physiology

Hormone Function

Hormones can affect cellular communication and response in various ways.
- Change the Receptor: Modulations of hormone receptors can occur, either increasing or decreasing their availability.
- Downregulate the Receptor: This lowers the number or affinity of receptors available for hormone binding, which affects how cells respond to hormones. Insulin resistance in type 2 diabetes exemplifies downregulation.
- Break Down the Hormone: Enzymes can degrade hormones, removing them from circulation and reducing their effect.
- Upcycle the Hormone: Hormones can be recycled back into the body for future use. This includes recycling processes that moderate hormone action.

Saturation Level: Refers to the number of available receptors bound to hormones, neurotransmitters, or oxygen.
- Adjusting saturation can be achieved via:
  - Downregulation: Lower receptor count results in decreased binding ability.
  - Lower Hormone Availability: Reducing hormone amounts can impact saturation.
Upregulation: Refers to the process of increasing receptor sensitivity or number, often through mechanisms like exercise that enhance insulin receptor availability.

Neurons communicate via electrical and chemical signals across synaptic clefts using neurotransmitters.
- Dendritic Spines: Critical for neuron-to-neuron communication; excessive pruning or damage can impair signal transmission.
- Learning and Memory: Dendritic spines are dynamic and correlate with cognitive functions; diseases affecting spine density may hinder learning and response times.

Microglia: These cells play an essential role in central nervous system health, aiding in neuron maintenance and response to injury.
- Chronic Inflammation: Poor diet and microbiome imbalances can lead to increased microglial activation, impacting neuronal health and contributing to diseases like Alzheimer's.
- Dendritic Changes: Illness may reduce the density of dendritic spines, inhibiting neural communication and functioning.

Phineas Gage: Survived a railroad spike accident; his case illustrates the role of the prefrontal cortex in executive function.
- Traumatic Brain Injury (TBI): Injuries can lead to impaired signaling and neuronal shearing, limiting cognitive function despite some physical recovery.

Neuronal Signal Transmission: Signals can diverge to multiple targets or converge from many sources. This flexibility allows for efficient nervous system regulation.
- Electrical vs. Chemical Signals: Different signaling methods enable diverse regulatory processes and modulations in neurotransmitter release.

Myelin Sheath: Insulates axons, crucial for rapid signal conduction.
- Multiple Sclerosis (MS): An autoimmune condition where myelin is damaged, resulting in inefficient signal transmission and various symptoms, including coordination issues.

Autoimmune diseases, such as MS, are more prevalent in women and have geographical variations based on sunlight exposure. Vitamin D supplementation may be beneficial in regions with low sunlight.
- Efficiency in Development: The nervous system’s structure and function aim for maximum efficiency, which involves modifications and adaptations in response to environmental or physiological changes.