Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

4 Clinical Physiology > L4 Metabolic Regulation > Flashcards

L4 Metabolic Regulation Flashcards

1
Q

Absorptive state

A

period when ingested nutrients are entering the blood from the GI tract, occurs DURING meal digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Postabsorptive state

A

period when the GI tract is empty of nutrients, therefore energy must be supplied from catabolism of body stores

normal blood glucose concentration must be maintained

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True fasting

A

no food for 24 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Digestion

A

not equivalent to absorption

breakdown of food into molecules small enough to be absorbed, accomplished by enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Absorption

A

movement of food molecules from the GI tract into the blood

digestion occurs before absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Carb & Protein absorption

A

breakdown of these products are absorbed by the GI tract directly into the blood, circulates to the liver via the portal vein and then into systemic circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Fat absorption

A
  1. ingested fats are emulsified by bile salts
  2. gut cells transform fats into chylomicrons
  3. Travel to the blood via lymph system, end up in adipose and muscle
  4. Broken down into FFA and chylomicron remnant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Chylomicrons

A

enable fats to move within the aqueous environment of blood

travel through lymph vessels/lacteals to use lymph to enter the blood via the thoracic duct

chylomicron remnants become VLDLS to be resecreted into the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens to absorbed glucose

A

Enters cells to become ATP if energy is needed

Energy not needed: make fat or make glycogen in muscle and liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to glucose in the liver?

A
  1. Made into glycogen
  2. Processed to form triglycerides
  3. MOST is packaged to form VLDLs, which are then stored as triglycerides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

VLDLs and Triglyceride storage

A

VLDL is made of cholesterol and triglycerides

Adipose tissue contains lots of lipoprotein lipase, which breaks down VLDL

VLDL becomes fatty acid and monoglyceride (remains in blood and are metabolized by liver)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to absorbed triglycerides?

A

absorbed fat becomes stored fat

Comes from the chylomicrons that transfer FFA to adipose tissue

lipoprotein lipase breaks down these into FFA, monoglycerides, chylomicron remnants.

absorbed fat from your food becomes stored as fat in adipose tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens to absorbed amino acids?

A
  1. Majority are taken up by cells for protein synthesis
  2. Others enter the liver to make liver proteins, plasma proteins, or keto acids
  3. Protein only replaces protein that was lost in postabsorptive state
  4. Any excess becomes stored as fat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Summary of absorptive state

A
  1. most of cells energy needs are provided by absorbed glucose
  2. Some glucose is stored as glycogen in liver and skeletal, most excess is stored as fat
  3. There is a net uptake of glucose by the liver
  4. Synthesis of body proteins, much of dietary protein is used for energy or converted to fat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

As the absorptive state ends…

A

net synthesis ceases
net catabolism begins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Events that maintain normal blood glucose during postabsorptive state

A
  1. Processes that provide sources of blood glucose (Glycogenolysis, Gluconeogenesis from fat or protein)
  2. Increased fat utilization, which spares glucose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Glycogenolysis

A

from liver directly
muscle only indirectly via cori cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Gluconeogenesis

A

pyruvate, lactate, glycerol, amino acids

from fat = only glycerol

from protein = few hours into postabsorptive state, AA become source of blood glucose. large quantities of protein can be catabolized from muscles if needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Glucose sparing

A

Includes all processes that enable to utilize fat for energy vs glucose in postabsorptive state, accelerated lipolysis is necessary

Most tissues use GLUCOSE in absorptive state
Most tissues use FAT in post absorptive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Summary of postabsorptive

A
  1. Glycogen, fat, protein anabolism are curtailed, net catabolism begins
  2. Glucose is formed by glycogenolysis and gluconeogenesis
  3. Accelerated lipolysis releases FFA into blood, through beta oxidation, and ketones
  4. Brain uses glucose and ketones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Hormonal regulation of metabolsim

A

The most important regulators with respect are 2 peptide hormones, both produced and released from islets of langerhans in pancreas

insulin = beta
glucagon = alpha

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Insulin

A

anabolic hormone of absorptive state

Secretion INCREASES during absorptive
Secretion DECREASES during postabsorptive

has two actions, metabolic and growth-promoting effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Metabolic effects of insulin

A

effects on carbohydrates, lipid, and protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What occurs after a meal?

A
  1. Plasma glucose concentration rises, stimulates insulin secretion from beta pancreatic cells
  2. Insulin is released into the blood and binds to muscle, fat, and liver cells, resulting in glucose being taken up
  3. Insulin inhibits gluconeogenesis in the liver
  4. Blood glucose level decreases, which serves as a negative feedback signal
25
Q

GLUT4 transporters

A

when insulin binds to its receptor, signal transduction pathway leads to movement of glucose transporters from inside of cell to surface of cell

GLUT4 transporters move glucose from blood into the cell

the more glucose transporters in the cell membrane, the more glucose that can be taken up by the cell

26
Q

What stimulates insulin release?

A

high blood glucose
high blood amino acid
activation of parasympathetic nerves to islets
peptides secreted from GI tract due to eating

27
Q

What inhibits insulin secretion?

A

activation of sympathetic nerves to islets
and/or increase in circulating epinephrine

28
Q

Glucagon

A

hormone of the postabsorptive state
overall effect of glucagon is to increase plasma glucose concentration
main target organ is the liver

29
Q

Main effects of glucagon

A

increases glycogen breakdown
increases gluconeogenesis
promotes ketone synthesis

30
Q

Plasma concentrations in the postabsorptive state

A

plasma glucose is low
glucagon is high
insulin is low

31
Q

Regulators of glucagon secretion

A

Low blood glucose concentration is the major stimulus

sympathetic innervation to islets stimulates glucagon secretion

circulating epinephrine stimulates glucagon secretion

32
Q

What’s happening when you become hypoglycemic?

A

Glucagon secretion and activation of the SNS
hormonal and neural responses

insulin is low, glucagon is high
hypothalamus mediates the response

increased SNS causes increased glycogenolysis, gluconeogensis, lipolysis
increase in plasma glucose, fatty acids, glycerol

33
Q

Additional hormones that regulate metabolism

A

Cortisol and Growth hormone

their secretion is not strictly tied to transition between absorptive and postabsorptive states

both produce actions that are opposite to insulin, they both increase blood glucose levels

34
Q

Cortisol

A

many metabolic reactions cannot occur unless a small amount of cortisol is present

cortisol is necessary to maintain necessary concentrations of enzymes required for gluconeogensis and lipolysis

cortisol also plays a role in counter regulatory mechanisms that protect against hypoglycemia

35
Q

What does cortisol do?

A

it is catabolic
increases protein catabolism
increases fat catabolism
increases gluconeogenesis

net result = increased plasma concentration of AA, glucose, FFA = fuel in the blood!

36
Q

Growth hormone

A

stimulate growth and protein synthesis

has minor effects on metabolism, severe changes in amounts affects carb/lipid metabolism

can increase gluconeogenesis, reduces isulins ability to promote glucose uptake

37
Q

Counter-regulatory hormones

A

hormones that have effects opposite to insulin

glucagon, cortisol, growth hormone, epinephrine

they are the ones that save your life during times of fasting, because they raise plasma glucose levels

38
Q

Similarities in Postabsorptive and Exercise state

A

Both have an increase in SNS, increased levels of glucagon, cortisol, GH, low plasma insulin

39
Q

Fuel during exercise

A

during exercise, large quantities of fuel must be mobilized to provide energy for muscle contraction

major sources are plasma glucose and FFA, muscle glycogen

40
Q

Plasma glucose during exercise

A

SHORT TERM: remains unchanged for 50 min

LONG TERM: falls about 25% 4 hrs

41
Q

Plasmas Concentrations during exercise

A

Glucagon–> increases with a trigger of low glucose

Insulin–> preprogrammed actions, preparing for the changes in the body

Lipolysis is increasing as this is happening

42
Q

Changes during exercise

A
  1. All exercise intensities cause SNS activity increases and circulating epinephrine increases
  2. These changes are independent of blood glucose levels, they are a part of preprogrammed response to exercise
  3. During prolonged exercise, hypoglycemia stimulates glucagon secretion
  4. Exercise inhibits insulin secretion
43
Q

What is the time course of fuel utilization during mild/moderate intensity exercise?

A
  1. During a brief period of moderate exercise, energy is derived from carbs and lipids equally
  2. As exercise continues, glycogen decreases, blood glucose becomes main source
  3. With increasing time, glucose utilization may outpace gluconeogensis and glycogen stores are depleting. Hypoglycemia is what triggers glucaogn secretion
  4. After 1 hr, gradual increase in utilization of lipid for energy
44
Q

Lipid utilization during exercise

A

increases as exercise duration increases
during 1st 40-90 min = 40% of energy comes from FFA
by 4th hour of exercise, lipid is 62%
Very long exercise , FFA supplies 80%

45
Q

Hitting the wall

A

-glycogen depleted state
-work capacity progressively decreases
-due to a slower rate of energy released from lipid, compared to carb catabolism

S/S: weakness, fatigue, dizziness

46
Q

Techniques to prevent hitting the wall

A
  1. Consume carbs during exercise
  2. Consume carbs before exercise
  3. Decrease exercise intensity
47
Q

Consume carbs before exercise

A

Helps to maximize initial glycogen levels in muscles

includes combo of increasing complex carb intake and decreasing training intensity during few days before event

recommended for events that last more than 60-90min

48
Q

Decrease exercise intensity

A

Lowers total energy requirements
also lowers the percentage of energy that comes from glycogen

49
Q

Lipid and exercise intensity

A

Lipid utilization increases as exercise intensity decreases
-Mild exercise intensities have main source as lipids
-

50
Q

Lipid and training

A

Lipid utilization increases as training increases

more aerobically trained individuals use more plasma FFA and conserve glycogen stores

Why? have increased # of enzymes involved in FFA use, improve transport of FFA through membrane, proliferation of capillaries in trained muscle

51
Q

Immediate energy…

A

ATP-CP system
walking briskly for 1 min
all out exercise for 6 sec

uses Stored ATP

52
Q

Short term energy…

A

anaerobic glycolysis
all out exercise for 1-2 minutes

uses blood glucose

53
Q

Long-term energy…

A

aerobic metabolism
prolonged exercise

uses kreb cycle

54
Q

Short-term energy transfer system

A

Provided by anaerobic glycolysis and lactate production

allows for rapid ATP formation, not as fast as ATP-CP

has a power output of 45% of the immediate energy system

55
Q

Blood lactate accumulation

A

Most rapid and highest lactate levels are reached during 1-2 minutes of all out exercise

lactate is formed continuously at rest and during exercise

in aerobic, lactate production rate matches lactate removal rate

blood lactate rises exponentially at 55% of healthy untrained VO2 max

56
Q

Aerobic conditioning and lactate levels

A

Lactate marks anaerobic system uses or the limit of aerobic production of ATP

Aerobic conditioning causes:
1. production of less lactate
2. increased rate of lactate removal
3. increased capillarization
4. Increased mitochondrial density
5. Increased concentration of enzymes
6. Increased intramuscular glycogen stores

57
Q

Factors related to lactate threshold

A

low tissue O2
reliance on glycolysis
activation of fast-twitch muscle fibers
reduced lactate removal

58
Q

Long-term energy system

A

source is aerobic metabolism
-O2 uptake rises exponentially during first minute of moderate exercise
-plateaus to reach steady state
-theoretically, you can continue indefinitely at this level

59
Q

Steady-state

A

balance between energy requirements and ATP production by aerobic metabolism
lactate produced is oxidized

4 Clinical Physiology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions