Lipids are stored in connective tissues called adipose tissue and are known to play vital roles in the body in terms of hormone regulation as well as intercellular signaling. The major functions of these lipids are as discussed below;
Provision and Storage of Energy.
The main role of lipids is the storage and provision of energy in the body. Lipids that have the role of energy storage are triacylglycerols which constitute three fatty acids and a glycerol. The fatty acids in triacylglycerols act as a source of energy from cells structural component during starvation.
Membrane Lipid Layer Formation
Membrane lipids constitute of polyunsaturated fatty acids that are part of phospholipids make up a semi-permeable membrane main role is to aid in membrane flexibility and fluidity and controlling substances entering and leaving the cell.
Maintenance of Body Temperature
Subcutaneous fat layer found under the skin insulates and protects the body from cold hence maintaining the body temperature to optimum. This is the main reason why babies have a lot of brown fat due to their large surface area to volume ratio.
Lipids molecules are insoluble in water and hence they are used for signaling in communication between cells and organelles in multicellular organisms.
Role of the Liver in Metabolizing and Processing Fats.
The liver converts excess proteins and carbohydrates into fatty acids which are stored in the adipose tissue. It breaks down fatty acids by to acetoacetate which is carried by blood to be utilized in metabolic activities in tissues.
The liver also synthesis a lot of lipoproteins that enables fats to be carried in the blood stream.
Blood sugar level is a measure of the amount of glucose in the blood that should be maintained in a very narrow range and measured in mmol/l. Blood sugar levels regulation is stimulated by negative feedback either high blood sugar level or low blood sugar level in order to keep the body in homeostasis. Regulation of the blood sugar level is made by insulin and glucagon hormones. Concentration of glucose in the blood is detected by glucose transporter receptors known as alpha and beta cells.
At high blood sugar levels that results either from glycogen conversion or from a meal digestion, beta cells located in the pancreas secretes insulin. The released insulin triggers the liver to convert more of glucose to glycogen forcing fat tissue cells, red blood cells and muscles to utilize glucose from the blood stream thereby decreasing the level of blood sugar to the normal range.
At low blood sugar level (during starvation or at fasting state) insulin secretion is inhibited and alpha cells secretes glucagon hormone that stimulates adipose tissue to digest lipids into fatty acids and glycerol as well as liver to breakdown glycogen into glucose. Fatty acids and glycerol are then released to the blood stream. Glucagon also induces the liver to synthesize more glucose and subsequent release to the blood stream. All these metabolic activities bring about leveling of the blood sugar level back to normal.