Homeostasis and Regulation in the Human Body

These flashcards cover key concepts related to homeostasis and regulation in the human body, including feedback systems, thermoregulation, and glucose regulation.

What is homeostasis?

The process of keeping the environment inside the body fairly constant.

How do homeostatic mechanisms benefit the body?

They help maintain independence from external environmental changes.

What is a dynamic equilibrium in the context of homeostasis?

A state where input and output of materials are balanced, allowing for changes while maintaining stability.

Which body systems contribute to homeostasis?

The nervous and endocrine systems.

What type of feedback do the nervous and endocrine systems operate through for homeostasis?

Negative feedback systems.

What does negative feedback do in homeostasis?

It reduces or eliminates the stimulus that caused it.

What is a steady state control system?

A negative feedback system that returns the body to a steady state.

Define set point in homeostasis.

The point around which the conditions fluctuate.

What are tolerance limits?

Upper and lower limits between which levels fluctuate normally.

Give an example of a process that uses positive feedback.

Blood clotting and release of oxytocin during childbirth.

What is the primary response of positive feedback?

It reinforces and intensifies the stimulus.

How does the body regulate blood glucose?

Through the release of insulin and glucagon by the pancreas.

Why is it important to regulate blood glucose?

Cells require a constant supply of glucose for energy.

What is cellular respiration?

The process by which glucose and oxygen are converted into carbon dioxide, water, and energy (ATP).

What happens to glucose levels after a meal?

They rise sharply and homeostatic mechanisms begin to regulate them.

What form is glucose stored in the body?

As glycogen.

Where is glycogen predominantly stored?

About 100g in the liver and 400g in skeletal muscles.

What role does the liver play in blood glucose regulation?

It absorbs nutrients from digested food and regulates blood glucose levels.

What is the function of beta cells in the pancreas?

They release insulin in response to high blood glucose levels.

What do alpha cells in the pancreas do?

They release glucagon in response to low blood glucose levels.

What does lipogenesis refer to?

The conversion of glucose into fats (lipids) for storage.

What term describes the breakdown of glycogen to glucose?

Glycogenolysis.

What is thermoregulation?

The process of regulating body temperature within its tolerance limits.

What is the optimal temperature for human cellular metabolism?

Approximately 37ºC.

What happens if the body temperature exceeds normal levels?

It can cause nerve malfunction, denaturation of proteins and death

What are thermoreceptors?

Receptors that detect changes in temperature.

What is the effect of vasodilation on body temperature?

It increases heat loss by widening blood vessels in the skin.

What occurs during vasoconstriction?

Blood vessels narrow to reduce heat loss when body temperature decreases.

How does sweating help regulate temperature?

Sweating cools the body down through evaporation, increasing heat loss.

How does exercise affect metabolic rate?

It significantly increases metabolic rate due to higher muscular activity. (up to 40x normal rate)

What is the effect of stress on metabolic rate?

It can increase metabolic activity significantly, but usually for a short duration.

What hormonal response occurs during decreased body temperature?

Increased secretion of thyroid hormones like thyroxine to boost metabolic rate.

What is the consequence of heat stroke?

It can be fatal as it affects brain cell function due to extreme body temperatures.

What is the difference between heat stroke and heat exhaustion?

Heat stroke occurs from inability to remove heat, while heat exhaustion involves a drop in blood plasma volume leading to faintness.

Which system detects changes in body temperature?

The thermoregulatory center in the hypothalamus.

What is the result of a high fever on metabolic rate?

It can nearly double the metabolic activity.

What processes occur in response to glucagon?

Glucagon promotes glycogenolysis (the breakdown of glycogen to glucose), gluconeogenesis (the production of glucose from non-carbohydrate sources), and inhibits lipogenesis (the storage of fat).

What processes occur in response to insulin?

Insulin promotes lipogenesis (the storage of fat), glycogenesis (the formation of glycogen from glucose), and protein synthesis, while inhibiting gluconeogenesis and glycogenolysis.

What is the effect of cortisol release?

Cortisol increases blood sugar through gluconeogenesis, suppresses the immune response, and aids in the metabolism of fats, proteins, and carbohydrates.

What are behavioral responses to increased temperature?

Behavioral responses include seeking shade, drinking water, reducing activity levels, and wearing lighter clothing.

What are behavioral responses to decreased temperature?

Behavioral responses include seeking warmth, wearing heavier clothing, huddling for warmth, and increasing physical activity.

What are hormonal responses to increased temperature?

Hormonal responses include increased sweating and vasodilation due to the release of heat-dissipating hormones.

What are hormonal responses to decreased temperature?

Hormonal responses include increased metabolic rate and production of thermogenic hormones like thyroid hormones to generate heat.

What is vasodilation?

Vasodilation is the widening of blood vessels, which increases blood flow to the skin and helps dissipate heat during elevated body temperatures.

What is vasoconstriction?

Vasoconstriction is the narrowing of blood vessels, which reduces blood flow to the skin and preserves body heat during decreased body temperatures.

What is the role of sweating in temperature regulation?

Sweating helps cool the body through evaporative cooling, as sweat evaporates off the skin's surface, reducing body temperature.

What is the physiological response of shivering in temperature regulation?

Shivering involves rapid involuntary contractions of skeletal muscles, generating heat to raise body temperature during cold exposure.

What is the response of thyroxine to an increase in temperature?

Stimulus: Increased body temperature;
Receptor: Peripheral heat thermoreceptors in the skin and hypothalamus;
Modulator: Hypothalamus release TSHrf which stimulates the release of TSH from anterior pituitary gland;
Effector: Thyroid gland releases less thyroxine; Response: Decreased metabolic rate and heat production.

What is the response of thyroxine to a decrease in temperature?

Stimulus: Decreased body temperature;
Receptor: Peripheral cold thermoreceptors in the skin and hypothalamus;
Modulator: Hypothalamus releases TSHif which stops the release of TSH from anterior pituitary gland; Effector: Thyroid gland releases more thyroxine; Response: Increased metabolic rate and heat production.

How does adrenaline/noradrenaline respond to a decrease in body temperature?

Stimulus: Decreased body temperature;
Receptor: Peripheral cold thermoreceptors in skin/mucous membranes + central thermoreceptors in hypothalamus;
Modulator: Hypothalamus stimulates Adrenal Medulla via activating sympathetic nervous system;
Effector: Adrenal medulla releases adrenaline/noradrenaline;
Response: Increased metabolic rate and heat production, leading to heat conservation.