This document provides an overview of cell anatomy and physiology. It describes the basic structural levels of the human body from atoms to organ systems. It then focuses on cells, explaining their structure including the plasma membrane and organelles like the nucleus, mitochondria, ER, Golgi apparatus, lysosomes, microtubules and microfilaments. It details the functions of these structures. The document also explains the two types of cell division - mitosis which produces identical daughter cells and meiosis which reduces chromosome number in sex cells. It defines mutation and its potential effects.

1. ANATOMY AND
PHYSIOLOGY I
CELLS

2. LEARNING OBJECTIVES
After studying this section you should
be able to:
Odescribe the levels of structural
complexity of the human body.
Odescribe the structure of the plasma
membrane

3. LEARNING OBJECTIVES CONT.
Oexplain the functions of the
following organelles: nucleus,
mitochondria, ribosomes,
endoplasmic reticulum, Golgi
apparatus, lysosomes,
microtubules and microfilaments

4. LEANING OBJECTIVE CONT.
Ooutline the two types of cell
division
Odefine the term 'mutation'

5. The levels of structural
organization of the body
OThe human body has different
structural levels of organization,
starting with atoms, molecules and
compounds and increasing in size
and complexity to cells, tissues,
organs and the systems that make
up the complete organism.

6. The levels of structural
organization of the body cont.
OAt its simplest level, the body
is composed of atoms.
OThe most common elements
in living organism are carbon,
hydrogen, oxygen, nitrogen
phosphorus and sulfur.

7. The levels of structural
organization of the body cont.
Atoms
Molecule
Compounds
Cell
Tissue
Organ
System

9. The Cell
OCells are the basic units of life.
OAll life depends on the many
chemical activities of cells.
OSome of the basic functions of cell
are: growth, metabolism, irritability
and reproduction.

10. THE ANIMAL CELL: STRUCTURE AND
FUNCTIONS
OA cell consists of a plasma
membrane, inside of which there are
a number of organelles floating in a
watery fluid called cytosol.
OOrganelles are small structures with
highly specialized functions, many of
which are contained within a
membrane.

11. The organelles
The organelles include:
OThe nucleus
OMitochondria
ORibosomes
Oendoplasmic reticulum,

12. The organelles cont.
OGolgi apparatus
OLysosomes
Omicrofilaments
Omicrotubules

13. THE SIMPLE CELL

14. Plasma membrane
OThe plasma membrane consists of two
layers of phospholipids (fatty
substances) with some protein
molecules embedded in them.
OThose that extend all the way through
the membrane may provide channels
that allow the passage of, for example,
electrolytes and non-lipid-soluble
substances.

15. The plasma membrane

16. Functions of the plasma
membrane
OBranched carbohydrate molecules
attached to the outside of some
membrane protein molecules, give the
cell its immunological identity
OIt separates the cytoplasm inside a cell
from extra cellular fluid.

17. Functions of the plasma
membrane cont.
OIt separates cell from one another
OIt provides an abundant surface on
which chemical reaction can occur.
OSome are involved in transport
across the membrane

18. Cytoplasm
OCytoplasm is a matrix or ground
substance in which various cellular
components are found.
O It is thick semi transparent, elastic
fluid containing suspended particles
and a series of minute tubules and
filaments that form cytoskeleton.

19. Cytoplasm
OWater constitutes 75-90% of the
cytoplasm.
OIt also contains solid components,
proteins, carbohydrates, lipids and
inorganic substances.

20. Organelle
OOrganelles are specialized portion of
the cell with a characteristic shape
that assume specific role in growth,
maintenance, repair and control

22. Organelles
Nucleus
OIt is oval in shape and is the largest
structure in the cell.
OIt contains the hereditary factor in the cell.
Hence it controls cell activity & structure.
OMost cell contain single nucleus but some
like matured Red Blood cell do not contain
nucleus
OHowever Muscle cell contain several
nucleuses.

23. Nucleus cont.
OThe nucleus separated from other
cell structure by double membrane
called nuclear membrane.
OPores over the nuclear membrane
allow the nucleus to communicate
with the cytoplasm.

24. Nucleus cont.
OIn the nucleus a jelly like fluid that fill
the nucleus is karylymph
(nucleoplasm), which contain the
genetic material called chromosome.
ONucleus also contain dark, somewhat
spherical, non-membrane bound
mass called nucleolus. It contains
DNA, RNA and protein, which assist
in the construction of ribosome

25. Ribosomes
OThese are tiny granules composed of RNA
and protein.
OThey synthesize proteins from amino
acids, using RNA as the template
OWhen present in free units or in small
clusters in the cytoplasm, the ribosomes
make proteins for use within the cell.
ORibosomes are also found on the outer
surface of rough endoplasmic reticulum.

26. Endoplasmic reticulum (ER)
cont.
OEndoplasmic reticulum is a series of
interconnecting membranous canals in
the cytoplasm.
OThere are two types: smooth and
rough.
OSmooth ER synthesizes lipids and
steroid hormones, and is also
associated with the detoxification of
some drugs.

27. Endoplasmic reticulum (ER)
cont.
ORough ER is studded with ribosomes.
OThese are the site of synthesis of
proteins that are 'exported' (extruded)
from cells, i.e. enzymes and
hormones that pass out of their parent
cell to be used by other cells in the
body.

28. Mitochondria
OMitochondria are sausage-shaped
structures in the cytoplasm,
sometimes described as the 'power
house' of the cell.
OThey are involved in aerobic
respiration, the processes by which
chemical energy is made available
in the cell.

29. Mitochondria cont.
OThis is in the form of ATP, which
releases energy when the cell breaks
it down.
OSynthesis of ATP is most efficient in
the final stages of aerobic respiration,
a process requiring oxygen.

30. Golgi apparatus
OThe Golgi apparatus consists of stacks
of closely folded flattened
membranous sacs.
OIt is present in all cells but is larger in
those that synthesize and export
proteins

31. Golgi Apparatus cont.
OThe proteins move from the
endoplasmic reticulum to the Golgi
apparatus where they are 'packaged'
into membrane-bound vesicles called
secretory granules.
OThe vesicles are stored and, when
needed, move to the plasma
membrane, through which the proteins
are exported.

32. Lysosomes
OLysosomes are one type of secretory
vesicle formed by the Golgi apparatus.
OThey contain a variety of enzymes
involved in breaking down fragments of
organelles and large molecules (e.g. RNA,
DNA, carbohydrates, proteins) inside the
cell into smaller particles that are either
recycled, or extruded from the cell as
waste material.

33. Lysosomes
OLysosomes in white blood cells
contain enzymes that digest foreign
material such as microbes.

34. Microfilaments and
microtubules
Microfilaments.
OThese are tiny strands of protein that
provide structural support and maintain
the characteristic shape of the cell.

35. Microfilaments and
microtubules
Microtubules.
OThese are contractile protein structures
in the cytoplasm involved in the
movement of the cell and of organelles
within the cell, the movement of cilia
(small projections from the free border
of some cells) and possibly the
organization of proteins in the plasma
membrane.

36. Cell division
OThere are two types of cell division:
mitosis and meiosis

37. Mitosis
OBeginning with the fertilized egg, or
zygote, cell division is an ongoing
process.
OAs the fetus develops in the mother's
uterus, its cells multiply and grow into
all the specialties that provide the sum
total of the body's physiological
functions.

38. Mitosis cont.
OThe life span of most individual cells is
limited.
OMany become worn out and die, and
are replaced by identical cells by the
process of mitosis.

39. Mitosis cont.
OMitosis occurs in two stages:
replication of DNA, in the form of 23
pairs of chromosomes, then division of
the cytoplasm.
ODNA is the only type of molecule
capable of independently forming a
duplicate of itself

40. Mitosis cont.
OWhen the two identical sets of
chromosomes have moved to the
opposite poles of the parent cell, a
'waist' forms in the cytoplasm, and the
cell divides.
OThere is then a complete set of
chromosomes in each daughter cell.

41. Mitosis cont.
OThe organelles in the cytoplasm
of the daughter cells are
incomplete at cell division but
they develop as the cell grows to
maturity.
OThe frequency with which cell
division occurs varies with
different types of cell

42. Meiosis
OThis is the process of cell division that
occurs in the formation of reproductive
cells (gametes — the ova and
spermatozoa).
OThe ova grow to maturity in the
ovaries of the female and the
spermatozoa in the testes of the male.
OIn meiosis four daughter cells are
formed after two divisions.

43. Meiosis cont.
ODuring meiosis the pairs of
chromosomes separate and one from
each pair moves to opposite poles of
the 'parent' cell.
OWhen it divides, each of the 'daughter'
cells has only 23 chromosomes, called
the haploid number.

44. Meiosis cont.
OThis means that when the ovum is
fertilized the resultant zygote has
the full complement of 46
chromosomes (the diploid
number), half from the father and
half from the mother.

45. Meiosis cont.
OThus the child has some
characteristics inherited from the
mother and some from the father,
such as color of hair and eyes,
height, facial features, and some
diseases

46. Meiosis cont.
ODetermination of sex depends upon
one particular pair of chromosomes:
the sex chromosomes.
O In the female both sex chromosomes
are the same size and shape and are
called X chromosomes.

47. Meiosis cont.
OIn the male there is one X
chromosome and a slightly smaller Y
chromosome.
OWhen the ovum is fertilized by an X-
bearing spermatozoon the child is
female and when it is fertilized by a Y-
bearing spermatozoon the child is
male

48. Meiosis cont.
OSperm X + ovum X —> child XX =
female
OSperm Y + ovum X —> child XY = male

50. Mutation
OCells are said to mutate when their
genetic make-up is altered in any
way.

51. Mutation may cause:
O1. no significant change in cell function
O2. modification of cell function that may
cause physiological abnormality but
does not prevent cell growth and
multiplication, e.g. inborn errors of
metabolism, defective blood clotting
O3. the death of the cell.

52. Mutation
OSome mutations occur by chance,
which may be accounted for by the
countless millions of cell divisions
and DNA replications that occur in
the body throughout life.

53. Mutation
OOthers may be caused by
extraneous factors, such as X-
rays, ultraviolet rays or some
chemicals

54. Mutation
OThe most important mutations are
those that occur in the ova and
spermatozoa.
OGenetic changes in these cells are
passed on to subsequent generations
although they do not affect the parent

55. Reading Assignment
Tissues
OEpithelial tissue
OConnective tissue
OMuscle tissue
ONervous tissue