Physiology Exam 2

Define gray matter and describe what you would find.

Nerve cell bodies. You would find nuclei, dendrites, and axon terminals.

Define white matter and describe what you would find.

Myelinated axons. You would find tracts.

Define tracts and describe what you would find.

Axon bundles connecting CNS regions. You would find very few cell bodies.

Define nuclei and describe what you would find.

Clusters of cell bodies in the CNS.

What is cerebrospinal fluid (CSF)?

A clear, watery liquid that flows through and around the hollow cavities of the brain and the outside of the spinal cord.

What is CSF produced by?

Choroid plexus.

What is the blood-brain barrier?

A highly selective, protective wall of tightly packed cells that lines the blood vessels in the brain and filters what enters the central nervous system.

What is the function of the BBB?

It protects the brain from toxic water-soluble compounds and pathogens.

What are the cells that form the BBB?

Astrocyte, endothelial cells

What can cross the BBB?

Specific gases, small fat-soluble substances, and essential nutrients using special transport proteins.

Where is the BBB reduced and why?

The circumventricular organs. For functional reasons.

What info does the dorsal roots carry?

Sensory info.

What info does the ventral roots carry?

Motor info.

With dorsal roots, where does info come from and go to?

Peripheral receptors → the body

With ventral roots, where does the info come from and go to?

Muscles → glands

Gray matter =

Dorsal, lateral, and ventral horns.

What are the two tracts in white matter?

Ascending and descending tracts.

What type of info does the ascending tract carry?

Sensory info.

What type of info does the descending tract carry?

Motor info.

What is the function of the pyramids in the medulla?

They have involuntary functions like blood pressure, breathing, swallowing, and vomiting.

What is the function of the pons?

Coordinates control of breathing.

What is the function of the midbrain?

Relay signals for hearing and seeing.

What is the function of the cerebellum?

Process sensory info and equilibrium and balance from somatic receptors.

In the diencephalon, there are centers for _____

Homeostasis.

What does the thalamus do?

Is a relay station integrating center.

What does the hypothalamus do?

Control of homeostasis and for behavioral drives and produce torpic hormones.

What do tropic hormones do?

Control secretion of anterior/pituitary hormones.

What are tropic hormones target?

Other endocrine glands.

What does the pineal gland do?

Releases the hormone melatonin to help control your body's sleep and wake cycle.

What two lobes is the pituitary divided into?

Anterior and posterior.

What are the eight major hormones of the anterior pituitary?

Thyroid-stimulating, Adrenocorticotropic, Follicle-stimulating, Luteinizing, Prolactin, Growth, Melanocyte-stimulating, and Endorphins.

Which of the anterior pituitary hormones are tropic?

Thyroid-stimulating, Adrenocorticotropic, Follicle-stimulating, and Luteinizing.

Which anterior pituitary hormones are hypertrophy?

Growth.

Which anterior pituitary hormones are atrophy?

Tropic.

What are the two hormones of the posterior pituitary?

Antidiuretic and Oxytocin.

Primary motor cortex.

Frontal lobe. Controls skeletal muscle activity on opposite side of body.

Primary somatosensory cortex.

Parietal lobe. Receives somatic sensory info from proprioceptors, touch, pressure, pain and temperature receptors.

Primary visual cortex.

Temporal lobes. Receives, processes, stores visual info.

Primary auditory cortex.

Temporal lobe. Receives, processes, store auditory info.

Primary olfactory cortex.

Inferior/medial temporal lobe. Receives, processes, stores odor info.

Primary gustatory cortex.

Insula. Receives, processes, stores taste info.

Define transduce.

Environmental info into action potentials.

What initiates membrane potential change?

Ion channels or second messengers.

What is a modality?

Each receptor type responds to particular info.

What are the two types of neural receptors? Are they myelinated?

Naked (free) nerves which is unmyelinated. Complex neural receptors which is myelinated.

What type of information do nonneural receptors receive?

Olfaction, gustation, vision, and hearing and balance.

Define adequate stimulus.

Form of energy to which a receptor is most responsive.

Define threshold.

Minimum stimulus.

Define receptor potential.

Change in sensory receptor membrane potential.

Define receptive field.

Physical area where stimuli activates neuron.

What are the four major groups of receptors?

Chemoreceptors, mechanoreceptors, temperature, light

What does it mean when we say "receptive field size determines sensitivity"?

The physical area a sensory neuron monitors dictates how precisely the brain can locate or distinguish fine details of a stimulus.

How does sensory info travel?

To the brain via ascending pathways or cranial nerves.

What are perceptual thresholds?

Stimulus level to be aware of sensation.

What is habituation?

Decreased perception through inhibitory modulation.

Explain how tonic and phasic receptors adapt to a continuous stimulus.

Tonic receptors adapting slowly to provide ongoing information and phasic receptors adapting rapidly to signal changes.

What are nociceptors and where are they located?

Specialized sensory nerve endings that detect harmful or potentially damaging stimuli and signal them to the brain as pain. Found in skin, joints, muscles, bones, viscera.

How is fast and slow pain different (in sensation and fibers)?

Fast pain is sharped and localized. Slow pain is duller and more diffuse.

Example of mechanical.

Pinching, cutting.

Example of thermal.

Extreme heat or cold.

Example of chemical.

Acid, capsaicin.

What is referred pain?

Poorly localized pain perceptions from visceral pain and somatic pain.

Two subdivision of the Efferent Division of PNS?

Somatic motor neurons and autonomic neurons.

Somatic motor neurons.

Control skeletal muscles.

Autonomic neurons.

Control smooth muscle, cardiac muscle, many glands, and some adipose tissue.

What autonomic reflexes are directed by the medulla?

Cardiovascular, respiratory, and digestive functions.

Which autonomic reflexes are directed by the hypothalamus?

Sympathetic and parasympathetic preganglionic neurons in the brainstem and spinal cord.

Antagonistic control is the hallmark of the ANS. What does that mean, and what are some examples?

It means the sympathetic and parasympathetic branches of the autonomic nervous system (ANS) exert opposing effects on the same target organ or tissue to maintain internal balance (homeostasis). Examples: Heart (Cardiac Muscle) / Increases heart rate and force of contraction / Decreases heart rate.

Where are the ganglia located in each? And how is their location related to their target and effect?

The sympathetic ganglia is close to the spinal cord. This setup triggers a widespread, mass response activating multiple organ systems at the same time. The parasympathetic ganglia is near or directly inside the walls of the target organs. This close setup allows for localized, precise control letting the body target a single organ without broad activation of the whole body.

What neurotransmitters are released by sympathetic and parasympathetic preganglionics and postganglionics?

Acetylcholine (ACh).

Discuss the role of cholinergic and adrenergic synapses.

Primary communication junctions of the autonomic and central nervous systems.

What is the importance of varicosities and synapses en passant?

They allow a single neuron to release neurotransmitters at multiple swollen sites along the length of an axon rather than only at the very end.

Where is ACh used as a neurotransmitter?

In the CNS and PNS.

What are the two types of cholinergic receptor subtypes?

Nicotinic and muscarinic.

Where would you find adrenergic receptors?

On target organs and tissues throughout the sympathetic nervous system.

How does adrenergic stimulation vary among different tissues?

Different organs express distinct adrenergic receptor subtypes that trigger unique intracellular pathways when bound by catecholamines like norepinephrine and epinephrine.

What is the sarcoplasm?

The specialized cytoplasm found within muscle cells.

What is the sarcolemma?

The specialized cell/plasma membrane that surrounds a striated muscle fiber or cardiac muscle cell.

What are Transverse Tubules?

Extensions of the cell membrane (sarcolemma) that associate with the ends (terminal cisternae) of the sarcoplasmic reticulum.

What type of channels do Transverse Tubules have?

Voltage-sensitive calcium channels.

What are Myofibrils?

Bundles of myofilaments enclosed in sarcoplasmic reticulum.

Order muscle fibers, myofilaments, and myofibrils from largest to smallest?

Muscle fiber, myofibril, myofilament.

What is the sarcoplasmic reticulum?

A specialized network of membranes inside muscle cells that stores and releases calcium ions to control muscle contraction and relaxation.

What are Terminal Cisternae?

Blind sacs of sarcoplasmic reticulum.

What are the functions of Sarcoplasmic Reticulum?

Store, release, and reabsorb calcium ions to control muscle contraction and relaxation.

What are the functions of Terminal Cisternae?

Serves as reservoirs for calcium ions.

What is a Triad?

A specialized structural repeating unit in skeletal muscle fibers, consisting of one transverse tubule (T-tubule) sandwiched between two terminal cisternae of the sarcoplasmic reticulum.

What types of pumps are in the sarcoplasmic reticulum?

Calcium pumps.

What are myofilaments?

Contractile proteins within myofibrils.

What are thick filaments?

Consist of bundles of many myosin protein molecules.

What are thin filaments?

Twisted strands of actin. With a myosin binding site where myosin heads attach.

Which of those (thick or thin) would you find myosin-binding sites, tropomyosin, and troponin on?

Thin.

Which of these are regulatory proteins?

Tropomyosin and troponin.

What is a sarcomere?

Myofilaments arranged in repeating units.

What are Z-discs?

Protein-rich boundary structures that mark the ends of each sarcomere, the basic contractile unit of striated muscle.

Identify and define A-bands.

Dark-appearing region that contains thick filaments and overlapping thin filaments. Contains the H zone and M line. Makes up the central region of the sarcomere.

Identify and define I-bands.

Light-appearing regions that contain only thin filaments. Bisected by Z disc. Get smaller when muscle contracts.

Which band gets smaller with contraction?

I band.

Where is the H-zone?

In the central portion of A band.

Where would you find the thick and thin filaments in the areas above?

Within the sarcomere of a muscle myofibril.