Autonomic Nervous System

Definition: The autonomic nervous system (ANS) is a branch of the nervous system that regulates involuntary actions, such as heart rate, blood pressure, digestion, and respiration.
Divisions:
- Sympathetic nervous system (SNS): "fight or flight" response, prepares body for action
- Parasympathetic nervous system (PNS): "rest and digest" response, promotes relaxation and reduces energy expenditure
Functions:
- Regulates heart rate and blood pressure
- Controls digestion and absorption of nutrients
- Modulates respiration and pH balance
- Influences body temperature and sweating

Definition: Chemical messengers that transmit signals between neurons
Types:
- Excitatory neurotransmitters: stimulate the next neuron, e.g. glutamate, aspartate
- Inhibitory neurotransmitters: reduce the activity of the next neuron, e.g. GABA, glycine
- Modulatory neurotransmitters: influence the strength of synaptic transmission, e.g. dopamine, serotonin
Functions:
- Regulate mood, motivation, and reward
- Involved in muscle contraction and relaxation
- Modulate pain perception
- Play a role in appetite and sleep regulation

Definition: The body's defense against pathogens, such as bacteria, viruses, and other foreign substances
Types of immune responses:
- Innate immunity: non-specific, immediate response to pathogens
- Adaptive immunity: specific, acquired response to pathogens
Phases of immune response:
1. Recognition: identification of pathogens by immune cells
2. Activation: activation of immune cells to respond to pathogens
3. Elimination: removal of pathogens from the body
4. Memory: retention of immune cells to recognize and respond to future infections

Definition: Hormones are chemical messengers produced by endocrine glands that regulate various physiological processes
Types of hormones:
- Steroid hormones: derived from cholesterol, e.g. testosterone, estrogen
- Peptide hormones: composed of amino acids, e.g. insulin, growth hormone
- Amino acid hormones: derived from amino acids, e.g. thyroid hormone
Functions:
- Regulate growth and development
- Control metabolism and energy production
- Influence reproductive processes
- Modulate stress response and mood

Definition: A network of vessels, organs, and tissues that defend the body against infection and disease
Components:
- Lymphatic vessels: transport lymph fluid throughout the body
- Lymph nodes: filter lymph fluid and trap pathogens
- Spleen: filters blood and removes old red blood cells
- Thymus: produces immune cells called T-lymphocytes
Functions:
- Defends against infection and disease
- Regulates fluid balance and blood pressure
- Aids in the absorption of fats and fat-soluble vitamins
- Plays a role in the immune response

Regulates involuntary actions, such as heart rate, blood pressure, digestion, and respiration
Divided into Sympathetic Nervous System (SNS) and Parasympathetic Nervous System (PNS)
SNS triggers "fight or flight" response, preparing the body for action
PNS promotes relaxation and reduces energy expenditure with a "rest and digest" response
Regulates heart rate and blood pressure, controls digestion and absorption of nutrients
Modulates respiration and pH balance, influences body temperature and sweating

Chemical messengers transmitting signals between neurons
Types include excitatory, inhibitory, and modulatory neurotransmitters
Excitatory neurotransmitters (e.g. glutamate, aspartate) stimulate the next neuron
Inhibitory neurotransmitters (e.g. GABA, glycine) reduce the activity of the next neuron
Modulatory neurotransmitters (e.g. dopamine, serotonin) influence the strength of synaptic transmission
Regulate mood, motivation, and reward, involved in muscle contraction and relaxation
Modulate pain perception, play a role in appetite and sleep regulation

The body's defense against pathogens, such as bacteria, viruses, and other foreign substances
Types of immune responses include innate immunity and adaptive immunity
Innate immunity is non-specific, immediate response to pathogens
Adaptive immunity is specific, acquired response to pathogens
Phases of immune response: recognition, activation, elimination, and memory

A network of vessels, organs, and tissues that defend the body against infection and disease
Components include lymphatic vessels, lymph nodes, spleen, and thymus
Lymphatic vessels transport lymph fluid throughout the body
Lymph nodes filter lymph fluid and trap pathogens
Spleen filters blood and removes old red blood cells
Thymus produces immune cells called T-lymphocytes
Defends against infection and disease, regulates fluid balance and blood pressure
Aids in the absorption of fats and fat-soluble vitamins, plays a role in the immune response