Human Anatomy Overview

Human Anatomy Study Notes

• Human anatomy: Study of body structures.
• Regional anatomy: Structures in specific body regions.
• Systemic anatomy: Structures in discrete body systems.
• Interneurons focused on: Integration.
• Nuclei: Clusters of neurons in the CNS.
• Ganglia: Clusters of neurons in the PNS.
• Tracts: Bundles of axons in the CNS.
• Nerves: Bundles of axons in the PNS.
• Neuroglia (glial cells): Supporting cells of the nervous system.

Anatomical Directional Terms

• Ventral/anterior: Belly/front.
• Dorsal/posterior: Back/back.
• Superior/cranial: Up/skull.
• Inferior: Down.
• Caudal: Tail.
• Rostral: Nose.
• Medial: Towards the midline.
• Median: Midline.
• Lateral: Towards the sides.
• Ipsilateral: Same side.
• Contralateral: Opposite side.
• Bilateral: Both sides.

Planes of Section

• Sagittal plane: Divides into right and left.
• Frontal/coronal plane: Divides into front and back.
• Transverse plane: Divides into top and bottom.

Neurodevelopment

• Neurodevelopment: Neural stem cells differentiate into neurons and glial cells.
• Gastrulation: Transforms 2D to 3D embryo, head-to-tail and front-to-back.
• Inner cell mass (embryoblast): Develops into the baby.
• Trophoblast: Develops into the placenta.
• Blastocyst cavity (blastocoele): Hollow space filled with fluid.
• Neurulation: Ectoderm forms neural plate, which forms neural tube (brain and spinal cord).
• Notochord: Develops into the spine.
• Endoderm: Develops into internal organs.
• Mesoderm: Develops into muscles and red blood cells.
• Ectoderm: Develops into skin and the nervous system.

Brain Development

• Primary brain vesicles: Prosencephalon (forebrain), mesencephalon (midbrain), rhombencephalon (hindbrain).
• Secondary brain vesicles: Telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon.
• Telencephalon: Develops into the cerebrum.
• Diencephalon: Develops into the thalamus, hypothalamus, and epithalamus.
• Mesencephalon: Remains the midbrain.
• Metencephalon: Develops into the pons and cerebellum.
• Myelencephalon: Develops into the medulla oblongata.

Neuronal Migration

• Neural migration: Radial glial cells guide neurons to their correct positions in the brain.
• VZ migration: Neurons migrate to deep cortex layers.
• SVZ migration: Neurons migrate to superficial cortex layers.
• Cortical development: Inside-out process (VZ, inner SVZ, outer SVZ, IZ, CP).

Neuron Classifications

• Neuron classifications: Morphology, neurotransmitter released, target cell response type, electrophysiological properties, discoverers.
• Glutamatergic neurons: Glutamate; excitatory.
• GABAergic neurons: GABA; inhibitory.
• Glycinergic neurons: Glycine; inhibitory (spinal cord interneurons).
• Cholinergic neurons: Acetylcholine; mainly excitatory.
• Monoaminergic neurons: Norepinephrine, epinephrine, dopamine, serotonin; mostly inhibitory neuromodulators.
• Neurons use mitochondria: Provide energy for sodium-potassium pumps.
• Multipolar neurons: Many dendrites, one axon (most common).
• Bipolar neurons: One axon, one dendrite (retina).
• Unipolar neurons: One process (rare in mammals, common in insects).

Synaptic Types

• Axodendritic synapse: Axon to dendrite; excitatory.
• Axosomatic synapse: Axon to cell body; inhibitory.
• Axoaxonic synapse: Axon to axon; presynaptic inhibition.
• Dendrodendritic synapse: Dendrite to dendrite; local interactions.

Glial Cells

• Astrocytes: Structural/metabolic support, Blood Brain Barrier.
• Oligodendrocytes: Myelination in the CNS (multiple axons).
• Schwann cells: Myelination in the PNS (one axon).
• Pericytes: Regulate capillaries.
• Ependymal cells: CSF formation.
• Microglia: Immune cells; phagocytosis.

Neuronal Activity

• Generator potentials: Local, fluctuating membrane changes.
• Action potentials: All-or-none electrical impulses.
• Sodium-potassium pump: Restores ionic balance; 3 Na+ out, 2 K+ in.
• Nerve fiber types: A (large, myelinated, fast); B (smaller, myelinated, slower); C (smallest, unmyelinated, slowest).
• Autoreceptors: Regulate neurotransmitter release.
• Receptor types: Ionotropic (direct, fast) vs. metabotropic (indirect, slow).
• End-plate potential: Depolarization at the NMJ triggered by acetylcholine release.
• Quanta: Fixed number of neurotransmitter molecules released.

Telencephalon

• Telencephalon: Cerebrum (cortex, white matter, basal nuclei).
• Cerebral lobes: Frontal, temporal, parietal, occipital, insular.
• Corpus callosum: White matter connecting hemispheres.
• Sulci (fissures): Central, parieto-occipital, lateral.

Lobes of the Cortex

• Frontal lobe: Voluntary movement, language, executive functions.
• Parietal lobe: Spatial processing, sensory processing (somatosensory, sensory-motor, visual association).
• Temporal Lobe: Senses, limbic system (emotions, memories).
• Limbic system: Amygdala and hippocampus.
• Occipital lobe: Visual processing.

Neocortex

• Neocortex: Outermost layer of cerebral cortex; 6 layers, pyramidal, stellate, fusiform neurons.
• Cortical columns: Functional units in neocortex.
• White matter tracts: Transverse (hemispheres), projection (cortex to subcortex/spinal cord), association (ipsilateral cortex areas).

Thalamus

• Thalamus: Relay station for sensory impulses, regulates arousal.
• Thalamic functional groups: Sensory, motor, limbic, multimodal, intralaminar.
• Thalamic nuclei: Anterior group, midline nuclei, medial nuclei, lateral nuclear mass, posterior nuclei.