Human Physiology Exam 2

Central nervous system

Brain and Spinal Cord

Peripheral nervous system

afferent, efferent, somatic, autonomic

Afferent

Carries incoming messages to CNS

Efferent

Carries outgoing messages from CNS to effector organs

Somatic

motor neurons

Autonomic

Smooth muscle, cadiac muscle, glands

Sympathetic

“fight or flight”

Parasympathetic

“rest and digest”

Enteric nervous system

separate portion of the autonomic nervous system, neural network linking the digestive tract, functions independently but also communicates with CNS

Afferent Neuron

Distal sensory receptor initiates action potential, deliver input signal to CNS

Efferent Neuron

Originates at CNS, delivers commands to muscles and glands

Interneuron

Entirely in CNS, integrates afferent to efferent and throughout CNS

Glial Cells

Astrocytes, Oligodendrocytes, Microglia, Ependymal cells

Astrocytes

Star-like, abundant

Oligodendrocytes

Form myelin in CNS

Microglia

CNS immune cells

Ependymal cells

Glial stem cells and form CSF

Astrocytes provide

scaffold and structure to neurons, help form blood-brain barrier, help store nutrients to neurons

Microglia function

Immune defense cells, Type I inflammatory or Type II anti-inflammintory, respond to damage and inflamation

Ependymal cells functions

Line internal fluid cavities, help form CSF, cilia to move CSF through ventricles, function as stem cells glial cells

Cranial Meniges

Dura Mater, Arachnoid Mater, Pia Mater

Cerebrospinal Fluid

Cushions and bathes brain, not continuous with brain interstitial fluid

Cerebrospinal Fluid flows through

4 interconnected ventricles and into spinal cord

Cerebrospinal Fluid is formeed in the

choroid plexus

Production and flow of Cerebrospinal Fluid

1. Fromed by ependymal cells in choroid plexus along ventricle wall 2. Circulates through ventricles 3. Exists 4th ventricle at base of brain 4. flows through subarachnoid space 5. Reabsorbed across arachnoid villi (dural sinus)

Neurovascular unit

integrates neural, glial, and vascular components

Blood-Brain Barrier

Not a continous barrier surrounding the brain, but an integrated part of brain vasculature

Endothelial cells form

tight junctions only in association with astrocytes and pericytes in brain, substances must pass through endothelial cells and not between

Claudin-5

makes proteins that perform tight junctions

Number of neurons in the brain

86 billion neurons

Brain regions

Brain stem, cerebellum, Forebrain (Diencephalon and Cerebrum)

Diencephalon

Hypothalamus, Thalamus

Cerebrum

Basal Nuclei (Basal Ganglia), Cerebral Cortex

Gray Matter

Neuron cell bodies, dendrites, and glial cells, integrates and processes information, Functional connectivity

Neural processing is

regionally organized by task

White Matter

Bundles of mylenated axons, Transmit signal between different parts of brain and body

4 paired lobes

Occipital Lobe, Temporal Lobe, Parietal Lobe, Frontal Lobe

Occipital Lobe

Visual input

Temporal Lobe

Auditory input

Parietal Lobes

Sensory input

Frontal Lobes

Motor, speaking, thought

Frontal lobe functions

Higher-order thinking, executive function, planning, movement, emotion, problem solving, motor control, speech

Sections of Frontal Lobes

Primary Motor Cortex (precentral gyrus), Premotor Cortex, Prefrontal cortex

Function of Parietal Lobes

Somesthetic (body feeling) and proprioception, Contralateralization of sensation

Parts of Parietal Loes

Somatosensory cortex (postcentral gyrus), Posterior parietal cortex (integrates complex sensory information)

Function of Temporal Lobes

Auditory processing, language processing, memory formation/retrival, visual perception, emotional processing

Parts of the Temporal Lobes

Wernicke’s area (speech planning), Broca’s area (planning of sound patterns to coordinate primary motor cortex)

Functions of Occipital Lobes

Receive, process, and interpret visual input, primary visual cortex, visual association cortex, also plays a role in spatial reasoning and spatial memory

Parietal-temporal-occipital association cortex

Integrates somatic, auditory, and visual input

Basal Nuclei functions

Motor control (patterns), motor learning, habits, reward, inhibition of muscle tone and unwanted motor movement, routes motor signals via thalamus to motor cortex

Dopaminergic neurons

in Basal Nuclei regulate direct (excitatory) and indirect (inhibitory) motor pathways

Parkinson’s Disease

degeneration of cells in substantia nigra reduces dopamine (associated with Basal Nuclei)

Tourettes’s Syndrome

thought to be related to over-abundance of dopamine in some Basal Nuclei regions

Thalamus

Relays sensory signals to cortex for processing, relays motor signals from cerebellum and basal nuclei to motor cortex, regulates consciousness, sleep, and awareness

Hypothalamus

Homeostatic function, links autonomic and endocrine, Helps control: body temperature, hunger, thirst, urine output, Emotional and behavioral patterns, pituitary hormone output, autonomic cooridination

Working Memory

Prefrontal cortex, active manipulation and “rehearsed” echo of input

Short-term Memory

Hippocampus and surrounding medial temporal lobe, temporary storage

Long- term Memory

Cerebral cortex