Hemostasis is the body's natural reaction to stop bleeding from an injury by forming a blood clot. It is a multi-step process involving platelet clotting to form a temporary plug, coagulation factors that stabilize the plug through a cascade, and fibrin clots that permanently seal the damage. Homeostasis maintains stable conditions in the body through feedback loops, but can fail due to diseases like diabetes that disrupt regulation of blood glucose. Tissues also have natural surface fluctuations driven by cell dynamics of rearrangement, division and death that help maintain homeostasis.

1. HISTOLOGY IWS 3
Submitted by- Shamim Mustafa
Barbhuiya
Group- 163

2. 1.Hemostasis

3. HEMOSTASIS
Hemostasis is your body’s natural reaction to an injury that stops bleeding
and repairs the damage. This capability is usually for your benefit,
conserving blood and preventing infections. In rare cases, the process
doesn't work as it should, and this can cause problems with too much or
too little clotting.
Hemostasis is your body’s normal reaction to an injury that causes
bleeding. This reaction stops bleeding and allows your body to start
repairs on the injury. This capability is essential to keep you alive,
particularly with significant injuries. However, in uncommon cases, the
processes that control hemostasis can malfunction, causing potentially
serious — or even dangerous — problems with bleeding or clotting.

5. How does hemostasis work?
Hemostasis combines the terms “hemo” (meaning “blood”) and
“stasis” (meaning “standing still”). In this context, it’s the term for
how your body stops bleeding. Rather than being just a single
process, hemostasis is actually a collection of several processes.
Though they look like separate processes, these all happen at the
same time when your body forms a blood clot.

7. Primary hemostasis (platelet clotting)
Primary hemostasis is when your body forms a temporary plug to seal
an injury. To accomplish that, platelets that circulate in your blood stick
to the damaged tissue and activate. That activation means they can
“recruit” more platelets to form a platelet “plug” to stop blood loss from
the damaged area. That clot works much like a cork or bottle stopper,
keeping blood in and debris or germs out. Primary hemostasis may
also involve constriction (narrowing) of the damaged blood vessel,
which can happen because of substances that activated platelets
release.

9. Secondary hemostasis (coagulation
cascade)
The platelet plug is the first step to stop bleeding, but it isn’t stable enough to stay in
place without help. The next step, which stabilizes the plug, is secondary
hemostasis. This step, sometimes called coagulation, involves molecules in your
blood called “coagulation factors.” Those factors activate in sequence, the
“coagulation cascade,” which amplifies clotting effects as the sequence continues.
Ultimately, the coagulation cascade forms a substance called fibrin. During this step,
the platelet plug acts like bricks and the fibrin acts like mortar. Together, they form a
solid, stable clot.

10. Fibrin clot remodeling
The last stage of hemostasis is when your body remodels the existing clot
into a fibrin clot. Your body does that because blood clots are a temporary
patch, not a permanent solution. That removal involves a process called
fibrinolysis. During fibrinolysis, your body remodels the clot into the same
kind of tissue that was there before the injury.

11. Osmoregulation
Osmoregulation is the process of maintaining salt and water balance (osmotic balance) across
membranes within the body. The fluids inside and surrounding cells are composed of water,
electrolytes, and nonelectrolytes. An electrolyte is a compound that dissociates into ions when
dissolved in water. A nonelectrolyte, in contrast, does not dissociate into ions in water. The
body’s fluids include blood plasma, fluid that exists within cells, and the interstitial fluid that
exists in the spaces between cells and tissues of the body. The membranes of the body (both
the membranes around cells and the “membranes” made of cells lining body cavities) are
semipermeable membranes. Semipermeable membranes are permeable to certain types of
solutes and to water, but typically cell membranes are impermeable to solutes.
The body does not exist in isolation. There is a constant input of water and electrolytes into the
system. Excess water, electrolytes, and wastes are transported to the kidneys and excreted,
helping to maintain osmotic balance. Insufficient fluid intake results in fluid conservation by the
kidneys. Biological systems constantly interact and exchange water and nutrients with the
environment by way of consumption of food and water and through excretion in the form of
sweat, urine, and feces. Without a mechanism to regulate osmotic pressure, or when a
disease damages this mechanism, there is a tendency to accumulate toxic waste and water,

13. Thermoregulation
Animals can be divided into two groups: those that maintain a constant body temperature
in the face of differing environmental temperatures, and those that have a body
temperature that is the same as their environment and thus varies with the environmental
temperature. Animals that do not have internal control of their body temperature are
called ectotherms. The body temperature of these organisms is generally similar to the
temperature of the environment, although the individual organisms may do things that
keep their bodies slightly below or above the environmental temperature. This can
include burrowing underground on a hot day or resting in the sunlight on a cold day. The
ectotherms have been called cold-blooded, a term that may not apply to an animal in the
desert with a very warm body temperature.
An animal that maintains a constant body temperature in the face of environmental
changes is called an endotherm. These animals are able to maintain a level of activity
that an ectothermic animal cannot because they generate internal heat that keeps their
cellular processes operating optimally even when the environment is cold.

15. Animals conserve or dissipate heat in a variety of ways. Endothermic animals have
some form of insulation. They have fur, fat, or feathers. Animals with thick fur or
feathers create an insulating layer of air between their skin and internal organs.
Polar bears and seals live and swim in a subfreezing environment and yet maintain
a constant, warm, body temperature. The arctic fox, for example, uses its fluffy tail
as extra insulation when it curls up to sleep in cold weather. Mammals can increase
body heat production by shivering, which is an involuntary increase in muscle
activity. In addition, arrector pili muscles can contract causing individual hairs to
stand up when the individual is cold. This increases the insulating effect of the hair.
Humans retain this reaction, which does not have the intended effect on our
relatively hairless bodies; it causes “goose bumps” instead. Mammals use layers of
fat as insulation also. Loss of significant amounts of body fat will compromise an
individual’s ability to conserve heat.

16. Ectotherms and endotherms use their circulatory systems to help maintain body
temperature. Vasodilation, the opening up of arteries to the skin by relaxation of
their smooth muscles, brings more blood and heat to the body surface,
facilitating radiation and evaporative heat loss, cooling the body.
Vasoconstriction, the narrowing of blood vessels to the skin by contraction of
their smooth muscles, reduces blood flow in peripheral blood vessels, forcing
blood toward the core and vital organs, conserving heat. Some animals have
adaptions to their circulatory system that enable them to transfer heat from
arteries to veins that are flowing next to each other, warming blood returning to
the heart. This is called a countercurrent heat exchange; it prevents the cold
venous blood from cooling the heart and other internal organs. The
countercurrent adaptation is found in dolphins, sharks, bony fish, bees, and
hummingbirds.

18. Thermoregulation is coordinated by the nervous system. The processes of
temperature control are centered in the hypothalamus of the advanced animal
brain. The hypothalamus maintains the set point for body temperature through
reflexes that cause vasodilation or vasoconstriction and shivering or sweating.
The sympathetic nervous system under control of the hypothalamus directs the
responses that effect the changes in temperature loss or gain that return the
body to the set point. The set point may be adjusted in some instances. During
an infection, compounds called pyrogens are produced and circulate to the
hypothalamus resetting the thermostat to a higher value. This allows the body’s
temperature to increase to a new homeostatic equilibrium point in what is
commonly called a fever. The increase in body heat makes the body less optimal
for bacterial growth and increases the activities of cells so they are better able to
fight the infection.

19. Mechanisms of Tissue Homeostasis
Maintenance of homeostasis usually involves negative feedback loops. These loops act to oppose the
stimulus, or cue, that triggers them. First, high temperature will be detected by sensors—primarily nerve
cells with endings in your skin and brain—and relayed to a temperature-regulatory control center in your
brain. The control center will process the information and activate effectors—such as the sweat glands—
whose job is to oppose the stimulus by bringing body temperature down. Homeostatic circuits usually
involve negative feedback loops. The hallmark of a negative feedback loop is that it counteracts a change,
bringing the value of a parameter—such as temperature or blood sugar—back towards it set point.
Some biological systems, however, use positive feedback loops. Unlike negative feedback loops, positive
feedback loops amplify the starting signal. Positive feedback loops are usually found in processes that
need to be pushed to completion, not when the status quo needs to be maintained.
A positive feedback loop comes into play during childbirth. In childbirth, the baby's head presses on the
cervix—the bottom of the uterus, through which the baby must emerge—and activates neurons to the
brain. The neurons send a signal that leads to release of the hormone oxytocin from the pituitary gland.
Oxytocin increases uterine contractions, and thus pressure on the cervix. This causes the release of even
more oxytocin and produces even stronger contractions. This positive feedback loop continues until the
baby

21. When homeostasis fails
Homeostatic mechanisms work continuously to maintain stable conditions in the human
body. Sometimes, however, the mechanisms fail. When they do, homeostatic
imbalance may result, in which cells may not get everything they need or toxic wastes
may accumulate in the body. If homeostasis is not restored, the imbalance may lead to
disease or even death. Diabetes is an example of a disease caused by homeostatic
imbalance. In the case of diabetes, blood glucose levels are no longer regulated and
may be dangerously high. Medical intervention can help restore homeostasis and
possibly prevent permanent damage to the organism.

22. Homeostatic fluctuations of a Tissue
Surface
the surface fluctuations of a tissue with a dynamics dictated by cell-rearrangement, cell-
division, and cell-death processes. Surface fluctuations are calculated in the homeostatic
state, where cell division and cell death equilibrate on average. The obtained fluctuation
spectrum can be mapped onto several other spectra such as those characterizing
incompressible fluids, compressible Maxwell elastomers, or permeable membranes in
appropriate asymptotic regimes. Since cell division and cell death are out-of-equilibrium
processes, detailed balance is broken, but a generalized fluctuation-response relation is
satisfied in terms of appropriate observables.

24. CONCLUSION
In conclusion, all of the body's organ systems provide help in homeostasis; although, all
systems may play vital roles in maintaining homeostasis throughout the body, those are the
key components to keeping a healthy homeostatic equilibrium in order to survive
Homeostasis maintains optimal conditions for enzyme action throughout the body, as well as
all cell functions. It is the maintenance of a constant internal environment despite changes in
internal and external conditions. In the human body, these include the control of: blood
glucose concentration

25. REFERENCE
https://www.scientificamerican.com/article/what-is-homeostasis/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3212030/
https://www.sciencedirect.com/topics/medicine-and-dentistry/homeostasis
https://hal.sorbonne-universite.fr/hal-01235789v2/document
https://www.pnas.org/doi/10.1073/pnas.1011086107