Insulin and Glucose Regulation

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Questions and Answers

What happens to blood glucose concentration between meals in a person with untreated diabetes?

It fluctuates randomly

It decreases steeply (correct)

It remains constant

It increases rapidly

What is a possible consequence of dehydration, salt loss, and low blood pH in extreme situations?

Coma (correct)

Hypoglycaemia

Diabetes

Hyperglycaemia

What is hyperglycaemia associated with?

Stem cell therapy

Ketoacidosis (correct)

Hypoglycaemia

Diabetes

What is the main difference between Type 1 and Type 2 diabetes treatment?

Insulin injections vs. diet control Signup and view all the answers

What is the goal of stem cell therapy in treating diabetes?

To form new beta cells that secrete insulin Signup and view all the answers

What is a characteristic of stem cells?

They are capable of cell division and forming specialised cells Signup and view all the answers

What is the primary function of the Hypothalamus-Pituitary-Thyroid Axis?

Regulation of metabolism Signup and view all the answers

What happens when thyroid hormone levels drop below the normal range?

Sensory neurons send nerve impulses to the hypothalamus Signup and view all the answers

What is the role of TRH in the HPT axis?

Stimulates the anterior pituitary to release TSH Signup and view all the answers

What is the effect of thyroid hormone on target cells?

Increases bioenergetics Signup and view all the answers

What is the result of thyroid hormone levels increasing in the blood and body tissues?

Thyroid hormone levels return to the normal range Signup and view all the answers

What is the role of TSH in the HPT axis?

Stimulates the thyroid gland to release thyroid hormone Signup and view all the answers

What type of feedback loop is formed when thyroid hormone levels return to the normal range?

Negative-feedback loop Signup and view all the answers

What is the outcome of the negative-feedback loop in the HPT axis?

Maintenance of normal thyroid hormone levels Signup and view all the answers

What is the main function of insulin in the body?

To stimulate cells to absorb glucose from the blood Signup and view all the answers

Where are insulin receptors found in the body?

In many cells, including liver, muscle, and adipose tissue Signup and view all the answers

What is the result of insulin stimulating cells with receptors?

Decrease in glucose concentration in the blood Signup and view all the answers

How does insulin affect cells?

Indirectly, through the mediation of intracellular messengers Signup and view all the answers

What type of protein is involved in glucose transport into cells?

GLUT protein Signup and view all the answers

What is the effect of insulin on GLUT4 proteins in muscle cells?

It stimulates the movement of GLUT4 proteins to the cell surface Signup and view all the answers

What is the effect of glucokinase on glucose?

It phosphorylates glucose, trapping it inside cells Signup and view all the answers

What is the result of insulin stimulating the activation of glycogen synthase and phosphofructokinase?

Addition of glucose molecules to glycogen Signup and view all the answers

What is the term for the increase in body temperature due to the production of heat?

Calorigenic effect Signup and view all the answers

What is the main function of the hypothalamus in the brain?

To regulate body temperature Signup and view all the answers

What is the hormone that stimulates the thyroid gland to produce triiodothyronine and thyroxine?

Thyroid Stimulating Hormone (TSH) Signup and view all the answers

What is the result of too much T3 and T4 in the body?

A decrease in body temperature Signup and view all the answers

What is the term for the process of controlling body temperature?

Thermoregulation Signup and view all the answers

Which part of the brain is responsible for regulating body temperature?

Hypothalamus Signup and view all the answers

What is the role of the anterior pituitary gland in thermoregulation?

To stimulate the thyroid gland Signup and view all the answers

What is the result of negative feedback in thermoregulation?

A decrease in body temperature Signup and view all the answers

What is homeostasis?

The process of maintaining a constant internal environment Signup and view all the answers

Which of the following is NOT a physiological factor controlled in mammals through homeostasis?

Hair growth Signup and view all the answers

What is the role of the hypothalamus in homeostasis?

To regulate hormone production Signup and view all the answers

What is the term for the process by which the body responds to changes in the internal environment?

Negative feedback Signup and view all the answers

What is the main function of the pituitary gland in homeostasis?

To regulate hormone production Signup and view all the answers

What is the primary function of thermoregulation in mammals?

To maintain a constant body temperature Signup and view all the answers

What is the role of glucagon in blood glucose regulation?

To increase blood glucose levels Signup and view all the answers

What is the main difference between type 1 and type 2 diabetes?

Type 1 is caused by insulin deficiency, while type 2 is caused by insulin resistance Signup and view all the answers

Study Notes

Insulin Regulation

Insulin is carried to all parts of the body through the blood.
Insulin receptors are found on many cells, including those in the liver, muscle, and adipose (fat storage) tissue.
Insulin stimulates cells with these receptors to:
Increase the rate of glucose absorption from the blood
Convert glucose into glycogen
Use glucose in respiration
This results in a decrease in the concentration of glucose in the blood.

Glucose Transport

Glucose can only enter cells through transporter proteins known as GLUT.
There are several types of GLUT proteins, including:
GLUT4 (found in muscle cells)
GLUT1 (found in brain cells)
GLUT2 (found in liver cells, which are always on the cell surface membrane)
When insulin binds to receptors on muscle cells, vesicles with GLUT4 proteins are moved to the cell surface membrane, facilitating the movement of glucose into the cell.

Insulin's Effect on Glucose Metabolism

Insulin stimulates the activation of the enzyme glucokinase, which phosphorylates glucose, trapping it inside cells.
Insulin also stimulates the activation of two other enzymes, phosphofructokinase and glycogen synthase, which together add glucose molecules to glycogen, increasing the size of glycogen granules inside the cell.

Decrease in Blood Glucose

α cells and β cells in the Islets of Langerhans detect decreases in blood glucose levels.

HPT Axis: Thyroid Regulation

The Hypothalamus-Pituitary-Thyroid Axis (HPT axis) is part of the neuroendocrine system responsible for regulating metabolism.
The HPT axis depends on three organs: the hypothalamus, the anterior pituitary gland, and the thyroid gland.
The sequence of events in the HPT axis is:
1. Thyroid hormone levels drop below the normal range.
2. Sensory neurons respond by sending nerve impulses to neurosecretory cells in the hypothalamus.
3. Neurosecretory cells secrete thyrotropin-releasing hormone (TRH) into the blood, which carries it to the anterior pituitary.
4. TRH causes the anterior pituitary to secrete thyroid-stimulating hormone (TSH) into the circulatory system.
5. TSH stimulates endocrine cells in the thyroid gland to secrete thyroid hormone (T3 and T4) into the circulatory system.
6. Thyroid hormone levels increase in the blood and body tissues, acting on target cells to control:
Bioenergetics (e.g., increase metabolism)
Maintain normal blood pressure, heart rate, and muscle tone
Regulate digestive and reproductive functions 7. As thyroid hormone levels return to the normal range, they block TRH release from the hypothalamus and TSH release from the anterior pituitary, forming a negative-feedback loop that prevents overproduction of thyroid hormone.

Homeostasis

Homeostasis is the maintenance of a stable internal environment for life functions.
Physiological factors controlled in mammals include:
Core body temperature
Metabolic wastes (e.g., carbon dioxide and urea)
Blood pH
Blood glucose concentration
Water potential of the blood
Concentrations of respiratory gases (oxygen and carbon dioxide)

Thermoregulation

Thermoregulation is the control of body temperature.
This involves both coordination systems – nervous and endocrine.
The hypothalamus in the brain is the central control for body temperature.
The hypothalamus actively monitors temperature of the blood and the temperature of the surroundings.

Diabetes Mellitus

Diabetes mellitus is characterized by high blood glucose levels (hyperglycaemia) and associated with ketoacidosis.
In untreated diabetes, blood glucose concentration may decrease steeply between meals, leading to:
No glycogen storage
Lack of glucose for respiration
Coma in extreme situations

Treating Diabetes

There is no cure for diabetes.
Type 1 diabetes treatment involves:
Monitoring blood glucose levels
Taking insulin injections
Most common form of insulin is now GM insulin
Type 2 diabetes treatment involves:
Well-controlled diet/weight loss diet

Stem Cell Therapy

Stem cells are undifferentiated cells capable of cell division and forming specialized cells.
Transplanting stem cells into a pancreas that has no functioning beta cells can persuade these cells to form new beta cells that can secrete insulin.
Stem cells can also be used to produce white blood cells that do not attack the beta cells in the pancreas.

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Description

This quiz covers the role of insulin in regulating blood glucose levels, including its transportation and reception in the body, and its effects on glucose absorption and storage.