BIOL 1117 Lecture Notes - Lecture 2: Anterior Pituitary, Posterior Pituitary, Pituitary Gland
3 Oct 2017
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Document Summary
Overview of cell communications: four major mechanisms of communication between cells. Gap junctions: pores in cell membrane allow signaling molecules, nutrients, and electrolytes to move from cell to cell. Neurotransmitters: released from neurons to travel across synaptic cleft to bind to receptors on a second cell. Paracrines: secreted into tissue fluids to affect nearby cells of same tissue. Hormones: chemical messengers that travel in the bloodstream to other tissues and organs. Comparison of endocrine and exocrine glands: exocrine glands. Have ducts carry secretion to an epithelial surface or the mucosa of the digestive tract: external secretions. No ducts and release their secretions into bloodstream. Contain dense, fenestrated capillary networks which allows easy uptake of hormones into bloodstream. Differences between nervous and endocrine systems: both serve for internal communication. Endocrine - only chemical speed and persistence of response. Nervous: reacts quickly (few milliseconds); stops quickly. Endocrine: hormone release may occur slowly; long term effect: adaptation to long-term stimulation.
