Part One
Neurons are throughout our entire body and are what allow our central nervous system and brain communicate with your whole body. Nerve impulses among motor neurons are what allow our bodies to move when we want to. A nerve impulse is an electrical signal that travels down the axon to transmit information to other neurons to allow movement. In order for a nerve impulse to be generated, a stimulus must be strong enough to cause an “all-or-nothing” response. If the signal is strong enough the reach the neuron’s threshold, then the neuron will “fire”, or send the impulse down the axon. Before this happens, the resting neuron must be polarized by having different charges on either side of the cell membrane. This is because the outside of the cell membrane is more positive due to the presence of sodium ions while the inside is more negative due to the presence of potassium ions. Normally the resting neuron has an electrochemical value of -70 mV. In order for the electrical balance to remain stable and for the cell the maintain homeostasis, the sodium/potassium moves sodium ions out of the cell and potassium ions into the cell using ATP. When the nerve impulse is generated the balance that was created by the cell membrane is reversed, causing sodium ions to go into the cell and potassium ions to leave the cell. The cell is now in a depolarized state due to a more positive charge inside the cell and a more negative charge outside the cell. This depolarization causes the
To send a message, a neuron will send a ripple of electrical energy down its axon. This ripple is called "action potential." The way it works is by changing the chemical makeup of the axon's negatively charged interior. Positively charged sodium ions move into the cell and negatively charged potassium ions move out, then the ions move to their original positions. This produces a wave of positively charged
This stage is called repolarisation. The K+ channels then close, the sodium-potassium pump restarts, restoring the normal distribution of ions either side of the cell surface membrane and thus restoring the resting potential. In response to this the Na+ channels in that area would open up, allowing Na+ ions to flood into the cell and thus reducing the resting potential of the cells. If the resting potential of the cell drops to the threshold level, then an action potential has been generated and an impulse will be fired.
Those cells must receive nutrients and gases in order to undergo the metabolic processes that maintain homeostasis. In paragraph form, explain how you think the nutrients and gases enter the cell. Distinguish between the molecules that can enter by diffusion by simply moving across the membrane and those that must expend energy to cross the cell membrane.
1. Neurons is a basic building block of the nervous system. The sensory nerves carry the message from body tissues to the brain and spinal chord to be processed. The motor neurons are then used to send instructions to the body tissue from the brain and spinal cord. Dendrites, which are connected to the body cell (soma) receive information and pass it through the axon. Myelin sheath covers the axon and helps speed the process. When triggered by a signals from our senses or other neurons, the neuron fires an impulse called the action potential. The resting potential is the neuron’s visual charge of positive
As an action potential travels down the axon of the presynaptic neuron, the action potential reaches the axon terminal synaptic vesicles which migrate toward the synapse. They then release neurotransmitters into the synaptic cleft. The neurotransmitters travel through the synaptic cleft and bind to ligand-gated ion channels on the postsynaptic neuron membrane. The channels open and allow chemicals to enter the cell (i.e. sodium). Then positively charged sodium enters the cell and causes the cell to depolarize. The depolarization spreads down the axon and an action potential is generated. The process then starts over at the axon terminals.
The plasma membrane surrounds all eukaryotic and prokaryotic cells. Eukaryotic cells have membrane bounded organelles whereas prokaryotic cells do not. The plasma membrane forms the boundary between the cell cytoplasm and the environment. Its function are to allow different environments to be established inside and outside the cell. It also controls the movement of substances into and out of the cell.
Impulses will travel along the neuron pathways as the electrical charges move across each neural membrane. Ions that are moving across the membrane can cause the impulse to move along the nerve cells.
Neurons respond to two different ions: potassium(Na+) and sodium(K+). There is usually a higher concentration of Na+ ions outside the cell(extracellularly) which makes the cell more positive, rather than inside the cell(intracellularly) where there is a higher concentration of K+ ions which makes the cell more negative. This is explained as the resting membrane potential of a neuron; where there is a potential deferens of ion concentration. In cells ions will move from a region of higher concentration to a region of lower concentration and that is the concentration gradient. If channels permeable to an ion, then it will allow it to diffuse to where the ion
When a skeletal muscle fires it is caused by a signal in a motor neuron. Voltage gated sodium channels open up after a threshold stimulus of -55mV is reached. Next, Sodium ions move into the cell membrane, thus depolarizing the cell at +30mV, which is its action potential. Sodium channels close and Potassium channels open. Potassium moves out, which repolarizes the cell. Hyperpolarization
9-2: What are the parts of a neuron and how are neural impulses generated? Neurons are the elementary components of the nervous system, the body 's speedy electrochemical information system. A neuron receives signals through the branching dendrites, and sends signals through its axons. Some axons are encased in a myelin sheath, which enables faster transmission. If the combined receive signals exceed a minimum threshold, the neuron fires, transmitting an electrical impulse (action potential) down it 's axon by means of the chemistry to electricity process. The neuron 's reaction is an all or none process.
was running around, using the water he had in his body and he wasn’t drinking
1 - Describe the normal structure and functioning of cell membranes, and explain how they compare to the membranes relating to a specific abnormality in cystic fibrosis?
The purpose of this experiment was to indirectly study the effects of environmental stress on cell membranes. Watercourses have been with discarding of domestic and manufacturing, for centuries. Alarms have only escalated about the ecological alterations in the recent years of what would be the consequences. Scientists have developed a thorough investigation in search of various man harmful waste that is damaging the environment of watercourses.
A nerve cell has a negative charge at a resting state due to negatively charged proteins within the cell.[3] Although the inside of the cell contains positively charged potassium ions as well, overall the charge is still negative. Along with potassium on the inside of the cell, positively charged sodium ions are located around the exterior of the cell.[3] When an action potential occurs, the cell becomes even more negatively charged. In turn, this causes sodium transport molecules in the membrane of the cell to open.[3] Sodium will then enter the cell during active transport. The positively charged sodium will cancel out the negatively charged active potential which will depolarize the cell. This allows neurotransmitters to transfer from cell to cell.[3] These neurotransmitters are what allows the body to feel pain. Local anesthetics work by diffusing through nerve fibers. Once they’ve reached the cells, they block the sodium transport molecules in the cell.[2] Therefore neurotransmitters cannot transfer information from cell to cell and the feeling of
The cell membrane consists of eight distinctive parts that each have their own unique structure and function. The phospholipid bilayer is an integral part of the cell membrane because it is the external layer of the cell membrane and composes the barriers that isolate the internal cell components and organelles from the extracellular environment. It is composed of a series of phospholipids that have a hydrophobic region and a hydrophilic region. These regions are composed of the hydrophilic heads and the hydrophobic tails of the phospholipids, this organization of the polar heads and nonpolar tails allows the heads of the cell to form hydrogen bonds with water molecules while the tails are able to avoid water. The phospholipid bilayer also has many important functions within the cell, it gives the cell shape, provides protection, and it is selectively permeable which allows it to only let very specific molecules pass through its surface. The phospholipid bilayer is an important structure because it prevents harmful and unwanted molecules from entering the cell and isolates organelles which helps to maintain the internal environmental homeostasis of the cell.