1QQ# 4 for 10:30

1. Which cell type(s) have Glut-4 transporters?a) liver b) skeletal muscle c) adipose d) neurons

2. True or False: Excess amino acids are stored as glycogen in hepatocytes.

3. Which cell type(s) have insulin receptors?a) liver b) skeletal muscle c) adipose d) neurons

1QQ# 4 for 11:30

1. Which cell type(s) lack Glut-4 transporters?a) liver b) skeletal muscle c) adipose d) neurons

2. True or False: Excess amino acids are stored as triglycerides in adipocytes.

3. Which cell type(s) have insulin receptors?a) liver b) skeletal muscle c) adipose d) neurons

Fig. 16.01A

bsor

ptiv

e P

hase

Lipoprotein Lipase

Once inside, glucose is converted to something else, thereby maintaining a concentration gradientfor facilitated diffusion ofglucose into cells.

=“sinks”Entry requiresGlut-4 transporters

Stimulatory actions of insulin in green

Inhibitory actions of insulin in dashed red

?

The Integrator integrates multiple inputs

Glucose uptake, Storage, Lipogenesis

WHY? FF

Thinking about food, aroma,Factors that influence Insulin Secretion

and other Incretins

Fig. 16.02

Post-absorptive phase

Glucose SparingSpecial case:

Muscle wasting of starvation

Note: Nervous tissuecan use glucose and ketones

Special term:Glycogenolysis &Gluconeogenesis

Kidneys can convert amino acids to glucose!

The Issues

• How do cells “know” which fuel to “burn?”• How do cells “know” when to synthesize

glycogen and lipids and when to break down glycogen and lipids?

• What is responsible for the transitions from the absorptive and post-absorptive states?

Another hormone that regulates plasma glucose concentration

Glucagon prevails during post-absorptive phase

Transition from absorptive to post-absorptive phase?

Glucose-counterregulatory controls

(oppose effects of insulin)

Glucagon (target = hepatocytes)

Epinephrine (liver, adipocytes, skeletal muscle)Cortisol (permissive effect for liver, adipocytes, skeletal muscle)Growth hormone (permissive effect for liver, adipocytes, skeletal muscle)

Fig. 16.02

Post-absorptive phase

Glucose SparingSpecial case:

Muscle wasting of starvation

Note: Nervous tissuecan use glucose and ketones

Special term:Glycogenolysis &Gluconeogenesis

Kidneys can convert amino acids to glucose!

Insulin Receptor

Adrenergic Receptor

Cortisol Receptor

Glucagon Receptor

Fig. 16.10Don’t fret about receptors, afferent pathway, and integrator for this feedback loop.

Adrenergic receptor

Who Cares?

A Case Study of Glucose Homeostasis A 35 year old male presented with the following complaints: frequent severe headaches upon awakening at 4:30 am, blurred vision, and fatigue due to excessive stress at work. The patient complained of routine 16 hr workdays followed by a midnight snack of breakfast cereal.

An OGTT was ordered and provided the following results: During the second hour of the OGTT, the patient exhibited anxiety, paleness, hunger, tremulousness, and cold sweat. No additional tests were ordered.

The patient was instructed to replace the midnight snack of cereal with a protein-rich snack.

Oral Glucose Tolerance Test

• Overnight fast, no beverages other than water

• Fasting blood sample• Ingest 75 grams glucose• Blood samples every 0.5

hours for 3-5 hours• Plot plasma glucose

concentration over time• Compare curves Sugar content

of Red Bull?

60

Stress,Emergency (fight or flight)

Effect onBeta cells

Effect on Alpha Cells

The Answer to the Problem?

• Rationale for substituting protein for carbohydrate midnight snack?