reproductive behavior

female

male

copulatory stage

postcopulatory stage: period of refractivity

precopulatory stage

receptivity: copulatory behavior of females that ensures insemination

proceptivity: behaviors exhibited by females toward males that stimulate male to copulate or that reinitiate sexual behavior after copulation

attractivity: behaviors and other signals that serve to attract males

erection

penile protrusion

sexual arousal: followed by erection and penile protrusion

courtship: specific behavior is initiated after a sexual partner has been identified

mounting

intomission

ejaculation

refreactory period

memory

dismount

search for sexual partener

this can vary significantly among species with regard to duration

programmed during penatal development

feminization

development of female-like behavior

masculinization

develops in males by high estradiol in brain causing defeminizatino

reproductive behaviors are sexually differentiated

the presence of gonadal steroids is obligatory for normal reproductive behavior in both the male and the female

females will display male reproductive behavior following injections of testosterone

when overiectomized females receive injections of estradiol, estrous behavior is reestablished, but at a less than maximum level

controlled by the CNS

reproductive behavior can only occur if the neurons in the hypothalamus have been sensitized to respond to sensory signals

reproductive behavior is initiated by

tactility

audition

vision

olfactory

olfactory and vomeronasal system respond to pheromones that trigger reproductive behavior

pheromones from female reproductive tract serve to sexually stimulate and attract the male to the female

males also produce sex pheromones that attract and stimulate females

flehmen behavior is a close range investigative behavior

visual signals are valuable for close encounters

tactile stimulation is generally the final stimulus before copulation

auditory stimulation can serve as a long-range signal

penile erection and protrusion completes the precopulatory phase of reproductive behavior

erection of the penis requires

dilation of corporal sinusoids

restricted venous outflow

elevated arterial blood inflow

elevated intrapenile pressure

relaxation of the retractor penis muscle

contractions of the ischiocavernosus muscles cause compression of hte penile veins

viagra: provides a therapy for erectile dysfunction in men

erectile dysfunction is defined as the inability to achieve and maintain a penile erection

basic steps in the erectile process

step 3: stimulation of parasympathetic nerves that innervate penile arterioles

step 4: parasympathetic nerve terminals release nitric oxide (NO)

step 2: sensory nerves activate "reproductive behavior center" in hypothalamus

step 5: nitric oxide initiates biochemical cascade that causes erection

step 1: erotegenic stimuli cause sensory nerves to fire

erection of the penis requires sensory input and a local vascular response

complex series of neural and vasomotor events, can be divided into a nervous component

cerebral

spinal

copulatory behavior includes

ejaculation is caused by

intromission

mounting

stimulation of the glans penis

forceful muscle contraction

intromission

defined as the reflex expulsion of spermatozoa and seminal plasma from the male reproductive tract

emission : the movement of the seminal fluids from the accessory sex glands into the pelvic urethra so they can mix with spermatozoa

postcopulatory behavior involves refractivity and recovery

reproductive behavior can be enhanced by

introducing novel stimulus animals

changing stimulus settings

reproductive behavior and spermatozoal output can be manipulated

coolidge effect: restoration of mating behavior in males when the original female is replaced by a novel female

sexual stimulation: presentation of a stimulus situation that will achieve mounting and ejaculation

sexual preperation prolongs sexual stimulation and increases spermatozoa per ejaculation

sexual preperation may include

false-mounting

restraint

false-mounting plus restraint

manually deviating the penis during a mount so that intromission cannot occur

prevents male from mounting even though he wishes to do so

homosexual-like behavior

common among domestic animals especially in cattle

theories that cows mounting each other provides a visual signal that attracts a bull to the cow in estrus

another theory is the evolution of homosexual-like behavior among cows involves inadvertent genetic selection by man fro this behavior