Physiology Chapter 8

integrative functions

include wakefulness and sleep, language, emotions, motivation, and learning and memory

hemispheric lateralization

specialization separation of the hemispheres of the brain

functional areas

specific types of sensory, motor and integrative signals are processed in certain regions of the cerebral cortex

coma

state of unconsciousness in which individual has little or no response to stimuli

spinal nerves

-are part of the PNS; they connect spinal cord to sensory receptors and effectors (muscles & glands) in most parts of body -there are 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, and 1 pair of coccygeal nerves

spinothalamic tract

conveys action potentials for sensing pain, temperature, itch, and tickle

what two components surround and protect the brain?

cranium and the meninges

arachnoid villi

structures that return cerebrospinal fluid to the venous blood in the dural sinuses

Cerebrum

is the seat of intelligence: provides us ability to read, write, and speak, remember past events, plan for future, & imagine.- cerebrum consists of an outer rim of cortex, an integral region of white matter, and nuclei deep within white matter -cerebral cortex contains billions of neurons arranged into six layers -Stellate cells are main input cells of cerebral cortex, and Pyramidal cells are main output cells -grooves between folds of gyrus are called fissures, the main longitudinal fissure separates cerebrum into right&left halves called cerebral hemispheres -each hemisphere has 4 lobes:frontal lobe, parietal lobe, temporal lobe, and occipital lobe -insula is part of brain located deep in the parietal, frontal, and temporal lobes

choroid plexuses

sites of CSF production - networks of capillaries in the walls of the ventricles. -capillaries are covered by ependymal cells that form CSF from blood plasma by filtration secretion

plasticity

the brains capability for change associated with learning -it involves changes in individual neurons and synaptic connections among neurons

Associative learning

occurs when a connection is made between two stimuli

ventricles

-are cavities in the brain 4 ventricles: -two lateral ventricles -a third ventricle -a fourth ventricle

what does supply does the Brain depend on?

a continuous supply of oxygen & glucose

reticular activating system (RAS)

when active, many action potentials are transmitted to areas of cerebral cortex both directly & via thalamus increasing cortical activity

cerebral cortex contains what two language areas?

Wernicke's area-translates words into thoughts Broca's area- translates thoughts into speech

motor areas

control the execution of voluntary movements (contractions of skeletal muscles) -important areas are: primary motor cortex-located: precentral gyrus of frontal lobe & controls voluntary contractions of specific muscles/groups Broca's area-located: frontal lobe & involved in articulation of speech

spinal cord

a cylinder of nervous tissue that extends from the brain

integration

the processing of sensory info by analyzing and storing it & making decisions for various responses

roots

-a spinal nerve is connected to the spinal cord by two bundles of axons (classified as mixed nerve) -dorsal root contains only sensory axons which conduct action potentials from sensory receptors in the skin, muscles, and internal organs into CNS -each dorsal root has a swelling, the dorsal root ganglion, containing cell bodies of sensory neurons -ventral root contains axons of motor neurons, which conduct action potentials from CNS to effectors

spinal cord has two principle functions maintaining homeostasis?

-action potential propagation (sensory &motor tracts) :white matter tracts in spinal cord serve as "highways", sensory input travels on these tracts -integration of info (reflex) : gray matter of spinal cord receives and integrates incoming&outgoing info

motor output to skeletal muscles travels down the spinal cord by what two types of descending pathways?

-direct motor pathways convey action potentials that originate in the cerebral cortex and cause voluntary movements. -indirect motor pathways convey action potentials from the brain stem to cause involuntary movements. Include: tectospinal, vestibulospinal, rubrospinal, lateral reticulospinal, and medial reticulospinal tracts.

horns

-gray matter on each side of the spinal cord is subdivided into regions called horns -dorsal gray horns contain axons of incoming sensory neurons as well as cell bodies and axons of interneurons -ventral gray horns contain cell bodies of somatic motor neurons that convey action potentials to skeletal muscles -lateral gray horns are present in thoracic and upper lumbar segments of spinal cord. They contain cell bodies of autonomic motor neurons that convey action potentials to cardiac muscle, smooth muscle, and glands

reflex arc (reflex circuit)

-pathway followed by action potentials that produce a reflex. -includes 5 functional components: 1. sensory receptor-end of a neuron that responds to a stimulus 2. sensory neuron-if receptor potential reaches depolarization threshold, it triggers one or more action potentials in sensory neuron 3. integrating center-region of gray matter that processes sensory info 4. motor neuron-recieves action potentials from integration center & sends to effector 5. effector-part of body that responds to neuron

sensory input and motor output spinal cord process

-sensory receptors detect a sensory stimulus>>sensory neurons convey sensory input in the form of action potentials along their axons>>axons may extend into white matter of spinal cord and ascend to brain>>axons may enter dorsal gray horn and synapes with interneurons whose axons extend to white matter & then to brain>>axons may enter dorsal gray horn & synapse with interneurons that synapse with somatic motor neurons involved in spinal reflex>>motor output from spinal cord to skeletal muscles involves motor neurons of ventral gray horn>>activated somatic motor neurons convey action potentials along axons into ventral gray horn & ventral root of spinal nerve>>motor output from spinal cord to cardiac muscle, smooth muscle, and glands involves autonomic neurons of lateral gray horn>>through spinal nerve, autonomic motor neurons synapse with another fellow group located in PNS

meninges

-tough connective tissue coverings that encircle the spinal cord and brain -3 spinal meninges are: outer dura mater, middle arachnoid mater, and inner pia mater. -between arachnoid mater and pia mater is the subarachnoid space containing cerebrospinal fluid (CSF)

white matter of spinal cord is subdivided into what three columns?

1. dorsal white columns 2. ventral white columns 3. lateral white columns -sensory (ascending) tracts consist of axons that conduct action potentials toward the brain -Motor (descending) tracts consist of axons that carry action potentials away from the brain

what are important functions of the hypothalamus?

Control of autonomic nervous system(ANS)-regulates contraction of smooth muscle & cardiac muscle & secretion of many glands Production of hormones-releases hormones known as releasing hormones & inhibiting hormones -synthesize hormones oxytocin & antidiuretic hormone (ADH) Regulation of emotional & behavioral patterns Regulation of eating/drinking-contains a feeding center that promotes eating, a satiety center that promotes drinking, and a thirst center Control of body temp-functions as body's thermostat Regulation of circadian rhythms-patterns of biological activity such as: sleep-wake cycle, secretion of hormones, and fluctuations in body temp

Cerebrospinal fluid (CSF)

a clean colorless liquid that protects the brain and spinal cord from chemical and physical injuries -carries oxygen, glucose, and other chemicals from blood to neurons and neuroglia -contributes to homeostasis in 3 ways: 1. Mechanical protection-shock absorbing medium that protects tissues of brain &spinal cord 2. Chemical protection- provides optimal chemical environment for neuronal signaling 3. Circulation- exchange of nutrients &waste products between blood and nervous tissue

reflex

a fast, involuntary, unplanned sequence of actions that occurs in a response to a particular stimulus. -spinal reflex: integration that takes place in the spinal cord gray matter. ex: patellar reflex(knee jerk) -cranial reflex: integration that that occurs in the brain stem. ex: eye tracking when reading -somatic reflexes: involve contraction of skeletal muscles -autonomic(visceral) reflexes: involve responses of smooth muscle, cardiac muscle and glands. ex: heart rate, digestion

basal nuclei

are several masses of gray matter found in different parts of brain

dorsal columns

are tracts that convey action potentials for touch, pressure, vibration, and prioception

association areas

deal with more complex integrative functions such as memory, emotions, reasoning, will , judgement, personality trains, and intelligence -important areas are: somatosensory association area-located: parietal lobe & receive input from primary somatosensory cortex. stores memories of past sensory experiences visual association area-located: occipital lobe & receives input from primary visual cortex facial recognition area- located: inferior temporal lobe & receives input from visual association area auditory association area-located: temporal lobe & allows you to recognize a particular sound orbitofrontal cortex- located: frontal lobe & receives input from olfactory cortex. (identifies odors) Wernicke's area- located: temporal lobe & interprets meaning of words common integrative area-located: parietal lobe & receives input from somatosensory, visual, and auditory association areas of cerebral cortex prefrontal cortex-located: frontal lobe & makeup of a persons personality, intellect, learning, initiative, judgement, intuition, mood etc premotor cortex- located: frontal lobe & deals with learned motor activities of a complex

Diencephalon

extends from brain stem to cerebrum; includes the thalamus, hypothalamus, and pineal gland -thalamus is the upper part of diencephalon, consists of gray matter organized into nuclei with tracts of white matter.-It relays sensory input that reaches cerebral cortex from spinal cord & brain stem -hypothalamus is a small part of diencephalon located below thalamus that is composed of nuclei that control body activities related to homeostasis.-recieves sensory input from receptors for vision, taste and smell -pineal gland is pea sized & located behind thalamus.-considered part of endocrine system bc it secretes hormone melatonin which regulates circadian rhythms -circumventricular organs (CVO's) lie in the wall of the 3rd ventricle & monitor changes in blood bc they lack a blood-brain barrier.

REM sleep

eyes move rapidly back and forth under closed eyelids -known as paradoxical sleep bc readings show high frequency, amplitude waves -REM sleep center: in the pons and midbrain

what are the three parts of the brain stem?

medulla oblongata: the lower portion of brain stem that contains several important nuclei that control body functions including cardiovascular center-regulates heartbeat &blood vessels, and the medullary respiratory center-regulates breathing pons: middle portion of brain stem that consists of nuclei and tracts. Within pons is the pontine respiratory center which functions with medullary respiratory center for breathing midbrain: upper portion of brain stem that includes nuclei called substantia nigra & red nucleus that play roles in controlling body movements -nuclei on back of midbrain superior colliculi & inferior colliculi serve as reflex centers for visual activities -reticular formation is a netlike region of white& gray matter including neurons that have both ascending(sensory) & descending(motor) functions

declarative (explicit) memory

memory of experiences that can be verbalized such as facts, events, objects, names, and places -requires conscious recall & is stored in association areas of cerebral cortex

Procedural (implicit) memory

memory of motor skills, procedures, and rules -include riding a bike, serving a tennis ball, & performing a dance -does not require conscious recall & is stored in basal nuclei, cerebellum, and premotor cortex

NREM sleep

non-rapid eye movement sleep; stage 1: transition stage between wakefulness and sleep (eyes closed & fleeting thoughts) stage 2: first stage of tru sleep stage 3: period of moderately deep sleep stage 4: the deepest level of sleep (slow, large delta waves) -NREM sleep centers: in hypothalamus and basal forebrain

Nonassociative learning

occurs when repeated exposure to a single stimulus cause change in behaviour

cranial nerves

part of the PNS and they connect the brain to sensory receptors and effectors in the head, neck, and many organs of thoracic and abdominal cavities -cranial nerves are calssified sensory nerves if contain only axons of sensory neurons, motor nerves if contain axons of motor neurons, or mixed nerves if contain both sensory and motor neurons

Cerebellum

part of the brain located behind brain stem -primary function is to evaluate & correct movements initiated by motor areas -regulates posture and balance

blood-cerebrospinal fluid barrier

permits certain substances to enter CSF but excludes others, protecting brain and spinal cord from harmful blood-borne substances

memory consolidation

process by which a short term memory is transformed into a long term memory

long-term potentiation

process by which transmission at synapses is enhanced (potentiated) for hours or weeks after high-frequency stimulation

blood-brain barrier (BBB)

protects brain cells from harmful agents by preventing passage of substances from blood into brain tissue -the BBB has 2 components: Structural component-consists of tight junctions that seal together endothelial cells of brain capillaries Functional component-consists of membrane transport proteins in endothelial membranes that move water-soluble substances across brain capillaries

sensory areas

receive sensory info and are involved in perception, the conscious awareness of a sensation -important areas are: primary visual cortex-located: occipital lobe & receives info for vision primary auditory cortex-located: temporal lobe & receives info for sound gustatory cortex-located: insula receives info for taste olfactory cortex-located:inner temporal lobe & receives info for smell

sensitization

repeated exposure to a noxious stimulus cases an increased behavioral response

habituation

repeated exposure to an irrelevant stimulus causes a decreased behavioral response

limbic system

ring of structures that plays a role in learning and emotional behavior -connections that generate emotional behavior: Sensory stumuli are conveyed to cerebral cortex>> cerebral cortex conveys info to limbic system>> limbic system forms an emotion about situation>> emotion is sent from limbic system to cerebral cortex to be perceived>>emotion is also sent to hypothalamus>> hypothalamus produces involuntary autonomic & somatic motor responses based on emotion