2. INTRACELLULAR FLUID EXTRACELLULAR FLUID
• Fluid inside the cell
• Forming 2/3rd
i.e. around
55% of total body water
• mainly a water solution of
ions and other substances.
• ICF has more proteins
• contains potassium,
magnesium and
phosphate ions
• Fluid outside the cell
• is in constant motion throughout
the body
• Forming 1/3rd
i.e. around 45% of
TBW
• Contains the ions like large
amounts of sodium, chloride, and
bicarbonate ions and nutrients
such as oxygen, glucose, fatty
acids, and amino acids needed by
the cells to maintain cell life
• Also contains carbon dioxide and
other cellular waste products
• Types:-
Interstitial,Intravascular,Transcell
ular fluid
3. 1. Interstitial – fluid around/between cells mainly in
tissue spaces.
2. Intravascular –fluid inside specialized vessels i.e. blood
and lymph.
3. Transcellular-fluid accumulated in specific areas. Does
not normally collect in larger amounts.
For example,
The aqueous humor and the vitreous humor in the
eye
The cerebrospinal fluid in the brain
The serous fluid inside the peritoneal and pleural
cavities
The synovial fluid inside the joints
4. HOMEOSTASIS
• It is the maintenance of the internal environment within narrow
limits
• Internal environment refers to extracellular fluid which contains
nutrients, ions and all other substances needed for the survival
of cells. Human body has a perfectly organized and well
controlled internal environment.
• For homeostasis to work we should recognize the deviation or
changes from the normal environment. It is done with the help
of components of homeostasis.
• It includes 3 components ;
• Detector/sensors / receptor which recognise the variations
• Control centre to which information about deviation send
• Effectors which receive information from control centre for
correcting deviation
5. POSITIVE FEEDBACK
• Positive feedback is the one in which the system reacts in such
a way as to amplify the change in the same direction
• It is less common in naturally occurring systems than negative
feedback, but it has its applications in emergency conditions .
• This has a destabilizing effect, so does not result in
homeostasis.
• Examples are ;
1. Blood clotting
2. Milk ejection reflex
3. Parturition reflex
• The homeostatic system acts through feedback mechanism
• Feedback mechanism are of two types;
• Positive
• Negative
6. NEGATIVE FEEDBACK:
• It is the mechanism in which the particular system responds
in such a way as to stop or reverse the direction of change.
That means the system stabilizes it’s own functions either by
sending inhibiting signals or by reversing the signals.
• Examples are
1. Regulation of secretion of thyroid hormones by TSH.
2. Maintenance of water balance
3. Thermoregulation
8. Two basic mechanisms for membrane transport are;
PASSIVE TRANSPORT:
• It is the transport of the substances along the
concentration(chemical) gradient or electrical gradient
or both.
• Here the substances move from the region of higher
concentration to the region of lower concentration.
• It is also known as diffusion or downhill movement.
• It does not need energy.
• It is of three types;
I. Simple diffusion
II. Facilitated diffusion
III. Osmosis
9. SIMPLE DIFFUSION
It is the kinetic movement of molecules or ions occurs
without any carrier proteins in the membrane.
It occurs either through the lipid layer of the cell membrane
mainly lipid soluble substances or through protein channels
i.e. water soluble substances with smaller size.
The protein channels are selectively permeable to
only one type of ion. The protein channels are of
two types;
Ungated channels which are opened
continuously
Gated channels are opened only when required.
Voltage gated, ligand gated, mechanically
gated channels
10. FACILITATED DIFFUSION
• Facilitated diffusion is the diffusion of solutes
through channel proteins in the plasma membrane.
• It requires interaction of a carrier protein.
• The water soluble substances with larger molecules
which cannot pass through the protein channels by
simple diffusion are transported through this
method.
• This type of diffusion is faster than simple diffusion.
• Glucose and aminoacids are transported by this
method.
• No expenditure of energy is needed.
11. OSMOSIS
• It is the special type of diffusion.
• Osmosis is the diffusion of water molecules
across a selectively permeable membrane.
• It is the movement of water or any other solvent
from an area of lower concentration to a area of
higher concentration through a semipermeable
membrane.
• It is of two types;
1. Endosmosis by which water moves in to the
cell
2. Exosmosis by which water moves out of the
cell.
12. ACTIVE TRANSPORT:
• It is the movement of substances against the
chemical or electrical or electrochemical
gradient.
• It is also called uphill transport.
• It requires energy which is obtained from ATP.
• It also needs a carrier protein.
• It is divided in to two categories;
1. Primary active transport
2. Secondary active transport
13. PRIMARY ACTIVE TRANSPORT
• Here the energy is liberated directly from the breakdown of
ATP.
• Substances like sodium, potassium, calcium, hydrogen and
chloride are transported across the membrane by this method.
SECONDARY ACTIVE TRANSPORT
• It is the transport of a substance with sodium ions by a
common carrier protein. It is of two types;
• Cotransport or symport in which the transport of substance
in the same direction along with sodium. Glucose, chloride,
iodide, iron, urate and aminoacids are transported by this
method.
• Counter transport or antiport in which the transport of
substances occurs in the opposite direction to that of
sodium. Examples are sodium- calcium counter transport
and sodium- hydrogen transport.
14. • Active transport is achieved through protein pumps. They are
transport proteins in the plasma membrane transfer solutes such as
small ions (Na+, K+, Cl-, H+), amino acids, and monosaccharides.
• The proteins involved with active transport are also known as ion
pumps.
• The protein binds to a molecule of the substance to be transported
on one side of the membrane, then it uses the released energy
(ATP) to change its shape, and releases it on the other side.
• The protein pumps are specific, there is a different pump for each
molecule to be transported.
• Protein pumps are catalysts in the splitting of ATP → ADP +
phosphate, so they are called ATPase enzymes.
• The sodium-potassium pump (also called the Na+/K+-ATPase
enzyme)actively moves sodium out of the cell and potassium into
the cell. These pumps are found in the membrane of virtually every
cell, and are essential in transmission of nerve impulses and in
muscular contractions.
15.
16. The movement of macromolecules such as proteins or
polysaccharides into or out of the cell is called BULK /VESICULAR
TRANSPORT.
There are two types of bulk
transport, exocytosis and endocytosis, and both require the
expenditure of energy (ATP).
In EXOCYTOSIS, materials are exported out of the cell via
secretory vesicles.
• In this process, the Golgi complex packages
macromolecules into transport vesicles that travel to and
fuse with the plasma membrane.
• This fusion causes the vesicle to spill its contents out of
the cell.
• Exocytosis is important in expulsion of waste materials
out of the cell and in the secretion of cellular products
such as digestive enzymes or hormones.
17. • In pinocytosis or “cellular drinking,” the cell engulfs drops of
fluid by pinching in and forming vesicles that are smaller
than the phagosomes formed in phagocytosis.
• In phagocytosis or “cellular eating,” the cell’s plasma
membrane surrounds a macromolecule or even an
entire cell from the extracellular environment and buds off
to form a food vacuole or phagosome. The newly-formed
phagosome then fuses with a lysosome whose hydrolytic
enzymes digest the “food” inside.
ENDOCYTOSIS, on the other hand, is the process by which
materials move into the cell.
There are three types of endocytosis:
phagocytosis, pinocytosis, and receptor-mediated
endocytosis
18. Receptor-mediated endocytosis
• Receptor-mediated endocytosis occurs when specific
molecules in the fluid surrounding the cell bind to
specialized receptors in the plasma membrane
• It is an extremely selective process mediated by receptor
proteins located on the cell membrane called coated
pits.
• In receptor-mediated endocytosis, extracellular
molecule binds to its specific receptor protein on the
cell’s surface. Once bound, the coated pit invaginate, to
form a coated vesicle. This coated vesicle then fuses
with a lysosome to digest the engulfed material and
release it into the cytosol.
• Mammalian cells use receptor-mediated endocytosis to
take cholesterol into cells.
19. Glands are divided based on
their function into two
groups:
Endocrine gland
• Endocrine glands secrete
substances that circulate
through the blood stream.
• These glands lack a duct
system.
• These glands secrete
hormones, and play an
important role in
maintaining homeostasis.
20. Exocrine gland
• Exocrine glands secrete their products through a duct
onto an outer surface of the body, such as the skin or
the gastrointestinal tract.
• Secretion is directly onto the apical surface.
• Examples of exocrine glands are sweat, salivary,
mammary, ceruminous, lacrimal, sebaceous and
mucous
21. Holocrine glands
• The entire cell
disintegrates to secrete its
substances
• (e.g., Sebaceous glands),
According to the mode of secretion ,the exocrine glands can be
divided into three groups:
1. Apocrine
2. Merocrine
3. Holocrine
22. Apocrine glands
• A portion of the secreting cell's
body is lost during secretion.
• e.g. mammary gland, sweat
gland of arm pit, pubic region,
skin around anus, lips, nipples.
23. Merocrine glands
• Cells secrete their substances by
exocytosis (e.g., Mucous and serous
glands).
• Also called "eccrine".
• e.g. most of the sweat gland of
humans, goblet cells, salivary gland,
tear gland, intestinal glands.
24. According to the type of secretory product it is classified into
three categories:
1. Serous glands secrete a watery, often protein-rich, fluid-
like product, e.g. sweat glands.
2. Mucous glands secrete a viscous product, rich in
carbohydrates (such as glycoproteins), e.g. goblet cells.
3. Sebaceous glands secrete a lipid product. These glands
are also known as oil glands, e.g. Fordyce spots and
meibomian glands
25. Exocrine glands perform a variety of bodily functions
• Sweat glands produce sweat which regulate body temperature
• Mammary glands by producing milk nourishes the young
• Tear glands by producing tears which clean, moisten, and
lubricate the eye
• Salivary glands by producing saliva begin digestion and
lubricate the mouth .
• Sebaceous glands produce oil (sebum) which keeps skin and
hair, conditioned and protected.
• Ceruminous glands produce wax (cerumen)in the outer ear
and protects ears from foreign matter.
• Exocrine glands in the testes produce seminal fluid, which
transports and nourishes sperm.
• Exocrine gland secretions also aid in the defence against
bacterial infection by carrying special enzymes, forming
protective films, or by washing away microbes
26. SEBACEOUS GLANDS :
• Simple or branched alveolar glands situating the dermis of the
skin open in to neck of hair follicle through a duct
• In some areas like face, lips, nipple, glans penis, labia minora,
these glands open directly in to the exterior
• These glands are inactive till puberty and then activated in the
presence of male and female sex hormones after puberty
• Secretion is sebum which contains free fatty acids,
triglycerides, squalene, sterols, waxes, paraffin
• Functions:
• Free fatty acid content of the sebum has antibacterial and
antifungal actions which prevent skin infections
• The lipid nature of sebum provides smoothness and oily
nature to skin and thus preventing dryness of skin
• The lipids of sebum prevent heat loss
SEBACEOUS GLANDS :
• Simple or branched alveolar glands situating the dermis of the
skin open in to neck of hair follicle through a duct
• In some areas like face, lips, nipple, glans penis, labia minora,
these glands open directly in to the exterior
• These glands are inactive till puberty and then activated in the
presence of male and female sex hormones after puberty
• Secretion is sebum which contains free fatty acids,
triglycerides, squalene, sterols, waxes, paraffin
• Functions:
• Free fatty acid content of the sebum has antibacterial and
antifungal actions which prevent skin infections
• The lipid nature of sebum provides smoothness and oily
nature to skin and thus preventing dryness of skin
• The lipids of sebum prevent heat loss
27.
28. ECCRINE GLANDS APOCRINE GLANDS
• Abundant sweat glands
distributed throughout the
body
• Open out through a sweat
pore
• Function throughout life
since birth
• Secrete a clear watery sweat
containing water, sodium
chloride, urea and lactic acid
• Secretion increases during
emotional conditions and
play an important role in
thermoregulation
• Eccrine glands are supplied
by cholinergic nerve fibres
• Less numerous
• Are situated only in certain
parts of the body like axilla,
pubis, areola and umbilicus
• Open in to hair follicle
• Are non-functional till puberty
and become active after
puberty
• Secretion is thick and milky,
odourless initially.
• Secretion increases only in
emotional conditions and not
have any role in
thermoregulation
• Innervated by sympathetic
adrenergic nerve fibres
