Erection and ejaculation Flashcards
Define libido
The behavioural manifestation of sexua desire
Define intromission
The entrance of he penis into the vagina
Define erection
The firming and enlargement of the penis
Define emission in ejaculation
The movement of accessory gland fluid into the male urethra to mix with sperm
Define ejaculation
The reflex expulsion of sperm and seminal plasma from the male reproductive tract
What are the 2 structural types of penis?
- Fibroelastic
- Musculocutaneous
What are the muscles of the penis?
- Paired ischiocavernosus
- Urethralis
- Bulbospongiosus
- Paired retractor penis muscle
Where is the ischiocavernosus muscle?
Originates at the ischial arch and inserts on the roof of the penis
What is the function of the ischiocavernosus muscle?
Forces bood into the corpus cavernosum and corpus spongiosum during erection
Where are the urethralis muscle and the bulbospongiosus muscle?
Surround the urethra
What is the function of the urethralis and bulbospongiosus?
Transport of semen
Where is the paired retractor penis muscle?
Originates at caudal vertebrae and inserts on sigmoid flexure in ruminants/pigs or the distal penis
What is the function of the retractor penis muscle?
- Allows retraction and protrusion of the penis
- Realxes at time of sexual excitement to allow lengthening of sigmoid fexure and thus erection can occur
Describe precopulatory behaviour
- Search for sexual partner
- Courtship (usually initiated by female)
- Sexual arousal
- Erection
- Penile protrusion
What is required in order for erection to occur?
- Elevated arterial blood inflow
- Dilation of corporal sinusoids
- Restricted venous outflow
- Elevated intra-penile pressure
- Relaxation of the retractor penis muscle
What are the corporal sinusoids?
- Within erectile tissue, dormed from connective tissue trabeculae
- Are what fills with blood during erection
How is venous return from the penis altered in order to maintain erection?
- Engorgement of cavernous tissue causes blockage of venous return
- Ischiocavernosus causes blockage of penile veins
- Intermittent contractions causes pump-like action at base of penis
Describe the role of the sympathetic nervous system in the penis
- In flaccid, lumen of helicine arteries closed by sympathetic tone in muscles of vessel walls
- Adrenergic nerves secrete norepinephrine
- Causes vasoconstriction
- Unabe to deliver blood to sinusoids
Describe the neuronal component of erection
- erection caused by firing of parasympathetic neurones
- Inhibit (relax) longitudinal muscle fibres in helicine arteries
- Blood into central sinusoids, swelling
- Compression of oblique veins
- Further penile swelling
Where do the helicine arteries empty into?
Venous sinuses
How does the parasympathetic nervous system initiate erection?
- NANC neurones innervate helicine arteries
- Nerve terminals release nitric oxide
- NO stimulates guanylate cyclase to conver GTP to cGMP
- cGMP causes smooth muscle to relax
- Sinuses engorge
- Intracorporal pressure increases
- Venules and veins compressed
What are NANC neurones?
Nonadrenergic noncholinergic parasympathetic neurones
What are the components of copulatory behaviour?
- Mounting
- Intromission
- Ejaculation
Describe erection of the fibroelastic penis
- Mostly fibrus tissue
- Little increase in length and girth
- Length increased by straightening of sigmoid flexure as a result of relaxation of the retractor penis muscle
Describe erection of the musculocavernous penis
- Expansion in diameter and length during erection
- Engorgement with blood more significant in stallion, dog and man more than bull, ram and boar
What are the different ways in which penile enlargement can occur?
- Lengthening of majority of penis via sigmoid flexure lengthening (ruminant, pig)
- Swelling of penile body and glans penis (stallion/man)
- Swelling of mainly glands penis (dog)
When does swelling of the penis occur in the dog?
After intromission
What can intromission be aided by?
- Penile lengthening (ruminants,, pig)
- Engorgement (stallion, man)
- Os penis (dog)
Describe the loss of erection following copulation
- Sympathetic tone predominates
- Closure of helicine arteries
- Blood flows out of sinusoids and erection subsides slowly
Describe the process of ejaculation
- Stimualtion of glans penis (pressure and temperature) viainternal pudendal nerve to lumbosacral region of spinal cord
- Firing of nerves within spinal cord
- Reflex innervaiton of urethralis (bulbospongiosus) and ischiocavenosus
- Reflex expulsion of sperm and seminal plasma form male reproductive tract
Compare the duration of ejaulation in different species
- Rapid: small volume of ejacullate e.g. ruminant, tom cat
- Long: medium/large colume ejaculate e.g. stallion
- Prolonged: large volume of ejaculate e.g. pig and dog
Describe the ejaculate of stallions
- Series of jets
- Sperm rich fraction ejaculated in 3-4 jets
- Last 5-8 jets at lower pressure and less sperm
Describe the ejaculate of boars
- Series of seminal fractions
- First fraction: accessory fluids and few sperm
- Second fraction: rich in spermatozoa
- Final fraction: thick coagulum
What is the function of the coagulum produced by boars?
Prevent loss of sperm from female tract
Describe the ejaculate of dogs
- 3 fractions
- Pre serm fraction from prostate
- Sperm rich fraction
- Prostate dervied fraction delivered with greater force
What is the function of the final ejaculatory fraction produced by dogs?
Large volume to push sperm rich fraction into uterus, increasing chance of conception
Desribe the Canine Tie
- Male mounts female (intromission)
- Pre-serm and sperm rich fraction released
- Male turns around
- Bulbus glandis swells, locked together
- Swelling maintained by contraction of vagina
- Male ejaculates prostatic fluid in this phase
What penile disorders could occur with injury to the pelvic region and why?
- Sympathetic supply from hypogastrics
- Semi-permanent erection (priapism)
- Or penis unable to return to prepuse (paraphimosis)
What is the site of ejaculation in bulls?
Vagina
What is the site of ejaculation in stallions?
Uterus
What is the site of ejaculation in rams?
Vagina
What is the site of ejaculation in boars?
Uterus
What is the site of ejaculation in dogs?
Vagina
What is the site of ejaculation in tomcats?
Vagina
What are the components of semen?
- Spermatozoa
- Seminal plasma
- Preputial secretions
What makes up preputial secretions?
- Aka smegma
- Contains cellular material and bacteria
What does total sperm output and semen quality vary according to?
- Species
- Season (in seasonal breeders)
- Individuals within a species
- Method of collection
- Degree of excitement/teasin
- Frequency of ejaculation
- Nutrition, ag, illness
What are common assessments of semen quality?
- Total sperm output = volume x concentration
- Percentage of normal motility sperm
- Percentage of normal morphology sperm
What is venereal transmission?
Transmition at mating (may or may not cause disease)
Where are most veneral organisms found?
In the normal waxy discharge of the sheath (smegma)
What can the effects be if disease occurs due to veneral bacteria?
- Reproductive diseased, generalised disease or both
- Within adult male, female, either or both
- Can be associted with subsequent pregnancy fialure
Identify dog veneral pathogens
- Canine herpesvirus 1
- Brucella canis (not present in UK)
Identify bovine veneral pathogens
- Bovine herpesvirus 1
- Brucella abortus
- Campylobacter fetus (subspecies venerealis)
- Chlamydophila abortus
- Leptospira interrogans serovars
- Mycoplasma bovigenitalium
- Ureoplasma diversion
- Bluetongue can survive in seminal plasma
Identify equine veneral pathogens
- Equine herpesvirus 3
- equine viral arteritis virus
- Klebsiella pneumoniae
- Pseudomonas aeruginosa
- Taylorella equigenitalis
What does Taylorella equigenitalis cause?
- Equine contagious metritis
- Does not affect males but severe effects in females
- Can be passed male to female
Identify sheep veneral pathogens
- Brucella ovia
- Chlamydophila abortus
- Brucella melitensis (rare)
Idenify pig venereal pathogens
- Brucella suis
- Porcine reproductive and respiratory virus
- Porcine herpesvirus 1
- Porcine parvovirus
How can Campylobacter fetus act as a commensal and a pathogen?
- Commensal in males, carried for life with no clinical signs or effect on semen quality
- In female results in uterine infection and devastating infertility or early pregnancy loss
What are the diagnostic tests for Campylobacter fetus?
- Identification of organism in preputial washings
- Direct smears, culture or fluorescent antibody testing
- Vaginal mucus agglutination test of cows
Describe the treatment and control of herd infection with Campylobacter fetus
- Testing and removal of bulls
- Treatment and removal of bulls with appropriate antibiotic
- Insemination using clean AI
- Vaccination of cow prior to breeding
Describe how Haemophilus somnus can act as a commensal and a pathogen in cattle
- In cows can cause vaginitis, cervicitis, endometritis and abortion
- In bulls usually asymptomatic, can cause epididymitis and testicular degeneration
- Found in 30% of normal cows, 80% of norma bulls
What methods can be used in to monitor herds or individuals for potential pathogenicorganisms?
- Identification of organism by microbiology or pCR
- Fluorescent antibody testing
- Serological testing
Explain the principles of a full breeding soundness examination of a ram
- Need to assess genital organs, sperm production and quality
- Full clinical exam, need to check for other sources of pain/discomfort
- Jaw/mouth injury could mean not eating = decreased fertility/energy for mating
- Conformation could affect mouning ability
- Pain will affect libido
- Cataracts would decrease libido
- Brisket sores would discourage mounting
How is scrotal circumference in the ram measured?
- Tape
- Colours showing if poor, normal or enlarged for adults and lambs
Describe inspection ofhte external genitalia of the ram
- No obvious sores or pain response to palpation
- Extrude penis from pepuce
- Ensure testes are correct size and symmetrical, no swelling or damage
- Feel for lumps
How is a semen sample collected from a ram?
- Teaser ewe and artificial vagina
- Can use electroejaculation
