Lecture 7-Semen, capacication, hyperactivation Flashcards
Fertilization can not occur until sperm:
- Has had proteins added (and some removed)
- Capacitation has to occur
Role of epidiymis:
Adds new protiens to sperm like:
-SMA4: prevents agglutination of sperm (sperm stuck together)
-PH20: a hylaurondias that helps break though the cumulous of an oocyye
- CRISP1: Receptor on sperm to allow for zona pellucida interaction (acrosomal reaction)
Many of these proteins will be removed one they’re inside the female reproductive tract because the whole point of them was to penetrate and get into the oocyte.
Vas Deferens:
Two tubes that carry the sperm from the epididymis to the urethra via peristalsis.
Sperm is held in the _____ until ejaculation
ampullae
Male reproductive system have 3 gland secretions that mix with sperm to form semen. They are called:
- Seminal vesicles
- Prostate glands
- Bulbo-urethral glands
Seminal vesicles secrete:
Semenogelin 1: helps with form of sperm coagulation (coagulation helps with getting through cervical mucuous)
Prostate glands secrete:
Prostate-specific anitgen(PSA): helps dissolve coagulated semen; helps with dissolving cervical mucous. You want to dissolve coagulated semen so that it has better motility so it can move through the cervix
Bulbo-urethral glands secrete:
Alkaline pH so that sperm can survive in the acidic enviroment in the uterus. Out of the 3 secrections this one is secreted first.
Coitus:
Synonym for sexual intercourse. Purpose is to get the sperm as close as possible to the ovum.
How an erection happens:
Blood vessels of the corpora cavernosa and corpus spongiosum become relaxed=more blood enters area=erection
Movement of sperm towards the oviduct:
- Sperm first meets the cervix, which has a thick mucus protection the uterus. This is where semenogelin 1 secreted from seminal vesicles come into play. Coagulation helps sperm get through this thick mucus. After the sperm goes through the mucus, PSA disingrates the coagulation and cervical mucus so that the sperm has increased motility and can get through the cervix.
- Sperm ascend the uterus and go toward the oviducs, with help from uterine contractions.
Sperm capacitation involves in initating/increasing motility and preparing acrosmal cap. It occurs in two ways. What are the two ways?
Purpose of capcitation is to help sperm reach the egg for fertilization.
- Removal of cholesterol- this helps sperm with movement. Imagine a packed bus and everyone has big backpacks on, it’s hard to move. Remove backpacks and now its easier to move around.
- Phospohorylation of proteins involved in motility-increasing the speed of proteins involved in propeling sperm.
Removal of Cholesterol happens because of:
albumin. It is a protein that is found in the vagina/cervix/uterus. It strips cholesterol off the sperm to increase motility.
Second way of capacitation: Phosphorylation of protiens is activated due to:
The activation of adenylate cyclase.
Steps involved to activating adenylate cyclase: Bicarbonate (HCO3-) enters the cell–→ Activates AC–→ AC causes an increase in cAMP and PKA–→ Increases phosphorylation of proteins involved in motility.
After capacitation, sperm go through the oviduct and rest on epitheleal cells along the oviduct. They wait for what cheimcal signal?
Progesterone from the oocyte will hyperactivate sperm so that they can come penetrate the oocyte to begin fertilization. Hyperactivation has to happen so that sperm are able to dislodge themselves from the oviduct, increase motility to get through the cumulus oophorus and the zona pellucida.