Metabolic, Endocrine Control During Special Circumstances Flashcards
Name 5 fuel stores available in the blood.
Which of these are normally available?
Which are available under special conditions?
Normally available;
- Glucose
- Fatty acids (can’t be used by RBCs and CNS)
Available under special conditions;
- Amino acids (Converted to glucose or ketone bodies)
- Ketone bodies (Mainly from fatty acids, can be used by brain)
- Lactate (Can be converted to glucose in liver, or used in Krebs cycle in other tissues such as heart)
Name 3 energy stores
Glycogen
Fat
Muscle protein (Used in emergency)
What are 4 metabolic effects of feeding:
Insulin release;
- Increased glucose uptake and utilisation by muscle and adipose (GLUT 4)
- 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 fatty acids as TAG
What are 4 metabolic effects of fasting:
Insulin secretion reduced;
- Reducde glucose uptake by adipose and muscle
Glucagon secretion increased;
- Glycogenolysis in liver
- Lipolysis in adipose tissue
- Gluconeogenesis to maintain glucose supplies for brain
Fasting becomes starvation after how many hours
10
What are 6 metabolic effects of starvation
- Reduction of blood glucose stimulates release of cortisol and glucagon
- Stimulate gluconeogenesis and breakdown of protein and fat
- Reduction in insulin + effects from cortisol prevent most cells from taking in glucose and preferentially metabolise fatty acids
- Liver makes ketone bodies, used by the brain instead of glucose
- Kidneys contribute to gluconeogenesis
- Once fat stores depleted, protein used as fuel (death usually due to loss of muscle)
What is a typical net weight gain by the end of pregnancy?
8kg ( 3.5kg foetus, 3kg maternal fuel stores, placenta 0.6kg)
What hormones are involved in regulating maternal nutrient metabolism during pregnancy?
Maternal insulin
Fetal-placental hormones, made by Fetal-placental unit;
- Placental lactogen
- Progesterone
- CRH
(Fetal-placental hormones have an anti-insulin effect)
What 3 structures make up the fetal-placental unit
Placenta
Fetal adrenal glands
Fetal liver
What are the 2 main phases of metabolic adaptation during pregnancy
Anabolic state (1st half of pregnancy)
Catabolic state (2nd half of pregnancy)
Describe the Anabolic state during pregnancy
Increasing insulin levels promotes an anabolic state in the mother, resulting in increased nutrient storage (mainly fat).
(This prepares the mother for rapid fetal growth, birth and eventually lactation)
Describe the Catabolic state during pregnancy
Maternal insulin levels still increase, but fetal-placental hormone production increases faster.
To meet the needs of the increasing demand by the fetal-placental unit, the concentration of nutrients in maternal circulation is kept high by;
- Reducing maternal utilisation of glucose (use fatty acids instead)
- Delaying nutrient disposal after meals
- Releasing fatty acids from stores
What is the effect on maternal ketogenesis in the catabolic state?
Increase Fatty Acid availability + fall in insulin/ anti insulin ratio leads to ketone body production in liver
(Used as fuel by fetal brain)
As pregnancy proceeds the rate insulin secretion normally increases.
What are 3 ways that pancreatic Beta-cells meet this increased demand?
Oestrogen and progesterone caused increased sensitivity of Beta-cells to blood glucose;
- Beta cell hyperplasia
- Beta cell hypertrophy
- Rate of insulin synthesis in Beta cells increases
What is Gestational Diabetes?
A disease in which pancreatic Beta-cells are unable to produce enough insulin to meet the increased requirement in late pregnancy
After birth, how does Gestational Diabetes change?
What is the correlation between Type 2 and Gestational diabetes
After birth, the diabetes disappears
Women who experience gestational diabetes are more likely to develop Type 2 Diabetes later in life
What are 4 clinical consequences of Gestational Diabetes
- Increased chance of Miscarriage
- Increased chance of Congenital Malformation
- Can lead to Fetal Macrosomia (large body), which could lead to Shoulder Dystocia (shoulders get stuck during birth, due to large amount of adipose around shoulders)
What are 2 hypertensive disorders associated with Gestational diabetes
- Gestational hypertension
- Preeclampsia (High BP, Protein in urine)
What are 5 risk factors for gestational diabetes
- Maternal age>25
- BMI>25
- Ethnicity (More common in Asian, Black, Hispanic)
- Personal/ family history of diabetes
- Family history of macrosomia
What are 3 methods of management of gestational diabetes
- Change in diet (lower calorie intake in obese patients)
- Insulin injection
- Regular ultrasounds to assess fetal growth and well being
Switching from rest to exercise causes rapid changes in which 4 systems?
- Temp regulation
- Respiratory system
- MSK system
- Cardiovascular system
What are 4 goals of the metabolic response to exercise?
- Energy stores mobilised to meet increased energy demands of skeletal and cardiac muscle
- Glucose supply to brain is maintained
- End products of metabolism are removed as quickly as possible
- Minimal disturbance to maternal homeostasis
What 3 aspects of exercise does the magnitude and nature of the metabolic response depend on?
- Type of exercise (muscles used)
- Intensity and duration of exercise
- Physical condition and nutritional state of individual
In the first 5 sec of high intensity-low duration exercise (100m sprint) where does required energy comes from?
ATP stores and Creatine Phosphate breakdown (makes more ATP from ADP)
Anaerobic glucose metabolism produces Lactate and H+, which impairs muscle function.
Give 3 ways H+ does this
H+;
- Inhibits glycolysis
- Interferes with Actin/ Myosin interactions
- Causes SER to bind Ca (inhibits contraction)
How is the Metabolic response to Low duration- High intensity exercise regulated?
- Mainly by nervous system (Noradrenaline)
- Some input from endocrine system (Adrenaline)
What are 6 features of the Metabolic response to Low duration- High intensity exercise?
- Initially, muscle ATP and C-P used (5 sec)
- Muscle glycogen rapidly mobilised-> G6P
- G6P provides ATP (from ADP) via glycolysis
- Glycolysis carried out under anaerobic conditions
- Large increase in Lactate and H+ from anaerobic glycolysis
- H+ build up produces fatigue
How much glycogen metabolism is Aerobic and Anaerobic in Medium duration- Medium intensity exercise?
Is there a major problem with H+ (Impairment of muscle function)?
Why?
Aerobic- 60%
Anaerobic-40%
No problem with H+, as the amount made can be buffered by the muscle
Describe the Metabolic response in each of the 3 stages of Medium duration- Medium intensity exercise (1500m)?
- Initial sprint- Uses muscle ATP, C-P and Anaerobic glycogen metabolism
- Long middle phase- Aerobic glycogen metabolism
- Final finishing burst- Anaerobic glycogen metabolism (Lactate produced)
In Long duration- Low intensity exercise, carbohydrate stores are not sufficient to provide enough energy, so fatty acids are oxidised.
Compare the speed of metabolic changes during a marathon with that of sprinting
During a marathon, metabolic changes are more gradual
What are 2 major features of the metabolic response to Long duration- Low intensity exercise?
- Muscles work aerobically, can use all fuel molecule types
- Origin and type of fuel changes as exercise proceeds
Describe the control of changes in Fuel origin+type as Long duration-Low intensity exercise proceeds.
Largely hormonal, with some nervous system input
Describe the Metabolic response in each of the 3 stages of Long duration- Low intensity exercise (Marathon)?
- Initial stage: Major fuel is muscle glycogen metabolised aerobically
- As marathon proceeds: Increased utilisation of blood glucose, replaced by breakdown of liver glycogen
- Eventually: Blood glucose falls, and fatty acids begin to be used, and their utilisation increases with time
What are the major hormonal changes during a marathon?
What is the net effect?
- Progressive fall in insulin level
- Rapid increase in adrenaline, noradrenaline and GH levels
- Gradual increase in Cortiol and Glucagon levels
- Progressive fall in insulin/ anti insulin ratio (No effect on ketogenesis in liver as insulin is still present)
Fatigue is the inability to maintain a given power output affecting the intensity and/or duration of exercise.
What are 3 biochemical causes of fatigue
- Depletion of muscle glycogen
- H+ accumulation in muscle
- Dehydration
What are 6 benefits of exercise?
- Change in body composition
- Improved glucose tolerance
- Increased sensitivity of tissues to insulin
- Decrease in blood TAGs
- Reduced BP
- Positive psychological effects
