Final Exam Review Flashcards
What are the functions of epithelia?
Protection (mechanical, chemical, infectious) (skin), absorptions (GI tract), filtration (kidneys), excretion (kidney), secretion (glands) and sensory reception (taste buds)
What are the 5 characteristics of epithelial tissue?
- Polarity
- Specialized contacts
- Supported by connective tissue
- Innervated but avascular
- Regeneration
How are epithelial cells classified?
By shape (squamous, cuboidal, columnar)
By number of layers (simple, stratified)
Describe simple squamous epithelium
Single layer of flattened cells; diffusion, filtration and secretion; found in kidneys, lungs, heart, blood vessels, lymphatic vessels and serosae
Describe simple cuboidal epithelium
Single layer of cuboidal cells; secretion and absorption; found in kidney tubules, ducts and secretory portions of small glands and ovary surface
Describe simple columnar epithelium
Single layer of tall cells; many have microvilli or cilia; may contain mucus-secreting unicellular glands; absorption and secretion; found in digestive tract, gallbladder, excretory ducts, small bronchi, uterine tubes and regions of the uterus
Describe pseudostratified columnar epithelium
Single layer of cells of differing heights (all touch basement mem., not all reach surface); may contain mucus-secreting cells and bear cilia; secrete substances (particularly mucus); non-ciliated in sperm-carrying ducts and ducts of large glands; ciliated line trachea
Describe stratified squamous epithelium
Basal cells are cuboidal or columnar and metabolically active, surface cells are squamous; protects underlying tissues in areas subjected to abrasion; linings of esophagus, mouth and vagina, skin
Describe stratified cuboidal epithelium
Rare in the body; found in sweat and mammary glands; has 2 layers of cuboidal cells
Describe stratified columnar epithelium
Rare; small amounts found in pharynx, male urethra and glandular ducts; occurs in transition areas; only apical layer is columnar
Describe transitional epithelium
Basal cells are cuboidal or columnar; surface cells dome shaped (squamous-like); stretches readily; lines ureters, bladder and part of urethra
Describe endocrine glands
Internally secreting; ductless (empty hormonal products into blood); mostly compact multicellular organs, some unicellular
Describe exocrine glands
Externally secreting; secrete products onto body surfaces or into cavities (i.e. mucous, sweat, oil, saliva)
Describe unicellular exocrine glands
No ducts; found in epithelial linings of intestinal and respiratory tracts; mucous and goblet cells; exocytosis
Describe multicellular exocrine glands
Consist of an epithelium-derived duct and secretory unit; supportive CT surrounds secretory unit, supplies it with blood vessels and nerve fibers
Describe merocrine glands
Secrete products by exocytosis; pancreas, salivary glands and most sweat glands
Describe holocrine glands
Accumulate products until they rupture; replaced with underlying cells; sebaceous (oil) glands
Describe apocrine glands
Accumulate products just beneath the free surface; apex of cell pinches off, releasing secretory granules; controversial; mammary glands are both holocrine and apocrine
What are the functions of connective tissue?
Binding and supporting (ligaments, bones); protecting (bone, adipose); insulating (fat tissue); storing reserve fuel; transporting (blood)
What are the 3 characteristics of connective tissue?
Common Origin - arise from mesenchyme (embryonic tissue); Degrees of Vascularity; Extracellular Matrix - largely composed of nonliving extracellular matrix which separates living cells; allows tissue to bear weight
What is connective tissue ground substance?
Unstructured material that fills the space between the cells and contains fibers; composed of interstitial fluid, cell adhesion proteins (CT glue) and proteoglycans (trap water, GAGs); molecular sieve for nutrients and other substances to diffuse through to capillaries/cells
Describe collagen CT fibers
Cross-linked; extremely tough
Describe elastic CT fibers
Branching network; snap CT back into place after being stretched
Describe reticular CT fibers
Collagenous fibers; delicate network; surround blood vessels and support soft tissue of organs
Describe the 2 types of connective tissue cells
Immature (-blast) cells are actively mitotic
mature (-cyte) cells maintain health of the matrix
Describe areolar CT
gel-like matrix with all 3 fiber types, cells - fibroblasts, macrophages, mast cells and some WBCs, loose arrangements of fibers, reservoir of water and salts
What is the function of areolar CT?
cushions organs, role in inflammation and fluid reservoir
Where is areolar CT found?
under epithelia, surrounds organs and capillaries; most common CT
Describe adipose CT
closely packed fat-filled adipocytes with displaced nuclei, do not reproduce, sparse matrix
What is the function of adipose CT?
fuel reservoir, insulation, supports and protects organs
Where is adipose CT found?
under skin, around kidneys and eyeballs, in bones and within abdomen, in breasts
Describe reticular CT
Loose network of reticular fibers in a gel-like ground substance
What is the function of reticular CT?
fibers form a soft internal skeleton that supports free blood cells
Where is reticular CT found?
lymphoid organs (lymph nodes, bone marrow, spleen)
Describe dense regular CT
bundles of collagen fibers running parallel to the direction of the pull
What is the function of dense regular CT?
withstands great tensile stress in one direction
Where is dense regular CT found?
tendons (attach muscles to bones, ligaments (attach bones to bones) and aponeuroses
Describe dense irregular CT
same as regular, but collagen bundles are thicker and arranged irregularly
What is the function of dense irregular CT?
withstand tension exerted in many directions; structural strength
Where is dense irregular CT found?
dermis of the skin, submucosa of digestive tract and fibrous capsules of organs and joints
Describe elastic CT
regular CT with a high proportion of elastic fibers
What is the function of elastic CT?
allows tissue to recoil after stretching
Where is elastic CT found?
walls of arteries; within certain ligaments; within walls of bronchial tubes
Describe cartilage
Stands up to both tension and compression; tough but flexible; lacks nerve fibers and is avascular; ground substance contains lots of GAGs; large amounts of fluid
Describe bone
Supports and protects body structures; harder than cartilage b/c more collagen fibers and calcium; osteoblasts produce organic portion of matrix; well supplied by blood vessels
Describe blood
Classified as CT b/c it consists of cells surrounded by a nonliving fluid matrix (blood plasma); carries nutrients, wastes and respiratory gases
What are tight junctions?
Fusion of adjacent plasma membranes to prevent passage of molecules; impermeable junction
What are desmosomes?
Anchoring junctions; act like velcro; molecular linking of cells to resist mechanical stress; reduced chance of tearing; found in skin
What are hemidesmosomes?
multiprotein complexes that facilitate the stable adhesion of basal epithelial cells to the underlying basement membrane.
What are gap junctions?
Molecular channels between cells that allow passage of cytoplasmic molecules; important for communication; found in heart
What is exocytosis?
Secretion of substances (i.e. hormones, neurotransmitters); substance is enclosed in a vesicle which migrates to plasma membrane, fuses with it and then ruptures
What is a cell?
A fundamental structural and functional unit of a living thing
What is a tissue?
Groups of similar cells that have a common function
What is an organ?
A structure composed of at least 2 (but usually 4) tissue types that performs a specific function
What is an organ system?
A group of organs that work closely with one another to accomplish a common purpose
What is the axial part of the skeleton?
The head, neck, and trunk
What is the appendicular part of the skeleton?
Appendages or limbs attached to axis
What is a sagittal plane?
A vertical plane dividing the body into left and right parts
What is a frontal (coronal) plane?
A vertical plane that divides the body into anterior and posterior parts
What is a transverse plane?
A horizontal plane that divides the body into superior and inferior parts
What is the dorsal body cavity?
The body cavity containing the cranial and vertebral (spinal) cavity
What is the cranial cavity?
The body cavity containing the brain. It is enclosed by the skull
What is the vertebral (spinal) cavity?
The body cavity containing the spinal cord. It is enclosed by the vertebral column
What is the ventral body cavity?
The body cavity containing the thoracic and abdominopelvic cavities
What is the thoracic cavity?
2 lateral pleural cavities for the lungs, and one central pericardial cavity for the heart.
What is the abdominopelvic cavity?
A superior abdominal cavity and an inferior pelvic cavity
What organs does the abdominal cavity contain?
The stomach, intestines, liver, and spleen
What organs does the pelvic cavity contain?
The bladder, some reproductive organs, the rectum
What structure separates the thoracic and abdominopelvic cavities?
The diaphragm
What structure separates the abdominal and pelvic cavities?
Nothing
In which cavity do organs receive the least protection from physical trauma?
The abdominal cavity
What are the 9 abdominopelvic regions?
hypochondriac (L/R), epigastric, lumbar (L/R), umbilical, iliac (L/R), hypogastric
What is homeostasis?
A self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival
What are the 3 essential characteristics of homeostasis?
Receptor, control center, effector
What is the function of the receptor in homeostasis?
Senses change (stimulus) and sends information (via the afferent pathway) to the control center
What is the function of the control center in homeostasis?
Determines the set point for variable maintenance, analyzes information and determines the appropriate response
What is the function of the effector in homeostasis?
Provides a means for response (output along the efferent pathway). Feedback (negative or positive) allows for regulation within a range or an enhanced response
Describe the goal of negative feedback
To prevent sudden, severe changes
Describe the process of negative feedback
Output reduces or shuts off the stimulus.
Describe the goal of positive feedback
To enhance the original stimulus so that output is further stimulated
The anterior regions of the hypothalamus control the:
parasympathetic nervous system
The posterior regions of the hypothalamus control the:
sympathetic nervous system
What is a hormone?
A chemical substance released directly into the ECF that regulates the function of other cells in the body
Level of target cell activation depends on:
- Hormone concentration
- Target cell receptor content
- Affinity of hormone for receptor
What are integral membrane proteins?
Proteins that span the plasma membrane. They have hydrophilic and hydrophobic regions, and function as channels or carriers
What are peripheral proteins?
Proteins that are attached to integral proteins, often on the internal face of the plasma membrane. Involved in attachment functions and shape changes. Can also function as receptors if they are on the cell surface
What is the cytoskeleton?
Anchors to the plasma membrane, organizes other constituents of the cell, maintains the cell’s shape, and is responsible for the locomotion of the cell itself and the movement of the various organelles within it.
What is the glycocalyx?
Mix of carbohydrates attached to lipids and proteins on the outer face of the of the plasma membrane. Allows cells to recognize one another
What is the function of cholesterol?
Reduces general membrane fluidity and stabilizes its structure.
What are connexons?
An assembly of six proteins called connexins that form the pore for a gap junction between the cytoplasm of two adjacent cells. This channel allows for bidirectional flow of ions and signaling molecules. Electrically excitable.
What are some functions of plasma membrane proteins?
Transport, intercellular joining, enzymatic activity, cell-cell recognition, receptors for signal transduction, attachment to ECM
What is a function of plasma membranes?
To provide a selectively permeable, hydrophobic barrier between the interstital fluid and the cytoplasm
What is interstitial fluid?
A filtrate of blood containing salts, sugars, amino acids, vitamins, hormones, metabolites, and gases such as CO2 and O2
What does excess cholesterol do?
Cause the membrane to lose flexibility
How do water-soluble molecules cross the plasma membrane?
Facilitated diffusion
What is facilitated diffusion?
The passive movement of molecules across the cell membrane via the aid of a transmembrane integral protein
What are 4 characteristics of facilitated diffusion for water-soluble molecules?
- Specific
- Not ATP requiring
- Limited by carrier/channel saturation
- movement DOWN a concentration gradient
What is carrier-mediated facilitated diffusion?
Molecules are “helped” through the membrane by a membrane component
When is carrier-mediated facilitated diffusion used?
With lipid-insoluble molecules that are too large to pass through membrane channels or pores
What are leaky channels?
Some ion channels that are always slightly open
Channel mediated facilitated diffusion is ___ due to ___ and ___ of ___ that line the channels
Selective
Pore size
Charges
Amino acids
What are gated channels?
Ion channels that require some signal in order to be activated and opened
What are aquaporins?
Water channels on many cells
What is osmolarity?
Total concentration of solute particles in a solution
What is tonicity?
Ability of a solution to change the shape of a cell by altering its water content
What is an isotonic solution?
Solutions that contain the same concentration of water and solutes as the cell cytoplasm
What is a hypertonic solution?
The solute concentration is higher than that inside the cell, and the solutes cannot cross the membrane
What is a hypotonic solution?
The solute concentration is lower than that inside the cell
Molecules that are ionically bonded have ___ than those that are covalently bonded
Greater osmotic power
How are hypertonic solutions used in patients?
Used carefully and with monitoring for edema; pull water out of swollen cells
How are hypotonic solutions used in patients?
Used carefully and with monitoring to rehydrate severely dehydrated patients
Active transport requires ATP because the substance is:
1) Too large for pores and is lipid insoluble
2) Moving against its concentration gradient
Active transport requires a carrier. What does it do?
Combines specifically and reversibly with a substance to help it across the plasma membrane
Unlike facilitated diffusion, active transport solute pumps move substances:
AGAINST their concentration gradients
What is a symporter?
A membrane protein that facilitates the simultaneous transport of two distinct substances across the cell membrane in the SAME DIRECTION (S for same!)
What is an antiporter?
A membrane protein that transports two molecules across the cell membrane at the same time in the OPPOSITE DIRECTION
Does passive transport require energy?
NO!
Oxygen and water enter the cell through:
Simple diffusion
How do aquaporins work?
The inside of the channel protein is hydrophilic, drawing water to/through it
Describe osmosis and explain its role in fluid homeostasis
Unassisted diffusion of water from area of more water to area of less water across a semipermeable membrane
What is endocytosis?
Means by which large particles can enter the cell. Vesicle encloses substance, pinches off, and moves into the cytoplasm. Contents may be digested, or they may traverse the cell to exit the other side
What are 3 types of endocytosis?
Phagocytosis (bacteria, cell debris), Pinocytosis (fluid plus dissolved substances), Receptor-mediated (allows hormones, enzymes, and other important macromolecules to be concentrated within a cell)
What is a tract?
Bundle of nerve processes in the CNS
What is a nerve?
Bundle of nerve processes in the PNS
What is anterograde transport?
When substances are going toward the axon terminal
What is retrograde transport?
When substances are going toward the cell body
What are the 4 types of neuroglia in the CNS?
- Astrocytes
- Microglia
- Ependymal cells
- Oligodendrocytes
What are astrocytes?
Star-shaped, most abundant, anchor neurons close to capillaries
What are microglia?
Protective. Touch neurons to monitor wellbeing. Can transform into macrophages to engulf micro-organisms and cellular debris
What are ependymal cells?
Line cavities of the brain and spinal cord. Barrier between CSF and fluid bathing cells of CNS. Cilia circulate CSF
What are oligodendrocytes?
Provide myelin sheaths to CNS neurons
What are the 2 types of neuroglia in the PNS?
- Satellite cells
- Schwann cells
What are satellite cells?
Surround cell bodies in ganglia. Thought to perform similar functions to astrocytes in the CNS.
What are schwann cells?
Form myelin sheaths around larger neurons in PNS. Vital to peripheral nerve cell regenration.
Sensory neurons carry signals:
Towards the CNS
Motor neurons carry signals:
Away from the CNS to effector organs
What are association neurons (interneurons)?
Neurons between sensory and motor neurons. Most entirely within the CNS. Make up around 99% of neurons in the body
Without the sodium-potassium pump, the electrochemical gradient would be:
Lost because all the potassium would leave the cell.
What are graded potentials?
Graded potential is a small transient change in the membrane potential that occurs in varying grades or degrees of magnitude or strength.
What are action potentials?
Action potentials are brief, rapid, large changes in the membrane potential and are produced in excitable cells (nerve and muscle) when the resting potential is altered
What makes graded potentials and action potentials different?
- Action potentials serve as long-distance signals whereas graded potentials serve as short-distance signals.
- The graded potentials are small changes in the membrane potential that can reinforce or negate each other. In contrast, the action potentials are large (100 mV) changes in the membrane potential that can serve as faithful long- distance signals.
What are the steps of an action potential?
Resting potential - depolarization - repolarization - hyperpolarization
What is the function of myelin sheath?
Speeds up propagation of action potentials.
What are the 3 types of termination?
- Degradation by enzymes of postsynaptic membrane
- Reuptake by presynaptic terminal
- Diffusion away from synaptic site
What are the 7 chemical classifications of neurotransmitters?
- Acetylcholine
- Biogenic amines
- Amino acids
- Neuropeptides
- Purines
- Gases and lipids
- Endocannabinoids
What are the 2 functional classifications of neurotransmitters?
- Effects (Excitatory vs Inhibitory)
- Actions (Direct vs Indirect)
What is temporal summation?
Additional stimuli added before muscle relaxation is complete. This is also known as the staircase effect, as each addition of stimuli results in higher muscle tension
What is unfused tetanus?
Higher stimulation frequency results in unfused tetanus. Near constant muscle tension, but short waves are present in the graph
What is fused tetanus?
At even higher stimulus frequencies, there is no relaxation at all between stimuli.
What are isotonic muscle contractions?
Muscle contractions where the muscle changes in length
What are the 2 types of isotonic muscle contractions?
Concentric (shortening) and eccentric (lengthening)
What are isometric muscle contractions?
Muscle contractions where the muscle does not change in length (M for maintain)
The sympathetic NS controls:
Fight or flight
The parasympathetic NS controls:
Rest and digest
What are the parts of the brain that compose the diencephalon?
Thalamus, hypothalamus, epithalamus
What parts of the brain compose the brainstem?
Midbrain, pons, medulla
Where is the cerebellum located?
At the back of the brain
What is gray matter?
Short, nonmyelinated neurons and neuron cell bodies
What is white matter?
Primarily myelinated axons
The spinal cord has a central cavity surrounded by:
Gray matter (in the shape of a butterfly)
The ventricles of the brain are continuous with one another and the spinal cord, filled with __, and lined with __
CSF, ependymal cells
The paired lateral ventricles are separated by the:
septum pellucidum
Each ventricle communicates with the third ventricle in the diencephalon via the:
Interventricular foramen
3 apertures (paired lateral and single median) connect ventricles to the:
subarachnoid space
Where is the median aperture located?
Near the base of the cerebellum
A gyrus is an:
outwards projection of the brain (a bump)
A sulcus is an:
indentation of the brain (invagination)
Fissures are:
very deep sulci
The central sulcus separates the:
Frontal and parietal lobes
The lateral sulcus separates the:
Parietal and temporal lobes
The parieto-occipital sulcus separates the:
Parietal and occipital lobes
The transverse cerebral fissure separates the:
Occipital lobe and cerebellum
The longitudinal fissure separates the:
Left and right hemispheres of the brain
The corpora ………………………………. are part of the midbrain and are composed of visual reflex centres and also house the startle reflex.
quadrigemina
Region of the limbic system that is associated with the emotions of anger and fear.
amygdala
Term that indicates that each cerebral hemisphere has some abilities that are slightly different from those of the opposite hemisphere.
lateralization
This is often referred to as the gateway to the cerebral cortex.
thalamus
This cranial nerve handles sensory information pertaining to hearing and balance.
vestibulocochlear
Connective tissue wrapping around a single nerve fiber.
endoneurium
The name of this midbrain nucleus (2 words) refers to its dark colour due to a high content of melanin.
substantia nigra
The cerebellum consists of the anterior, posterior, and …………………….. lobes.
flocculonodular
This cranial nerve stimulates the lateral rectus muscle of the eye.
abducens
The gray …………………………….. connects the left and right wings of gray matter in the spinal cord.
commissure
The …………….. gyrus is the primary somatosensory cortex.
postcentral
This type of sensory information (adjective)) tells you where parts of your body are at any moment in time.
proprioceptive
The lentiform nucleus consists of the ………………… and the globus pallidus.
putamen
Supporting cell that lines the fluid-filled cavities of the brain.
ependymal
Neural supporting cell that surrounds neural cell bodies in ganglia
satellite
This spinal nerve targets the diaphragm and is essential for breathing.
phrenic
The cerebral …………………….. connects the third and fourth ventricles.
aqueduct
The mapping of a body area to a specific region in the brain.
somatotopy
There are three of them and they connect the cerebellum to different areas of the brainstem.
peduncles
Name the 12 cranial nerves
- olfactory
- optic
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- vestibulocochlear
- glossopharyngeal
- vagus
- accessory
- hypoglossal
The primary motor cortex is located in the:
precentral gyrus
What is the function of the premotor cortex?
Helps plan movements by selecting and sequencing basic movements into more complex tasks. Coordinates movement of several muscle groups sequentially/simultaneously by activating the motor cortex
What is broca’s area?
an area of the brain devoted to speech. Present in only one hemisphere - usually the left.
What is the function of frontal eye field?
controls voluntary movements of the eyes
What is the primary somatosensory cortex?
An area of the brain in the postcentral gyrus that receives information from somatic sensory receptors and proprioceptors
What is the somatic association cortex?
Integrates and analyzes somatic inputs. Interprets size, texture, relationship of parts based on prior experience
What is the primary visual cortex?
An area of the brain that contains a map of visual space on the retina. Located at the posterior tip of the occipital lobe
What is the function of the visual association area?
Interprets a visual image based on prior experience
What is the result of damage to the visual association area?
Vision is not impaired, but the individual will not know what they are looking at
What is the result of damage to the primary visual cortex?
The individual cannot see
What is visual agnosia?
The inability to recognize/understand what you are seeing
What happens in the primary auditory cortex?
Sound is evaluated for pitch, rhythm, and loudness
What happens at the auditory association area?
Sounds are interpreted based on memory
What happens in the vestibular cortex?
Awareness of balance. Posterior part of the insula and the adjacent parietal cortex. Located deep in the lateral sulcus
Where is the olfactory cortex?
The medial aspects of the temporal lobes (uncus)
What is the function of the olfactory cortex?
Conscious awareness of different odours
Where is the gustatory cortex located?
The insula
What is the function of the gustatory cortex?
Conscious awareness of different flavours
Where is the visceral sensory area located?
Posterior to the gustatory cortex
What is the function of the visceral sensory area?
Continuously monitors the activities of the visceral organs so that the autonomic motor neurons can make adjustments as necessary to ensure optimal performance of visceral functions.
What is the anterior association area (prefrontal cortex)?
Most complicated cortical area, associated with intellect, complex learning, recall, personality, abstract ideas, judgement, reasoning, persistence, planning, concern, conscience. Matures slowly, relies on feedback from social environment. Closely linked to the limbic system and involved in mood.
What is the posterior association area?
Parts of temporal, parietal, and occipital lobes. Input from all sensory association areas allows for the storage of complex memories. Linked to sensory input and localization of self and surroundings in space.
Someone with damage to the posterior association area might:
Unknowingly neglect one side of their body because they do not perceive it as their own. This is called contralateral neglect
What is the function of wernicke’s area?
Understanding written and spoken language
What is the function of the limbic association area?
Provides emotional impact/insight based on prior experience or learning.
What are commissural fibers?
Connect corresponding areas between the 2 cerebral hemispheres. largest is the corpus collosum
What are association fibers?
Form connections within a hemisphere (connect gyri, lobes, etc.)
What are projection fibers?
Fibers to or from the cortex and the rest of the nervous system. These fibers runs vertically.
What are basal nuclei?
The basal ganglia, or basal nuclei, are a group of subcortical structures found deep within the white matter of the brain. They form a part of the extrapyramidal motor system and work in tandem with the pyramidal and limbic systems.
What is the function of the putamen?
The putamen is involved in learning and motor control, including speech articulation, language functions, reward, cognitive functioning, and addiction
What is the function of the globus pallidus?
The main function of the globus pallidus is to control conscious and proprioceptive movements
What is the function of the caudate nucleus?
The caudate nucleus functions not only in planning the execution of movement, but also in learning, memory, reward, motivation, emotion, and romantic interaction
Disorders with basal nuclei can result in:
Too much movement (huntingtons) or too little movement (parkinsons)
What is the thalamus?
2 masses of gray matter held together by a midline commissure called the interthalamic adhesion
What is the hypothalamus?
Autonomic control center, center for emotional response and behaviour, body temperature regulation, regulation of food intake, regulation of water balance, regulation of sleep, control of endocrine system
What part of the hypothalamus controls sleep-wake cycles?
The suprachiasmatic nucleus
Which parts of the hypothalamus controls the endocrine system?
Supraoptic and paraventricular nuclei
What is the epithalamus?
The most dorsal part of the diencephalon, and forms roof of the third ventricle. The pineal gland extends from its dorsal border. The choroid plexus (CSF producing) is also part of the epithalamus
Order the layers of the spine from deep to superficial
Pia mater, subarachnoid space, arachnoid mater, subdural space, meningeal layer of the dura, epidural space, periosteal layer of the dura
The brainstem controls:
automatic behaviours essential to survival
What are the components of the midbrain?
2 cerebral peduncles, cerebral aqueduct, periaqueductal gray matter, corpora quadrigemina (2 superior and 2 inferior colliculi)
The superior colliculi are:
Visual reflex centers when visually following a moving object
The inferior colliculi are:
Part of auditory relay, also house the startle reflex
What is the substantia nigra?
A band-like nucleus with high melanin content, linked to basal nuclei of cerebral hemispheres
What is the function of melanin in the substantia nigra?
Synthesizes dopamine
What is the red nucleus?
Rich vascular supply, iron pigment in cell bodies, relay nuclei for descending pathways influencing limb flexion
What is the pons?
Primarily conduction tracts, some run longitudinally between higher brain centers and spinal cord, others oriented transversely to communicate with the cerebellum
Trigeminal, facial, and abducens nerves and other pons nuclei are:
Part of the reticular formation and others are involved in respiration
The medulla oblongata runs from the:
pons to the spinal cord
What is the function of the medulla?
Autonomic reflex center for homeostasis. Cardiovascular centers, respiratory centers, vomiting, swallowing, hiccupping, coughing, sneezing
What is the function of the cerebellum?
Processes inputs from cerebral motor cortex, brainstem nuclei, and sensory receptors. Influences the timing and patterns of skeletal muscle contraction for smooth, daily movements.
What are the 3 lobes of the cerebellum?
Anterior, posterior, flocculonodular
Anterior and posterior lobes of the cerebellum have overlapping:
Sensory and motor maps of the body
What is the function of the flocculonodular lobes?
Receive input from equilibrium sensors. Controls balance and some eye movements
What is the function of the cerebellar peduncles?
Connect the cerebellum to the brainstem. Virtually all fibers are ipsilateral
Function of the superior (outgoing) peduncles:
Connect cerebellum and midbrain. Fibers originate from neurons in deep cerebellar nuclei and project to cerebral motor cortex via the thalamus
Function of the middle (incoming) peduncles:
Connect pons and cerebellum. One-way communication from pons to cerebellar neurons (informs cerebellum of voluntary motor activities initiated by motor cortex).
Function of inferior (incoming) peduncles:
Connect cerebellum and medulla. Sensory information is sent to the cerebellum from muscle proprioceptors and vestibular nuclei of brainstem.
Cerebellar processing to fine-tune motor activity:
- Cerebellum receives proprioceptive info from visual and equilibrium pathways
- Cerebellar cortex receives info and decides how to coordinate the body
- Via superior peduncles, cerebellum dispatches blueprint for coordination to CMC and brainstem nuclei, which project to motor neurons of the spinal cord
Where is the limbic system located?
Medial aspect of each cerebral hemisphere and diencephalon; encircles the upper part of the brainstem
What are the parts of the brain in the limbic system?
Amygdala, hippocampus, anterior cingulate gyrus
What is the reticular formation?
Central core of medulla oblongata, pons, midbrain. Neurons project to hypothalamus, thalamus, cortex, cerebellum, and reticular activating system.
What is the function of the reticular activating system?
- Maintains arousal by letting enough information in
- Filters incoming signals (disregard ~99% of incoming sensory stimuli so that volume of info is manageable)
What is the conus medullaris?
Termination of the spinal cord
What is the function of dorsal root ganglia?
House cell bodies of associated sensory neurons. Their axons enter the spinal cord to
1. travel to higher cord/brain centers
2. synapse with interneurons in posterior horns at the level they enter
Layers of protection of the CNS:
- Bones
- Meninges
- CSF
- Blood-brain barrier
What is the function of the meninges?
- cover and protect the CNS
- protect blood vessels and enclose venous sinuses
- contain CSF
- form partitions within the skull
What is the dura mater?
Tough, 2 layers around the brain (outer periosteal, inner meningeal). Around the brain, 2 layers are fused except where they enclose dural sinuses
What are the 3 dural septi?
- Falx cerebri
- Falx cerebelli
- Tentorium cerebelli
What is the arachnoid mater?
Loose covering separated from dura mater by the subdural space.
he space between the arachnoid and pia mater is called the:
Subarachnoid space
What is the role of arachnoid granulations (villi) in accumulation of CSF?
They are sites of resorption
What is meningitis?
Inflammation of the meninges
What is encephalitis?
Inflammation of the brain
What is CSF?
Liquid cushion to give buoyancy to CNS tissue, also protective and nutritive roles. Secreted by choroid plexus
What is hydrocephalus?
Accumulation of CSF in the CNS
What is the purpose of the blood-brain barrier?
Some hormones also act as neurotransmitters; some ions can increase the rate of neuronal firing. The blood-brain barrier prevents these hormones from adversely impacting the brain
What are the 3 layers of the blood-brain barrier?
- Continuous epithelium of capillary wall (very impermeable tight junctions)
- Thick basal lamina containing enzymes to destroy chemicals that can act on neurons
- bulbous feet of astrocytes + pericytes (maintain endothelial cells and stimulate formation of tight junctions)
What gets through the blood-brain barrier?
Glucose, essential amino acids, some electrolytes, fats, fatty acids, oxygen, carbon dioxide, fat-soluble molecules
What are metabolic effects of the sympathetic NS?
- Increases metabolic rate of body cells
- Raises blood glucose levels
- Stimulates mobilization of fats
- Increases mental alertness
- Increases speed/strength of muscle contraction
What is a portal system?
A direct link between capillaries in 2 different organs
What connects the pituitary to the hypothalamus?
Infundibulum
What is the function of the posterior lobe of the pituitary gland?
Consists of axon terminals, serves as a hormone storage area. Does NOT produce hormones
