1. The process of excitation contraction-coupling begin when an action potential is generated. This action potential travels down the somatic motor neuron until it reaches the motor end plate, also known as the synaptic knob. Once it reaches the motor end plate, it causes the exocytosis of the synaptic vesicle containing the neurotransmitter, Acetyl Choline (ACh). ACh is the neurotransmitter needed for all muscle contractions. ACh is spit out into the myoneural synapse. Then, the ACh diffuses the short distance across the myoneural synapse. Once it reaches the other side, it has reached the muscle cell membrane, also called the sarcolemma. Then, the ACh is going to plug into the receptor sites on the sarcolemma, triggering an action potential. …show more content…
As the action potential passes through the terminal cisterni, it opens the voltage gated calcium ion gates within the walls of the sarcoplasmic reticulum. Once the gates are open, calcium will be released and it will diffuse from the inside of the sarcoplasmic reticulum, to the sarcoplasm, which is cytoplasm of the muscle cell. The calcium ions will temporarily attach to any troponin molecule it can find. Troponin is a protein molecule attached to tropomyosin. Tropomyosin is wrapped around an actin filament, and it covers the binding sites for myosin heads. When calcium attaches to troponin, it causes a shift in the tropomyosin, revealing the binding sites on the actin filament. Then the cross-bridge cycle begins. With the binding sites uncovered, the myosin heads are free to attach to the actin filament. The myosin head has two things attached to it: ADP and an inorganic phosphate, later an ATP will be attached. When the myosin head attached to the binding site, the ADP and the inorganic phosphate group pop off of the myosin head. This causes the power stroke. The power stroke is when the myosin head cocks one way, causing the actin filament to slide in that …show more content…
The integument is a physical barrier that provides protection. It protects the body from injury and trauma, harmful chemicals, toxins, microbes, temperature extremes, and deeper tissue from solar radiation. The integument also prevents the gain and loss of water. The integument is composed of a deep dermis layer, and a superficial epidermis layer. The epidermis layer is water resistant, but not waterproof, water is sometimes lost through sweat. Another function of the integument is metabolic regulation, and vitamin D3 synthases upon UV exposure. There are also many substances that are secreted and absorbed through the integument. Waste products are secreted from the skin through sweating. The skin also absorbs certain chemicals and drugs. There are also epidermal dendritic cells that attack cancer cells and initiate immune response against pathogens. Another function of the integument is temperature regulation of the body by dermal blood vessels and sweat glands. When the body is placed in a cold environment, the dermal blood vessels constrict so less blood travels through, allowing the body to conserve heat. When the body is placed in a hot environment, the dermal bold vessels dilate, allowing more blood to circulate closer to the surface of the skin. One final function of the integument is sensory reception. The skin has broad innervation, and a large distribution of nerve fibers. Touch receptors detect
In the beginning phases of muscle contraction, a “cocked” motor neuron in the spinal cord is activated to form a neuromuscular junction with each muscle fiber when it begins branching out to each cell. An action potential is passed down the nerve, releasing calcium, which simultaneously stimulates the release of acetylcholine onto the sarcolemma. As long as calcium and ATP are present, the contraction will continue. Acetylcholine then initiates the resting potential’s change under the motor end plate, stimulates the action potential, and passes along both directions on the surface of the muscle fiber. Sodium ions rush into the cell through the open channels to depolarize the sarcolemma. The depolarization spreads. The potassium channels open while the sodium channels close off, which repolarizes the entire cell. The action potential is dispersed throughout the cell through the transverse tubule, causing the sarcoplasmic reticulum to release
To begin we will look at the integumentary system and its entire multitude of functions. The main components of the integumentary system are the skin, hair, nails, glands and nerves. For the purpose of this paper we will focus mainly on the levels of the skin and their functions. While the integumentary
The immune system is made up of a network of cells, tissues, and organs that work together to protect the body, and it defends the body from “foreign invaders.” Immunity can be divided in two three different defenses, and these are defined as first, second and third lines of defense. The first line of defense for the immune system is the primary defense against pathogens entering the body from the surface in order to prevent the start of disease and infection. Some examples of the first line of defense is the skin, protecting the external boundaries of the body, and the mucous membranes, protecting the internal boundaries of the body. Although the skin and mucous membranes work on the internal and external boundaries, they both release chemicals
When a muscle contracts and relaxes without receiving signals from nerves it is known as myogenic. In the human body, the cardiac muscle is myogenic as this configuration of contractions controls the heartbeat. Within the wall of the right atrium is the sino-atrial node (SAN), which is where the process of the heartbeat begins. It directs consistent waves of electrical activity to the atrial walls, instigating the right and the left atria to contract at the same time. During this stage, the non conducting collagen tissue within the heart prevents the waves of electrical activity from being passed directly from the atria to the ventricles because if this were to happen, it would cause a backflow. Due to this barrier, The waves of electrical energy are directed from the SAN to the atrioventricular node (AVN) which is responsible for transferring the energy to the purkyne fibres in the right and left ventricle walls. Following this, there is a pause before the wave is passed on in order to assure the atria has emptied. After this delay, the walls of the right and left ventricles contract
...st the sacrolemma will depolarized, thus activation potentials along the T-tubules. This signal will transmit from along the T-tubules to sarcroplasmic reticulum's terminal sacs. Next, sarcoplasmic reticulum will release the calcium into the sarcroplasm leading to the next second event called contraction. The released calcium ions will now bind to troponin. This will cause the inhibition of actin and mysoin interaction to be released. The crossbridge of myosin filaments that are attached to the actin filaments, thus causing tension to be exerted and the muscles will shorten by sliding filament mechanism. The last event is called Relaxation. After the sliding of the filament mechanism, the calcium will be slowly pumped back into the scaroplasmic reticulum. The crossbridges will detach from the filaments. The inhibition of the actin and myosin will go back to normal.
Hair is considered one of the components of the integumentary system, along with the skin, nails, glands and nerves. Mammalian hair has many functions including protection from environmental factors and the ability to disperse sweat gland products such as pheromones. Almost every part of the human body is covered by hair except for the palms, hands and bottoms of the feet. On average, every person has about five million hairs; each of these hairs is born from a follicle or tiny tube-like structure that grows into the dermis layer of the skin. Oftentimes this follicle even reaches the subcutaneous layer, which is made of fat and connective tissue. (UXL Complete Health Research, 2001)
The presynaptic terminal stores high concentrations of neurotransmitter molecules in vesicles, which are tiny nearly spherical packets. These molecules are then released by depolarization. Depolarization opens voltage-dependent calcium gates in the presynaptic terminal. After calcium enters the terminal, it causes exocytosis, which is the burst of release of neurotransmitters from the presynaptic neuron. After its release from the presynaptic cell, the neurotransmitter diffuses across the synaptic cleft to the postsynaptic membrane, where it attaches to the receptor.
For muscles to contract then there must be a presence of calcium within the fibers as it connects with troponin protein and orders tropomyosin to clear the binding sites to allow myosin to attach to these sites, which allows the muscle to contract and produces movement. Without all of these elements working in sync then the function of skeletal muscle would no longer work or even exist.
Our skin functions as a daily defense for our bodies against disease because of skin and mucous membranes. The skin is a massive organ and it protects everything inside our bodies such as our muscles, bones and organs. Our skin protects us from bacteria, parasites, viruses and pathogens ...
Dendrites are located on either one or both ends of a cell.The peripheral nervous system then takes the sensory information from the outside and sends the messages by virtue of neurotransmitters. Neurotransmitters are chemicals that relay signals through the neural pathways of the spinal cord. The neurotransmitter chemicals are held by tiny membranous sacs located in the synaptic terminals. Synaptic terminals are located at the ends of nerve cells. The release of neurotransmitters from their sacs is stimulated once the electrical nerve impulse has finished travelling along a neuron and reaches the synaptic terminal. Afterward, neurotransmitters travel across synapses thus stimulating the production of an electrical charge that carries the nerve impulse onward. Synapses are junctions between neighboring neurons. This procedure is reiterated until either muscle movement occurs or the brain picks up on a sensory reaction. During this process, messages are being transmitted from one part of the body onto the next. The peripheral and central nervous system are two crucial subdivisions of the nervous system. The brain and spinal cord make up the central nervous
...d at the axon endings of motor neurons, where they stimulate the muscle fibers to contract. And they and their close relatives are produced by some glands such as the pituitary and the adrenal glands. In this chapter, we will review some of the most significant neurotransmitters.
The sarcomere is found in structures called myofibrils which make up skeletal muscle fibres. Within the sarcomere there are various different proteins. One of the most significant, myosin is found in the thick filaments of the sarcomere. Although both cells contain myosin, it is important to highlight that smooth muscle cells contain a much lower percentage of myosin compared to skeletal muscle cells. Despite this, myosin filaments in smooth muscle cells bind to actin filaments in a manner similar to that in skeletal muscle cells; although there are some differences. For instance, myosin filaments in smooth muscle cells are saturated with myosin heads so that myosin can glide over bound actin filaments over longer distances, enabling smooth muscle cells to stretch further, whilst in skeleta...
The integumentary system is composed of the skin and the structures related to the skin, which include the hair, the finger nails, the sensory receptors and the glands (Shier, Butler, & Lewis, 2009). This system has an important function since it provides protection to the body, helps to maintain body temperature, and contains sensory receptors (p.117). The skin has essential function such as regulating homeostasis and body temperature, also delaying the loss of water from deeper tissues, storing sensory receptor, synthesizing biomechanical, and discharging waste from the body (p.117). The skin has two layers: the epidermis (outer layer) and the dermis (inner layer) (p.117). There is also a subcutaneous layer or hypodermis (p.117). According to Shier, Butler, and Lewis 2009 “as its name indicates, this layer is beneath the skin and not a true layer of the skin” (p.117). This layer has the blood vessels that supply the skin (p.117).
Action potentials are started at one end of the node, flow passively through the myelinated axon, and pop out the other side to jump to the next node. This jumping of action potentials is called saltatory.
The skin has 3 main function. It has to regulate body temperature, remove waste (perspiration), and protect. The skin is made up of 3 layers. The epidermis is the outer thinner layer of the skin that is made up of dead and living cells. The dermis is the thicker middle layer of the skin that contains blood vessels and nerves. Sweat glands are found in the dermis, they secrete perspiration through ducts to pores on the skin’s surface. To avoid problems like warts, boils, moles, acne, and sunburn you can wash your body daily, wear sunscreen that is 15 or higher, and check your body often...