PBL - Obesity

Physiology of Appetite and Hunger and Stuff

Definitions in Physiology
Hunger = a craving for food, rhythmical contractions of the stomach, restlessness. A desire to search for adequate food supply
Appetite = a desire for food, usually of a particular type, and quality of food.
Satiety = success in achieving hunger and appetite.

Each of these is associated with specific centres in the brain, esp. the hypothalamus, which responds to environmental and cultural factors as well as neural, chemical and endocrine messengers.

There are two types of neurons in the arcuate nuclei of the hypothalamus that have really long complicated names and descriptions. POMC decreases food intake, increases energy expenditure. NPY-AGRP does the reverse. These are the major targets for appetite-regulating hormones such as leptin, insulin, CCK and grehlin.

Not Hungry:
Gastrointestinal filling: stretch receptors send inhibitory signals via the vagus nerve
Gastrointestial hormones that suppress hunger:
" CCK is released in response to fat in duodenum to stimulate gall bladder contractions, but also directly affects POMC.
" PYY is released mostly from ileum and colon, 1-2 hours after eating esp in response to fat.
" Insulin is released from beta-cells in the pancreas in the presence of glucose, and to some degree at food intake.
" GLP is released by intestines when filled with food, enhances insulin secretion from pancreas.
Leptin is a peptide hormone released from adipocytes that acts on POMCs and NPY-AgRP receptors as well as the pancreas re: insulin levels.

Hungry:
Grehlin is released from the fundus of the stomach in increasing amounts leading up to a meal. It stimulates NPY/AgRP receptors in the hypothalamus,
Appetite is also increased when blood levels of glucose, amino acids and fatty acids decrease.
Temperature also plays a role in hunger - when it's cold, we need more energy/food to keep warm. Temperature regulation occurs in the hypothalamus, so it's not too far for the to travel

Table 71-2 from guyton and hall summarises the neurotransmitters and hormones that influence feeding centres in the hypothalamus.
Anorexogenic:
-MSH, Leptin, Serotonin, Norepinephrine, CRH, Insulin, CCK, GLP, CART, PYY
Orexogenic:
NPY, AGRP, MCH, Orexin A + B, Endorphins, Galanin, Amino acids, Cortisol, Grehlin

refs:
Chapter 71 of Guyton and Hall - Dietary Balances; regulation of feeding obesity and starvation.
Wilcox, G "Food composition and its effect on human biology" - 21/9/2007 Monash MBBS 2042 Lecture
Saladin

DVT/PE

hey, to keep things in order, pls "comment" on this post rather than "new post"

CBL – Deep Venous Thrombosis/Pulmonary Embolus

Differential Diagnoses for presentation with symptoms discussed in case:
- AMI: Tightness, central crushing squeeziness. Radiating pain, dyspnoea, sweating, quick onset.

- Pulmonary oedema: Usually due to left ventricular failure or ischemic heart disease. May present with Dyspnoea, orthopnoea, pink frothy sputum, pale & sweaty, ­pulse and ­JVP, Tachypnoea, lung crackles.

- Pneumonia: This is an acute lower respiratory tract illness involving infection of the lung parenchyma. Main clinical symptoms include dyspnoea, pleuritic chest pain, haemoptysis, cough, purulent sputum, malaise, fever.

- Cellulitis: (Differential for DVT): Cellulitis is an acute inflammation of the connective tissue of the skin, caused by infection with staphylococcus, streptococcus or other bacteria Localized skin inflammation with pain or tenderness in the area, warmth over area of redness. May present with fever, chills, sweating, fatigue, and ache.

- Hyperventilation: Main symptom is dyspnoea, dizziness with tingling of and numbness of limbs, ¯PaCO2 and normal or ­ PaO2.

- Oesophageal spasm: Heartburn and worse with straining. Most common cause of chest pain

- Pulmonary embolism: Dyspnoea, Tachypnoea, Hypoxemia, Hypocarbia with clinical presentation resembling hyperventilation. ¯PaO2 and decrease in partial pressure of PaCO2. Results in a positive D-dimer assay

- Pericarditis: Sudden onset pleuritic pain. Change of posture can influence pain and a friction sound can be heard.

- Costochondral pain: Palpation tenderness and movements of chest influence pain.


References:- http://www.guideline.gov/summary/summary.aspx?doc_id=6534
- Oxford Handbook

T2DM + CAD

Diabetes and Heart Troubles
Type 2 Diabetes Mellitus has been shown increase the risk of coronary artery disease in both men and women. Men are at two to four-fold increased risk of CAD, and women three to five-fold. This risk is primarily due to diabetes assisting in plaque formation.

The effects of diabetes are also thought to magnify other underlying risk factors such as obesity, hypercholesterolaemia, hypertension and smoking. As such, it is vital that a multidisciplinary team is involved to treat those with CAD.

The primary care physician may be able to be involved in most areas of treatment and prevention, however, it may be best to refer on for additional support.

A dietitian can assist with improved eating habits and understanding of food and its effects on the body. Through this, it is possible to reduce hyperlipidaemia and hypertension, respectively responsible for an estimated 45% and 12% of deaths due to CAD. A Mediterranean diet has, in some cases, been responsible for a 75% reduction in CAD events in post MI patients.

Exercise physiologists can be employed to assist in modifying diet, responsible for up to 30% of deaths due to CAD, and also in eliminating obesity, responsible for 5% of deaths due to CAD.

Finally, a psychologist or support groups may assist in the cessation of smoking, responsible for approximately 20% of deaths due to CAD.

All stats kindly donated by Kumar and Clark.