Human Physiology Week 3 - Metabolism (Transcripts)

Questions and Answers

What is the primary function of ATP in the body?

To serve as the universal currency of energy. (correct)

To act as a chemical messenger.

To build muscle tissue.

To store long-term energy.

Which pathway is primarily used for quick, instantaneous energy needs?

Aerobic metabolism.

Adenylate kinase pathway. (correct)

Glycolytic pathway.

Creatine phosphate pathway.

For activities lasting up to ten seconds, which method is most effective for ATP production?

Adenylate kinase pathway.

Creatine phosphate pathway. (correct)

Glycolytic pathway.

Aerobic metabolism.

Which pathway is commonly used to produce ATP during exercises up to about two minutes in duration?

Glycolytic pathway. Signup and view all the answers

What is the common intermediate produced in aerobic metabolism for energy production?

Acetyl-CoA. Signup and view all the answers

What is produced when phosphocreatine is combined with ADP?

Creatine and ATP Signup and view all the answers

Which process occurs in the absence of oxygen?

Glycolysis Signup and view all the answers

What is the end product of glycolysis?

Pyruvate and ATP Signup and view all the answers

What is the primary function of the aerobic pathway?

Generate large amounts of ATP Signup and view all the answers

Which molecule is essential for the initiation of the aerobic pathway?

Acetyl-CoA Signup and view all the answers

Where does glycolysis take place within the cell?

Cytoplasm Signup and view all the answers

Which of the following can be converted into Acetyl-CoA for ATP generation?

Fatty acids Signup and view all the answers

What is the primary storage form of glucose in the body?

Glycogen Signup and view all the answers

How much energy does one gram of fat provide compared to carbohydrates?

Nine calories Signup and view all the answers

How long could 10 kilograms of excess fat theoretically provide ATP for a starving person?

40 days Signup and view all the answers

Which statement is true regarding muscle energy during exercise?

Fat is available for muscle contraction during exercise. Signup and view all the answers

What is the total amount of glycogen stored in the liver approximately?

100 grams Signup and view all the answers

Which macronutrient provides the least amount of energy per gram?

Carbohydrates Signup and view all the answers

Approximately how many grams of glucose can the body utilize at once for energy?

20 grams Signup and view all the answers

What is a likely consequence of having excess body fat?

Increased reserve of energy for survival. Signup and view all the answers

Which process is primarily used for the breakdown of liver glycogen?

Glycogenolysis Signup and view all the answers

What is the primary process for breaking down glycogen into glucose?

Glycogenolysis Signup and view all the answers

What promotes the uptake of glucose into muscle and adipose tissue?

Insulin Signup and view all the answers

What does gluconeogenesis refer to?

The formation of new glucose Signup and view all the answers

What is the main issue in Type 1 diabetes?

Insufficient insulin production Signup and view all the answers

What leads to sweet-smelling urine in diabetes?

Excessive glucose in urine Signup and view all the answers

What is the typical condition of insulin levels in Type 2 diabetes?

High insulin levels are ineffective Signup and view all the answers

What measurement indicates a normal fasting blood glucose level?

Under 100 mg/dL Signup and view all the answers

Which hormone is primarily responsible for increasing glucose production in the liver during exercise?

Glucagon Signup and view all the answers

What is the primary reason for elevated blood glucose levels in Type 2 diabetes?

Inadequate insulin response in target tissues Signup and view all the answers

Study Notes

ATP Production and Pathways

ATP (adenosine triphosphate) serves as the universal energy currency in the body, powering cellular functions like muscle contraction and nerve signaling.
Continuous ATP production is essential due to constant ATP usage.
Four main pathways generate ATP based on energy needs:
- Adenylate Kinase Pathway: Converts ADP to ATP for immediate energy bursts.
- Creatine Phosphate Pathway: Provides energy for short bursts (up to 10 seconds), crucial for activities like sprints.
- Glycolytic Pathway: Uses glucose/glycogen to produce ATP quickly for activities lasting about 2 minutes.
- Aerobic Metabolism: Involves oxidative phosphorylation and electron transport chain, utilizing glucose/glycogen or fatty acids to produce large amounts of ATP.

Anaerobic and Aerobic Pathways

Anaerobic Pathways: Function without oxygen.
- Creatine Phosphate Reaction: ADP receives a phosphate from creatine phosphate, producing ATP and creatine.
- Glycolysis: Breaks down glucose/glycogen into pyruvate, generating 2-3 ATP molecules in the cytoplasm.
Aerobic Pathway: Requires oxygen and takes place in mitochondria.
- Converts pyruvate or fatty acids to acetyl-CoA, followed by the Krebs cycle and electron transport chain, producing a significant amount of ATP.

Energy Storage in the Body

The body has limited immediate glucose reserves (about 20 grams) that support roughly one hour of energy.
Glycogen: Stored primarily in the liver (100 grams) and muscles (200 grams), serves as a critical reservoir of glucose.
Fat Storage: More energy-dense than carbohydrates; about 250 grams of fat can provide approximately 2,000 calories, while 500 grams of glucose would equal the same caloric energy.
Carbohydrates and proteins yield about 4 calories per gram, while fats provide around 9 calories per gram.

Glucose Metabolism and Regulation

Glucose in the bloodstream originates from dietary intake and liver glycogen stores.
Glycogenolysis: Breakdown of glycogen to glucose in the liver.
Gluconeogenesis: Formation of new glucose from non-carbohydrate sources (e.g., proteins).
Insulin promotes glucose uptake in muscles and adipose tissues, while epinephrine stimulates glucose production in the liver during exercise.

Diabetes and Metabolic Diseases

Type 2 Diabetes Mellitus: Common metabolic disease characterized by high blood glucose levels. Excess glucose in urine gives it a sweet taste.
Type 1 Diabetes Mellitus: Often occurs in early life due to autoimmune destruction of insulin-producing cells in the pancreas, resulting in insufficient insulin production.
In Type 2 diabetes, insulin is present, but the body's response to it is impaired, often due to less sensitive insulin receptors or reduced receptor numbers, leading to elevated blood glucose levels.### Understanding Type 2 Diabetes Mellitus
Normal fasting blood glucose level is under 100 mg/dL; levels above indicate potential diabetes.
Type 2 diabetes can cause fasting blood glucose levels to rise significantly, often exceeding 200 or even 300 mg/dL.
Excess glucose persists in the bloodstream, affecting various body cells, including blood vessel linings.

Effects of Elevated Glucose

High glucose levels cause glycosylation, triggering biochemical changes in cell membranes of blood vessels and red blood cells.
Chronic excess glucose leads to vascular damage and increased inflammation, setting the stage for atherosclerosis.
Atherosclerosis results in blood vessels becoming sticky and bumpy, increasing risks of heart attacks (myocardial infarction) and strokes.

Complications Associated with Type 2 Diabetes

Vascular damage from diabetes can restrict blood flow, leading to peripheral neuropathy and retinal neuropathy, potentially causing blindness.
Diabetes is correlated with various morbidities due to the vascular changes caused by prolonged high glucose levels.

Symptoms and Early Indicators

Key signs of diabetes include polyuria (excessive urination) and polydipsia (excessive thirst).
Polyuria occurs because glucose in urine attracts extra water, leading to increased urination and subsequent thirst.

Diagnostic Testing

Fasting glucose levels are essential for diagnosing Type 2 diabetes and for ongoing management.
HbA1C test measures glycosylated hemoglobin, reflecting average blood glucose levels over the past 4 to 6 weeks.
Higher HbA1C levels indicate more prolonged high glucose exposure, while lower levels suggest better glucose control.

Pre-diabetes

Defined as fasting blood glucose levels between 100 mg/dL and 125 mg/dL, indicating a risk of progressing to Type 2 diabetes.
Impaired glucose tolerance may be observed, where blood glucose spikes after meals despite normal fasting levels.
This state signals increasing insulin resistance, suggesting the need for lifestyle changes, including improved diet and increased physical activity.

Importance of Lifestyle Intervention

Early intervention during the pre-diabetic stage can delay or potentially reverse the onset of Type 2 diabetes.
Emphasis on a healthy lifestyle is crucial for preventing the progression of glucose intolerance to diabetes.

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