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Results for: 'activated helper T cell'
Cytotoxic T cell receptors, activation, proliferation, differentiation & action
By: HWC, Views: 8053
• Most cells which have CD8 on their surface become cytotoxic T cells (Tc cells). • CD8 T cells recognize a foreign antigen when it is presented in conjunction with the protein, MHC-I. • Nearly all nucleated cells in the body express MHC-I molecules. • T cells that recognize self-pe...
Phases of an Action Potential - Resting Potential, Threshold, Rising, Falling, & Recovery Phases
By: HWC, Views: 7154
In this tutorial, we will review the phases of an action potential measured from a small area of a neuron's membrane. The action potential can be divided into five phases: the resting potential, threshold, the rising phase, the falling phase, and the recovery phase. When the neuron is at rest,...
Components of the Nervous System
By: Administrator, Views: 435
The nervous system is the part of an animal that coordinates its actions by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue...
Plant Defense Mechanisms from Pathogens
By: HWC, Views: 7193
Plants and pathogens have coevolved such that pathogens can recognize plants by the sugars, or other molecules, they produce. Plants, in turn, can recognize pathogens by the molecules they produce. The ability to recognize pathogens allows plants to activate defense systems that can prevent wides...
Primary and secondary response to infection
By: HWC, Views: 7486
• Pathogens enter the body by penetrating the non-specific barriers in the skin and mucus membranes. • Pathogens first encounter macrophages and natural killer cells that carry out phagocytosis and cytolysis respectively. • A pathogen's first encounter with the immune system can promo...
By: HWC, Views: 5111
A neuromuscular junction is a chemical synapse between the axon endings of a motor neuron and a muscle cell. A narrow synaptic cleft separates the presynaptic cell (the motor neuron) from the postsynaptic cell (the muscle cell). The presynaptic cell contains vesicles filled with neurotransmitt...
Osmosis - Isotonic, Hypotonic, and Hypertonic Solutions
By: HWC, Views: 7843
Isotonic: Equal Water moves in and out of the cell at an equal rate. The cell remains unchanged. Hypotonic: "hypo" hippo Water moves into the cell, making it swell and get fat (like a hippo). Eventually the cell can rupture and burst (aka lyse). Hypertonic: "like a raisin" Water leaves...
Action potentials - electrical characteristics and generation
By: HWC, Views: 7582
• An action potential is the nervous impulse or signal for long distance communication. Each action potential is generated at the cell's trigger zone. • Action potentials are considered an all-or-nothing phenomena because they are either generated or not. • The generation of an action...
By: Administrator, Views: 10781
The clinical manifestations of sickle cell anemia result from pathologic changes to structures and systems throughout the body.
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