The sarcolemma is a specialized cell membrane which surrounds striated muscle fiber cells. ... The sarcolemma also contains an extracellular matrix consisting of various polysaccharides which allows the cell to anchor into the tissues that build and support muscle fibers. Smooth muscle fibers have a limited calcium-storing SR but have calcium channels in the sarcolemma (similar to cardiac muscle fibers) that open during the action potential along the sarcolemma.

Digestion of food in human beings begins in the mouth. The mouth cavity contains teeth, tongue and salivary glands. The teeth cut the food into small pieces, chew and grind it. This is called physical digestion. Salivary glands produce saliva which mixes with the food. This involves chemical digestion of food. The saliva contains an enzyme called salivary amylase which digests the starch and converts it into maltose sugar. Mouth opens into a small funnel shaped area called pharynx which leads to a long tube called oesophagus. It carries the food down into the stomach. The wall of oesophagus is muscular. When the slightly digested food enters the food pipe, the walls of the oesophagus starts contraction and expansion movements called peristaltic movements which push the food into the stomach. Digestion does not take place in the oesophagus.
The glands present on the walls of the stomach secrete gastric juice that contains hydrochloric acid, the enzyme pepsin and mucus. A small amount of gastric lipase is also present that breaks down the fats present in the food. Gastric juice is acidic due to the presence of HCl which is necessary for the pepsin to become active and converts the proteins into peptones. The mucus protects the stomach walls from HCl. From the stomach, the partially digested food goes into the small intestine through sphincter muscle. Small intestine is divided into two parts: Duodenum and Ileum.
Duodenum receives the secretions of two glands, liver and pancreas through a common duct. Liver secretes bile which is alkaline and contains salts to emulsify the fats (or lipids). The bile secreted by the liver is stored in the gall bladder. Pancreas secretes pancreatic juice which contains trypsin, lipase and pancreatic amylase. Trypsin digests the proteins, lipase emulsifies the fats and pancreatic amylase breaks down the starch. Thus, small intestine is the site of complete digestion of carbohydrates, proteins and fats. The walls of ileum secrete succus entericus which completes the digestion process.

The heart is roughly triangular in shape. It has four compartments called chambers inside it. The upper two chambers of the heart are called atria and the lower two chambers are called ventricles. The atria receive blood from the two main veins. The left atrium is connected to the left ventricle through a valve V1 and the right atrium is connected to the right ventricle through another valve V2. These valves prevent the backflow of blood into atria when the ventricles contract to pump blood out of the heart to the rest of the body because when the ventricles contract, the valves V1 and V2 close automatically so that the blood may not go back into the atria. The job of heart is to pump blood around our body. All the atria and ventricles of the heart contract and relax at appropriate times and make the heart behave like a pump. A sheath of tissue called pericardium protects the muscular heart.Working of Human blood circulatory system takes place in the steps below:

(i) When the muscles of all the four chambers are relaxed, the pulmonary vein brings the oxygenated blood from the lungs in the left atrium of the heart.

(ii) When the left atrium contracts, the oxygenated blood is pushed into the left ventricle through valve V₁.

(iii) When the left ventricle contracts, the oxygenated blood enters the main artery called aorta from which it goes to the different body organs through small branches called arterioles and capillaries.

(iv) The main artery carries the blood to all the organs of the body head, arms etc except the lungs. The oxygenated blood gives off oxygen, digested food and dissolved materials to the body cells. The carbon dioxide produced in the cells enters the blood. The deoxygenated blood enters main vein called vena cava which carried it to the right atrium of the heart.

(v) When the right atrium contracts, the deoxygenated blood enters right ventricle through valve V₂.

(vi) When the right ventricle contracts, the deoxygenated blood enters the lungs through pulmonary artery and releases carbon dioxide and absorbs fresh oxygen from air. The blood becomes oxygenated again and is sent to the left atrium of heart by pulmonary vein for circulation in the body. This whole process is repeated continuously.

The cervix is part of the female reproductive system. Around 2–3 centimetres (0.8–1.2 in) in length, it is the lower narrower part of the uterus continuous above with the broader upper part—or body—of the uterus. The lower end of the cervix bulges through the anterior wall of the ******, and is referred to as the vaginal portion of cervix (or ectocervix) while the rest of the cervix above the ****** is called the supravaginal portion of cervix. A central canal, known as the cervical canal, runs along its length and connects the cavity of the body of the uterus with the lumen of the ******. The openings are known as the internal os and external orifice of the uterus (or external os) respectively. The mucosa lining the cervical canal is known as the endocervix, and the mucosa covering the ectocervix is known as the exocervix. The cervix has an inner mucosal layer, a thick layer of smooth muscle, and posteriorly the supravaginal portion has a serosal covering consisting of connective tissue and overlying peritoneum.

The caecum is called blind sac because caecum looks like a sac which has sphincter at the ileocaecal junction and it remains closed and is invisible. Hence, it is called a blind sac. The main functions of the cecum are to absorb fluids and salts that remain after completion of intestinal digestion and absorption and to mix its contents with a lubricating substance, mucus. The internal wall of the cecum is composed of a thick mucous membrane, through which water and salts are absorbed.

Annelids like oligochaetes exhibit tube within a tube body plan with multicellularity and bilateral symmetry.  It refers to the development of a fluid-filled cavity between the outer body wall and the digestive tube. This plan calls for two openings, one for food to enter the body (mouth), one for wastes to leave the body. 

The key difference between reductive amination and transamination is that the reductive amination is the conversion of a carbonyl group into an amine group whereas the transamination is the transfer of an amine group from one molecule to another.

Amination is the process that we can use to introduce an amine group to a molecule. The reductive amination and transamination are two forms of amination processes. Therefore, these processes also involve in the introduction of an amine group to a molecule, but in different pathways; reductive amination involves the conversion of an existing group into an amine group whereas transamination involves the transferring of an amine group.

Lysosomes are a kind of waste disposal system of the cell. They help to keep the cell clean by digesting any foreign material as well as worn-out cell organelles. Lysosomes are rich in a variety of hydrolytic enzymes or acid hydrolases such as nucleases, proteases, lipases, phosphatases, etc. These membranous structures are responsible for the degradation of the cellular debris like proteins, mRNA and other molecules. These are commonly known as the waste disposal system of the cell which degrades and then removes all the wastes from the cell.