Appetite, Metabolic Syndrome And DOHD Flashcards
Describe how the location of the arcuate nucleus is ideal for controlling appetite
- Located at base of hypothalamus
- Can sense substances such as appetite hormones from bloodstream e.g. Ghrelin, fatty acids, Leptin
Explain how the primary neurones in the arcuate nucleus control appetite
- 2 types: excitatory and inhibitory
- Excitatory neurones contain NPY and AgRP which promote HUNGER
- Inhibitory neurones contain POMC (yields neurotransmitters α-MSH and β-endorphin) which promote SATIETY
Describe how feeding behaviour can be altered
Primary neurones synapse with secondary neurones in other regions of the hypothalamus and the signals are INTEGRATED
What 2 substances promote hunger?
- NPY (neuropeptide Y)
- AgRP (Agouti-related peptide)
What substance in the inhibitory primary neurones promote satiety?
- POMC (pro-opiomelanocortin)
- Yields several neurotransmitters including α-MSH and β-endorphin (involved in pleasure)
What hormone detected in the arcuate nucleus promotes hunger and where is it released from?
- GHRELIN
- Released from stomach wall when empty
- Stimulates excitatory primary neurones in arcuate nucleus, promoting hunger
- Filling of stomach inhibits release of ghrelin
What hormone released in the colon promote satiety?
- PEPTIDE TYROSINE TYROSINE (PYY)
- Short 36AA peptide released from ILEUM OF COLON in response to feeding
- Stimulates inhibitory primary neurones and inhibits excitatory primary neurones
- SUPPRESSES APPETITE
Describe the affect of LEPTIN on appetite
- Released by adipocytes
- Stimulates inhibitory primary neurones (POMC)
- Inhibits excitatory primary neurones (NPY and AgRP)
- SUPPRESSES APPETITE
Explain the action of LEPTIN in mitochondria
- Induces expression of UNCOUPLERS - uncouple electron transport from ATP synthesis
- Increases permeability of inner membrane to H+
- Energy from PMF is dissipated as heat
Name 4 hormones that suppress appetite
- PYY
- Leptin
- Insulin
- Amylin
Define METABOLIC SYNDROME
A group or recognisable pattern of symptoms or abnormalities that indicate a particular trait or disease
- CLUSTER of the most dangerous risk factors associated with cardiovascular disease
What risk factors may be associated with metabolic syndrome/CVD?
- Abdominal obesity
- High blood pressure
- Insulin resistance
- High fasting plasma glucose
- Dyslipidaemia (⬇️HDL cholesterol, ⬆️TAGs)
Describe the aetiology of metabolic syndrome
- Exact underlying cause UNKNOWN
- Insulin resistance and abdominal (central) obesity are significant risk factors
Explain how insulin resistance can cause metabolic syndrome
- Cells less sensitive to insulin so glucose is not efficiently utilised
- High plasma glucose leads to increased insulin production and eventually β cells wear out
- Type II diabetes
- Risk of micro/macrovascular damage due to glycosylation of vessels
Describe the treatment methods associated with metabolic syndrome
- PRIMARY methods include change to diet and lifestyle by moderate calorie restriction and increase daily exercise
- SECONDARY methods (when primary methods are unaffective) involves drug intervention e.g. Statins. anti hypertensive drugs (lower BP) and antidiabetic drugs (lower BG)
What is meant by EPIGENETICS?
- Changes in the organism that result from modifications in expression of genes rather than the genetic code itself
- MODIFICATIONS CAN BE INHERITED
State 5 factors that can affect epigenetic mechanisms
- Development in childhood
- Environmental chemicals
- Drugs
- Ageing
- Diet
Describe how methylation of DNA can affect gene expression
- METHYLATION OF DNA
- Additional methyl group added to DNA structure (but DNA sequence is unchanged)
- Can affect expression or inhibition of genes
- Methylation pattern can be INHERITED from one generation to the next
State 3 epigenetic mechanisms that can affect the expression of genes
- Methylation of DNA
- Phosphorylation of histone tails
- Non coding RNA initiation of mRNA degradation
Name the 6 distinct nuclei of the hypothalamus
PADAVS:
- Paraventricular
- Anterior
- Dorsomedial
- Arcuate
- Ventromedial
- Supraoptic
Explain what is meant by the THRIFTY PHENOTYPE HYPOTHESIS
- States that reduced fetal growth is strongly associated with development of chronic conditions later on in life such as obesity, diabetes and CVD
- If mother experiences low nutrition during pregnancy then child is “programmed” to expect a similar life
- If child experiences plentiful nutrition, the adaptations can result in development of metabolic syndrome and other chronic conditions
What is the clinical importance of understanding DOAHaD?
- Potentially understand the origins of some diseased states
- Highlights importance of ANTENATAL CARE in terms of adequate nutrition
What are the potential socioeconomic issues surrounding DOAHaD?
Women with greatest risk of poor nutrition during pregnancy (those who come from a low socioeconomic background) may be least likely to present for antenatal care
