Cells, Tissues and Body Systems

P2

Nervous Tissue
A number of components make up the nervous system and these are also composed of the nervous tissue. The nervous tissue performs an imperative part in the fact that it is in charge for accepting, distributing and handling sensory input. It can be found in the three main areas of the nervous system which are the brain, nerves and the spinal cord. The nervous system contains two significant parts which are defined as peripheral and central. The peripheral nervous system (PNS) includes the nerves that spread to all ends of the body and the central nervous system (CNS) consists of the spinal cord and the brain where it acts as the fundamental processing interior for all stimuli.

Neurons are the specialised basic elements that work inside the nervous tissue. The functional and structural organisation of neurons can be described by elements such as an axon. This transmits information to different neurons, muscles and glands and is usually made from a nerve fibre which is a single process expanding from the cell body of a neuron and carrying nerve impulses away from it.
Dendrites carry nerve impulses from adjacent neurons into the cell body and are one of the shorter branching processes of the cell body of a neuron. A motor neuron transmits electrical signals for communication within the body from the central nervous system to the brain and the spinal cord, to muscles and glands elsewhere in the body. The synapse causes the release of a neurotransmitter and it is the minute gap across which nerve impulses pass from one neuron to the next at the end of a nerve fibre. Interneurons create neural circuits, enabling communication between sensory or motor neurons and the central nervous system.

Neuroglia cells are not neurons and these are the cells that formulate myelin, guard, provide sustenance and conserve stability in the nervous system. The basic responsibility of neuroglia is to offer vital support and functions for the neurons. These cells are categorised in the following manner such as microglial cells which are the macrophage cells that make up the principal immune system for the CNS and they are also one of the smallest neuroglia cell. Astrocytes are star shaped microglial cells which have several procedures discovered in the CNS and they are the most lavish cell type in the brain and vital to a vigorous CNS. Oligodendrocytes are the cells within the central nervous system that have a small range of practices however, they develop myelin sheaths on the axons of a neuron which are lipid based insulation that increases the quickness at which the action potential can transport down the axon. Ependymal cells are found in the central Nervous System (CNS) that is in the tissues of the brain and the spinal cord. They form lining of the ventricles of the brain and central canal of the spinal cord. They also create cerebrospinal fluid (CSF) and aid circulation of cerebrospinal fluid. Ependymal cells form the extremely thin membrane called the ependymal that lines the ventricles of the brain and choroid plexuses. Schwann cells are the peripheral nervous system equal of oligodendrocytes as they benefit to preserve axons and develop myelin sheaths in the PNS. The satellite glial cell lines the exterior of neuron cell bodies in ganglia.
Muscle tissue
The entire muscle, including the biceps is surrounded in a cover of connective tissue called the epimysium. This cover doubles within the element of the muscle to enclose a great amount of smaller bundles such as the fasciculi. The substance known as fasciculi contains still smaller bundles of extended, cylinder-shaped muscle cells which are the fibres. Every fibre is referred to as a syncytium meaning that each cell contains various nuclei. The nuclei have a structure which is oval shaped and are discovered at the boundary of the cell, just under the shrill, flexible membrane (sarcolemma). The sarcoplasm has several interchanging light and dark bands that give the fibre a streaked or striated aesthetic which is where the name striated muscle comes from. Through the help of an electron microscope it can be distinguished that each muscle fibre is prepared with many smaller units such as the myofibrils. These myofibrils entail of small protein filaments identified as actin and myosin filaments. However, myosin filaments are faintly thicker and complete what is known as the dark band and the active filaments complete the light bands most likely to be found on either side of the dark band. Actin filaments are connected to the Z-line and this organisation of actin and myosin filaments is branded as a sacromere. Throughout the contraction of skeletal muscle tissue, active filaments slither in amongst the myosin filaments whilst the mitochondria deliver the energy for this to be carried out. In addition this action results in the Z-lines becoming closer collected and in turn allows the entire muscle fibre to contract. This can bring about the restriction of the whole muscle including the biceps and having to rely on the amount of muscle fibres that were stimulated. Skeletal muscle tissue is able to contract quite rapidly and compellingly. The functions of the skeletal muscle tissue are that they work in sets to carry out the synchronised movements of the limbs, trunk, jaws and eyeballs but are also intimately part of the breathing process.

The smooth muscle tissue is constructed of thin-long muscle cells and fibres. These fibres are positioned at their ends and each fibre has a single large oval nucleus. All the cells in the tissue are packed with a particular cytoplasm and an element called the sarcoplasm is also encircled by a thin cell membrane called the sarcolemma. Within each cell there are several myofibrils which lay equivalent to each other towards the course of the long alignment of the cell. Even though the name of the muscle tissue is called the smooth muscle, this does not necessarily mean they are organised in a fixed striated form like the arrangement of skeletal muscles. The fibres of the smooth muscle intertwine in order to develop sheets or coats of muscle tissue instead of packages. The brain does not regulate the smooth muscle as it is spontaneous tissue matter. It produces the layers in the walls of resonating organs such as the digestive tract, the walls of bladder, uterus, numerous duct glands and the walls of blood vessels. The functions of the smooth muscle tissue are that it controls relaxed unintentional actions for contractions in the wall linings of the stomach and intestines and further contractions are made in the muscle of the arteries as they ease to control the pressure of blood and overall blood flow.
The cardiac muscle is a distinctive tissue which is found exclusively in the walls of the heart. A few features of the smooth muscle and the skeletal muscle are portrayed in the cardiac muscle tissue as well. The fibres of the cardiac muscle, similar to those of the skeletal muscle contain cross striation and include various nuclei. Though, this is also uncontrolled like the smooth muscle. There are many differences of the characteristics of the cardiac muscle which the skeletal muscle does not display such as shorter length, hard to recognise the striations, the sarcolemma is narrower and not visibly apparent, about one nucleus is exists in the middle of each cardiac fibre and neighbouring fibres divide but are connected to each other by supposed muscle bridges. Areolar connective tissues are occupied in the spaces amid different fibres and it consists of blood capillaries which source the tissue with the required oxygen and nutrients. The functions of the cardiac muscle are that they perform the most significant part in the contraction of the atria and ventricles of the heart. They also are the reason for the rhythmical beating of the heart whilst circulating the blood and its substances all through the body as a result.

Connective Tissue
Connective tissue is tissue that connects, supports, binds, or separates other tissues or organs and they can be found in the Blood, Cartilage, Bone, Areolar and Adipose tissue.

Blood is the red liquid that circulates in our blood vessels which is known as veins and arteries. It is categorised as connective tissue because it comprises of proteins mixed with water and produces gels. Blood is used for three main reasons, transportation of gasses and nutrients all around the body, immunity and regulating bleeding. There are three types of cells to be known of which are the plasma cells and the red/white blood cells.

Plasma cells are the liquid percentage of your blood and their function is to transport water, hormones and nutrients to the different tissues in your body. They are also a form of white blood cells that produce antibodies to help the body fight against diseases and can be considered as a significant part of the immune system.

Red blood (erythrocytes) cells do not contain a nucleus and are these disc shaped cells enclosing haemoglobin, which allows the cells to pick up and distribute oxygen to all fragments of the body, then pick up carbon dioxide and eliminate it from the tissues.

White blood (leukocytes) cells contain a nucleus and are the body’s principal resistance against infection and allergic reactions as they classify and target pathogens that could be attacking bacteria, viruses and other foreign organisms. These types of cells are developed continually and may only live for hours and days whereas some can live for years.

Cartilage
Cartilage is the most important formational module of the body. The cartilage is a malleable and strong connective tissue which can be found in many parts in the larynx and respiratory tract. However, they can also be found in the arrangements that consist of the articulating surfaces of joints and the peripheral ear. Cartilage is usually known to be discovered in certain areas of the body such as the joints between bones i.e. the elbows, knees and ankles, the ends of the ribs, amid the vertebrae in the spine, the ears and the nose and the bronchial tubes or airways. It is constructed of a specific cell named chondrocytes. This is a cell which has concealed the mix of cartilage and become rooted in it. Chondrocytes create large quantities of extracellular matrix composed of collagen fibres, proteoglycan and elastin fibres and no nutrients are delivered to the cell as no blood vessels exist in the cartilage. Nonetheless, nutrients navigate through the connective tissue and enter the primary cartilage. The cartilage has three types called the elastic cartilage, the fibrocartilage and the articular (hyaline) cartilage. Elastic cartilage makes up the exterior of the ears, a bit of the nose and the epiglottis which is the term used to describe the flap of tissue at the back of the throat that averts food entering into the airways. Fibrocartilage is found among the disks of the vertebrae in the spine and between the bones of the hips and the pelvis. Articular (hyaline) cartilage is an elastic and strong type of cartilage that exists between the ribs, around the windpipe (trachea) and among the joints.

Bone
The bones in the human skeleton are not entirely concrete. Bones such as the outside bone are solid but with selected minute passages and the interiors of the bone enclose trabecular bone which acts like a scaffolding or a honey comb. The areas between the bones are occupied with fluid bone marrow cells and they produce the blood and some fat cells. The functions of the bones are to arrange for maintenance to the body, guard vital organs, and allow movement, storage of minerals and to sustain blood calcium levels. Stem cells that exist in particular bone marrow allow for blood cell regeneration. In addition, it can be noted that the bone is an organ which consists of the skeletal structure and joints are described as two or more bones assembling. There are joints that remain fixated, some which move to an extent and some that are completely movable. Immovable joins would be classified as the joints of the skull and freely movable joints would be considered as the shoulders or the hips. Four simple bone forms are present in the body such as long bones, short bones, flat bones and irregular bones. Long bones entail a tubular shaft at each culmination whereas short bones have a cube like structure and the length, width and height are all alike. Flat bones are extended, wide, flat plates and irregular bones are strangely formed as they cannot be gathered into the bone categories of flat, short or long bones.

Areolar tissue
Areolar tissue is a mutual type of loose connective tissue and it is present in several areas of the body. The most significant area it originates in is the skin where it is also resides in both the dermis and sub-cutaneous layers. The tissue found inside the skin bounds the external layers of the skin to the muscle and is concealed around the mucous membranes, the blood vessels, organs of the body and the nerves. A mesh organisation is what the areolar tissue is developed from and it comprises of three fibres which are collagen fibres, elastic fibres and the reticular. The work of the areolar tissue is to bind the skin to the muscle and it should also be able to produce a bond concerning the organs at the same time as permitting a high volume of movement with the nearby body parts. Support, strength and elasticity are its chief roles.

Adipose tissue
This is one of the central types of connective tissue and in biology it is explained as a loose connective tissue composed generally of adipocytes. Adipose tissue is a resultant from preadipocytes with its key responsibility to accumulate energy in the arrangement of lipids, even though it cushions and insulates the body. In current years, adipose tissue has been identified as an important endocrine organ due to the fact it produces hormone such as leptin, estrogen, resistin and cytokine. Furthermore, this tissue can affect other organ systems of the body and could most likely be vulnerable to disease. Adipose tissue has two types and these are white adipose tissue (WAT), which stores energy and brown adipose tissue (BAT) which creates body heat.

Epithelial Tissue
Epithelial tissues conceal the entire surface of the body and are constructed of cells closely assembled and extended in one or more layers. The tissue is specifically designed to create the layering or coating of all linings which are inside and outside. Epithelial tissue that arises on the exteriors on the inner body is classed as endothelium. The epithelial cells are crowded narrowly together giving them practically no intercellular spaces and just about a slight amount of intercellular matter. Epithelial tissue, irrespective of the kind is typically detached from the core tissue by a thin piece of connective tissue such as the basement membrane. This membrane delivers structural provision for the epithelium whilst also connecting it to bordering structures.

Simple epithelial * Simple cuboidal epithelium - cuboidal cells are about square or cuboidal in figure. Each cell has a round nucleus in the core. The cuboidal epithelium is present in the glands and in the covering of the kidney tubules including the ducts of the gland. They also establish the germinal epithelium which creates the egg cells in the female ovary and the sperm cells in the male testes.

* Simple columnar epithelium - These cells happen in one or more coatings with the structure of the cells being extended and column shaped. They have a nucleus which is lengthened and is commonly situated near the foundation of the cells. Columnar epithelium cells mould the inside layer of the stomach and the intestines whereas some cells are specifically designed for sensory response in the nose, ears and the taste buds on the tongue. In addition, goblet cells also exist between the columnar epithelium cells of the duodenum.
They discharge mucus or slime which is an oiling element in order to keep the surface even.

* Squamous epithelium - Squamous cells have the look of thin, smooth plates. To recognise the type of epithelium, the outline of the nucleus will generally parallel to the cells form. An example of why squamous cells are likely to have straight compressed, elliptical nuclei is due to the thin compressed form of the cell. These cells form the lining of openings such as the mouth, blood vessels, heart and lungs and make up the external layers of the skin.

* Ciliated columnar epithelial -These types of cells are considered the simple columnar epithelial cells however; they also retain fine hair like extensions known as cilia on their open exteriors. These cilia are skilled enough to give quick, regular, wavelike beatings in a certain way. This movement of the cilia in a certain way results in the mucus which is produced and is discharged by the goblet cells, to travel in that course. Ciliated epithelium is typically established in the air passages like the nose or originates in the uterus or fallopian tubes of females. The ovum is pushed to the uterus by the movement of the cilia.

Compound epithelial
Where body coatings have to endure wear and tear, the epithelia are made up of numerous sheets of cell and are then referred to as compound or stratified epithelium. The upper cells are flat and scaly and they could or could not be keratinised. The mammalian skin is an example of dry keratinised, compound epithelium. The inside layer of the mouth opening is an example of something which is not keratinised compound epithelium.

The kidneys are detained in their place by connective tissue known as renal fascia which aims to provide protection. They are enclosed by a thick coat of adipose tissue called perirenal fat. The kidney has strong connective tissue that allow for care to be given to the weaker tissue that exists inside. Cuboidal epithelial cells are also present and these cells offer defence against abrasion but correspondingly permit the absorption and conveyance of materials. The kidney comprises of immense amounts of blood resources through the renal artery and renal vein and simple squamous epithelium in the glomerular capsule as this assists the kidney in its purification purpose.

The stomach contains different cell types that aid with digestion and there are four key types of cells for stomach discharges that are scattered all over the internal surface of the stomach. Mucous cells discharge the alkaline mucous for protecting the epithelium from hydrochloric acid and these exist in the fundic, cardiac and pyloric region. Parietal cells which are situated in the fundic, cardiac and pyloric region and discharge hydrochloric acid is where the acid stimulates release of pepsin for protein digestion as well as terminating micro organisms that are absorbed with food. The chief cells discharge pepsin and are sited in the fundic region and G cells are located in the fundic, pyloric and gastric region. These cells discharge gastrin which is used to fuel the emission of hydrochloric acid.

P3

Cardiovascular System
The cardiovascular system comprises of the heart which is frequently defined as a dual pump. It propels blood to the lungs to accumulate oxygen and then pumps it to the rest of the body. The vessels which blood transport through are known as veins, arteries and capillaries. They source all tissues and cells in the body, supplying them with oxygen and glucose for respiration and other nutrients.

Digestive System
The digestive system consists of the gastrointestinal (GI) tract also known as the digestive tract and includes other organs such as the liver, pancreas and the gallbladder. The digestive tract is a sequence of empty organs combined in an extensive, winding cylinder from the mouth to the anus. These empty organs that construct the digestive tract are the mouth, esophagus, stomach, small intestine and the large intestine which contains the rectum as well as the anus. Food goes into the mouth and travels through to the anus and also through the resonating organs of the digestive tract. The concrete organs of the digestive system entail the liver, pancreas, gallbladder and the main function of the system is to aid the body in digestion of food.

Endocrine System
The endocrine system involves glands that create and discharge hormones and chemical elements developed in the body that control the activity of cells or organs. These chemical messengers control the body’s development and metabolic rate as well as the sexual development and function. These hormones are then let free into the blood stream and could possibly affect a few organs throughout the body. The main glands of the system are the pancreas, hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal body and the reproductive organs such as the ovaries and the testes.

Immune System
The immune system is an assortment of organisations and procedures inside the body which aid to defend against infection or other possible foreign bodies. If the immune system is working correctly, then it is able to detect a range of risks which consist of viruses, bacteria and parasites by identifying them from the body’s personal healthy tissue. The main components of the immune system comprise of lymph nodes, spleen, bone marrow, lymphocytes, thymus and leukocytes.

Lymphatic System
The lymphatic system is a collection of thin tubes and lymph nodes that travel through the body. These tubes are known as lymph vessels or lymphatic vessels. The lymph system is a significant fragment of the immune system as it acts out the role of fighting infection and other bacteria and terminating old or unusual cells such as cancer cells. Other lymphatic system organs consist of the spleen, the thymus, the tonsils and the adenoids.

Musculoskeletal System
The musculoskeletal system is a structure that gives humans the skill to move by using their muscular and skeletal systems. This organisation delivers support, form, constancy and movement to the body. It is constructed of the bones of the skeleton, muscles, cartilage, tendons, ligaments, joints, and additional connective tissue that cares for and fixes tissues and organs as one piece. The principal purposes entail assisting the body, permitting motion, and defending important organs. The skeletal percentage of the system works as the key storing system for calcium and phosphorus and encloses serious mechanisms of the hematopoietic system. In addition, the muscular system can be broken down into three types of muscles called the skeletal, smooth and cardiac.

Nervous System
The nervous system contains the brain, spinal cord, sensory organs, and all of the nerves that link these organs with the entire body. Together, these organs are accountable for the mechanism of the body and communication between its parts. The brain and spinal cord arrange the control centre known as the central nervous system (CNS), where information is assessed and the conclusions are decided. The sensory nerves and sense organs of the peripheral nervous system (PNS) observe situations in the interior and exterior of the body and deliver this information to the CNS. Efferent nerves in the PNS transmit signals from the control centre to the muscles, glands, and organs to control their tasks. Most of the nervous system is tissue consisting of two cells known as neurons and neuroglia and the three primary functions are sensory, integration, and motor.

Renal System
The renal system also known as the urinary system entails of the kidneys, ureters, urinary bladder, and urethra. The kidneys clean the blood to eliminate wastes and produce urine. The ureters, urinary bladder, and urethra together arrange the urinary tract, which performs as a sanitation system to drain urine from the kidneys, stock it, and then discharge it through urination. As well as purifying and eradicating toxins from the body, the urinary system also sustains the homeostasis of water, ions, pH, blood pressure, calcium and red blood cells.

Reproductive System (Male and Female)
The reproductive system is an assortment of inside and outside organs in males and females that come together for the function of reproducing.
The male reproductive organs are the penis, the testicles, the epididymis, the vas deferens and the prostate gland. The penis comprises of tissue that seals with blood during sexual stimulation, which results in the penis becoming hard. Semen is a combination of sperm and fluid from the male reproductive organs. It departs the penis, through the urethra, whilst ejaculation occurs. The testicles (testes) are small egg-shaped sex glands found in a skin sack titled the scrotum. Sperm and sex hormones are constructed by the testicles. Choosing to keep the testicles outside of the body is so that they have a decreased temperature, which is vital for sperm production. Epididymis is a sequence of small pipes joined to the rear of each testicle. The epididymis gathers and stocks sperm. The vas deferens is the epididymis which ultimately becomes the vas deferens, a bigger pipe that transfers sperm to the urethra.
The female reproductive organs are the vagina, uterus, fallopian tubes and ovaries.
The vagina is a well-built channel around 7.5 cm long that prolongs from the neck of the uterus to the genitals, or vulva. The uterus is a strong organ, formed like an upside down pear. It’s inside layer is called the endometrium. The admission to the uterus is the cervix, which has a slight hole in its centre called the os. Fallopian tubes are these tubes that spread from the uterus with one on each side. They both open nearby an ovary. These tubes transport the egg from the ovary to the uterus.
Ovaries are two small almond-shaped glands that enclose ova. Sex hormones are also produced by the ovaries.

Respiratory System
The cells of the human body need a continuous stream of oxygen to remain alive. The respiratory system delivers oxygen to the body’s cells whilst eliminating carbon dioxide, an excess product that can be fatal if it is permitted to gather. There are three main fragments of the respiratory system which are the airway, the lungs, and the muscles of respiration. The airway, which contains the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles, conveys air amongst the lungs and the body’s peripheral. The lungs perform as the efficient components of the respiratory system by letting oxygen into the body and carbon dioxide out of the body. Finally, the muscles of respiration, as well as the diaphragm and intercostal muscles must function as one to perform as a pump that impulses air into and out of the lungs during breathing.
Bibliography

Dr. C. George Boeree. (2003, 2009). The Neuron. Available: http://webspace.ship.edu/cgboer/theneuron.html. Last accessed 30th November 2015.

David Darling. (N/A). Skeletal muscle. Available: http://www.daviddarling.info/encyclopedia/S/skeletal_muscle.html. Last accessed 30th November 2015.

The University of the Western Cape. (N/A). Muscle Tissues. Available: www.botany.uwc.ac.za/sci_ed/grade10/mammal/muscle.htm. Last accessed 30th November 2015.

Dougherty, Mr.|Science. (2002-2015). BIOLOGY II: HUMAN ANATOMY & PHYSIOLOGY. Available: http://www.rtmsd.org/page/1790. Last accessed 30th November 2015.

N/A. (2000-2014, 2015). Cardiac Muscle Structure. Available: http://www.buzzle.com/articles/cardiac-muscle-structure.html. Last accessed 30th November 2015.

Bhagawati lal Mali. (2014). Circulatory System. Available: https://www.pinterest.com/pin/100486635410587922/. Last accessed 30th November 2015.

N/A. (2015). The Human Digestive System. Available: http://www.2beingwell.com/human-digestive-system/. Last accessed 30th November 2015.

N/A. (1995-2015). Endocrine System. Available: http://kidshealth.org/parent/general/body_basics/endocrine.html. Last accessed 30th November 2015.
N/A. (2015). Absorption & Excretion: Urinary System-Kidneys. Available: http://www.mhhe.com/biosci/esp/2001_saladin/folder_structure/ab/m2/s2/index.htm. Last accessed 30th November 2015.

N/A. (N/A). Anatomy of the Stomach. Available: http://www.aboutcancer.com/stomach_anatomy.htm. Last accessed 30th November 2015.

The University of the Western Cape. (2015). Epithelial Tissues. Available: http://www.botany.uwc.ac.za/sci_ed/grade10/mammal/epithelial.htm. Last accessed 30th November 2015. m0casa02. (2013). Ehlers-Danlos syndrome and autism. Available: http://corticalchauvinism.com/2013/08/12/ehlers-danlos-syndrome-and-autism/. Last accessed 30th November 2015.

N/A. (2015). What Is Plasma?. Available: https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=160&ContentID=37. Last accessed 30th November 2015.

N/A. (2015). What is bone?. Available: https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=85&ContentID=P00109. Last accessed 30th November 2015.
Sarah Phenix. (2003- 2015). Function of Areolar Connective Tissue. Available: http://study.com/academy/lesson/function-of-areolar-connective-tissue.html. Last accessed 30th November 2015.

Wikipedia.com Editors. (2015). File:409 Adipose Tissue.jpg. Available: https://commons.wikimedia.org/wiki/File:409_Adipose_Tissue.jpg. Last accessed 30th November 2015.

N/A. (2006-2013). The Immune System: “Catch Me If You Can”. Available: http://cisncancer.org/research/what_we_know/advances/immune_system.html. Last accessed 30th November 2015.
N/A. (2014). The lymphatic system and cancer. Available: http://www.cancerresearchuk.org/about-cancer/what-is-cancer/body-systems-and-cancer/the-lymphatic-system-and-cancer. Last accessed 30th November 2015.
Presley Cundiff. (2015). Musculoskeletal System.. Available: https://prezi.com/z7ejtm80xtig/musculoskeletal-system/. Last accessed 30th November 2015.

N/A. (2015). Human Nervous System. Available: http://aamhinashikkar.com/human-nervous-system. Last accessed 30th November 2015.

Kim Ann Zimmermann, Live Science Contributor. (2015). Urinary System: Facts, Functions & Diseases. Available: http://www.livescience.com/27012-urinary-system.html. Last accessed 30th November 2015.

N/A. (N/A). Differences Between the Male & Female Reproductive Structures. Available: https://www.premedhq.com/differences-between-the-male-and-female-reproductive-structures. Last accessed 30th November 2015.
Fawne Hansen. (2014–2015). Anatomy Of The Respiratory System. Available: http://adrenalfatiguesolution.com/anatomy-of-the-respiratory-system/. Last accessed 30th November 2015.