Bio 111 lecture 21

what are homeotic genes?

genes critical for making sure anatomical structures develop in the correct location and in the correct number

what can mutations in homeotic genes lead to?

body parts in innapropriate places and/or the wrong number

what is an example of a homeotic gene mutation?

polydactyl

what are morphogens?

diffusible ligands that affect cell fate during development

what are the two ways morphogens can be secreted?

by groups of cells within the embryo called organizers

into the embryo from the mother

what are morphogen gradients a representation of?

the concentration of morphogens

morphogens affect cells in a ______ dependent manner

concentration

what do different morphogen concentrations lead to?

different cell fate decisions

what response does the nervous system initiate?

fight flight freeze

what are the two subdivisions of the nervous system?

central and peripheral

what does the central nervous system consist of?

the brain, spinal cord, and interneurons within the brain and spinal cord

what does the peripheral nervous system consist of?

sensory neurons and motor neurons

what are the three types of neurons?

sensory neurons

interneurons

motor neurons

what do sensory neurons do?

carry information about the body and environment to the CNS

what do interneurons do?

provide a link between the sensory neurons, brain, and motor neurons

what do motor neurons do?

carry impulses from CNS to effectors(muscles and glands)

what do dendrites do?

receive signals using receptors and send electrical pulses to the cell body

what does the cell body consist of?

the nucleus and other metabolic machinery

what does the cell body do?

transmit the action potential from the dendrite to the axon

what does the axon do?

conducts the action potential to the axon terminals

what do axon terminals do?

transmit the signal through a synapse to the next cell

what is the myelin sheath?

a discontinuous covering around the axon, formed by layers of schwann cells

what are gaps in the myelin sheath called?

nodes of ranvier

what does the myelin sheath do?

speeds the transmission of action potentials down the axon

what is multiple sclerosis a result of?

damage to the myelin sheath

what are nerves surrounded by?

nerve sheath

what do nerves consist of?

a collection of axon bundles(fascicles),veins, arteries, and connective tissue

what is a neuromuscular junction?

connection between neurons and muscles