Exam 2 Flashcards
How many pairs of cranial nerves are there?
12
What are cranial nerves I and II connected to?
The cerebrum
What are cranial nerves III-XII connected to?
The brain stem
Which portion of the nervous system is the optic nerve considered to be a part of?
The central nervous system
Which portion of the nervous system are all cranial nerves (other than the optic nerve) a part of?
The peripheral nervous system
What do the afferent neurons in cranial nerves do?
Transmit sensory information to the brain or brain stem.
What is cranial nerve II (optic nerve) responsible for? What type of nerve is it?
Vision, sensory nerve
What does cranial nerve VIII (vestibulocochlear nerve) responsible for?What type of nerve is it?
Balance and hearing, sensory nerve
What is cranial nerve I (olfactory nerve) responsible for? What type of nerve is it?
Smell, sensory nerve
Cranial nerves can contain _____, ___________, and ________ neurons that control effector tissues.
somatic, parasympathetic, sympathetic
What is cranial nerve III (oculomotor nerve) responsible for? What type of nerve is it?
Extraocular eye muscle movement, motor nerve
What is cranial nerve XII (hypoglossal nerve) responsible for? What type of nerve is ti?
Muscles of tongue; motor nerve
What does cranial nerve I (olfactory nerve) arise from?
The olfactory bulb
What does cranial nerve II (optic nerve) arise from?
The diencephalon
What does cranial nerve III (oculomotor nerve) arise from?
The midbrain
What does cranial nerve VIII (vestibulocochlear nerve) arise from?
The medulla
What does cranial nerve X (vagus nerve) arise from?
The medulla
What does cranial nerve XII (hypoglossal nerve) arise from?
The medulla
What is the nictitating membrane?
A third eyelid, mostly found in birds
What does the granula iridica do? Where is it found and in what animal is it most commonly seen in?
It reduces glare and increases visual clarity, found in the eye around the pupil, most commonly seen in horses
What part of the eye makes a cat’s eye glow?
The tapetum lacidum
What does the suspensory ligament of the eye do?
It connects the ciliary body with the lens, holding it in place.
What is the ciliary body of the eye?
A circular structure that is an extension of the iris
What is the iris of the eye?
The colored portion around the pupil
What is the pupil of the eye?
The opening at the center of the iris through which light passes
What is the lens of the eye?
A curved structure in the eye that bends light and focuses it for the retina (located behind the pupil and iris)
What is the cornea of the eye?
The outer layer at the front of the eye
What is the aqueous humor of the eye?
The clear liquid inside the front of the eye
What is the vitreous humor of the eye?
A clear, colorless fluid that fills the space between the lens and the retina
What is the optic disc of the eye?
The round spot on the retina formed by the passage of the axons of the retinal ganglion cells. Where the retina and optic nerve connect.
Why is there an optic disc blind spot?
The point where the optic nerves converge to exit the eye (the optic disc). This area of the eye has no light-sensitive cells. This results in a break in the visual field.
What is the sclera of the eye?
The white of the eye. A protective covering that wraps over most of the eyeball.
What is the retina of the eye?
A layer of photoreceptor cells and glial cells within the eye that captures incoming photons and transmits them along neuronal pathways.
What is the choroid of the eye?
The layer of blood vessels and connective tissue between the sclera and the retina.
What type of muscle in the iris controls pupil dilation? What is the name of the muscle?
Smooth muscle, ciliary muscle
What portion of the nervous system controls pupillary constriction?
The parasympathetic nervous system
What muscle (other than smooth) controls pupillary constriction?
Circular muscle
What portion of the nervous system controls pupillary dilation?
The sympathetic nervous system
What muscle (not smooth) controls pupillary dilation?
Radial muscle
What does changes in cornea shape cause?:
Visual impairment
What are the components of the retina?
Fibers of the optic nerve, ganglion cells, amacrine cells, bipolar cells, horizontal cells, cone and rod cells (photoreceptor cells), pigment layer, choroid layer, and sclera
What do rod cells do?
Provide light vision
What are the characteristics of rod cells?
Rhodopsin photopigment absorbs all wavelengths of light, more sensitive but cannot distinguish color, results in shades of gray based on light intensity
What do cone cells do?
Provide color vision
What are the characteristics of cone cells?
Three types in primates with different scotopsin proteins; scotopsin photopigment can detect red, green, and blue wavelengths
How does information from rod and cone cells reach the optic nerve?
Light reduces rod and cone cell neurotransmitter release
Where does light hit in the eye for someone who is nearsighted?
Before the retina
Where does light hit in the eye for someone who is far sighted?
After the retina
How does light hit in the eye for someone who has astigmatism?
The light is scattered on and around the retina
What does the vestibular apparatus contribute to?
Sense of balance
What portion of the ear are semicircular canals located in?
The vestibular apparatus
What do semicircular canals do?
Detect changes in head position and rotational or angular acceleration of the head.
Which structures are included in the otolith organs?
The utricle and saccule
What do otolith organs do?
Detect changes in head position and linear acceleration of the head
What provides positioning information?
Movement of fluid over hair cells
What type of receptor are hair cells?
Mechanoreceptors
How is information transmitted from the ear to the brain?
Through the vestibulocochlear nerve (VIII) to the cerebellum.
What are the hairs of hair cells in the ear called?
Kinocilium and stereocilia
What connects to hair cells in the ear?
Vestibular nerve fibers
What are the bands between stereocilium called?
Tip links
What are the steps of depolarization of hair cells in semicircular canals?
1) Tip links stretch and open channels when stereocilia bend towards tallest member.
2) K+ enters hair cell, depolarizing it.
3) Depolarization opens voltage gated Ca^2+ channels.
4) Ca^2+ entry causes greater release of neurotransmitter.
5) More neurotransmitters leads to higher rate of action potential.
What are the steps of hyperpolarization of hair cells in semicircular canals?
1) Tip links slacken and close when stereocilia bend away from the tallest member.
2) No K+ enters cell, hyperpolarizing it.
3) Ca^2+ channels close
4) No neurotransmitter is released .
5) No action potentials occur.
What do otoliths do?
Provide weight to fluid overlaying hair cells.
What structures are included in the otolithic membrane?
Otoliths and a gelatinous layer
What is the tympanic membrane?
The eardrum
Where is the tympanic membrane found?
The middle ear of mammals
What does the tympanic membrane do?
Vibrates in response to sound waves and provides sound intensity and pitch information.
What is intensity?
Loudness
What does intensity depend on?
Wave amplitudes
What is pitch?
Tone
What does pitch depend on?
Wave frequency
What is ultrasound frequency? How far does it travel?
High frequency; 20,000 Hz; travels short distances
What is infrasound frequency? How far does it travel
Low frequency; 20 Hz; travels through land and water over long distances
What animal can hear ultrasound frequency?
Bats
What animals can hear infrasound frequency?
Whales and elephants
What are ossicles?
Three small bones in mammals that transfer vibrations from the tympanic membrane to the cochlea oval window.
What is the ossicle order?
Tympanic membrane —> malleus —> incus —> stapes —> oval window
How many ossicles are found in reptiles, tailless amphibians, and birds?
One
What is the ossicle in reptiles, tailless amphibians, and birds called?
Columella
What is the cochlea?
A coiled tubular system with three fluid filled compartments
What is the upper compartment of the cochlea called?
Scala vestibuli
What is the middle compartment of the cochlea called?
Scala media or cochlear duct
What is the lower compartment of the cochlea called?
Scala tympani
What is the organ of corti?
Thousands of hair cells arranged in four parallel rows found on top of the basilar membrane in the cochlear duct.
What is the organ of corti responsible for?
A sense of hearing
How does the organ of corti work?
Inner row of hair cells transform cochlear vibrations into action potentials that are then transmitted to the brain temporal lobe by cranial nerve VIII.
What is the oval window?
A membrane covering the entrance to the cochlea in the inner ear.
What is the round window?
One of the two openings into the cochlea from the middle ear. Serves to decompress acoustic energy that enters the cochlea.
What is the malleus?
A hammer-shaped bone that connects to the tympanic membrane.
What is the incus?
Anvil-shaped bone that connects to the malleus and the stapes.
What is the stapes?
Stirrup-shaped (smallest bone in the body) bone that connects to the incus and the oval window.
What is the cochlear duct/ scala media?
A fluid-filled, spiral-shaped cavity found in the inner ear.
What is the basilar membrane?
The main mechanical element of the inner ear. It separates incoming sounds into its component frequencies that activate different cochlear regions.
What is the tectorial membrane?
A highly hydrated matrix above hair cells in the cochlea. Plays a vital role in stimulation of hair cells.
How are oval window vibrations transmitted?
Through fluid (perilymph) within the scala vestibuli and then the scala media (cochlear duct) over the organ of corti.
How are different pitches perceived?
Different sound wave frequencies cause peak vibrations at different positions along the basilar membrane.
How is sound intensity perceived?
Greater sound wave amplitudes cause greater basilar membrane movement.
What part of the brain turns sounds into coherent and meaningful sounds?
The cerebrum temporal lobe
How do the basilar membrane and tectorial membrane interact?
The stereocilia of the basilar membrane contact the overlying tectorial membrane. The hairs are bent when the basilar membrane is deflected in relation to the tectorial membrane. The bending of the hair cell opens mechanically gates channels.
What are gustatory cells?
A type of chemoreceptor found in the tongue taste buds that prove a sense of taste.
How many gustatory cells are there per taste bud?
About 50
How is the sense of taste created?
Food molecules bind to receptors in gustatory cells that trigger cell action potentials. Action potential are sent via cranial nerve VII and X to the cerebrum parietal and temporal lobes and the hypothalamus.
What tastes can gustatory cells sense?
Bitter, sweet, sour, or salty foods.
What does food bind to on gustatory cells?
Channels or 7TMDR
What are olfactory neurons?
A type of chemoreceptor found in the nasal cavity (believed to be the only type of neuron in mammals to undergo mitosis during adult life)
A specific type of ______ for each odor molecule.
neuron
How many different smells can the human olfactory system distinguish?
1 trillion
What is the pathway in when smells reach the brain?
- Odor present
- Nostrils
- Respiratory epithelium in the nasal passage
- Olfactory epithelium
- Olfactory bulb
- Brain
What is the passageway in which pheromones reach the brain?
- Pheromones present
- The moth of the vomeronasal channel
- Vomeronasal organ (Jacobson’s organ)
- Impulse transmitted
- Olfactory bulb
- Brain
Where do olfactory neurons synapse?
On mitral cells in olfactory glomeruli
What are olfactory glomeruli?
“Smell collection centers” where neurons for a specific odor molecule converge on mitral cells
Olfactory neuron action potential ________ with concentration of an odor molecule and _______ are released within glomerus on mitral cell.
increase, neurotransmitters
What do mitral cells do?
Send sensory information to cerebrum temporal lobe.
What is the vomeronasal organ (VNO)?
An addition sense organ in mammals and reptiles. Causes reproductive and social behaviors by reception of pheromones.
Where is sensory information from the vomeronasal organ sent?
The hypothalamus (region of the brain that controls reproduction)
What is the flehming response?
Animal opening of VNO to receive pheromones
What is the endocrine system?
A system of glands or tissues that secrete hormones into the blood and regulate animal homeostasis and physiology.
What is endocrinology?
The study of endocrine glands, their secretion of hormone into the blood, and the effects of endocrine hormones on tissues.
What is the rate of change in animal physiology for the endocrine system compared to the nervous system?
The endocrine system provides a slower rate of change - typically seconds, days, or weeks.
The endocrine system allows the animal to undergo necessary physiological changes for _______, _________, and response to _______.
growth, reproduction, stress
List examples of animal endocrine glands:
Pineal, hypothalamus, pituitary, parathyroid, thyroid, thymus, heart, liver, stomach, adrenal gland, pancreas, duodenum, kidney, adipose tissue, skin, ovaries, and placenta
What are the functions of the endocrine system?
- maintain animal temperature
- food, water, and mineral seeking and satiety
- water, ion, and pH balance
- digestion, metabolism, and growth
- behavior and stress response
- biological rhythms
- reproduction
What is compensatory hypertrophy?
An increase in the size of an organ to compensate for the activity of the other lost organ.
What was the first endocrine experiment and the first documentation of a successful organ transplant?
Arnold Bethold’s cockerel experiment
What cells do endocrine hormones influence?
Cells with receptors for the specific hormone
What is hormone half life?
The time it takes for half of a hormone concentration in blood to disappear.
What causes hormone half life?
Hormone metabolism
What the types of hormone secretion?
Basal or tonic, sustained, and episodic.
What is basal or tonic hormone secretion?
The hormone is secrete in low constant concentrations
What is sustained hormone secretion?
The hormone is secreted in high constant concentrations
What is episodic hormone secretion?
The hormone is secreted in pulses or episodes
When is episodic hormone secretion common?
Common for neuroendocrine hormones, pulses are related to neuron action potentials
Where are endocrine hormones metabolized?
In the liver, kidneys, or lungs
What is often collected to measure animal hormone concentrations?
Blood, urine, or feces.
What is negative feedback?
When the hormone reduces or turns off its own production
What is positive feedback?
When the hormone tends to increase its own production
When does positive feedback occur?
When rapid or drastic change is needed
Can positive feedback be sustained for long periods of time?
No
What is an example of positive feedback?
Parturition
What are major regulators of the endocrine system?
The hypothalamus and the pituitary gland
What does the pituitary gland consist of?
Two distinct glands- the anterior and posterior pituitary
What are hypothalamic nuclei?
Groups of nerve cell bodies that respond to specific sensory information and release neuroendocrine hormones into the anterior or posterior pituitary.
List the hypothalamic nuclei?
- Ventromedial nuclei (VMN)
- Arcuate nuclei (ARC)
- Anterior hypothalamic area (AHA)
- Preoptic nuclei (PON)
- Suprachiasmatic nuclei (SCN)
- Paraventricular nuclei (PVN)
- Supraoptic nuclei (SON
How does the anterior pituitary develop?
From oral tissue
How does the posterior pituitary develop?
From brain/neural tissue
What major hormones does the posterior pituitary produce?
Oxytocin and vasopressin
What does oxytocin do?
Stimulates milk ejection and uterine contractions in females.
What does vasopressin do?
Contributes to animal water retention and regulates blood pressure.
Is oxytocin an amino acid, a peptide, or a protein?
A peptide (8 amino acids)
How does vasopressin effect the nephrons in kidneys?
It increases the permeability of distal and collecting tubules to water.
How does vasopressin effect arterioles throughout the body?
It causes vasoconstriction.
What is the Ferguson reflex?
Contraction of muscle in the uterus for parturition.
What is the milk let-down reflex?
Contraction of smooth muscle in mammary glands for milk ejection.
What does oxytocin control in both males and females?
Animal behavior including mate choice and pair bonding, trust, mothering abilities, and orgasms.
What are the steps of the Ferguson reflex?
- Fetus presses on cervix
- Sensory neurons in cervix send information to the hypothalamus
- Oxytocin is released from posterior pituitary
- Oxytocin stimulates uterine smooth muscle contraction
- Fetus presses on cervix more vigorously - contributes to labor and parturition.
What is oxytocin used for by doctors?
Labor induction
What are the steps of the milk let-down reflex?
- Stimulation of neurons within the mammary gland during nursing.
- Information sent to the hypothalamus
- Oxytocin is released from the posterior pituitary
- Oxytocin stimulates contraction of myoepithelial cells surrounding glandular cells
- Milk is transported into mammary gland ducts and cistern.
Is vasopressin an amino acid, a peptide, or a protein?
Peptide (8 amino acids)
What are the names of some hormones that are the same as vasopressin?
Anti-diuretic hormone (ADH), Arginine vasopressin (AVP) in humans and other animals, Lysine vasopressin (LVP) in pigs
How does AVP control blood pressure through arterioles?
AVP binds to receptors (V1R) on smooth muscle cells around arteries causing vasoconstriction, arterial resistance, and elevated blood pressure.
How does AVP increase water retention?
AVP binds V2R in kidney, increases aquaporin activity, increases animal water retention and reduces urine volume.
What does increased water retention cause?
Increased blood volume and blood pressure.
What is central diabetes insipidus?
When the body cannot properly balance fluid levels due to damage of the pituitary gland or hypothalamus from surgery, a tumor, head injury, or illness.
What is a cause for diabetes insipidus?
A mutation on the vasopressin gene.
What is polydipsia?
Excessive drinking
What is polyuria?
Excessive urination
What does the hypothalamic-hypophyseal (HH) blood portal system do?
Allows small quantities of neuroendocrine hormone to act on cells in the anterior pituitary before they are diluted by general circulation.
What are acidophils?
Lactotropes and somatotropes