unit 7 Flashcards
Define metabolism
Set of life-sustaining chemical transformations within the cells of living organisms
Transformations of energy substrates are biased towards ____ / _____ or _____ / _____
Storage/anabolism
Breakdown/catabolism
Regulation of metabolism can be _____ or _____
Endocrine
neural
Ingested biomolecules three possible fates
Fuel
Build
Store
The three types of nutrients that are immediately able to be used (because they are circulating in the plasma)
Glucose
Free fatty acids
Amino acids
The fed/absorptive state of metabolism focuses on _____, products of digestion being ____ and used for ______
Anabolic
Absorbed
Synthesis or are stored
The fasted/postabsorptive state of metabolism focuses on ______, the energy will come from ______
Catabolism
Body stores
In fed state metabolism under influence of ____, enzyme activity for forward reaction increases. Enzyme for ______ breakdown are inhibited.
Insulin
Glycogen
In fasted state metabolism under influence of ____, enzymes that break down _____ are more active. Enzymes for _____ synthesis are inhibited.
Glucagon
Glycogen
Glycogen
Fasted state go through ______ to create glucose-6-phosphate
Gluconeogenesis
Carbs are stored as glycogen in the ___ which can be broken down and exported as free glucose
Liver
Carbs are stored as glycogen in the ___ which can NOT be broken down and exported as free glucose
Muscle
Glycogen in the muscles are used ______ or exported as _______ to the liver to enter the ________ pathway
Within the muscles
Pyruvate/lactate
Gluconeogenesis
Triglycerides in ________ is exported as glycerol into the ____ to enter the _______ pathway
Adipose
Liver
Gluconeogenesis
Fats within the ________ is exported as _______ and undergo ___________
Adipose
Fatty acids
Beta oxidation
If ______ proceeds faster then acetyl CoA can be used in ____, ketone bodies are formed
Lipolysis
TCA cycle
Ketone bodies enter the blood and serve as energy for _______
The brain
Why are ketone bodies potentially dangerous?
They can disrupt the acid base balance in the body, acid base balance
The glucostatic theory of eating
Intake is regulated by glucose levels monitored by centers in the hypothalamus
The lipostatic theory
Signals from fat stores to brain modulate eating behaviours
Leptin was discovered in 1994. It is a _____ ______ synthesized in _________ tissue
Protein hormone
adipose
A mutation was identified in mice that caused over eating called the _____ gene
Ob
The mutation of leptin receptors discovered in mice was called the _____ gene
Db
Cells of empty stomach secrete _____ which causes an _____ in appetite
Ghrelin
Increase
When the stomach is stretched there is a _________ in acid which innervates acid sensing ion channels
Increase
In response to fat or protein in the lumen of the small intestine there is an increase in _____
CCK
To decrease appetite the lower small intestine has increased concentrations of ______ and _____ which inhibits the release of _________. Both of these are triggered by _________ in the lumen and a _______ from the upper small intestine
GLP-1
Peptide yy
Neuropeptide y
Macronurtients
Neural reflex
Neuropeptide y is a __________ in the ________ of appetite
Neurotransmitter
stimulation
Alpha cells secrete ______, d cells secrete _______, beta cells secrete _______
Glucagon
Somatostatin
insulin
______ transporters move glucose into ______ cells by facilitated diffusion
GLUT2
Beta
ATP causes potassium leak channels on beta cells to _____
Close
When blood glucose is high glucose will enter the cell and go through _______ and the _________ to create ATP
Glycolysis
Citric acid cycle
When the beta cells have high concentrations of ATP the __________ will close and cause the ________ to become depolarized and ____ will enter the cell to push ____ to exocytosis
Potassium leak channels
Calcium channels
Calcium
insulin
In the fed state, high insulin causes….
Glucose oxidation
Glycogen synthesis
Fat synthesis
Protein synthesis
(GO GyS FP)
In the fasted state, high levels of glucagon cause…
Glycogenolysis
Gluconeogenesis
Ketogenesis
Insulin is released when these 5 things increase
Plasma glucose
Plasma amino acids
GLP-1
GIP
Parasympathetic activity
The three targets of insulin
Striated muscle
Adipose
Liver
There are 5 actions of insulin that increase
Glucose transport into Glut-4-expressing target cells
Glucose metabolism
Glycogenesis
Fat synthesis
Protein synthesis
The 5 steps in the mechanism of insulin
Insulin binds to tyrosine kinase receptor
Receptor phosphorylates insulin-receptor substrates (IRS)
Second messenger pathway alter existing proteins
Membrane transport is modified
Cells metabolism changes
Insulin effects in muscle and adipose when there is no insulin: GLUT4 transporters __________ and glucose _________ into cell
Are not on membranes
Cannot
Insulin effects in muscle and adipose when there is insulin: GLUT4 transporters __________ and glucose _________ into cell
Are inserted into the membrane by exocytosis
Moves into the cell
Insulin effects in hepatocytes when insulin is low: hepatocytes _______
Make glucose and export it via GLUT2 transporters
Insulin effects in hepatocytes when insulin is high: hepatocytes _______
Favor glucose import via glut2 and activate hexokinase to convert glucose to glucose-6-PO4
Insulin is ____bolic
Ana
Glucagon ______ the effects insulin
Antagonizes
The main function of glucagon is to prevent _______, the main target is the ______, the main trigger is ______
Hypoglycemia
Liver
Low blood glucose
In response to low glucose _______ will be inhibited and ______ will be innervated
Pancreatic beta cells
Pancreatic alpha cells
Pancreatic beta cells
Pancreatic alpha cells
Pancreatic beta cells release ____
Insulin
Pancreatic alpha cells release ____
Glucagon
Diabetes mellitus is characterized by ____________ resulting from __________ and/or __________
Elevated blood glucose
Not enough insulin secretion
Abnormal cell responsiveness
Type 1 diabetes is caused by __________, type 2 is caused by _________
Inadequate insulin secretion
Abnormal target cell responsiveness
Metabolic syndrome has at least three of…
(GOTCH)
High blood Glucose
Central Obesity
Elevated triglycerides
Low HDL-cholesterol
Hypertension
Type 2 diabetes often occurs with _____ and _______
Atherosclerosis
hypertension
larger animals (such as humans) have _______ so can go without food for relatively long periods but food restriction and fat depletion eventually lead to _______
significant energy stores
‘hungry brain’
major force ‘designing’ the metabolism system was _______ which resulted in strong defense for the __________
constant struggle throughout evolution to find enough food for survival
lower limits of adiposity
Adrenal glad secretes 4 hormones
Aldosterone
Glucocorticoids
Sex hormones
Catecholamines
Glucocorticoids can prevent ________ and supress ______
Hypoglycemia
Immune response
Norepinephrie comes from ______ _________ neurons
Sympathetic
Post-ganglionic
Cushing’s syndrome is caused by ________. Primary is caused by _______, secondary is caused by _______, iatrogenic is caused by _________
Hypercortisolism
Cortisol-secreting adrenal tumor
ACTH secreting pituitary tumor
Cortisol from therapy for other conditions
The ________ cells secrete thyroid hormone
follicular
The mechanism of action of thyroid is __________
Similar to steroids, binds to nuclear receptor
Thyroid is ____________ and travels by _____________
Lipophilic
Circulation bound to thyroid binding globulin
The active form of thyroid is _____, the main circulating form is _____
T3
T4
Thyroid hormone is converted to active form _________ by _________
Within target cells
Deiodinases
Thyroid hormone is more important for (young/old) people
Young
The main function of the thyroid hormone is to:
Provide substrates for oxidative metabolism
What are the two ways that thyroid hormone provides substrates for oxidative metabolism
Increase oxygen consumption and heat generation (basal metabolic rate) which then causes increased Na/K atpase activity
Interact with other hormones to modulate carbohydrate, protein and lipid metabolism
Growth hormone effects can be direct via _______ or indirect via _______
Target cells that express GH receptors
insulin-like factors (IGF/somatomedins) produced by liver or target cells
The metabolic actions of growth hormone:
Carbohydrate – indirect increase of plasma glucose
Fat – increased lipolysis, increased oxidation (catabolic)
Protein – increased amino acid uptake, increased protein synthesis, decreased oxidation for energy (anabolic)
The growth actions of growth hormone
Increased proliferation and differentiation of chondrocytes – cartilage and bone growth
Increased muscle growth
Increased growth of soft tissues
Deficiency of growth hormone caused by _________ or _________
Hypersecretion
GH-receptor mutations
Excess growth hormone before closure of growth plates _________, after _______
Giantism
acromegaly
How does calcium affect insulin secretion
It initiates exocytosis of insulin
What are the physiological functions of calcium
- It is an important signal molecule
- It is part of the intercellular cement that holds cells together at tight junctions
- It is a cofactor in the coagulation cascade
- Plasma calcium concentrations affect the excitability of neurons
How does plasma calcium concentrations affect the excitability of neurons?
- Too low means permeability of Na+ increases which makes the nervous system hyperexcitable
- Too high means Na+ won’t be permeable enough depressing neuromuscular activity
What is extracellular calcium involved in?
- Secretion/exocytosis
- Contraction of cardiac and smooth muscle
- Clotting cascade
What is intracellular calcium involved in?
- Muscle contraction, signalling pathways
- Component of extracellular matrix of bones and teeth
- Bone is largest reservoir of calcium but very little of it available for exchange
All of the calcium in the body which is distributed into 3 compartments:
- Extracellular fluid
- Intracellular Ca2+
- Extracellular matrix (Bone)
long bones grow by _________ _________ of chondrocytes at _______ ______ secrete ______ and other extracellular matrix components
-> Older chondrocytes degenerate, leaving spaces
-> _______ invade spaces, lay down ______ on cartilage base
-> revert to less active form (______)
proliferating columns
epiphyseal plate
collagen
Osteoblasts
Ca-PO4 matrix
Osteocytes
Calcium ingested in the diet and absorbed in __________ . Only about ____ of ingested Ca2+ is absorbed
the small intestine
1/3
Function of calcitonin?
Lowers blood calcium levels
What is the function for calcitrol?
Enhance calcium uptake in the small intestine
What is calcitrol?
Active form of vitamin D
What is the stimulus for parathyroid hormone?
Decrease in plasma calcium
What are the 3 hormones that regulate the movement of calcium between bone, kidney, and intestine?
- Parathyroid hormone
- Calcitriol (Vitamin D3)
- Calcitonin (Not as important in adult humans)
Calcium absorption occurs in ___________
Output of calcium takes place in ________
transcellular transport
kidneys with a small amount excreted in feces
steps of transcellular calcium transport
- It enters the enterocyte through apical calcium channels
- Once inside, it binds to the protein ‘Calbindin’ which helps keep free intracellular calcium concentration low
- On the basolateral side, Ca2+ exits through basolateral Ca2+-ATPase or Na+-Ca2+ exchangers
graves’ disease is caused by auto-antibodies that act as TSH agonist, which are not affected by the usual feedback loops. What will happen to thyroid gland size in a patient with Graves’ disease?
decrease
increase
no change
it will increase
which effect is unique to cortisol?
Question 15 options:
a) increased gluconeogenesis
b) suppression of immune function
c) increased proteolysis
d) increased lipolysis
e) increased blood glucose
b) suppression of immune function
A person with a mutation resulting in a 21-hydroxylase deficiency would be expected to have ____ ACTH level and ____ adrenals
a) normal, small
b) high, normal
c) high, enlarged
d) high, small
e) normal, enlarged
c) high; enlarged
Which group of hormones are most similar in their effects on metabolism?
a) glucagon, insulin, thyroid hormone
b) glucagon, cortisol, epinephine
c) glucagon, cortisol, growth hormone
d) cortisol, growth hormone, thyroid hormone
e) growth hormone, insulin, thyroid hormone
b) glucagon, cortisol, epinephrine
diabetics who require insulin usually inject it rather than taking it as a pill because …
a) injecting it helps it to cross the blood-brain barrier.
b) the hormone is a protein and will therefore be broken down in the digestive system.
c) they prefer injecting themselves over the hassle of taking pills.
d) injecting it protects it from being excreted by the kidney.
e) a rapid rise in plasma insulin is required, to drop blood glucose quickly.
the hormone is a protein and therefore be broken down in the digestive system
during the fasted/postabsorptive state, muslce can contribute to maintenance of blood glucose levels by …
a) breaking down proteins and exporting amino acids to be used by the liver as gluconeogenic substrates.
b) breaking down glycogen and exporting free glucose.
c) exporting pyruvate or lactate to be used by the liver as a gluconeogenic substrate.
d) a and c
e) a, b and c
d) a and c
- breaking down proteins and exporting amino acids to be used by the liver as gluconeogenic substrates
- exporting pyruvate or lactate o be used by he liver as gluconeogenic substrate
ketogenesis typically occurs in situation in which …
Question 1 options:
a) dietary carbohydrate intake is too high and excess sugars are converted to ketones.
b) more acetyl CoA is formed than can be used in the tricarboxylic acid cycle.
c) dietary fat intake is too high, and fatty acids are converted to keto-acids.
d) rates of lipolysis are high.
e) b and d
e) b and d
- more acetyl CoA is formed than can be used in the Krebs cycle
- rates of lipolysis are high
