to pass
into the new cells
– The resulting daughter cells are genetically
identical!!

37. The Four Stages of Mitosis
• Remember PMAT!
• P__rophase
• M__etaphase
• A__naphase
• T__elophase

38. Prophase
• Chromatin condenses into chromosomes.
• Chromosome consists of pair of identical strands called chromatids.
• Centromere holds the chromatid pair together.
• Two centrioles are separated by mitotic spindle
• The centrioles migrate, one to each end of the cell
• Nuclear envelope breaks down.

39. Metaphase
• The sister chromatids are pulled to the center of
the cell
• They line up in the middle of the cell

40. Anaphase
• Centromeres separate
• Spindle fibers begin to shorten
• The sister chromatids are pulled to the
opposite ends of the cell

41. Telophase
• The mitotic spindle disappears.
• The sister chromatids arrive at the opposite poles
of the cell and begin to unravel.
• The nuclear envelope reform.

42. Cytokinesis
• Cytokinesis is the division of the cytoplasm.
• Results in two separate daughter cells with
identical nuclei.

44. Meiosis
• The process of cell division that
produces haploid gametes (half
the number of chromosomes:
humans: 23)
• Cell undergoes 2 rounds of cell
division:
• Meiosis 1
• Meiosis 2

45. Meiosis-I (Prophase-I)
• Chromosomes shorten & thicken.
• Nuclear envelope & nucleoli disappear.
• Mitotic spindle forms.
• Synapsis: The pairing of two homologous
chromosomes.
• Crossing over is the exchange of chromosome
segments between non-sister chromatids during the
production of gametes

46. Prophase-I

47. Metaphase-I
• The homologous chromosomes line up in the
center of the cell and are still held together

48. Anaphase-I
• Spindle fibers shorten
• The homologous chromosomes are separated (the
sister chromatids are still paired)
• Independent assortment –
random chromosomes move to
each pole; some may be
maternal and some may be
paternal

49. Telophase-I
• The nuclear membrane reforms around each
daughter nucleus
• Each new cell now contains two sister
chromatids that are NOT identical due to
crossing over

50. At the end of Meiosis-I
• You have made 2 cells
• Each cell contains a haploid number of chromosomes
– 1 copy of each chromosome
(for humans, each haploid cell has 23
chromosomes)
• No DNA replication occurs between Meiosis I and
Meiosis II
• Meiosis II resembles normal, mitotic division

51. Meiosis-II (Prophase II)
Nuclear membrane breaks down again

52. Metaphase II
The chromosomes line up in the middle of the cell.

53. Anaphase II
• The spindle fibers shorten and the sister
chromatids move to opposite poles.

54. Telophase II
• Nuclear envelope re-forms around the four sets
of daughter chromosomes.

55. At the end of Meiosis II…
• At the end of Meiosis II, there are 4 haploid
cells. (only 1 copy of each chromosome)
– (for humans, each haploid cell has 23
chromosomes)
• No two of these haploid cells are alike due to
crossing over.
– This is why you and your siblings are genetically
unique!

56. Importance of mitosis
• Genetic stability: somatic cell produce the same
offspring (daughter cells).
• Growth: increasing the number of cells.
• Replacement and regeneration of new cells: replace the
damaged cell and regenerate the new cells.
• Asexual reproduction: mitosis is used in the production
of genetically similar offspring. E.g. budding

57. Importance of meiosis
• Production of gametes: Fertilization is impossible
without meiosis.
• Maintenance of chromosome number:
• Production of variation: meiosis cause genetic
variation in offspring. new individual do not resemble
to there parents closely.
• Genetic information: carry the parental
characteristics to offspring's.

58. Body Tissues
• Cells are specialized for particular functions
• Tissues: Groups of cells with similar structure
and function
– Four primary types
• Epithelium
• Connective tissue
• Nervous tissue
• Muscle

59. Epithelial Tissues
Tissue composed of layers of closely spaced cells that cover
organ surfaces, form glands, and serve for protection,
secretion, and absorption.
Functions:
1) Protection— skin
2) Absorption – stomach and intestinal lining
3) Filtration – kidneys
4) Secretion – glands

60. Classification of Epithelium
Classification (types):
1) By shape:
a) squamous –flat and scale-like
b) cuboidal –as tall as they are wide
c) columnar –tall, column-shaped
2) By arrangement:
a) simple epithelium - single layer of cells (usually for
absorption and filtration)
b) stratified epithelium - stacked up cell layers
(protection of underlying structures--- mouth, skin, and
Permits expansion as in bladder).
Figure 3.17a

61. Simple Epithelium
• Simple Squamous
• Single layer of flat cells
• Usually forms thin
membranes (Diffusion take
place)
– Hearts as endocardium
– Alveoli of the lungs
– Blood & Lymph vessels as
endothelium Figure 3.18a

62. Simple Cuboidal
Single layer of cube-like cells
– Common in glands and their
ducts
– Forms walls
of kidney tubules
– Covers the ovaries
Function:
Secretion, Absorption
Figure 3.18b

63. Non ciliated simple columnar
epithelium
Single layer of tall cells
– Often includes goblet
cells, which produce
mucus
– Lines digestive tract
Function
Absorption of digestive
product and secretion of
mucus Figure 3.18c

64. Ciliated columnar epithelium
• Cilia are hair like processes on
the free surface of columnar
epithelial cell lining certain
passageways: e.g. uterine tubes
and airways,

65. Stratified Epithelium
• Stratified squamous epithelium
– Composed of number of layers of cell
– Non keratinized stratified epithelium: found in wet
surfaces i.e lining of mouth, esophagus, pharynx etc.
– keratinized stratified epithelium: found on dry surfaces,
e.g. skin, hair and nails
• Transitional epithelium:
– Composed of several layers of pear-shaped cell
– Found in lining of urinary bladder and allow for
stretching as bladder wall fills

66. Definition: Connective tissue
Connective tissue:
A material made up of fibers forming a
framework and support structure for body tissues
and organs.
Connective tissue surrounds many organs.
Cartilage and bone are specialized forms of
connective tissue.

67. Connective Tissue Functions
1) Wraps around and protects organs.
2) Stores nutrients.
3) Support for visceral organs.
4) Blood transports nutrients, hormones, gases,
waste.
4) Connects, binds and supports structures i.e
Tendons connects muscle to bone &
Ligaments connects bone to bone

68. Components of Connective Tissue
Cells: Cells of fibrous connective tissue include the
following types:
• Fibroblasts:
Responsible for making the extracellular matrix and
collagen which form the structural framework of tissue.
Plays an important role in tissue repair.
• Leukocytes:
• Macrophages:
• Plasma cells: Originates in bone marrow, secretes
antibodies in response to antigens
• Mast cells: Found in blood vessels, secrete histamine
and heparin
• Adipocytes: Fat cells that store triglyceride.

69. Components of Connective Tissue
 Fibers: Three types of protein fibers.
• I- Collagenous Fibers:
Made of collagen, tough and flexible, resist stretching. White
in appearance
Tendons and ligaments are made up of collagen.
• ii- Reticular Fibers:
Thin collagen fibers coated with glycoprotein.
They form a sponge like framework of organs like spleen and
lymph nodes.
• iii- Elastic Fibers:
Thin fibers made up of elastin protein.
Stretch and recoil/spring back.
They enable arteries and lungs to stretch and recoil.
 Extracellular Matrix
Network of extracellular macromolecules, such as collagen,
enzymes, and glycoproteins, that provide structural and
biochemical support to surrounding cells.

70. Types of Connective Tissue
1. Loose connective tissue
2. Dense connective tissue
3. Special connective tissues

71. 1) Loose Connective Tissue:
a) Areolar Connective Tissue – cushion around
organs, loose arrangement of cells and fibers.
It gives strength, elasticity & support
b) Adipose Tissue – Kidney and eye ball is
supported by adipose tissue, act as insulator under
skin.
c) Reticular Connective Tissue – supporting
framework of organs, delicate network of fibers and
cells.
It filter & removes worn out cells in spleen &
microbes in lymph nodes.

72. 2) Dense Connective Tissue:
a) Dense Regular Connective Tissue – tendons
and ligaments, regularly arranged bundles
packed with fibers for strength in the same
direction.
b) Dense Irregular Connective Tissue –
Dermis, organ capsules, irregularly
arranged bundles packed with fibers for
strength in all directions.
c) Elastic Connective Tissue – Allows
stretching of various organs i.e in lung &
arteries.

73. 3. SPECIAL CONNECTIVE TISSUES
i) Cartilage
Functions:
i) provides strength with flexibility while resisting wear,
i.e. external ear, larynx, etc.
ii) cushions and shock absorbs where bones meet, i.e.
intervertebral discs, joint capsules
ii) Bone
Functions:
i) provides framework and strength for body
ii) allows movement
iii) stores calcium
iv) contains blood-forming cells

74. iii) Blood
Functions:
Blood is called a fluid connective tissue
Connects all the organ systems of the body by
transporting oxygen, nutrients, hormones, etc.,
and removing wastes from these organs.
immune response.

75. III. NERVOUS TISSUE
Functions:
i) Conducts impulses to and from body organs
via neurons.
ii) Coordinates with endocrine system
The 3 Elements of Nervous Tissue
1- Brain
2- Spinal cord
3- Nerves and supporting nervous tissues.

76. Muscle Tissue
Functions :
I ) Responsible for body movement
ii) Moves blood, food, waste through body’s organs
iii) Responsible for mechanical digestion
The 3 Types of Muscle Tissue
i) Smooth Muscle – organ walls and blood vessel walls,
involuntary, spindle-shaped cells for pushing things
through organs.
ii) Skeletal Muscle – large body muscles, voluntary,
contain multiple nuclei ,striated muscle packed in bundles
and attached to bones for movement
iii) Cardiac Muscle – heart wall, involuntary, striated
muscle having centrally located nucleus.

78. References
• Guyton, A. C. (2001). Medical Physiology (10th
ed) Washington: Kirokawa.
• Ross, & Wilson. (2000) Anatomy & Physiology
in Health & Illness. Edinburgh: Churchill, 10th
Edition