HLT31507 CERTIFICATE III IN NUTRITION
& DIETETIC ASSISTANCE
CELLS & TISSUES
delivered by:
Mary-Louise Dieckmann
Cells
• Cells are the building blocks of life
• They are comprised of four elements:
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Carbon
Oxygen
Hydrogen
Nitrogen
Structure of a Cell
Cells have three main parts:
• The plasma membrane
• The cytoplasm
• The nucleus
The Nucleus
Control centre of a cell. It contains:
• DNA – deoxyribonucleic acid
The Plasma Membrane
• is the outer boundary for the cell, also
referred to as cell membrane
• Is arranged ‘tail to tail’
• has a double phospholipid layer with
– Hydrophilic heads (water loving)
– Hydrophobic tails (water hating)
• contains proteins, cholesterol and
gylcoproteins (sugar-proteins)
The Plasma Membrane
The Cytoplasm
• is outside the nucleus but inside the plasma
membrane
• Contains:
– Cytosol
– Organelles
– Inclusions
The Cytoplasm
• The cytosol is the fluid that suspends other
elements
• The inclusions are chemical substances
(present depending on the type of cell)
The Organelles
• Metabolic machinery of the cell. They include:
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Mitochondria
Ribosomes
Endoplasmic Reticulum (rough and smooth)
Golgi Apparatus
Lysosomes
Peroxisomes
Cytoskeleton
Centrioles
Organelles
The Organelles
Mitochondria are the ‘powerplants’ of a cell
– They carry out reactions where oxygen is used to
break down food
– Provide ATP for cellular energy
Ribosomes are the actual sites of protein synthesis
They are made of protein and RNA
(riboxynucleicacid)
The Organelles
Golgi Apparatus is the ‘traffic director’ for cellular
proteins
Modifies and packages proteins for transport
Produces different types of ‘packages’:
• Secretory vesicles
• Cell membrane components
• Lysosomes
The Golgi Apparatus
The Organelles
Cytoskeleton is the framework that
determines the cell shape
A network of protein structures
Provides the cell with an internal
framework that helps to support
other organelles
Allows transport and types of cellular
movement
Cell Diversity
Two types of cells that connect body parts
• Fibroblasts
• Erythrocytes (red blood cells)
Cell Diversity
• Epithelial cells cover and line body organs
Cell Diversity
• Skeletal muscles and smooth muscle cells
have contractile filaments designed for
contraction that causes movement
Cell Diversity
• Fat cells store nutrients
Cell Diversity
• Macrophages or phagocytes fight disease.
The lysosomes digest infectious microorganisms
Cell Diversity
• Nerve cells gather information and control
body functions
Cell Diversity
• Reproductive cells include oocytes and sperm
CHAPTER 3 – PART 2
CELLULAR PHYSIOLOGY
Membrane Transport
• Membrane transport – movement of
substances into and out of the cell
• Two Transport Methods – passive (no energy)
and active (metabolic energy provided by the
cell)
Solutions
• Intracellular fluid (found inside the cell)
– cytosol and nucleoplasm
• Extracellular fluid (or interstitial fluid) (found
outside the cell)
– hormones, nutrients, neurotransmitters and waste
products
Passive Transport
• Two types – diffusion and
filtration
• Simple diffusion:
– substances move from an
area of higher concentration
to an area of lower
concentrations
Passive Transport
• Facilitated (helped)
diffusion – uses a
carrier or a channel
– Substances bind to
protein carriers
– Moves through a
channel constructed by
channel proteins
Passive Transport
Filtration
• water and solutes are forced through the
membrane wall by pressure
• Pressure can be caused by blood pressure ie.
Kidney filtration.
Active Transport
• Uses sodium-potassium pump to move ions
against the concentration gradient
• Requires ATP to energise the protein carriers
Active Transport
Active Transport
• Step 1 – Sodium
enters the protein
pump, and 1 ion of
phosphate binds
onto the pump,
causing it to change
shape
Active Transport
• Step 2 – The protein
pump changes shape
and then sodium ions
(Na) are forced out of
the cell.
• Next, potassium (K) ions
bind onto the pump
protein, and the
phosphate ion lets go.
Active Transport
• Step 3 – this causes
the pump protein to
return to its original
shape, and then
potassium ions are
released into the
cell.
Exocytosis (out of the cell)
• Bulk transport of substances – hormone,
mucus or ejection of waste products
Endocytosis (into the cell)
• Includes all of the ATP-fuelled processes
• Vesicular sac forms, bringing ingested
substance into cell
• Lysosomes digest vesicle, releasing contents
into cytoplasm
Endocytosis (into the cell)
CHAPTER 3 – PART 3
BODY TISSUES
Tissues
Tissues are groups of cells that are similar in
structure and function.
Four primary tissue types:
– Epithelial tissue
– Connective tissue
– Muscle tissue
– Nervous tissue
Epithelial Tissue
• Forms body coverings, body linings and
glandular tissue
• Major functions:
– Protection
– Absorption
– Filtration
– Secretion
Special Characteristics of
Epithelial Tissue
• Closely packed cells
• Always have apical (unattached) and basal
(attached) surfaces
• Innervated but avascular
• Two names – first indicates number of layers,
second describes the shape of the cell
Simple Epithelia
Stratified Epithelia
• More than one layer. More durable than
simple epithelia, mostly concerned with
protection.
Pseudostratified Columnar
Epithelium
• False (pseudo) impression of being stratified
Transitional Epithelia
Connective Tissue
Most abundant and widely distributed tissue in
human body
Functions:
• Binding and support
• Protection
• Insulation
• Transportation
Connective Tissue
Characteristics
• Blood supply varies – some are well
vascularized and others have poor blood
supply or are avascular
• Extracellular Matrix – non living material that
surrounds living cells
Extracellular Matrix
• Ground substance – mostly water, adhesion
proteins & polysaccharide molecules
• Fibers – provide support. Three types:
– Collagen (providing high tensile strength)
– Elastic (allowing stretch and recoil)
– Reticular (fine fibers that form networks)
Major Classes of Connective
Tissue
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Blood
Loose Connective Tissue
Dense Connective Tissue
Cartilage
Bone
Blood
• Blood cells surrounded by fluid matrix
(plasma)
• Fibers visible during clotting
• Functions as transport vehicle
Loose Connective Tissue
Areolar Connective Tissue
• Most widely distributed connective tissue
• Soft and pliable – ‘cob-web’ like
• Contains all fiber types
• Can soak up excess fluid
Loose Connective Tissue
Adipose (fat) Connective
Tissue
• Matrix is areolar tissue with
fat globules
• Cells contain large lipid
deposits
• Functions:
– Insulates the body
– Protects some organs (ie.
Kidneys)
– Site of fuel storage
Loose Connective Tissue
Reticular Connective Tissue
• Delicate network of interwoven fibers
• Forms internal supporting network (stroma) of
lymphoid organs, including:
– Spleen
– Lymph nodes
– Bone marrow
Dense Connective Tissue
• Major matrix element is
collagen fibers
• Cells are known as
fibroblasts
• Two major types:
– Tendon (attach muscle to
bone)
– Ligaments (attach bone to
bone)
Cartilage
Hyaline Cartilage
• Most abundant
cartilage in body
• Comprised of
collagen fibers and a
rubbery matrix
• Entire fetal skeleton is
hyaline cartilage
Cartilage
• Elastic Cartilage – provides
strength and stretchability –
ie. The external ear
• Fibrocartilage – highly
compressible, providing
cushioning – ie. The
intervertebral discs
Bone
• Also know as osseous tissue
• Protects and supports the
body
• Comprised of:
– Bone cells in lacunae
– Hard matrix of calcium salts
– Large numbers of collagen fibers
Muscle Tissue
• Highly specialised to contract or shorten to
produce movement.
• Three major types:
– Skeletal muscle
– Cardiac muscle
– Smooth muscle
Skeletal Muscle Tissue
• Under voluntary control
• Cells are striated, multi-nucleate
• Attaches to the bones
Cardiac Muscle Tissue
• Only found in the heart
• Involuntary
• Cells are uninucleate and
striated
• Cells attach to other
cardiac muscle cells at
intercalated disks
Smooth Muscle Tissue
• Involuntary
• No visible striations,
uninucleate
• Surrounds hollow organs
• Attaches to other smooth
muscle cells
Nervous Tissue
• Two principal types:
– Nerve Cells (Neurons)
Highly specialised in order to transmit nerve impulses.
All have a cell body, nucleus and one or more fibers
– Supporting Cells (Neuroglia)
Provide insulation, support and protection. They do not
transmit nerve impulses and can divide… (unlike
neurons)
Tissue Repair
• Regeneration
– Replacement of destroyed tissue by the same kind
of cells
• Fibrosis
– Repair by dense fibrous connective tissue (scar
tissue)
• Determination of method – type of tissue
and severity of the injury