TYPES OF PLANT CELLS

1. Types of Plant Cells

2. 1. Meristematic cells
 These cells are not yet
differentiated and divide
actively by mitosis.
 They are the stem cells of
plants, capable of giving
rise to any plant cell type.

3. 2. Parenchyma cells
 These cells synthesize and store organic products in the plant. Most of
the plant's metabolism takes place in these cells.

4. 2. Parenchyma cells
 They are involved chiefly in photosynthesis, food storage,
secretion, and phloem loading.
 They occur in vascular bundles, leaves, and epidermis.
 Parenchyma cells that are involved in photosynthesis are
called chlorenchyma cells.
 Guard cells are another specialized type of parenchyma
cells. They regulate the opening and closure of stomata
(plant pores for gas exchange).

5. Important points of Parenchyma
Tissue
1) Photosynthesis
2) Storage of air
3) Storage of water and minerals
Parenchyma performs photosynthesis where the rate is
very high because of high chlorophyll content and
spongy parenchyma acts as a air storage.

6. carbon dioxide + water glucose + oxygen

7. 3. Collenchyma cells
 These cells help to support plants while not restraining
growth due to their lack of secondary walls and the
absence of a hardening agent in their primary walls.

8. Important points of Collenchyma Tissue
 Collenchyma serve as supporting and strengthening tissue,
 Collenchyma with chloroplasts, photosynthesis takes
place.

9. 4. Sclerenchyma Tissue
 Sclerenchyma cells also have a support
function in plants but unlike Collenchyma
cells, they have a hardening agent and are
much more rigid.
 Have the property of elasticity: They can
be deformed, but they snap back to their
original size and shape when the pressure
or tension is released.
 Sclerenchyma cells develop mainly in
mature organs that have stopped growing
and have achieved their proper size and
shape.

10. Important points of
Sclerenchyma Tissue
 Most abundant cells in plants.
 Spherical cells which flatten at point of contact.
 Alive at maturity; pliable, primary cell walls.
 Large vacuoles for storage of starch, fats, and tannins (proteins)

12. Xylem and Phloem Diagram

13. Comparison of Phloem and Xylem
Character Phloem Xylem
Function Transportation of food and
nutrients from leaves to storage
organs and growing parts of plant.
Water and mineral transport from
roots to aerial parts of the plant.
Movement Bidirectional (Moves up or down
the plant's stem from "source to
sink")
Unidirectional (Moves up the
plant's stem)
Occurrence Roots, stems and leaves Roots, stems and leaves
Additional Functions Forms vascular bundles with
xylem
Forms vascular bundles with
phloem and gives mechanical
strength to plant due to presence
of lignified cells.
Structure Tubular with soft walled cells Tubular with hard walled cells
Elements Sieve tubes, companion cells,
phloem parenchyma, bast fibers,
intermediary cells, two tube flow
Tracheids, vessel elements, xylem
parenchyma, xylem Sclerenchyma
Nature of tissue Living tissue Non living tissue at maturity

14. Animal Cell Types

15. Muscle Cells
 Muscle cells, commonly
known as myocytes,
are the cells that make
up muscle tissue.

16. Blood Cells
Leukocytes, Erythrocytes, platelets.
hematology - the study of blood

17.  Blood is a specialized body fluid. It has four main
components: plasma, red blood cells, white blood
cells, and platelets. Blood has many different
functions, including:
• transporting oxygen and nutrients to the lungs and
tissues
• forming blood clots to prevent excess blood loss
• carrying cells and antibodies that fight infection
• bringing waste products to the kidneys and liver,
which filter and clean the blood regulating body
temperature

18. Plasma
 The liquid component of blood is called
plasma, a mixture of water, sugar, fat,
protein, and salts.
 The main job of the plasma is to
transport blood cells throughout your
body along with nutrients, waste
products, antibodies, clotting proteins,
chemical messengers such as
hormones, and proteins that help
maintain the body's fluid balance.

19. Red Blood Cells (also called
erythrocytes or RBCs)
 Known for their bright red color, red cells are the most
abundant cell in the blood, accounting for about 40 to 45
percent of its volume.
 The shape of a red blood cell is a biconcave disk with a
flattened center - in other words, both faces of the disc have
shallow bowl-like indentations (a red blood cell looks like a
donut).
 Production of red blood cells is controlled by erythropoietin, a
hormone produced primarily by the kidneys. Red blood cells
start as immature cells in the bone marrow and after
approximately seven days of maturation are released into the

20. Red Blood Cells (also called
erythrocytes or RBCs)
 The red blood cell survives on average only 120 days.
 Red cells contain a special protein called hemoglobin, which
helps carry oxygen from the lungs to the rest of the body and
then returns carbon dioxide from the body to the lungs so it can
be exhaled.
 The percentage of whole blood volume that is made up of red
blood cells is called the hematocrit and is a common measure
of red blood cell levels.

21. White Blood Cells (also called
leukocytes)
 White blood cells protect the body from infection. They are
much fewer in number than red blood cells, accounting for
about 1 percent of your blood.
 The most common type of white blood cell is the
neutrophil, which is the "immediate response" cell and
accounts for 55 to 70 percent of the total white blood cell
count. Each neutrophil lives less than a day, so your bone
marrow must constantly make new neutrophils to maintain
protection against infection. Transfusion of neutrophils is
generally not effective since they do not remain in the
body for very long.

22. White Blood Cells (also called
leukocytes)
 The other major type of white blood cell is a lymphocyte.
There are two main populations of these cells. T
lymphocytes help regulate the function of other immune
cells and directly attack various infected cells and tumors.
B lymphocytes make antibodies, which are proteins that
specifically target bacteria, viruses, and other foreign
materials.

23. Platelets (also called thrombocytes)
 Unlike red and white blood cells, platelets are not actually cells
but rather small fragments of cells.
 Platelets help the blood clotting process (or coagulation) by
gathering at the site of an injury, sticking to the lining of the
injured blood vessel, and forming a platform on which blood
coagulation can occur.
 This results in the formation of a fibrin clot, which covers the
wound and prevents blood from leaking out. Fibrin also forms
the initial scaffolding upon which new tissue forms, thus
promoting healing.

24. Platelets (also called thrombocytes)
 A higher than normal number of platelets can cause
unnecessary clotting, which can lead to strokes and
heart attacks; however, thanks to advances made
in antiplatelet therapies, there are treatments
available to help prevent these potentially fatal
events. Conversely, lower than normal counts can
lead to extensive bleeding.

25. Skin Cells
 Melanocytes, keratinocytes, Merkel cells and Langerhans
cells
 The epidermis has three main types of cell: Keratinocytes
(skin cells) Melanocytes (pigment-producing
cells) Langerhans cells (immune cells).

26. Epidermis
 The epidermis is the uppermost or epithelial layer of the skin.
 It acts as a physical barrier, preventing loss of water from the body, and
preventing entry of substances and organisms into the body.
 The epidermis consists of stratified squamous epithelium. That means it consists
of layers of flattened cells.
• Skin, hair and nails are keratinised, meaning they have a dead and hardened
impermeable surface made of a protein called keratin.
• Mucous membranes are non-keratinised and moist.

27.  The epidermis has three main types of cell:
• Keratinocytes (skin cells)
• Melanocytes (pigment-producing cells)
• Langerhans cells (immune cells).
 Special stains are often required to tell the difference between
melanocytes and Langerhans cells. The Merkel cell is a fourth, less
visible, epidermal cell.

28.  Keratinocytes
 The keratinocytes become more mature or differentiated and
accumulate keratin as they move outwards. They eventually fall
or rub off.
 Melanocytes
 Melanocytes are found in the basal layer of the epidermis. These
cells produce a pigment called melanin, which is responsible for
different skin colour. Melanin is packaged into small parcels
(or melanosomes), which are then transferred to keratinocytes.

29.  Langerhans cells
 Langerhans cells are immune cells found in the epidermis and are
responsible for helping the body learn and later recognise new ‘allergens’
(material foreign to the body).
 Langerhans cells break the allergen into smaller pieces then migrate from
the epidermis into the dermis. They find their way to lymphatics and blood
vessels before eventually reaching the lymph nodes. Here they present
the allergen to immune cells called lymphocytes. Once the allergen is
successfully ‘presented’, the lymphocytes initiate a sequence of events to:
(1) initiate an immune reaction to destroy the material, and (2)
stimulate proliferation of more lymphocytes that recognise and remember
the allergen in the future.
 Merkel cells
 Merkel cells are cells found in the basal layer of the epidermis. Their exact
role and function are not well understood. Special immunohistochemical
stains are needed to visualise Merkel cells.

30. Nerve Cells
 Neurons (also called neurones or nerve cells) are the
fundamental units of the brain and nervous system
 The cells responsible for receiving sensory input from the
external world, for sending motor commands to our muscles,
and for transforming and relaying the electrical signals at every
step in between.

31. Schwann cells are a type of glial cells of the
peripheral nervous system that help form the myelin
sheath around the nerve fibers.
Schwann cells are derived from the neural crest
and play crucial roles in the maintenance and
regeneration of the motor and sensory neurons of
the peripheral nervous system (PNS). They are
mainly required for insulating (myelinating) and
supplying nutrients to individual nerve fibers
(axons) of the PNS neurons.

32. Fat Cells
 Adipocytes
 Adipose tissue is a connective tissue, but it’s also an
interactive organ in your endocrine system.
 Adipose tissue communicates through hormone
signals with other organs throughout your body, as
well as with your central nervous system, to regulate
your metabolism.
 Adipose tissue, otherwise known as body fat, is a
connective tissue that extends throughout your body.
It’s found under your skin (subcutaneous fat),
between your internal organs (visceral fat) and even
in the inner cavities of bones (bone marrow adipose
tissue).

33. Fat Cells
 Body fat is primarily known for storing and
releasing energy and providing insulation.
 However, scientists now recognize that it’s also
an active organ in your endocrine system.
 Adipose tissue contains nerve cells and blood
vessels and communicates through hormone
signals with other organs throughout your
body.