exam 3 anatomy written

What are the 3 overlapping functions of the NS and their traits?

1. sensory input - monitors internal and external changes

2. integration - interprets sensory info and decides action

3. motor output - activates effectors to cause a response

What are the main components of the CNS?

Brain and spinal cord

What are the main components of the PNS and their function?

Cranial and spinal nerves; communication routes from CNS to the rest of the body

What are the 2 divisions of the PNS and their functions?

• afferent division: visceral and somatic sensory nerve fibers - conduct impulses from receptors

• efferent division: motor nerve fibers - conducts impulses from CNS to effectors

What are the 2 efferent divisions of the PNS and functions?

• somatic nervous system: voluntary motor function - conducts impulses from CNS to skeletal muscles

• autonomic nervous system: visceral motor (involuntary) - conducts impulses from CNS to cardiac muscle, smooth muscle, and glands

What are the divisions of the ANS and functions?

• sympathetic division: mobilizes body systems during activity/stress

• parasympathetic division: conserves energy, promotes housekeeping functions at rest

What are traits and functions of all neuroglia?

• smaller than neurons

• majorly outnumber neurons

• function to support, protect, and insulate neurons

List the types of neuroglia and their location?

• CNS: astrocytes, microglia, ependymal cells, oligodendrocytes

• PNS: Schwann cells, satellite cells

What are functions and traits of astrocytes?

• most abundant type

• highly branched

• recapture and recycle neurotransmitters that were released

• anchor neurons to nutrient supply line

• control BBB (blood-brain barrier) permeability

• regulate K+ balance

What are the traits and functions of microglia?

• small, ovid cells

• highly mobile

• monitor health of neurons

• phagocytic role (immunity)

What are the traits and functions of ependymal cells?

• ciliated, usually cuboidal cells

• line cavities of the brain and spinal cord

• forms a permeable barrier between CSF and cavities that bathe cells of the CNS

• cilia circulates CSF

What are the traits and functions of oligodendrocytes?

• form insulating myelin sheath on axons in the CNS

• protective function

What are the traits and functions of satellite cells?

• surround neuron cell body in the PNS

• support via protective barrier

• provide glucose nutrients

• regulates chemical environment

SIMILAR TO ASTROCYTE FUNCTION

What are the traits and functions of Schwann cells?

• surround all nerve fibers in the PNS

• form myelin sheath surrounding large nerve fibers in PNS

• regenerate damaged PNS nerve fibers

SIMILAR TO OLIGODENDROCYTE FUNCTION

What is the main function of neurons?

Transmit electrical and chemical signals throughout the body

What are the traits of dendrites?

• input region for receiving signals from other neurons

• convey incoming messages to cell body

• nonmyelinated mostly

What are the traits of axons?

• come from axon hillock

• generates nerve impulses, transmits them away from cell body to the axon terminal

What are the components of the neuron cell body?

• nucleus

• nucleolus: produces ribosomes

• Nissl bodies: protein synthesis

• Golgi apparatus: packaging and transporting proteins

What are the traits of the myelin sheath?

• fat insulating all but the smallest axons

• protects and electrically insulates fibers

• increases transmission speed of nerve impulses

• conducts nerve impulses rapidly

What are the traits of the Nodes of Ranvier?

• gaps in the myelin sheath

• prevent adjacent Schwann cells from touching

• occur at regular intervals

Define axon collaterals?

• occasional branches off of main axon

• talk to multiple neurons at once

What distinguishes types of neurons?

The number of processes found on the cell body

What are the 3 types of neurons?

• pseudounipolar

• bipolar

• multipolar

What are the traits of multipolar neurons?

• one axon

• one cell body

• MANY dendrites

What are traits of bipolar neurons?

• one dendrite and one axon extending on either side of cell body

• rare neurons - found in retina, inner ear, olfactory mucosa

What are the traits of pseudounipolar neurons?

• have a cell body with one single extension

• peripheral and central processes emerging from the cell body

• nociception

What are the 3 functional classifications of neurons?

• afferent (sensory) neurons

• efferent (motor) neurons

• interneurons (association neurons)

What are traits of afferent neurons?

• transmit impulses from sensory receptors in skin or organs towards the brain

• almost all are pseudounipolar

• cell bodies are located in sensory ganglia outside of CNS

What are traits of efferent neurons?

• carry impulses away from CNS to effector organs (muscles or glands)

• most are multipolar

What are traits of interneurons?

• lie between motor and sensory neurons

• shuttle signals through CNS pathways where integration occurs

• most confined in the CND

• make up majority of neurons in body

Define voltage?

Measure of PE generated by separated electrical charges, measured in V or mV

Define potential?

measurement of voltage between 2 points. greater difference between them = higher voltage

Define resistance?

hindrance of electrical flow which the current must pass

What are characteristics of the resting membrane potential?

• polarized

• more sodium outside the cell

• more potassium inside the cell

• Na-K pump, leaky channels maintain concentration gradient

What are the ion differences during depolarization and repolarization?

• depolarization: inside of membrane becomes more positive due to influx of Na+

• repolarization: K+ exits the cell due to concentration gradient, making the inside of the cell more negative

What are 3 the gated ion channels and how do they open?

1. chemical (ligand) gated: opens when appropriate chemical binds

2. voltage gated: opens in response to change in membrane potential

3. mechanically gated: opens in response to physical deformation of receptor (sensory)

Define action potential?

comes from a change in the membrane potential

How long is a typical AP?

1-3 milliseconds

What is the all-or-nothing principle?

The idea that the nerve or muscle fiber will either fire with full force or not at all; there is no halfway

Define threshold?

The value to be obtained for an action potential to begin the phases

What are the 3 phases of an AP?

1. depolarization

2. repolarization

3. hyperpolarization

What events occur at plasma membrane during AP stages?

• resting state: polarized, but no major movement. more sodium outside the cell

• depolarization: sodium floods into cell and increases voltage

• repolarization: potassium exits the cell rapidly

• hyperpolarization: potassium continues exiting the cell, sodium remains outside

Characteristics of absolute refractory period?

• immediately after the AP

• lasts until sodium channels fully recover

• during this time, sodium channels cannot open

Characteristics of relative refractory period?

• repolarization and hyperpolarization occur

• AP possible but needs bigger stimulus b/c K+ are in process of closing

What determines the rate of impulse of a conduction velocity?

• axon diameter: larger is faster

• degree of myelination: higher myelination conducts faster

What are the nerve fiber types?

• A alpha

• A beta

• A gamma

• A delta

• C fibers

What are the traits of A alpha fibers?

• largest and heavily myelinated

• proprioception and transmission of motor signals to skeletal muscles and joints

What are traits of A beta fibers?

• large to medium size

• skin, muscles, internal organs

• fine touch, pressure, vibration

• tested by 2-point discrimination

What are traits of A gamma fibers?

• medium sized

• moderately myelinated

• participate in muscle contraction

What are traits of A delta fibers?

• small, myelinated

• fast, sharp/dull, temperature

What are traits of C fibers?

• smallest diameter, unmyelinated

• slow, sharp/dull, temperature

What are components of the chemical synpase?

• presynaptic terminal (axon ending)

• voltage-gated calcium channels

• synaptic vesicles

• neurotransmitter

• synaptic cleft

• postsynaptic membrane (motor end plate)

Review steps involved in chemical synapse?

1. AP arrives at axon terminal

2. voltage-gated calcium channels open and it enters the axon terminal

3. calcium entry causes synaptic vesicles containing neurotransmitters to release contents via exocytosis

4. neurotransmitter diffuses across synaptic cleft and binds to specific receptors on postsynaptic membrane

What are general traits of neurotransmitters?

• language of the nervous system

• produced and released by neurons

• over 100 have been identified

• can excite or inhibit

• can bind to neurons and effectors (tissues, cells, glands)

What are the characteristics of ACh (its effects)?

1. muscarinic effect: found on all effector cells in parasympathetic target organs. can stimulate or inhibit based on subclass receptor of target organ

2. nicotinic effect: found on all postganglionic neurons in sympathetic and parasympathetic. hormone-producing cells of adrenal medulla. sarcolemma of skeletal muscle cells at NMJ. always stimulatory

What are the traits of biogenic amines?

• broadly distributed in the brain

• regulate function for movement, behavior, emotions, temperature, BP, endocrine secretion

List the 4 biogenic amines and traits of them?

1. norepinephrine: alertness/arousal/attention, constriction of BV, influence sleep-wake/mood/memory

2. dopamine: feel good neurotransmitter, motivation and reward, cognition

3. serotonin: sleep/mood, influence learning and memory

4. histamine: initiates allergic rxn to protect body

What are the 2 amino acids and their traits?

• aminobutyric acid (GABA): reduces neuronal excitability

• glutamate: regulates mood, controls memory, cognition

What are the 3 peptides and the traits?

• substance P: painful perception (physical or mental)

• endorphins: natural opiates, which reduces perception of pain under stressful conditions

• gut-brain peptides: produced by nonneural tissues and are within GI tract (ex. CCK and somatostatin)

What is the one purine & its traits?

ATP: universal form of energy, mediates calcium influx when it attaches to astrocytes

What are the 2 gaseous transmitters and their traits?

• NO: variety of brain processes, such as forming new memories and increasing synpase strength

• CO

*both activate guanylate cyclase - makes the second messenger cyclic GMP

What are the regions of the brain?

• cerebral hemispheres

• diencephalon

• brainstem

• cerebellum

What distinguishes gray and white matter?

• gray matter is short, nonmyelinated neurons

• white matter is myelinated axons in fiber tracts

What cells line the ventricles of the brain?

Ependymal cells

List the structures of the ventricles of the brain?

• lateral ventricles (R and L)

• 3rd ventricle

• 4th ventricle

• cerebral aqueduct

• lateral apertures

• median apertures

What percent of blood is pumped from the heart to the brain?

15-20%

List the arteries supplying blood to the brain?

• internal carotid arteries

• vertebral arteries

• basilar artery

• circle of willis (anterior & posterior cerebral and communicating arteries)

• middle cerebral artery

What are the hemispheres of the brain & what do they form?

Right and left; superior part

What are the 3 basic regions of the cerebral hemisphere?

1. cerebral cortex of gray matter

2. white matter

3. basal nuclei

The hemispheres form which part of the brain?

Superior

Describe the features of gyri and sulci of the cerebral cortex?

• gyri: elevated twists of tissue

• sulci: grooves separating gyri

What structure separates the two cerebral hemispheres?

Longitudinal fissure

List the lobes of the brain?

• frontal

• parietal

• temporal

• occipital

What are the anatomical traits of the central sulcus, precentral gyrus, and postcentral gyrus?

• central sulcus is the groove separating the frontal and parietal lobes of the brain

• precentral gyrus is the ridge anterior to it

• postcentral gyrus is the ridge posterior to it

What are some characteristics of the cerebral cortex?

• where our conscious mind is found

• accounts for 40% of total brain mass

• hemispheres connect to contralateral sides of body

• composed of gray matter, but has NO FIBER TRACTS

What is the cerebral cortex composed of?

Gray matter, neuron cell bodies, dendrites, associated glia, blood vessels

What are some functions of the cerebral cortex?

• determining intelligence

• personality

• motor function

• planning and organizing

• touch sensation

• processing special senses info

• language processing

What are the general functional areas of the cerebral cortex and their roles?

1. motor areas: control voluntary movement

2. sensory areas: conscious awareness of sensation

3. association areas: receives many inputs and integrates incoming sensory info; forms connections between sensory and motor areas

List the motor areas of the cerebral cortex?

• primary motor cortex

• premotor cortex

• Broca’s area

• frontal eye field

Location and function of primary motor cortex?

• location: precentral gyri of both hemispheres

• function: conscious control of precise, skilled, voluntary skeletal muscle movements (ex. picking up a cup)

Location and function of premotor cortex?

• located right in front of precentral gyri

• functions to sequence basic motor movements into more complex ones (instruments/typing), coordinate actions of multiple muscle groups, and control voluntary actions based on sensory feedback

Broca’s area location and function?

• found in front of inferior portion of premotor area - left hemisphere for most

• functions to direct muscles in speech production and also activate when preparing to talk

Frontal eye field location and function?

• found anterior to premotor cortex (in front of front of precentral gyrus)

• controls voluntary eye movements

List the sensory areas of the cerebral cortex?

• primary somatosensory cortex

• somatosensory association cortex

• visual areas

• auditory areas

• olfactory cortex

• gustatory cortex

• visceral sensory area

• vestibular cortex

Location and function of primary somatosensory cortex?

• found in postcentral gyrus of parietal lobe

• receives info from sensory receptors in skin and proprioceptors in muscles, joints, tendons

• spatial discrimination

Location and function of somatosensory association cortex?

• found posterior to primary somatosensory cortex

• integrates sensory input and relays it to the primary somatosensory cortex

• discriminates size, texture, parts of the object felt

• draws on stored memories of past sensory experiences to the object one is feeling (recognize w/o looking)

Location and function of primary visual cortex?

• found in occipital lobe

• receives visual info from the retina

Location and function of the visual association area?

• surrounds primary visual cortex and covers lots of the occipital lobe

• communicates with primary visual cortex

• interprets what we see (colors, depth, form)

• enables recognition of something (flower, face, etc)

Location and function of primary auditory cortex?

• found in superior margin of temporal lobes (next to lateral sulcus)

• activates hearing receptors of our inner ear

• interprets pitch, loudness, and location a sound comes from

Location and function of auditory association area?

• found in posterior margin of temporal lobe

• perceives a sound stimulus as a sound, talking, thunder, scream, etc

• memories of sounds are stored here

Location and function of olfactory cortex?

• found in medial aspect of the temporal lobe

• conscious awareness of odors

Location and function of gustatory cortex?

• found in insula of deep temporal lobe

• perceives taste

Location and function of visceral sensory area?

• cortex of insula (posterior to gustatory cortex)

• conscious perception of visceral sensations, such as full bladder, upset stomach

Location and function of vestibular cortex?

• found in posterior insula and adjacent parietal cortex

• conscious awareness of balance (head in space)

What are the general traits and functions of multimodal association areas?

• give meaning to the information that we receive, store it in memory, tie it to previous experience and knowledge, and decide what action to take

• receives input from multiple areas and sends outputs to multiple areas

What are the 3 divisions of the multimodal association areas?

• anterior association

• posterior association

• limbic association

What is another name for the anterior association area?

Prefrontal cortex or frontal lobe

Location and function of anterior multimodal association?

• found in frontal lobe

• most complicated cortical region - involved in intellect, complex learning (cognition), recall, reasoning, persistence, planning, personality

• development applies to social environment

• develops slowly in children

Location and function of the posterior multimodal association area?

• found in parts of temporal, parietal, and occipital lobes

• functions to integrate visual, auditory, and tactile sensory info

• binds different sensory inputs into a coherent whole (ex. dropping water and spilling it on yourself)

What composes the limbic association area?

• cingulate gyrus

• parahippocampi gyrus

• hippocampus