Topic 7: Control Systems and Biological Rhythms

CNS

brain and spinal cord

what does the CNS come from

develops from a dorsal, hollow nerve cord that differentiates during development into

what neurons does the CNS contain

all of the interneurons and most of the perikarya in the body.

also many sensory and motor neurons

What neurons does the PNS contain

only sensory and motor neurons

sensory neurons aka

afferent

motor neurons aka

efferent

what do the somatic motor division control

skeletal muscle

somatic motor division aka

voluntary division

visceral motor division controls

the visceral organs

what is the subset autonomic division part of

visceral motor control

purpose of spinal cord

connect the PNS to the brain

where is the spinal cord found

inside the vertebral canal

where do spinal nerves enter and exit the vertebral canal

intervertebral foramina

what pattern do spinal nerves form with the spinal cord

regular segmental pattern

where do reflex arcs occur

the spinal cord

what is unique about reflex arcs

they can act independently of the brain

Conus Medullaris

tapering structure at the end of the spinal cord

Cauda Equina

where numerous nerves arise from the Conus Medullaris and radiate in a regular segmental pattern

Medulla oblongata

the caudal most portion of the brain and a portion of the "brain stem"

what does the medulla oblongata contain

the perikarya of the posterior CN, ganglia for rigid autonomically controlled behaviors, and axons traveling to and from the cerebrum

cerebellum responsible for

the gracefulness and coordination of somatic motor activities

pons contains

the perikarya of certain CN, ganglia for autonomically controlled behaviors and axons traveling to and from the cerebrum

midbrain contains

perikarya of certain CN, ganglia for rigid autonomically controlled behaviors, and axons traveling to and from the cerebrum

Reticular Formation made up of

midbrain, pons, and medulla oblongata

what is the forebrain comprised of

diencephalon and cerebrum

what are the three divisions of the diencephalon

thalamus, epithalamus, hypothalamus

thalamus

main relay center between the cerebrum and the rest of the CNS

epithalamus

located dorsal to the thalamus and includes endocrine organ the Pineal Gland

hypothalamus

located ventral to the thalamus, main visceral control center for the body

hypothalamus functions

control of the ANS

regulation of body temp

monitoring thirst and hunger

circadian rhythms

control of endocrine system

cerebrum significance

portion of the brain that shows the most variation between mammalian orders and families

cerebrum structure

outer layer of grey matter surrounding a central core of white matter

cerebral white matter consists of

axons traveling to and from the outer cerebral layer

basal nuclei

clusters of grey matter within the cerebral white matter

example of basal nuclei

amygdala

Neocortex or Cerebral Cortex

highly convoluted outer layer of grey matter

what is the mammalian cortex arranged into

domains of specialized functioning

what does the cortex have a great number of

neurons dedicated to association areas which serve as memory banks and integration centers

mammalian cortex will show

somatotropy

first stage of light entering the eye

light passes through the cornea where it is refracted

second stage of light entering the eye

light passes through the lens, which will focus light on the retina where an inverted image will form

what controls the amount of light passing into the eye

the muscles of the iris control the size of the pupil

who has Tapetum Lucideum

many nocturnal and night active species

Tapetum Lucideum

structure composed of guanine crystals that reflect light back to the retina to increase the amount of photic stimulation

what causes eye shine

tapetum lucideum

why are pupils larger in nocturnal species

to allow more light into the eye

photoreceptors

special cells of the retina that start a chain of events allowing visual information to travel to the brain

what tissue type are photoreceptors

specialized neurons capable of converting light into a nervous signal

the two types of photo receptors

rods and cones

cones

conical shaped outer segments

work best under bright conditions

provide high degree of resolution

cone distribution

will vary between species based on the visual topography of their environment

visual streak

dense region of cones arranged linearly

found in animals inhabiting a flat visual field (ie prarie)

fovea

cone dense region in a pit

where light will be focused by the retina

what do cones allow for

color vision

why do many mammals lack color vision

cones require a high degree of photic stimulation. when mammals were forced into a nocturnal existence, few modern mammals possess enough cones to allow for color vision

rods

have rod shaped outer segments

work best under dim light conditions

provide a lower degree of resolution

rods allow for

achromatic, black and white, vision. because they require a lower degree of photic stimulation and work with lower energy levels

what do diurnal species have more of than nocturnal species

cones

what do nocturnal species have more of than diurnal species

rods

external ear purpose

collect sound and direct it inward

external ear consists of

pinna, external auditory canal, tympanic membrane

pinna

unique to mammals, present in most but not all.

serves to capture and concentrate sound waves

external auditory canal

tube leading from the pinna to the tympanic membrane

tympanic membrane

thin membrane located between the external auditory canal and the middle ear

middle ear

located in the temporal bone

receives sound waves conducted from the tympanic membrane

how are sound waves conveyed across the middle ear from the tympanic membrane

auditory ossicles

what are the auditory ossicles in mammals in order from TM to inner ear

Malleus, Incus, Stapes

which auditory ossicles have evolved from bones of the reptilian jaw

malleus and incus

cochlea

spiral shaped portion of the bony inner ear where sound waves are converted into nerve signals

cochlear duct

the middle canal of the cochlea

houses the sensory structure for hearing

organ of corti

organ of hearing

the limbic system

hard wires olfaction to the brain

can elicit strong memories and reactions

olfaction purposes

finding food, avoiding predators, identifying conspecifics, identifying social status, analyzing feces to identify available food, identifying territories

Olfaction is a ___ sense

chemoreceptive

olfactory mucosa

the tissue that detects olfactory information in the nasal cavity

what causes vomeronasal organ

evagination of the ventral olfactory mucosa that becomes isolated from the rest of the nasal cavity during development

pheromone

a chemical substance produced and released into the environment by an animal that affects the behavior or physiology of others of its species

the endocrine system

composed of glands that secrete hormones into the blood stream

hormones change...

the activities of target cells, tissues, or organs

hypothalmus

the master control structure of the endocrine system

pituitary

endocrine gland connected to the hypothalamus

pituitary function

secretes a variety of hormones including Tropic Hormones

tropic hormones

control the activity of other endocrine organs

posterior pituitary produces

ADH and oxytocin

the anterior pituitary produces

somatotropin (GH), TSH, ACTH, LH & FSH, PRL, MSH

thyroid

produces calcitonin and produces thyroxine

located in the thoracic cavity

parathyroids

produce PTH, the antagonist of calcitonin

found on the thyroid

the adrenal gland parts

adrenal medulla and adrenal cortex

adrenal medulla

the central portion, acts as a sympathetic ganglion priming the body for emergencies

adrenal cortex

the outer portion, produces many hormones including hydrocortisone

gonads

the testes and ovaries

produce male and female sex hormones and will play a role in behavior

circadian rhythms

biological process that displays an endogenous, entrainable oscillation of about 24 hours

entrainment

occurs when rhythmic physiological or behavioral events match their period and phase to that of an environmental oscillation

requirements to have circadian rhythm

1. rhythm lasts approximately 24 hours regardless of conditions (i.e. constant darkness)

2. rhythms are entrainable and can be reset by exposure to certain stimuli

3. rhythms exhibit temperature compensation

ultradian rhythms

rhythms shorter than 24 hrs

many different of these rhythms such as heart beat, respiration, sleep patterns

infradian rhythms

rhythms longer than 24 hour

ex; menstruation, breeding, tidal, or seasonal

circalunal rhythms

infradian rhythms that are synchronized with the lunar month

circannual rhythms

synchronized with a year long period