Biology 252 Exam 1 Questions and Answers

Biology 252 Exam 1 Questions and Answers What is homeostasis? - Ans:-how varied components of living things adjust to maintain a constant internal living environment. There is a balanced dynamic state! Diseases result from homeostatic imbalances (diabetes) What are the levels of organization? - Ans:-chemical - cellular - tissue - organ - organ system - organismal What is the nervous system made of? - Ans:-The Central nervous system (brain and spinal cord) and the peripheral nervous system (cranial nerves and spinal nerves). What is the big picture of the nervous system? What does this mean? - Ans:-Input - Processing - Output. Explain. Most of our wiring is _____. - Ans:-insulated. Neuron - Ans:- Describe the soma, neurofibrils, Nissl bodies, dendrites, axon and axon hillock. - Ans:-Soma- body of the neuron cell. ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 2/26 Neurofibrils- work with microtubules to compartmentalize rough ER into Nissl bodies. Nissl bodies- help identify neurons in tissue sections with mixed cell types Dendrites- primary site for receiving signals from other neurons axon hillock- nerve fiber where axon originates axon- conducs nerve signals to remote point from the soma. contains Varicosities secrete NTs. How are neurons classified? - Ans:-By number of processes extending from the soma. What is the difference in multipolar nerons, bipolar neurons, and anaxonic neurons? - Ans:- multipolar - one axon with multiple dendrites. Includes most neurons of the brain and spinal cord. bipolar- one axon and one dendrite. Anaxonic- multiple dendrites, no axon. Communicate through dendrites and produce no action. found in brain, retina, and adrenal medulla. What is axonal transport? - Ans:-two way passage of proteins, organelles, and other materials along the axon. What is anterograde and retrograde transport? - Ans:-anterograde- moves down the axon, away from the soma. retrograde- moves up the axon, towards the soma. ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 3/26 What are 3 properties that enable communication with other cells? - Ans:-1. Excitability (response to stimuli or environmental change). 2. Conductivity ( production of electrical signals that are conducted to other cells at distant locations). 3. Secretion (when a signal reaches the end of a nerve fiber, neuron secretes a NT that crosses gap and enters the next cell). What are sensory neurons? - Ans:-(dealing with the five senses) They are a part of the PNS (afferent). They conduct signals from receptors to the nervous system. Detect stimuli and transmit info TOWARDs the CNS. somatic: bones, joints, and muscles visceral: comes from inside us like internal organs (organized by location) What are interneurons? - Ans:-They lie within the CNS. They receive signals and carry out the integrative function of the nervous system. They take info from sensory neurons in the PNS and make decisions. What are motor (efferent) neurons? - Ans:-sends signals AWAY from the CNS to primarily muscle cells (effector). somatic: skeletal muscle ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 4/26 autonomic: things you can't control (like digestion, heartbeat, glands in hormonal signaling) -- smooth muscles, cardiac muscles, hormones. (organized by target cell) What is the myelin sheath? - Ans:-A whitish, fatty segmented sheath around most LONG (not all) axons. They increase the speed of nerve impulse transmission. It is formed by cells. The cell has concentric layers of membrane that make up the myelin sheath. What are neuroglia? - Ans:-glia cells that protect neurons by binging them together to provide a supportive framework for nervous tissue. Prevent neurons from contacting each other. What are the four neuroglia in the central nervous system ? - Ans:-Astrocytes, Oligodendrocytes, Ependymal cells, and Microglia Astrocytes - Ans:-- support and brace neurons - control the chemical environment - cover the brain and nonsynaptic regions of neurons - supportive framework of CNS - induce BBB - influence synaptic signaling ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 5/26 - secrete growth factors - removes K+ and some NTs from ECF of brain and spinal cord - form scar tissue Oligodendrocytes - Ans:-- insulators of the thick neurons of the CNS - form myelin in brain and spinal cord - bulbous shape w/ arms that wrap around it forming myelin sheath Microglia - Ans:-- The "immune cells" of the CNS - phagocytize and destroy microorganisms, foreign matter, and dead nervous tissue. Become concentrated in areas affected by infection, trauma, or stroke. ______ and _______ induce the formation of the BBB. - Ans:-Astrocytes and Pericytes Ependymal cells - Ans:-- Ciliated epithelial cells lining the central cavities of the brain and spinal column. - Forming a permeable barrier between the CSF and nervous tissue - beating cilia helps circulate the CSF - secrete and circulate CSF ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 6/26 Schwann Cells - Ans:-Form neurilemma around the PNS nerve fibers and myelin around majority of them. Aid in regeneration of damaged nerve fibers. Satellite Cells - Ans:-Surround somas of neurons in the ganglia, provide electrical insulation and regulate chemical environment of neurons (homeostasis?) What is hydrocephalus? - Ans:-The accumulation of CSF! can cause brain swelling What are leak channels? - Ans:-Always open! But they are not open to all ions. They are very specific per ion. Ions allow channels to move through the plasma membrane. But what drives them to move? - Ans:- They move to maintain equilibrium. Ex; there is a higher concentration of K+ inside the cytosol than in the ECF. K+ will leave the cell via leak channels due to the chemical gradient. Negative Proteins cannot leave the cell. The electrical gradient allows negatively charged proteins to pull K+ back in. What is the chemical gradient? - Ans:-causes ions to move from an area of high concentration to low concentration in order to create more balance and restore equilibrium. (Potassium would want to go out, Sodium wants to go in) What is the purpose of the electrical gradient? - Ans:-The electrical gradient counteracts the chemical gradient until K+ net flow is zero (which never happen