33.3 Homeostasis

• The cells that make up the nervous tissues are specialized to receive and send electrical impulses from one area of the body to another.
• The cell body of the neuron is the large structure with a central nucleus.
• Projections from the cell body are either dendrites or a single axon.
• Some glial cells are shown.
• Astrocytes regulate the chemical environment of the nerve cell, and oligodendrocytes insulate the axon so the electrical nerve impulse is transferred more efficiently.
• glial cells that aren't shown support the nutrition and waste requirements of the neuron

• The glial cells remove debris from the tissue.
• A nerve is made of cells.

• There are projections called dendrites that receive signals and projections called axons that send signals in the neuron.
• There are two types of glial cells that insulate the axon and regulate the chemical environment of the nerve cell.

• Click through the interactive review to learn more about the tissues.

• A Pathologist is a doctor who specializes in the detection of diseases in animals and humans.
• Medical school education is followed by an extensive post-graduate residency at a medical center.
• The evaluation of body tissue and blood samples for the detection of disease can be done by a pathologist.
• They use a microscope to look for cancer and other diseases.

• Pathologists perform autopsies to determine the cause of death.

• By the end of this section, you will be able to discuss positive and negative feedback mechanisms used in homeostasis.
• The changes might be in the level of blood sugar or calcium in the body.

• It is constantly adjusting to the changes in the body's systems.
• Body functions are kept within certain ranges.
• This homeostatic equilibrium is maintained by an animal that is inactive.

• The body's systems try to go back to this point when there are normal fluctuations from the set point.
• The response of the system is to adjust the deviation parameter toward the set point when a change in the internal or external environment is detected.
• Changes are made to cool the animal if it becomes too warm.
• If the blood's sugar goes up after a meal, it's a good idea to get the nutrition into tissues that need it or to store it for later use.

• An adjustment must be made when there is a change in an animal's environment.
• In most cases, the brain sends a signal to the control center when the environment changes, which in turn signals an effector.
• The effector is a muscle that contracts or relaxes.
• Homeostatsis is maintained by negative feedback loops.
• Positive feedback loops may be necessary for life to occur.
• Homeostasis is controlled by mammals.

• It can either increase or decrease theStimulus, but it is not allowed to continue as it was before.
• If a level is too high, the body does something to bring it down, and if a level is too low, the body does something to make it go up.
• An example is the maintenance of blood sugar levels in animals.
• Blood sugar levels rise when an animal eats.
• The nervous system senses this.
• The hormones in the endocrine system are released by specialized cells in the pancreas.
• If an animal doesn't eat or have low blood sugar levels, the hormone glucagon is released in another group of cells in the pancreas, which causes the levels to increase.
• The control of blood calcium is an example of an increase as a result of the feedback loop.
• The breakdown of bone in order to liberate calcium is possible if calcium levels decrease because specialized cells in the parathyroid glands sense this and release parathyroid hormone.
• Blood levels of the element are raised by the effects of PTH.
• Negative feedback loops are the main mechanism used in the body.

• A negative feedback loop controls blood sugar levels.

• There are few examples of positive feedback loops in animal bodies, but one can be found in the cascade of chemical reactions that result in blood clotting.

• When one clotting factor is activated, the next factor in sequence is activated.
• This is positive feedback because the direction is not changed.
• The contraction of the uterus is stimulated by the hormone oxytocin.
• This causes pain to be felt by the nervous system.
• Instead of causing the pain to go away, more oxytocin is produced until the baby is born.

• Positive feedback is what leads to the birth of a human infant.

• The following processes are regulated by a positive or negative feedback loop.

• A person feels happy after eating.

• There is a lot of red blood cells in the blood.
• Erythropoietin, a hormone that stimulates the production of new red blood cells, is no longer released from the kidneys.

• It's possible to change a system's set point.
• The feedback loop works to keep the new setting.
• Over time, the normal or set point for blood pressure can increase as a result of continued increases in blood pressure.
• The body no longer recognizes the elevation as normal and no attempt is made to return to the lower set point.
• Maintaining elevated blood pressure can have harmful effects on the body.

• The set point in the system can be lowered with medication.

• In order to maintain a set point in another system, changes can be made in a group of body organ systems.
• This happens when an animal migrates to a higher altitude than it is used to.
• The body increases the number of red blood cells in order to adjust to the lower oxygen levels at the new altitude.
• An example of acclimatization is an animal that has a heavier coat in the winter and a light coat in the summer to keep their body temperature from rising to harmful levels.

• If you want to understand feedback mechanisms, watch a short video lesson on positive and negative feedback loops.

• Body activities are affected by body temperature.
• As body temperature increases, the activity of the enzyme increases as well.
• The high heat of 50oC causes the body to denature and lose function.
• For every ten degree centigrade drop in temperature, the activity of the enzymes will decrease by half.
• Some fish can return to normal after being frozen solid.

• You can watch the Discovery Channel video on thermoregulation to see illustrations of the process in a variety of animals.

• Some animals have a constant body temperature in the face of differing environmental temperatures, while others have a body temperature that is the same as their environment.
• Animals rely on external temperatures to set their body temperature.
• The term cold-blooded may not apply to an animal in the desert with a very warm body temperature.
• Animals with constantly varying internal temperatures are called poikilotherms.
• A homeotherm is an animal that has a constant body temperature.
• Animals that rely on internal sources for body temperature maintenance are called endotherms.
• The animals are able to maintain a level of metabolism at cooler temperatures because of differing levels of activity.
• Some animals have relatively constant body temperatures due to the constant environmental temperatures in their habitats.
• These animals are similar to deep sea fish.

• Four mechanisms can be used to exchange heat between an animal and its environment.
• The emission of heat waves is called radiation.
• The heat comes from the sun and the heat comes from dry skin.
• Liquid can be removed from a surface.
• This happens when a mammal sweats.
• As the air passes over the dry skin, it removes heat from the surface.

• During direct contact with the surface, heat will be conducted from one surface to another.

• Four mechanisms can be used to exchange heat.
• There are a variety of ways animals conserve heat.
• Fur, fat, feathers, or some combination of these are some of the insulation animals have in certain climates.
• Animals with thick fur or feathers have an insulation layer between their skin and internal organs.
• The polar bears and seals live and swim in a warm environment.
• The fluffy tail of the arctic fox helps it sleep in cold weather.
• Small hairs stand up when the individual is cold because of the effect of arrector pili muscles, which causeose bumps.

• The same layers of fat are used by mammals.
• Losing body fat will affect an individual's ability to conserve heat.

• The body temperature can be maintained with the help of the circulatory systems.
• Vasodilation helps to cool the body by bringing more blood and heat to the surface.
• Vasoconstriction reduces blood flow in peripheral blood vessels, forcing blood to the core and the vital organs found there.
• Some animals have adaptions to their circulatory system that allow them to transfer heat from arteries to veins.
• The countercurrent heat exchange prevents the cold blood from cooling the heart and other internal organs.
• Some animals can be shut down to prevent overheating their internal organs.
• The adaption to countercurrents is found in many animals.
• Similar changes can help cool endotherms, such as dolphin ears.

• Some animals use changes in their behavior to regulate their body temperature.
• An animal in the desert may seek cooler areas during the hottest part of the day to keep from getting too warm.
• During a cold desert night, animals may climb onto rocks to capture heat.
• Some animals look for water to aid in cooling down.
• Bee activity is used to warm a hive to survive the winter.

• mammals use metabolic waste heat as a heat source Most of the energy used in muscle actions is wasted when the muscles are weakened.
• Cold causes the body to generate heat.
• Brown fat is a type of fat that is specialized in generating heat.

• The advanced animal brain is the center of the processes of temperature control and homeostasis.

• The body is able to regulate temperature.

• When leuckocytes destroybacteria, they release pyrogens into the blood.
• The body's thermostat is set to a higher temperature.

• The set point for body temperature is maintained by the hypothalamus through reflexes that cause sweating when the body is too warm or too cold.
• It responds to the body's chemicals.
• There are chemicals in the blood when a bacterium is destroyed.
• The hypothalamus can be used to reset the thermostat.
• This allows the body's temperature to go up.
• An increase in body temperature causes iron to be used less bybacteria.
• An increase in body heat increases the activity of the animal's protective cells and also increases the activity of the invading microorganisms.
• The pathogen may be killed by heat.
• A normal defense mechanism is believed to be the cause of a fever.

• There are different sizes and shapes of animal bodies.

• Four of the basic building blocks of complex animals are animal size and shape.
• These are combined to form organs.
• Their size and development are affected by Diffusion.

• Animals use and get energy from the skin and kidneys.
• Organs are organized according to their size, activity level, and environment.

• Epithelia, connective tissues, muscle tissues, and nervous tissues are the four primary tissues.

• It is in equilibrium because body functions are kept within a normal range, with some fluctuations around a Homeostasis being a dynamic equilibrium that is maintained in set point for the processes.

• A person feels happy after eating.

• Simple cells are involved in the b.
• There is a lot of red blood cells in the blood.

• Depending on how full the bladder is, Pyrogens reset.

• An animal is divided into equal right and left habitats by a plane.

• The name of the substance is Plasma.

• It confuses people.

• The animal can gather food from all sides.

• The movement in any direction is the type of muscle cell under voluntary control.

• The barriers between the cells are maintained by the discs.

• The type of cell found in the urinary beat is a single unit.

• There is a thermostat in the body.

• They are adjusting the timing of their activities.

• The size of animals is constrained by a bug.

How is a condition such as diabetes a good example of endotherms?

• If necessary, review it.

• The loss of insulation around neuron axons is a hallmark of multiplesclerosis.