exam 3

THE FOUR BRAIN LOBES AND INJURY

Frontal lobe - Movement, intelligence, behavior, memory, personality

  • Glioblastoma: Injury of the left frontal lobe that causes involuntary movement of right leg

  • Personalty change could also be a result of a left frontal lobe injury

Parietal Lobe - intelligence, reasoning, telling right from wrong, language, sensation, reading

  • Gerstman’s syndrome: Agraphia, acalucia, aphasia, agnosia, decline in spacial awareness

Occipital lobe- vision, letters, colors

  • Trauma can cause word blindness, visual illusions, movement agnosia

Temporal lobe - speech, behavior, memory, hearing, emotions, vision

  • right injury: Logorrhea (inability to stop talking); lesions cause inabilities to recognize instrumental music, drawings, or other nonverbal forms of communication.

• FUNCTIONAL AREAS OF THE BRAIN

Broca’s area - speech formation

Wernicke’s area - language com-prehension

Motor Area - voluntary muscle control

Cerebellum - balance, coordination, posture

Brain stem - breathing, heart rate, consciousness

If someone was in an accident, causing them to exhibit a loss of smell, which lobe is most likely injured? Frontal Lobe

Where is the olfactory bulb located? Underneath the frontal lobe

Where is the olfactory cortex located? Temporal lobe

• GLIAL CELLS OF THE CNS AND PNS NERVOUS SYSTEMS

Glial cells make up 90% of ins and provide support for blood supply

CNS has gray matter, oligodendrocytes which protect the soma

PNS has white matter, Schwann cells for myelin sheaths around axons and neurons

Gray matter in both consists of soma clusters, and white matter in both consists of axons

Oligodendrocytes myeline multiple nerve fibers in CNS

Myelin are lipids based structures that surround axons to insulate and protect nerve fibers

Schwann cells are cells that myelinated single nerve fibers in PNS

Axons conduct electrical impulses away from the cells body towards other neurons, muscles, or glands

Ependymal cells are glial cells that line the CNS constructing a membranous lining

Microglial are glial cells in the brain that regulate networks, development, and act as macrophages to protect the brain from foreign bodies and injured cells

Astrocytes provide nutrients, ons, supports, and protection of neurons in the CNS • BLOOD BRAIN BARRIER (BBB)

Blood brain barrier (BBB) supports cells, ions, and chemical messengers. Prevents intrusion of pathogens, toxins, and non specifics compounds. It also regulates the passage of solutes and cells from blood to the brain.

• NEUROGLIAL CELLS AND DISEASE –

Alzheimer’s: A form of dementia, in which a patient suffers memory loss, personality and behavior changes, impaired cognition, and brain cell apoptosis/death. Inflammatory cytokines from neuroglial cells prompted by astrocytes activating NF-kB causing pro-inflammatory cytokine secretions.

Parkinson’s: targets dopaminergic cells causing bradykinesia

Multiple sclerosis: Damaged myelin sheath

Cerebrospinal fluid

Provides protection between the brain and skull, exchange of nutrients and removal of waste between the brain. It is supplied by the internal carotid artery and vertebral artery.

Types of Strokes

  1. Ischemic stroke: lack of blood to the brain (clot or block)

  2. Hemorrhagic stroke: lack of blood to the brain (rupturing of blood vessel)

  3. Thrombotic stroke: ischemic blood clot moves from one part of the body to the brain

  4. Atherosclerosis: harding of arteries in the brain

  5. Lacunar stroke: occlude smaller vessels (little to no symptoms)

• THE NEURON: CLASSES OF NEURONS • 5 Classes of Sensory Neurons –

chemoreceptors: monitor chemicals in blood and tastings during taste reception

mechanoreceptors: detect mechanical aspects such as pressure, touch, or vibrations

nociceptors: “pain receptors”

photoreceptors: respond to changes in light/dark for visions and circadian rhythm/sleep-wake cycles

thermoreceptors: sense temperature changes

Neuron Anatomy–

Nucleus contains the genetic material of the neuron cells

Cell body contains the nucleus

axon is the electrical signaling pathway,

axon hillock is the segment between the soma and axon

axon terminal is where neurotransmitters are released

dendrites receive neural signals

Myelin sheath insulates the axon to help protect the neuron cell and speed up transmission of electrical impulses

unipolar neuron: soma at the end of axon

bipolar neuron: soma at the middle of axon

pseudounipolar neuron: soma extending from the midsection of axon multipolar neuron: soma above axon with connected dendrites

• Types of Synapses–

axosecretory: secretes neurohormones in to the bloodstream

axoaxonic: secretes neurotransmitters to the axon of another neuron

axodendritic: axon terminal of one neuron connects to the dendrite of another axoextracellular: axon terminal of one neuron does not connect, but releases neurotransmitters into extracellular fluid

axosomatic/axosynaptic: the axon terminal of one neuron connects with the soma/axon of another neuron

neuromuscular: Neuron to muscle communication neuroglandular: Neuron to gland communication

Afferent: In the PNS; carries info from somatic and visceral senses via neurotransmitters to the CNS - produces an autonomic response

Efferent: Motor neurons from the CNS to the PNS; help communication with CNS to somatic autonomic nervous system pathways (skeletal, cardiac, and smooth muscle, glands GI system)

• Somatic Motor Reflex (or Reflex Action): Somatic sense detect painful stimuli via nociceptors and send the message through afferent neurons (PNS) to interneurons (CNS) • Voluntary Muscle Movement:

  1. idea of movement (limbic system)

  2. planning (premotor region)

  3. starting (upper motor neurons in primary motor cortex)

  4. executing the move (motor neurons)

Circadian rhythm (or sleep–wake cycle):

  • regulated by CNS, hormone secretion and light/darkness • Electroencephalogram (EEG)

  • can incorporate up to 111 sensors to be distributed around the cranium, allows us to see electrical activity of the brain throughout the various stages of someone’s sleep architecture • Sleep Disorders–

  • narcolepsy: the brain cannot mediate sleep cycles, and patients fall asleep during normal. periods of wakefulness- the day

  • insomnia: an inability to progress through normal sleep cycles

  • parasomnias: disruptive actions to sleep patterns, due to excessive brain activity

• Ascending reticular activating system (ARAS): stimulates cerebral cortex and awakens conscious level. It also controls the state of wakefulness. Regulates transitions from wakefulness to sleep so that decreased ARAS activity ushers in a new sleep cycle.

  • neurotransmitters involved in ARAS: dopamine (motivation and movement), Acetylcholine (learning), and noradrenaline/norepinephrine (focus/concentration)

• NEUROTRANSMITTERS –

adrenaline (epinephrine): Fight or flight noradrenaline (norepinephrine): Concentration

Dopamine: Pleasure

serotonin: Mood

GABA: calming

Acetylcholine: Learning

Glutamate: Memory

endorphins: Euphoria

and histamine. • NEURON ACTION POTENTIALS • STAGES OF NEURON ACTION POTENTIALS

  • Threshold of excitation: Stimulus raises electrical impulse above -55 mV, unless it fails

  • When the threshold is reached, sodium (NA+) channels open, allowing NA+ ions to enter, which raises the voltage to +40 to +45 mV

  • Depolarization: at the peak, sodium channels close and potassium (K+) channels open. K+ exits th cell, lowering voltage

  • Hyperpolarization: more K+ leaves, voltage drops below -70 mV

  • Potassium channels close, Na+/K+ pump restores the resting voltage to -65 to -70mV • RESTING POTENTIAL, DEPOLARIZATION, HYPERPOLARIZATION, REPOLARIZATION – and voltages. How do Na+/K+ pumps and channels help? • TABLE 7.3 – ACTION POTENTIAL (presynaptic neuron) vs GRADED POTENTIAL (postsynaptic neuron) • EXCITATORY (EPSP) AND INHIBITORY (IPSP) POSTSYNAPTIC POTENTIALS

  • Which presynaptic neurotransmitter released into the synaptic cleft, will promote an EPSP in the postsynaptic neuron? Glutamate

  • An influx of positively charged ions (Na+ and K+) leads to depolarization of the postsynaptic neuron.

  • Which presynaptic neurotransmitter released into the synaptic cleft, will promote an IPSP in the postsynaptic neuron? GABA (glycine amino acid)

  • a voltage that is more negative than the resting potential, meaning hyperpolarization.

There are 68.1 billion neurons in the brain. Each can make up to 2,500 neuron to neuron connections at birth, with 100 trillion synapses.

Neurons that synthesize and release acetylcholine are called cholinergic neurons

Afferent neurons: In the PNS, they carry sensory + visceral info to CNS

Efferent neurons: leave the CNS and innervate organs, which are usually muscles or glands

Which of the following is a ligand for “umami” taste buds receptors? L-glutamate

Synpatic vesicles in the neuron store a neurotransmitter

Power stroke: Myosin head moves thin filaments forward during cross-bridge cycle

Myopia: nearsightedness

Emmetopia: normal vision

“memory” neurotransmitter: acetycholine

“Happiness/sleep” neurotransmitter: serotonin

Primary tastes

  • salty: Sodium (Ns+)

  • Sweet: Carbohydrates

  • Sour: acidic tastants (H+)

  • Bitter: Hydroxide ions (OH-)

The neurotransmitter that is released from the presynaptic neuron must diffuse across the synapse to reach the postsynaptic neuron

Ionotropic: Receptor responsible for the rapid opening of ion channels in response to the interaction between the ligand and receptor

What type of receptor is both metabotropic and cholinergic? Dopaminergic

Acetylcholine: a class of neurotransmitter released by motor neurons at the neuromuscular junction during signal transmission

Norepinephrine: A ligand for adrenergic receptors

At high energy myosin-ready for the power stroke-has ADP and inorganic phosphate bound to it

Rods: night/dim light, highly sensitive to light, doesn’t detect color

Cones: color vision and sharp detail to bright light

What cells does Parkinson’s disease target? Dopaminergic cells

There are over 600 muscles in the human body

An important electrolyte for muscle contraction is calcium.

Creatine kinase is an enzyme that transfers inorganic phosphate group from phosphocreatine to ADP.

Fracture repair begins with the bone remodeling process.

Calcium ions released from the sarcoplasmic reticulum bind troponin during excitation-coupling to shifting α-tropomyosin from covering myosin bind sites of F-actin filament.

Which troponin complex binds calcium ions prior to troponin shifting  α-tropomyosin? TnC

At high energy the “cocked” myosin – ready for the power stroke – has  ADP and inorganic phosphate bound to it.

BONE REMODELING STEPS

  1. resting to activation

  2. resorption: osteoclast removing old bone from the new bone matrix “pit”?

  3. reversal

  4. formation

  5. Mineralization

Which of the following stages of Fracture Repair prevents excess bleeding from the fracture site, through blood clotting? Hematoma Formation

Phosphocreatine for ATP production in muscle may be obtained from fish and meat.

Osteoblasts: Producing osteoid that mineralize into bone.

Osteocytes: inactive osteoblasts, mineralize and incorporate into newly created bone

What are osteoblasts derived from? Osteoblast progenitor stem cells

Osteoclasts: bone resorption and help mold injured bone during repair.

What are osteoclasts derived from? Monocytes

Yellow bone marrow has stem cells that produce cartilage, bone cells, and adipocytes.

Osteon: A single unit of cortical bones.

Ligaments: joints held together between each bone by strong connected fibrous tissues called ligaments

Cartilage: Resist inward pressing forces and provide flexibility to bones

CROSS BRIDGE CYCLE

Calcium: An important electrolyte in the cross bridge cycle for muscle contraction

Troponin: Binds to calcium ions and creates tropomyosin, exposing itself to myosin binding sites

tropomyosin: Interacts with actin, myosin, and troponin to control muscle contraction and relaxation. (ATP dependent protein)

actin:

myosin: interacts with F-actin to initiate muscle contraction (ATP dependent protein)

Muscle cells (myocytes) utilize ATP for work, such as muscle contraction (i.e., cross-bridge cycle mechanisms).

Once muscle movement or contraction starts, the system must quickly

convert CP and ADP to creatine and ATP in the presence of creatine kinase

enzyme

There are proteins, which play critical roles in muscle contraction, two of which are actin filament and α-tropomyosin.