Yr 12 Human Bio- Homeostasis

What form is sugar in the blood?

Glucose.

What is the main role of glucose in the body?

Glucose provides energy for cellular processes such as movement, reproduction, and synthesis of molecules.

How is energy released from glucose molecules?

Energy is released through cellular respiration, where glucose and oxygen produce carbon dioxide, water, and energy.

How are carbohydrates absorbed into the blood?

Carbohydrates are absorbed through the walls of the small intestine.

What is glycogen?

Glycogen is a long chain of glucose molecules stored in the liver and muscle cells.

What is the primary function of the liver in blood sugar regulation?

The liver converts glucose to glycogen for storage and converts glycogen back to glucose for release into the blood.

How does the liver receive its nutrient-rich blood?

The liver’s main supply comes from the hepatic portal vein.

What are the Islets of Langerhans and where are they located?

They are clusters of hormone-secreting cells located in the pancreas.

Which cells in the Islets of Langerhans secrete insulin and what is its effect?

Beta cells secrete insulin, which decreases blood sugar levels.

Which cells in the Islets of Langerhans secrete glucagon and what is its effect?

Alpha cells secrete glucagon, which increases blood sugar levels.

How does insulin lower blood sugar levels?

Insulin accelerates the transport of glucose into cells (especially skeletal muscles) and converts glucose into glycogen.

How does glucagon raise blood sugar levels?

Glucagon converts glycogen into glucose and stimulates gluconeogenesis to increase blood sugar levels.

What is glycogenesis?

Glycogenesis is the conversion of glucose into glycogen.

What is glycogenolysis?

Glycogenolysis is the breakdown of glycogen into glucose.

What is gluconeogenesis?

Gluconeogenesis is the production of new glucose molecules from fats and amino acids.

Besides its effect on glucose, what other process is stimulated by insulin?

Insulin also stimulates lipogenesis, the conversion of glucose into lipids, and increases protein synthesis.

What additional process does glucagon stimulate in the liver?

Glucagon stimulates gluconeogenesis, which produces glucose from non-carbohydrate substrates.

Which hormone is secreted by the adrenal medulla and what is its role in blood sugar regulation?

Adrenaline (and noradrenaline) are secreted by the adrenal medulla and promote glycogenolysis.

How does thyroxine affect blood sugar regulation?

Thyroxine increases absorption of glucose from the small intestine and increases cellular respiration, boosting glucose uptake.

What is the normal blood glucose level range?

The normal level of glucose in the blood is between 4 and 6 millimoles per litre.

Define homeostasis in the context of body regulation.

Homeostasis is the process of keeping the internal environment of the body fairly constant (steady state).

What is a negative feedback system?

A negative feedback system responds in a way that opposes the original stimulus to maintain stability.

What is meant by the term “set point” in homeostasis?

The set point is the ideal value around which the body’s parameters fluctuate.

What does the term “dynamic equilibrium” refer to?

It refers to any fluctuation around a normal level in the body’s internal environment.

How does a positive feedback system differ from a negative feedback system?

A positive feedback system reinforces and intensifies the stimulus rather than counteracting it.

What is thermoregulation?

Thermoregulation is the process of maintaining a stable body temperature, approximately 36.8°C.

How is most body heat produced?

Most heat is produced by cellular respiration during metabolic activity.

What are peripheral thermoreceptors and what is their function?

Peripheral thermoreceptors are located in the skin and mucous membranes

List the four methods of heat transfer involved in thermoregulation.

Conduction, convection, radiation, and evaporation.

How does sweating help in cooling the body?

Sweating releases water that evaporates, removing heat from the skin and cooling the blood.

What physiological changes help prevent heat loss in cold temperatures?

Vasoconstriction in the skin reduces blood flow and shivering increases heat production.

What physiological changes occur in hot temperatures?

In hot conditions, vasodilation increases blood flow to the skin and sweating increases to promote evaporative cooling.

What can result from a failure to maintain body temperature in extreme conditions?

In extremely hot conditions, heat exhaustion or heat stroke may occur

How do the adrenal glands affect blood sugar during stress?

The adrenal medulla secretes adrenaline (and noradrenaline) which promote glycogenolysis, and the adrenal cortex secretes cortisol which increases glycogenolysis and gluconeogenesis.

What role does the hepatic portal vein play in blood sugar regulation?

It carries nutrient-rich blood directly from the digestive organs to the liver, allowing the liver to regulate glucose levels.