SA node has an unstable resting membrane potential. The “resting membrane potential” of the sinus nodal fiber between discharges has a negativity of about −55 to −60 millivolts.

TLS Online TPP Program

#Id: 7578

#Unit 5. Developmental Biology

The molecular processes of capacitation prepare the sperm for the acrosome reaction and enable the sperm to become hyperactive

TLS Online TPP Program

#Id: 7579

#Unit 5. Developmental Biology

Capacitation

The sperm cell membrane

is altered by the removal of

cholesterol by albumin proteins in the female reproductive tract

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#Id: 7580

#Unit 5. Developmental Biology

The cholesterol efflux from the sperm cell membrane is thought to change the location of its “lipid rafts,” contain receptor proteins that can bind the zona pellucida and participate in the acrosome reaction

TLS Online TPP Program

#Id: 7581

#Unit 5. Developmental Biology

Particular proteins or carbohydrates on the sperm surface are lost during capacitation because these compounds block the recognition sites for the sperm proteins that bind to the zona pellucida

TLS Online TPP Program

#Id: 7582

#Unit 5. Developmental Biology

The membrane potential of the sperm cell becomes more negative as potassium ions leave the sperm. 

TLS Online TPP Program

#Id: 7583

#Unit 5. Developmental Biology

Negative membrane potential may allow calcium channels to be opened and permit calcium to enter the sperm.