Metabolic And Endocrine Control During Special Circumstances Flashcards
What are the 2 normal fuel sources that are available in the blood?
Glucose
Fatty acids
There is normally little free glucose available in the blood, how is glucose normally stored?
As Glycogen in the liver and muscles
How are fatty acids usually stored?
As Triacylglycerols in adipose tissue
What are the 3 fuel sources that are only available under special conditions?
Amino acids
Ketone bodies
Lactate
What are amino acids converted into in order to be utilised as a fuel source?
Glucose
Ketone bodies
Where were ketone bodies usually produced from?
Fatty acids
How is lactate produced in an individual?
Anaerobic respiration
What are the time frames for using glucose after feeding?
First 2 hrs glucose available from gut
Between 2-8 hrs glucose and fat being obtained from glycogen and Triacylglycerol stores
Between 8-10 hrs glycogen store’s depleted (Gluconeogenesis happens, more ketone bodies made, brain utilises ketone bodies for fuel)
What are the anabolic hormones?
Insulin
Growth hormone
What are the effects of insulin?
Promote fuel storage
What are the anabolic affects of growth hormone?
Stimulates protein synthesis
Stimulates Gluconeogenesis
What are the catabolic hormones?
(Promote release from stores and utilisation)
Glucagon
Adrenaline
Cortisol
Growth Hormone
Thyroid hormones
What are the catabolic affects if Growth hormone?
Increased lipolysis
Glycogenolysis
What does insulin inhibit?
Gluconeogenesis
Glycogenolysis
Lipolysis
Ketogenesis
Proteolysis
What does insulin stimulate?
Glucose uptake in muscle and adipose via GLUT4
Glycolysis
Glycogenesis
Protein synthesis
What effects does feeding cause?
Increased blood glucose stimulates insulin release causing:
-increased glucose uptake and utilisation by muscle and adipose via GLUT4
-promotes storage of glucose as glycogen in liver and muscle
-promotes amino acid uptake and protein synthesis in liver and muscle
-promotes lipogenesis and storage of FA as TAGs in adipose
What are the effects of fasting?
Blood glucose falls, insulin stops being released and glucagon is released stimulating:
-glycogenolysis
—lipolysis
-Gluconeogenesis
-
During starvation, what hormones are produced?
Cortisol
Glucagon
Which gland in the body produces Cortisol?
Which gland in the body produces Glucagon?
Adrenal cortex (Zona Fasiculata)
Pancreas (Alpha cells)
How does cortisol affect insulin?
It has an anti insulin affect
In energy starvation what is preferentially metabolised as fuel and why?
Fatty acids are preferentially metabolised
Anti insulin effect of cortisol and reduced insulin levels prevents cells taking up glucose
In energy starvation, which processes happen in what order?
Gluconeogenesis (glycerol from TAGs used reducing need to breakdown muscle protein)
Ketogensis in liver, brain utilises this sparing glucose requirement from protein
Once fat stores depleted, proteolysis must occur to use glucogenic and ketogenic amino acids for fuel for Gluconeogenesis and ketogenesis
When does the majority of Fetal growth take place?
3rd trimester (the last 1/3 of the pregnancy
What are the 2 main phases of metabolic adaptation during pregnancy?
1.) Anabolic phase
2.) Catabolic phase
What occurs in the anabolic phase of pregnancy?
Increase in maternal fat sores
Small increase in insulin sensitivity
What occurs in the catabolic stage of pregnancy?
Increased insulin resistance so decreased insulin sensitivity
Increased maternal glucose and free fatty acids
(Greater substrate available for Fetal growth
How do most substrates transfer across the placenta?
Simple diffusion
Glucose via GLUT1
What is the fetoplacental unit?
A new endocrine entity consisting of:
-placenta
-Fetal adrenal glands
-Fetal liver
How does the fetus control maternal metabolism?
Via the fetoplacental unit
In terms of the anabolic stage of pregnancy, what is the goal?
To increase the amount of nutrients stored in preparation for:
-rapid growth of fetus
-birth
-lactation
What is the goal of the catabolic stage of pregnancy?
Keep concentration of nutrients in maternal circulation high
What happens in the catabolic stage of pregnancy to keep the conc of nutrients high?
Reduced maternal utilisation of glucose (uses fatty acids)
Release of fatty acid stores from the anabolic stage of pregnancy
Maternal insulin levels increase but fetoplacental anti insulin hormones increasae faster
What is the main anti insulin hormone produced by the fetoplacental unit?
Corticotropin Releasing Hormone (CRH)
Leads to cortisol production
How is insulin secretion affected in pregnancy?
Increased synthesis and secretion
B cell Hyperplasia
B cell Hypertrophy
What can occur if B cells don’t produce more insulin in pregnancy to cope with the increased glucose intake?
Gestational Diabetes
What are the clinical implications of gestational diabetes?
Miscarriage
Congenital malformation
Macrosomia (big baby)
Shoulder dystopia (increased fat on shoulders, get stuck at birth)
Gestational hypertension and preeclampsia
What’s the risk factors for gestational diabetes?
Maternal age> 25 years
BMI > 25kg/m^2
Face/ethnicity
History of diabetes
History of macrosomia
How do we manage gestational diabetes?
Diet (reduce calorie intake of obese patients)
Insulin injection if persistence of hyperglycaemia
Ultrasounds to access Fetal growth
In exercise, what does the rate of ATP re synthesis depend on?
The rate of ATP hydrolysis (so the intensity of exercise)
How do ATP stores get replenished?
From Creatine Phosphate
Glycolysis
Oxidative phosphorylation
How can muscle glycogen stores sustain intensive exercise for a couple of mins?
Glycogen broken down into glucose 6 phosphate and can enter glycolysis
Pyruvate gets converted to lactate to regenerate the NAD+ needed for glycolysis
Which organ acts as a major buffer for blood glucose levels and how?
Liver
Exercise causes increased hepatic glycogenolysis and Gluconeogenesis
Liver recycles lactate
In what type of exercise can fatty acids be used as fuels?
Low intensity
Aerobic conditions needed
Describe metabolism in short high intensity exercise like a 100m sprint
Anaerobic production of ATP
Need muscle store of glycogen
Creatin phosphate used
Describe metabolism in a middle distance 1500m run
Some O2 delivered to muscles but anaerobic metabolism still happens
- Creatine phosphate and anaerobic glycogen metabolism
- ATP produced aerobically from muscle glycogen and fatty acids
- Anaerobic metabolism of glycogen makes lactate
Describe metabolism in long duration low intensity exercise
Mostly aerobic
Muscle glycogen
Liver glycogen
Fatty acids
What is the hormonal response to long exercise?
Insulin slowly decreases
Glucagon rises
Adrenaline and GH rise rapidly
Cortisol slowly rises
What is the affect of glucagon levels rising in prolonged exercise?
Inc glycogenolysis (glycogen phosphorylase activated)
Inc Gluconeogenesis (PEPCK and Fructose 1,6-bisphosphatase activated)
Inc lipolysis (Hormone sensitive Lipase activated)
What is the affect of the rapid rise in adrenaline and GH in prolonged exercise?
Adrenaline inc glycogenolysis and lipolysis
GH inc lipolysis and Gluconeogenesis
What is the affect of cortisol rising in prolonged exercise?
Inc lipolysis and Gluconeogenesis
What are the benefits of exercise?
Body comp changes (less adipose more muscle)
Improved glucose tolerance
Tissues sensitivity to insulin increases
Blood Triglycerides decrease
BP falls
Psychological effects of wellbeing
