Biol114- Module 4

How does autonomous cell specification differ from conditional cell specification?

Autonomous uses unequally inherited cytoplasmic factors; conditional relies on neighbor cell paracrine signals.

What is the difference between cell specification and cell determination?

Specification is acquiring identity signals; determination is the irreversible stabilization of fate.

What are the three main types of cell movements observed during gastrulation?

Invagination (infolding), Involution (rolling inward), and Ingression (individual migration).

What are the three functional classes of neurons found in the nervous system?

Sensory (afferent, slower), Motor (efferent, voluntary commands), and Interneurons (CNS processing).

What two structural components actively maintain a neuron's resting membrane potential?

ATP-powered Na+

What does the Nernst potential equation calculate for a specific ion?

The membrane potential at which that single ion is at electrochemical equilibrium.

What is a graded potential in a neuronal cell membrane?

A variable, local, decremental shift in voltage that does not trigger an action potential.

What membrane voltage threshold must be crossed to trigger an all-or-nothing action potential?

-55 mV

What happens to voltage-gated Na+ and K+ channels when an action potential spikes?

Na+ channels rapidly open at -55 mV, then inactivate at +40 mV as slower K+ channels open.

What mechanism creates the absolute refractory period in a propagating axon?

Inactivated sodium channels that lock closed, forcing the signal to travel only in one direction.

What is saltatory conduction in the nervous system?

The fast propagation of an action potential as it leaps between uninsulated Nodes of Ranvier.

What cellular steps occur when an action potential reaches a chemical synapse?

Voltage-gated Ca2+ channels open, prompting calcium influx to drive vesicle exocytosis.

Where and how does a neuron perform summation of incoming inputs?

At the axon hillock, where it adds up incoming positive EPSPs and negative IPSPs.

How does an ionotropic receptor differ functionally from a metabotropic receptor?

Ionotropic directly opens an ion channel; metabotropic uses a slower second-messenger cascade.

Which common neurotransmitters are classified as purely excitatory, purely inhibitory, or both?

Excitatory (Glutamate, Acetylcholine); Inhibitory (GABA, Glycine); Both (Serotonin, Dopamine).

What are the specialised evolutionary functions of the forebrain, midbrain, and hindbrain?

Forebrain (smell, sleep, learning); Midbrain (routing info); Hindbrain (motor control, involuntary activity).

What anatomical structures make up the central and peripheral nervous systems?

CNS consists of the brain and spinal cord; PNS consists of somatic and autonomic nerves.

What are the functional roles of the three divisions of the Autonomic Nervous System?

Sympathetic (fight-or-flight); Parasympathetic (rest-and-digest); Enteric (autonomous gut motility).

What are the primary functional specializations of the four cerebral cortex lobes?

Frontal (planning, decisions); Parietal (sensory); Temporal (hearing, speech); Occipital (vision).

What is the structural difference between grey matter and white matter in the cerebrum?

Grey matter contains cell bodies and synapses; white matter contains myelinated axon tracts.

Which brain structures form the emotional and memory-recalling limbic system?

Thalamus, hippocampus, and amygdala.

What are the primary homeostatic roles of the thalamus and hypothalamus?

Thalamus routes sensory info; hypothalamus regulates body temp, biological clocks, and behavioral drives.

What are the respective support functions of astrocytes, oligodendrocytes, and microglia?

Astrocytes (nutrients, blood-brain barrier); Oligodendrocytes (myelin insulation); Microglia (immune macrophages).

Through what two long-term plastic processes does the brain remodel its connection networks?

Long Term Potentiation (strengthening connections) and Synaptic Pruning (eliminating unused synapses).

Which specific neurotransmitter deficiencies are linked to depression and Parkinson's disease?

Depression is linked to decreased Serotonin; Parkinson's is linked to lost Dopamine cells in the basal ganglia.