mammalogy- control systems and biological rhythyms

CNS develops from

dorsal, hollow nerve cord that differentiates during development into a brain and spinal cord.

the CNS contains

all of interneurons and most of the perikarya. contains many sensory and motor neurons

the PNS contains

only sensory and motor neurons traveling to/from the CNS

PNS divisions

sensory(afferent) and motor(efferent)

spinal cord

connects the PNS to brain. nerves enter/exit vertebral canal by intervertebral foramina. where reflex arcs occur. begins at the medulla oblongata.

conus medullaris

the end of the spinal cord. a tapering structure with numerous spinal nerves that form the cauda equina.

medulla oblongata

caudalmost portion of brain. part of brain stem. contains perikarya of posterior cranial nerves, ganglia for rigin auto controlled behaviors.

cerebellum and pons

cerebellum responsible for coordination of somatic motor activities.

pons contains perikarya of certain cranial nerves, ganglia for auto controlled behaviors, and axons

midbrain

contains perikarya of certain cranial nerves, ganglia for rigid auto controlled behaviors, axons.

reticular formation

made up of the midbrain, pons, and medulla oblongata. responsible for rigid auto controlled behaviors

diencephalon subdivisions(3)

thalamus- main relay center between cerebrum and CNS.

epithalamus- dorsal to thalamus, has endocrine organ (pineal gland).

hypothalamus- ventral to thalamus, main visceral control center.

forebrain

made up on diencephalon and cerebrum

hypothalamus functions

control of ANS.

regulation of body temp.

monitors hunger and thirst.

circadian rhythyms.

control of endocrine system

cerebrum

shows the greatest degree of variation between species. has white and grey matter

cerebral white matter

cerebrum component- inner core. has clusters of grey matter within it called basal nuclei (ex-amygdala).

neocortex/ cerebral cortex

cerebrum component- grey matter. outer. highly convoluted. arranged into domains by function. shows somatotrophy

light entering the eye, steps

light passes through the cornea. it refracts and bends the light. light then passes through the lens. it focuses light on to the retina.

tapetum lucideum

for nocturnal animals. composed of guanine crystals that reflect light back into retina to increase photic stimulation. pupils larger in these animals.

photoreceptors

in the retina. convert light into a nervous signal. respond to specific wavelengths.

rods and cones

photoreceptors.

rods- dim light, lower resolution.

cones- color vision, fovea, higher resolution

the outer ear

collects sound, directs them inward. in order- pinna(unique to mammals), external auditory canal, tympanic membrane

middle ear

in the temporal bone. receives sound waves from tympanic membrane. ossicles in order- malleus, incus, stapes

inner ear

the cochlea. spiral shaped. sound waves converted into nerve signals.

cochlear duct- middle canal, houses sensory structure responsible for hearing (organ of corti)

limbic system

olfaction is hard wired into brain via the limbic system

vomeronasal organ

evagination of ventral olfactory mucosa that becomes isolated from nasal cavity during development. chemoreceptive.

horomones

secreted into blood stream which carries them to site of action.

control structure of endocrine system

hypothalamus. connected to pituitary organ, which secretes a variety of horomones including tropic horomones.

hypothalamus

well vascularized. monitors blood chemistry. causes increase/decrease in release of horomones

pituitary portions(2)

posterior- produces ADH and oxytocin.

anterior- produces GH, TSH, ACTH, LH, FSH, PRL, MSH.

pituitary plays role on physiology

thyroid endocrine organ

in thoracic cavity, produces calcitonin and thyroxine

parathyroid endocrine organs

in the thyroid, produces PTH, an antagonist of calcitonin

adrenal gland endocrine organ

adrenal medulla- central portion, sympathetic ganglion priming body for emergencies.

adrenal cortex- outer portion, produces hormones such as hydrocortisone.

entrainment

occurs when behavioral events match their period and phase of that of an environmental oscillation

to be called circadian, there are 3 criteria

rhythm has endogenous free-running period of ~24 hours.

it is entrainable.

it exhibits temperature compensation

ultraradian rhythms

period shorter than 24 hours. (blinking)

infraradian rhythms

periods longer than 24 hours. (seasonal)

circalunal rhythms

lunar months

are ultradian and infradian rhythms entrainable

yes

do smaller or larger mammals experience greater variation to rhythms

smaller