Anatomy and Physiology Unit 4 exam,

Integration

processes sensory information, controls all body responses and activities, stores information

Sensory input

detecting and monitoring internal and external stimuli (like the fullness of your stomach or a bee sting)

Motor output

causes a response in muscles and glands

Central Nervous System (CNS)

brain and spinal cord

Peripheral Nervous System (PNS)

cranial and spinal nerves and sensory receptors

Sensory or afferent pathway

receptors that detect stimuli and the neurons that carry information TO the CNS

Motor or efferent pathway

neurons that carry impulses FROM the CNS to various targets

Somatic Nervous System (SNS)

mostly voluntary-includes the neurons sending information to skeletal muscles

Autonomic Nervous System (ANS)

always involuntary-includes the sending information to smooth and cardiac muscle, organs, and glands (eyes dilating).

further divided into sympathetic and parasympathetic.

Neuron

the functional unit of the nervous system. Excitable cells that respond to both physical and chemical stimuli. They produce and conduct electrical signals and they release chemicals for regulation and communication called neurotransmitters

neuroglia (glial cells)

provide essential support, protection, and maintenance for neurons

Axon

to transmit electrical impulses, known as action potentials, away from the neuron’s cell body (soma) to other neurons, muscles, or glands

Axon Terminals

Branched ends of axon.Tips contain vesicles that are filled with whatever neurotransmitter it makes.

multipolar neurons

has several dendrites and one axon- these are the most common neurons in the body

bipolar neurons

has one dendrite and one axon (found in the retina of the eye, the inner ear, and in the nose for olfactory function)

unipolar neurons

has a single process that then splits into an axon and a dendrite (rare, always sensory)

Astrocytes (CNS Neuroglia)

common star shaped cells that form the blood-brain barrier by covering capillaries in the brain. Provide structural support to brain

Oligodendrocytes (CNS)

common glial cell that forms a myelin sheath around multiple axons in CNS neurons

Migroglia (CNS)

these cells are found near blood vessels and they are phagocytic-which means they "eat" and clear away dead cells and debris

Ependymal cells

these cells form an eptihelial membrane lining the cavities and canals of the brain and spinal cord. They produce cerebrospinal fluid

Satellite cells (PNS)

These are flat cells that surround cell bodies in ganglia ( a mass of mulitple cell bodies). They provide support for the neurons that make up the ganglia.

Schwann cells(PNS)

these wrap around axons of PNS neurons and produce a myelin sheath

Myelin Sheath

formed by cells wrapping tightly around axons, acts as an electrical insulator and speeds conduction of nerve impulses

White matter

made up of myelinated axons

gray matter

contain neuronal cell bodies esponsible for processing information, controlling movement, memory, and emotions

Resting membrane potential

occurs when all ions inside and outside of the membrane are in equilibrium. For neurons it is -70 mV

ligand-gated ion channel

A protein pore in the plasma membrane that opens or closes in response to a chemical signal, allowing or blocking the flow of specific ions.

mechanically gated ion channels

found in sensory neurons and open in response to physical forces such as pressure or stretch

electrochemical gradient

The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential.

sodium-potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

Graded Potentials

small changes in membrane potential that by themselves are insufficient to trigger an action potential

depolarize

the potential is making the inside of the cell less negative

repolarize

the potential is making the inside of the cell more negative

hyperpolarize

means the potential is making the inside of the cell even more negative than when it is at rest

chemical stimulus

like neurotransmitter

electrical stimulus

ions changing the membrane potential

Action Potential

All or nothing phenomenon based on if threshold is reached. All are identical in strength and duration. Driven by the activity of voltage-gated Na+ and K+ channels. 4 steps involved.

4 steps involved in Action Potential

1. Resting State-neuron at rest

2. Depolarization- makes cell less negative

3. Repolarization- more negative

4. Hyperpolarization- wayyy more negative because K+channels stay open and membrane overshoots RMP

Absolute Refractory Period

axon membrane is incapable of producing another AP

Relative Refractory Period

axon membrane can produce another AP but would require stronger stimulus than normal

Synapse

a junction that allows communication between a neuron and another cell. Could be neuron to neuron or neuron to an effector cell (like a muscle fiber)

electrical synapse

a type of synapse in which the cells are connected by gap junctions, allowing ions (and therefore the action potential) to spread easily from cell to cell/ multiple organs

chemical synapse

a type of synapse at which a chemical (a neurotransmitter) is released from the axon of a neuron into the synaptic cleft, where it binds to receptors on the next structure (either another neuron or an organ)/ sent individual organ

gap junctions

(communicating junctions) provide cytoplasmic channels between adjacent cells

The brain surface anatomy

Surface anatomy:

Cerebrum - seat of the conscious mind (conscious activity)

3 basic regions: cortex, white matter, and basal nuclei

2 hemispheres divided by the longitudinal fissure

Gyri - visible folds or ridges

Sulci - grooves or furrows separating each gyrus

Cerebellum - motor control and coordination

Brain stem - autonomic control

Composed of the midbrain, pons and medulla oblongata

Major Lobes of the Cerebral Hemispheres

Deep sulci divide each hemisphere into five lobes:

Frontal

Parietal

Temporal

Occipital

Insula

cerebral cortex

The cortex - superficial gray matter

Controls sensation, communication, memory, understanding, and voluntary movements

Each hemisphere acts contralaterally (controls the opposite side of the body)

Hemispheres are not equal in function

No functional area acts alone; conscious behavior involves the entire cortex

Primary Motor Homunculus

Control regions are laid out in a pattern determined by their location in the body with the amount of tissue corresponding to the degree of fine motor control required.

Sensory Areas

Primary somatosensory cortex

Somatosensory association cortex

Primary Somatosensory Cortex

Receives information from the skin and skeletal muscles

Exhibits spatial discrimination

Primary Somatosensory Homunculus

Somatosensory Association Cortex

Integrates sensory information

Forms comprehensive understanding of the stimulus

Determines size, texture, and relationship of parts

visual areas

Primary visual cortex

Receives visual information from the retinas

Converts nerve impulses into images

Visual association area

Interprets visual stimuli (e.g., color, form, and movement)

Allows you to recognize for instance a red hexagon.

Primary auditory cotex

Receives information related to pitch, rhythm, and loudness

Converts nerve impulses into sounds

Auditory association area

Stores memories of sounds and permits perception of sounds

Allows you for instance to recognize the note B flat.

Prefrontal Cortex

Located in the anterior portion of the frontal lobe

Involves intellect, cognition, recall, and personality

Judgment, reasoning, persistence, and conscience

Closely linked to the limbic system (emotional part of the brain)

Lateral prefrontal cortex

- language comprehension and word analysis

Left hemisphere

controls language, math, and logic

Right hemisphere

controls visual-spatial skills, emotion, and artistic skills

Roles reversed in left handed people

Cerebral White Matter

Consists of deep myelinated fibers and their tracts

It is responsible for communication between:

The cerebral cortex and lower CNS center, and areas of the cerebrum

Commissures - connect gray areas of cerebrum

Largest is Corpus Callosum - connects right and left hemispheres

basal nuclei

Masses of gray matter found deep within the cortical white matter

diencephalon

Central core of the forebrain

Encloses the third ventricle

Consists of three parts

Thalamus, hypothalamus and epithalamus

brain stem

Consists of three regions

midbrain

pons

medulla oblongata

Contains embedded nuclei

Pathway for tracts between higher and lower brain centers

Associated with 10 of the 12 pairs of cranial nerves

Controls automatic behaviors necessary for survival

midbrain

Located between the diencephalon and the pons

Midbrain structures include:

Cerebral aqueduct - hollow tube that connects the third and fourth ventricles

Various nuclei

pons

A brain structure that relays information from the cerebellum to the rest of the brain

medulla oblongata

Part of the brainstem that controls vital life-sustaining functions such as heartbeat, breathing, blood pressure, and digestion.

cerebellum

processes information from the cortex brain stem and senosry recepotors to provide movenemnt to skeltal muslce/calculates the best way to perform a movement

A "blueprint" of coordinated movement is sent to the cerebral motor cortex

limbac system

Seat of the "emotional brain"

Structures located on the medial aspects of cerebral hemispheres and diencephalon

Includes the amygdala, hypothalamus, and parts of the thalamus

Parts especially important in emotions:

Amygdala - deals with anger, danger, and fear responses

Cingulate gyrus - plays a role in expressing emotions via gestures, and resolves mental conflict

Limbic System: Emotion and Cognition

The limbic system interacts with the prefrontal lobes, therefore:

One can react emotionally to conscious understandings

One is consciously aware of emotion in one's life

Hippocampal structures - convert new information into long-term memories

Motor function

Helps control coarse motor movements

Autonomic centers regulate visceral motor

functions - e.g., vasomotor, cardiac, and respiratory centers

Meninges

three protective membranes that surround the brain and spinal cord

Dura matter

Outermost toughest layer

Leathery, strong meninx composed of two fibrous connective tissue layers

The two layers separate in certain areas and form dural sinuses

Aracnoid mater

The middle meninx, which forms a loose brain covering

It is separated from the dura mater by the sub-dural space

Pia Mater

Deep meninx composed of delicate connective tissue that clings tightly to the brain

Cerebrospinal fluid

Watery solution similar in composition to blood plasma

Contains less protein and different ion concentrations than plasma

Forms a liquid cushion that gives buoyancy to the CNS organs

Protects the CNS from blows and other trauma

Nourishes the brain and carries chemical signals throughout it

Degenerative brain disorders

Alzheimer's disease - a progressive degenerative disease of the brain that results in dementia

Parkinson's disease - degeneration of the dopamine-releasing neurons of the substantia nigra

Huntington's disease - a fatal hereditary disorder caused by accumulation of the protein huntingtin that leads to degeneration of the basal nuclei

Gray matter

a portion of the CNS consisting of cytons (cell bodies), their dendrites and synaptic connections consists of soma, unmyelinated processes, and neuroglia

Posterior (dorsal) horns

Anterior (ventral) horns

Dorsal root - sensory roots and ganglia

Ventral root - motor roots

Dorsal and ventral roots fuse laterally to form spinal nerves

simple spinal reflex arc

Involves receptor, sensory neuron, integration center, motor neuron, and effector. produces response to stimuli

Dendrites

a neuron's bushy, branching extensions that receive messages and conduct impulses toward the cell body

Ohm's Law

the current in a circuit equals the voltage difference divided by the resistance

voltage gated channels

open and close in response to changes in membrane potential/ generating and propagating electrical signals (action potentials) in neurons and muscle cells by allowing specific ions (

primary somatosensory cortex

area of the parietal lobe where messages from the sense receptors are registered

somatosensory association cortex

integrates sensory information and produces an understanding of the stimulus being felt.

primary visual cortex

the region of the posterior occipital lobe whose primary input is from the visual system

cotexs

auditory cortex- info from ear

vestibular cortex- concious awraeness of balnce

olfactory cortex- smell

gustatory cortex- taste

Ventricles of brain

canals in the brain that contain cerebrospinal fluid

Primary (somatic) motor cortex

located in the precentral gyrus of the frontal lobe of each hemisphere

Thalumus

the brain's sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

Hypothalamus

A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward./ autonomatic nervous system

Epithalamus

Contains pineal body. Involved in olfactory senses and sleep/wake cycle secretes melatonin

Boca's area

Controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

Hippocampus

A neural center located in the limbic system that helps process explicit memories for storage.

Voltage-Gated Sodium Channels

membrane proteins that open sodium channels in response to a sufficient voltage change, and initiate and transmit the action potential as Na+ enters through the channel

Mechonoreceptors

respond to touch, pressure, vibration, and stretch

Thermoreceptors

respond to changes in temperature

Photoreceptors

respond to light

Chemoreceptors

chemical sensors in the brain and blood vessels that identify changing levels of oxygen and carbon dioxide

Nociceptors

pain receptors

Exteroceptors

Respond to stimuli arising outside the body

Receptors in the skin for touch, pressure, pain, and temperature

Most special sense organs

Interoceptors

monitor visceral organs and functions

Proprioceptors

monitor the position and movement of skeletal muscles and joints

Tactile discs (Merkel discs)

Fine touch and pressure receptors

Extremely sensitive to tonic receptors

Have very small receptive fields

Lamellated (Pacinian) corpuscles

Common in deeper subcutaneous tissues, tendons and ligaments

Detect heavy pressure and vibrations