Determine whether each of the following characteristics is u

Determine whether each of the following characteristics is unique to a mature red blood cell (RBC), unique to a cardiac muscle fiber (muscle fiber), or common to both cell types (both). Is packed with proteins. ______ Is anucleate. _______ Is surrounded by a cell membrane. _______ Is packed with mitochondria. _______ Transports oxygen. _______

Solution

(a)both are packed with proteins.Cardiac muscle has cross striations formed by rotating segments of thick and thin protein filaments.The proteins of the membrane skeleton are responsible for the deformability, flexibility and durability of the red blood cell, enabling it to squeeze through capillaries less than half the diameter of the red blood cell (7–8 m) and recovering the discoid shape as soon as these cells stop receiving compressive forces, in a similar fashion to an object made of rubber.

(b)Only Mature RBC.cardiac muscle cells are mononucleated in humans.Red blood cells in mammals anucleate when mature, meaning that they lack a cell nucleus.

(c)Only RBC.The red blood cell membrane is composed of 3 layers: the glycocalyx on the exterior, which is rich in carbohydrates; the lipid bilayer which contains many transmembrane proteins, besides its lipidic main constituents; and the membrane skeleton, a structural network of proteins located on the inner surface of the lipid bilayer.The cardiac syncytium is a network of cardiomyocytes connected to each other by intercalated discs that enable the rapid transmission of electrical impulses through the network, enabling the syncytium to act in a coordinated contraction of the myocardium.

(d)Only cardiac tissue.As a result of not containing mitochondria, red blood cells use none of the oxygen they transport.

(e)Both cardiac tissues and RBC.The heart does not gather oxygen or nutrients from the blood flowing inside it. Instead, it receives blood from coronary arteries that eventually carry blood into the heart muscle.