In the heart-
The epithelial tissue protects the heart from rubbing and damaging the lobes in the heart against the lungs; it provides an extra barrier for security and saves the heart from injuries. Epithelial tissues line all the ducts and glands within the heart and protect it with an exterior membrane.
Connective tissue-
Connective tissues function primarily to support the body and to bind or connect together all types of tissue. Unlike epithelial tissue, connective tissue is characterised by the large amounts of intercellular substance (also called ground substance or the matrix) that it contains. Connective tissue is relatively few cells which are widely separated from each other. These living cells are responsible for secreting the large amounts of intercellular ground substance (matrix). The matrix is a non-living material which may be liquid, e.g. blood, semi-solid, e.g. connective tissue or solid, e.g. bone. The function of connective tissue is to transport materials, to give support and strengthen and to protect. Connective tissues are: blood, bone, cartilage, Areolar tissue and adipose tissue (fatty tissue). Blood is a specialized bodily fluid in animals that delivers necessary substances such as, nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. Bones have a rigid structure that constitutes part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a dense type of connective tissue. Cartilage is a flexible connective tissue found in many areas in the body including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs. It is not as hard and rigid as bone but is stiffer and less flexible than muscle. Areolar tissue is a common type of connective tissue, also referred to as 'loose connective tissue'. It is strong enough to bind different tissue types together, yet soft enough to provide flexibility and cushioning. Adipose tissue (fatty tissue) it provides insulation and protection of organs, muscle fibers, nerves, and supports blood vessels. It protects us from excessive heat loss or heat increase and also acts as a shock absorber to protect against injury.
In the intestine-
The lumen is the cavity where digested food passes through and from where nutrients are absorbed. Both intestines share a general structure with the whole gut,
and are composed of several layers. Going from inside the lumen radially outwards, one passes the mucosa (glandular epithelium and muscularis mucosa), submucosa, muscularis externa (made up of inner circular and outer longitudinal), and lastly serosa. Serosa is made up of loose connective tissue and coated in mucus to prevent friction damage from the intestine rubbing against other tissue. Holding all this in place are the mesenteries which suspend the intestine in the abdominal cavity and stop it being disturbed when a person is physically active.
In the heart-
Connective tissue provides the final pathway for diffusion of nutrients, oxygen, waste and metabolites to and from the cells of the body. All blood vessels are embedded in connective tissue. The only cells which receive their sustenance directly from the blood are the endothelial cells lining the vessels themselves. All other cells are supplied via diffusion through intermediary connective tissue. The transport functions of blood and connective tissue cannot be separated. The heart and circulatory system simply facilitate the movement of this travelling tissue. The valves in the heart are also made from connective tissues, they control the amount of blood that is passed through the heart and into the blood stream, and it also helps to reduce the flow back to the heart.
Nervous tissue-
Nervous tissue is found only in the nervous system and consists of nerves, brain and spinal column. Nervous tissue is responsible for sensing stimuli and transmitting signals to and from different parts of an organism. Neurons are the basic unit of nervous tissue; neurones are highly specialised nerve cells which transmit impulses. Present only in the brain and spinal cord but their long processes form the nerves. Nervous tissue receives stimuli from both inside and outside the body and it helps to create consistency, coordination and communication between different parts of the body. Neuroglia is the connective tissue cells that intermingle with neurones in the brain and spinal cord and offer support and protection. Nerve tissue requires more oxygen and nutrients than any other body tissue
In the heart-
The nervous tissue in the heart controls the heart’s main functions. It is controlled by specialised nerves called nodes. A node is a specialised type of tissue that behaves as both muscle and nervous tissue. When nodal tissue contracts (like muscle tissue) it generates nerve impulses (like nervous tissue) that travel throughout the heart wall. The heart has two nodes that are instrumental in cardiac conduction, which is the electrical system that powers the cardiac cycle. These two nodes are the sinoatrial (SA) node and the atrioventricular (AV) node. The sinoatrial node, also referred to as the pacemaker of the heart, coordinates heart contractions. Located in the upper wall of the right atrium, it generates nerve impulses that travel throughout the heart wall causing both atria to contract. The atrioventricular node lies on the right side of the partition that divides the atria, near the bottom of the right atrium. When the impulses generated by the SA node reach the AV node, they are delayed for about a tenth of a second. This delay allows the atria to contract, thereby emptying blood into the ventricles. The AV node then sends the impulses down the atrioventricular bundle. This bundle of fibers branches off into two bundles and the impulses are carried down the center of the heart to the left and right ventricles.
In the intestine
In order to propel the food into the small intestine, a small electrical impulse is passed down the vagus nerve into the lower part of the stomach to grind the food and expel it little by little. Then in order for digested food to pass through the intestine tract electrical impulses that are sent from the brain pass through the spinal cord to the nervous tissue within the intestines which then stimulates the muscle to contract causing the digested food to be passed down through to the rectum to the be excreted.
Muscle tissue-
Muscle tissue is an excitable tissue. It responds to stimuli that are capable of shortening and contracting which causes the movement of the skeleton. There are 3 types of muscle tissue; striated, non-striated and cardiac, each has fibres that can contract and relax. This generates heat and helps to control temperature. The striated muscle is also known as the skeletal muscle, because it is attached mainly to the bones and skin, and is responsible for the mobility of the body and limbs, the movement of striated muscle is controlled voluntarily. Non-striated muscle tissue is not connected to the bones. It is controlled involuntary, as it includes the organs that operate without conscious thought, although it still requires stimulation from the nervous system.
Cardiac muscles are only found in the heart. They are self-contracting, autonomically regulated and continue to contract in rhythmic fashion for the whole life of the organism. Some of the cardiac muscle cells contract without any nervous stimulation.
In the heart-
Cardiac muscle does have several unique features. Present in cardiac muscle are intercalated discs, which are connections between two adjacent cardiac cells. Intercalated discs help multiple cardiac muscle cells contract rapidly as a unit. This is important for the heart to function properly. Cardiac muscle also can contract more powerfully when it is stretched slightly. When the ventricles are filled, they are stretched beyond their normal resting capacity. The result is a more powerful contraction, ensuring that the maximum amount of blood can be forced from the ventricles and into the arteries with each stroke. This is most noticeable during exercise, when the heart beats rapidly. This pumps blood around to all the cells in the body, helps to retrieve it and re-oxygenate it and pump it back around.
In the intestine-
Smooth muscle is found in the walls of hollow organs like your intestines and stomach. The muscular walls of the intestines contract to push food through your body and help to break it up, this is an involuntary function.