Chapter 3 Flashcards
Na/k ATPase action
3 Na ions out, 2 K ions in with the hydrolysis of one ATP molecules through primary active transport
Resting membrane potential of neurons
-70mV
Voltage-gated sodium channels: activation threshold potential
-50mV
Neuron depolarization goes to what voltage
~+35mV
All-or-nothing response
All channels will open fully if the depolarization hits the threshold
Voltage-gated K channels compared to voltage-gated Na channels
Voltage-gated Na channels depolarize membrane where K channels open and repolarize the membrane
* K channels are slower to open but remain open for longer than Na channels
Axons of many neurons are wrapped in _____ created by ____
insulating myelin sheath
Schwann cells (type of glial cell)
Schwann cells
One of the two peripheral nervous system supporting (glial) cells. Schwann cells form the myelin sheath on axons of peripheral neurons
Nodes of Ranvier
where the channels are concentrated because there are no membrane depolarization and no voltage-gated sodium channels where the myelin is
Saltatory conduction
rapid jumping of action potentials between nodes
o Speeds up movement of APs
Types of effectors
muscles and glands
Central nervous system
- Spinal cord
- Hindbrain:
- Midbrain:
- Forebrain:
Hindbrain
Medulla
Pons:
Cerebellum:
Midbrain
relay for visual and auditory information and contains much of the reticular activating system (RAS) which is responsible for arousal or wakefulness
Forebrain
includes the diencephalon and telencephalon:
Diencephalon
thalamus and hypothalamus
thalamus
relay and processing centre for sensory info
hypothalamus
interacts directly with many parts of the brain. Contains centres for controlling emotions and autonomic functions
o Plays major role in hormone production and release
o Primary link between nervous and endocrine system
Telencephalon
cerebral hemispheres, corpus callosum, cerebrum
cerebrum
largest region of the human brain (encompasses the cerebral hemispheres)
o Cerebral cortex: outer layer of grey matter
Grey matter consists of somas and white matter consists of myelinated axons
Cerebral hemispheres (and their lobes)
generally, most people tend to be left brain dominant. Left hemisphere is responsible for speech and right hemisphere is responsible for visual-spatial reasoning and music
o Responsible for conscious thought processing and intellectual functions
o Play a role in processing somatic sensory and motor information
Composed of lobes:
Frontal lobe:
Parietal lobes:
Temporal lobes:
Occipital lobes:
Wernicke’s area
language comprehension
Broca’s area
language production
frontal lobe
initiates voluntary movement and involved in complex reasoning skills and problem solving
Parietal lobes
involved in general sensation (touch, temp, pressure, vibration, etc) and gustation (taste)
Temporal lobes
process auditory and olfactory sensation and involved in short-term memory, language comprehension, and emotion
Occipital lobes
process visual sensation
Basal nuclei (cerebral nuclei, basal ganglia)
gray matter deep within cerebral hemispheres. Broadly function in voluntary motor control and procedural learning related to habits
Works with cerebellum to process and coordinate movement initiated by the primary motor cortex
* Basal nuclei is inhibitory and cerebellum is excitatory
Limbic system
located between cerebrum and diencephalon. Includes: amygdala, cingulate gyrus, hippocampus.
Important for emotion and memory
Brainstem
medulla, pons, and midbrain
Quick summary of roles:
1. Spinal cord
2. Medulla
3. Pons
4. Cerebellum
5. Midbrain
6. Thalamus
7. Hypothalamus behaviour
8. Basal nuclei
9. Limbic system
10. Cerebral cortex
11. Corpus collosum
Quick summary:
1. Spinal cord –> simple reflexes
2. Medulla –> involuntary functions
3. Pons –> relay station and balance
4. Cerebellum –> movement coordination
5. Midbrain –> eye movement
6. Thalamus –> integrating center and relay station
7. Hypothalamus –> homeostasis and behaviour
8. Basal nuclei –> movement (inhibitory)
9. Limbic system –> emotion, memory, learning
10. Cerebral cortex–> perception, skeletal muscle movement, memory, attention, thought, language, and consciousness
11. Corpus collosum –> connection between hemispheres
Peripheral nervous system Anatomical Organization (think nerves)
All neurons entering and exiting the CNS are carried by 12 pairs of cranial nerves and 31 pairs of spinal nerves
Cranial nerves (one example)
covey sensory and motor information to and from brainstem
E.g., vagus nerve: acts on heart and GI tract to increase HR and decrease GI activity
* Part of the parasympathetic division of ANS
* Axons of the vagus nerve are preganglionic and end in ganglia which synapse to postganglionic neurons on surface of heart, stomach, and other visceral organs.
Spinal nerves
convey sensory and motor information to and from spinal cord
Somatic PNS anatomy: what do they innervate, what neurotransmitter do they use, what are their dendrites like?
o All somatic motor neurons innervate skeletal muscle cells, use Ach as their neurotransmitter and have cell bodies in the brain stem or ventral (front) spinal cord
o All somatic sensory neurons have a long dendrite extending from sensory receptors towards the soma (located just outside the CNS) in a dorsal root ganglion (spinal cord)
Dorsal root ganglion
a bunch of somatic (and autonomic) sensory neuron cell bodies located just dorsal (back) of the spinal cord
* There is a dorsal root ganglion for every segment of the spinal cord
* They are protected by vertebral column but are outside meninges (therefore outside the CNS)
preganglionic neuron
one of two efferents of the sympathetic and parasympathetic systems
Preganglionic neuron: has its cell body in brainstem or spinal cord and sends axon to an autonomic ganglion outside the spinal cor
sympathetic system (thoraco-lumbar system) efferent neurons
All sympathetic system (thoraco-lumbar system) has its preganglionic efferent neurons cell bodies in the thoracic or lumbar spinal cord
General function: fight or flight, mobilize energy
Preganglionic axon is relatively short, release ACh
Only a few ganglia which are quite large, close to the cord and far from target
Postganaglionic cells send a long axon to the effector (norephinephrine)
Parasympathetic system (craniosacral system) efferent neurons
Parasympathetic system (craniosacral system) has all its preganglionic neuron cell bodies in the brainstem or n the sacral portion
General function: rest and digest, store energy
Preganglionic neurons send a long axon (ACh)
Small ganglion, far from cord, close to targe
Postganglionic cells are close to the effector and release ACh
postganglionic cell
Postsynaptic neuron: synapses with the ganglion and sends an axon to an effector (smooth muscle of glad)
All autonomic preganglionic neurons release _____ as their neurotransmitter
acetylcholine
All parasympathetic postganglionic neurons release _____ as their neurotransmitter
acetylcholine
Nearly all sympathetic postganglionic neurons release _______
norepinephrine
Autonomic afferent (sensory) neurons similarity and difference to somatic afferent neurons
similar to somatic afferent neurons with one exception:
o they can synapse in the PNS (at autonomic ganglia) with autonomic efferent neurons in a “short reflex”
Adrenal medulla part of what nervous system?
Part of the sympathetic nervous system
o Embryologically derived from sympathetic postganglionic neurons and directly innervated by sympathetic preganglionic neurons