Carbohydrates

Structure of carbohydrate

carbon, hydrogen, and oxygen

How many calories it has

4 kcal/gram

Main role

Energy ( fuel for brain, nervous system, male reproductive system) Needed to make serotonin in the brain

serotonin

neurotransmitter critical for weight loss and gain, made of amino acids

Recommended daily allowance of carbs

130 grams/day or 45-65% of total daily calories

Classifications of sugar

simple : Made of one or two sugar molecules. Quickly broken down and absorbed → rapid rise in blood sugar. Known as “high glycemic”

Monosaccharides (Glucose, Fructose, Galactose)

Disaccharides Sucrose= glucose + fructose Lactose =glucose + galactose, Maltose =glucose + glucose

Simple sugars always end with -ose

complex: Made of many sugar molecules linked together, Slower to break down → gradual blood sugar rise (Starches and Fiber)

Known as “low glycemic”

Carbon in the body

carbon may become a building block for cholesterol and saturated fatty acids if eating in excess.

If it produced faster than it can be converted, the excess is converted to fat.

However, Carbon is not toxic itself.

Glucose

liberated from carbohydrates within the small intestine and absorbed into the blood

3 main functions:

1. Used directly by cells for energy

2. 2.Stored as glycogen in muscles and liver for later use

3. Converted to fat and stored for energy

Insulin

Elevated levels of glucose in blood stimulate insulin (from pancreas), which stimulates uptake, utilization, and storage of glucose.

It allows glucose to enter the adipose and muscle tissue through favilitates diffusion (passive)

Glucemic Index (GI)

provides a way to rank carbs according to the blood glucose response following intake

a ranking of how quickly carbohydrate-containing foods raise blood glucose (blood sugar) levels after eating.

Ingestion of 50 g test food

Glucose vs Glycogen usage

Glucose: Immediate Energy, fuels cells directly. It used right after eating, during short bursts of energy (e.g., sprinting), constantly used by the brain and red blood cells

Glycogen: Stored glucose that’s broken down when needed. Found in Liver (to regulate blood sugar) and Muscles (for muscle energy during activity). Used :

-Between meals or fasting
- During prolonged or intense exercise
- In fight-or-flight situations

Hypoglycemia occurs when blood glucose levels fall below normal, typically below 70 mg/dL. Can happen when glucose output can no longer keep up with muscke glucose uptake during prolonged exercise, so the blood glucose drops.

Insulin and Carb Metabolism

Elevated concentrations of glucose in blood stimulate release of insulin, which acts on cells throughout the body to stimulate uptake, utilization, and storage of glucose

1. Facilitates ewnergy into muscles and adipose

2. Stimulates the liver to store glucose on the form of glycogen

Physiological Effects of Insulin

It makes you build things up

Decreases the concentration of glucose in the blood

In the absence of insulin, a bulk of cells cannot take up glucose and begin to switch to fatty acids

Glucagon

Stimulates glycogen breakdown is stimulated by glucagon

Comes up when blood sugar levels are too low

Where and how much CHO are stored

muscle glycogen: 300-400 gramm/1200-1600kcal

Blood glucose: 25g/100kcal

Liver glycogen:75-100g/300-400 kcal

Every gram of glycogen stored=3-4 ounces of water

Energy demands

Carbs are preffered fuel for intensities above 65% of VO2 max

Muscle glycogen and blood glucose provide about half the energy for moderate

Utilization of muscle glycogen is most rapid during the early stages of exercise and us exponentially related

fiber

nonstarch, structural polys. includes cellulose

Two types:insoluble and soluble

no nutrients or calories

exists exclusevely in plants

women 25g/day

men 35g/day

Insoluble fiber

intact in H2o

creates bulk

makes you poop

prevents GI tract disease

Soluble fiber

changes in water

lowers cholesterol

removes bile (bile is made of cholesterol)

whole grain

broccoli heads

Starch

storage form of carbs in plants

2 forms

1. Amylose: long, straight chain (slower hydrolysis)

2. Amylopectin: highly branched monos. (digested quickly)

gluconeogenesis

animals produce glucose this way. synthesized from liver from carbon skeletons of amino acids and from glycerol, pyruvate, lactate

protein—> glucose

Glycogenolysis:

glycogen to glucose (controlled by phosphate enzymes)

Glycogenesis

glucose to glycogen

high blood glucose levels in type 2 diabetes can result from

1. Decreased effect of insulin on peripheral tissue( insulin resistance)

2. Inadequate insulin productionby the pancreas to control the blood sugar

3. combined effect of both factors

metabolic syndrome

1. Distributed glucose and insulin metabolism

2. Overweight and abdominal fat distribution\

3. Mild dyslipidemia

4. Hypertension