There are many internal and external causes to skin ageing. For example, ageing skin receives less blood flow and lower glandular activity. A validated comprehensive grading scale has categorized the clinical findings of skin ageing as laxity (sagging), rhytids (wrinkles), and the various facets of photoageing, including erythema (redness), and telangiectasia, dyspigmentation (brown discolouration), solar elastosis (yellowing), keratoses (abnormal growths) and poor texture.Cortisol causes degradation of collagen, accelerating skin ageing.Anti-ageing supplements are used to treat skin ageing. Photoageing
Photoageing has two main concerns: an increased risk for skin cancer and the appearance of damaged skin. In younger skin, sun damage will heal faster since the cells in the epidermis have a faster turnover rate, while in the older population the skin becomes thinner and the epidermis turnover rate for cell repair is lower, which may result in the dermis layer being damaged. Types
Though most human skin is covered with hair follicles, some parts can be hairless. There are two general types of skin, hairy and glabrous skin (hairless). The adjective cutaneous means "of the skin" (from Latin cutis, skin). Functions
Skin performs the following functions:

Protection: an anatomical barrier from pathogens and damage between the internal and external environment in bodily defence; Langerhans cells in the skin are part of the adaptive immune system. Perspiration contains lysozyme that break the bonds within the cell walls of bacteria. Sensation: contains a variety of nerve endings that react to heat and cold, touch, pressure, vibration, and tissue injury; see somatosensory system and haptics.
As of 2016, some genes of interest include:

Pathophysiology
Epileptic seizures occur due to changes in the brain that result in the lowering of the seizure threshold in a particular individual making that person vulnerable to recurring seizures. These changes can be a result of a structural abnormality, brain lesions, or simply a genetic disposition to seizures. In reflex epilepsy, these changes in the brain result in a small area that is capable of interrupting normal firing patterns and more likely to produce the synchronous firing patterns that characterize a seizure. These hyper-excitable areas may then be activated by certain stimuli resulting in a reflex seizure. Reflex seizures are thus notable because the presentation of a particular stimulus, that activates the hyper-excitable areas of the brain, directly overcomes the seizure threshold, and results in a reflex seizure.The activation of the hyper-excitable areas of the brain are additionally regulated by facilitating factors that may increase the likelihood of eliciting a seizure. Most commonly these include fatigue, sleep deprivation, or stress. Facilitating factors are different for each individual. Due to the large variance between the different kinds of reflex epilepsies, the specific mechanism causing reflex seizures may vary. Diagnosis
The diagnosis of reflex epilepsy usually includes a comprehensive medical and family history as well as a variety of tests. These tests may include a electroencephalography (EEG), magnetic resonance imaging (MRI), as well as genetic testing.The procedure for diagnosing epilepsy generally follows three steps:
Determining if the seizure or seizure like event is truly an epileptic seizure.