Action Potential
What is the phase called when the neuron membrane potential becomes positive?
Rising phase / Depolarization
What is the resting membrane potential of a neuron?
Around –70 mV
What are the 3 layers of the skin?
Epidermis, dermis and hypodermis
What cell produces keratin?
Keratinocyte
What is the main function of collagen?
Provides strength and structure
What is the membrane potential called when it returns to resting after depolarization?
Repolarization
Which ion is more concentrated inside the cell?
Potassium (K⁺)
Which layer lies below the dermis?
Hypodermis (subcutaneous tissue)
What cell produces melanin?
Melanocyte
What is the main function of elastin?
Provides elasticity (stretch and recoil)
Which ion enters the neuron during depolarization?
Sodium (Na⁺)
Which ion is more concentrated outside the cell?
Sodium (Na⁺)
Which skin type is found on palms and soles?
Thick skin
What is the function of Langerhans cells?
Immune defense / antigen-presenting cells
What is the main function of keratin?
Provides protection and waterproofing
Which ion exits during repolarization?
Potassium (K⁺)
Why is the inside of the cell negative compared to the outside?
More K⁺ leaves than Na⁺ enters, and negative proteins stay inside
What layer contains blood vessels and nerves?
Dermis
What cell produces collagen, elastin, and hyaluronic acid?
Fibroblast
How do collagen and elastin work together in the dermis?
Collagen gives strength, elastin gives elasticity
What restores the original ion concentration after an action potential?
Sodium-potassium pump (Na⁺/K⁺)
What pump restores ion gradients after an action potential?
Sodium-potassium pump (Na⁺/K⁺)
Which skin type lacks hair follicles and sebaceous glands?
Thick skin
What is the function of Merkel cells?
Sensory touch receptors
How do collagen, elastin, and hyaluronic acid work together in the dermis?
Collagen = strength, elastin = elasticity, hyaluronic acid = hydration/support for fibers