Nervous System and Brain Anatomy

• A reflex reaction involves parts of the nervous system to facilitate a quick response.
• A pathogen is an organism capable of causing disease or sickness.
• The skin and mucous membranes prevent pathogens from entering the body.
• Mucous membranes are sticky surfaces that trap invaders.

Brain Anatomy and Function

• The cerebrum is the main part of the brain, consisting of lobes and playing various roles in brain functions.
• The medulla is located on top of the spinal cord.

Neurons and Neurotransmitters

• Neurons send and receive neurotransmitters, which carry information between brain cells.
• Neurotransmitters are chemical messengers essential for body function, carrying chemical signals between nerve cells.
• Dopamine is a neurotransmitter responsible for feelings of happiness.
• Norepinephrine is a neurotransmitter that regulates blood pressure, heart rate, alertness, and attention.

Types of Neurons

• Sensory neurons carry information from the senses to the brain and spinal cord.
• Motor neurons carry information from the brain and spinal cord to muscles, organs, and glands.
• Interneurons connect sensory and motor neurons, processing information in simple and complex circuits.

Effectors and Receptors

• Receptors are specialized cells that detect stimuli from the environment.
• Effectors are organs (muscles and glands) that respond to signals by producing a physical action.

Brain Structures

• The thalamus acts as a relay station for sensory and motor information.
• The hippocampus helps with learning and memory and is located in the temporal lobe.
• The corpus callosum is a thick band of nerve fibers connecting the brain’s left and right hemispheres.

Brain Stem

• The medulla oblongata controls vital functions like breathing, heart rate, and blood pressure.
• The pons controls unconscious movements and processes, including breathing and sleep.
• The midbrain is responsible for motor control, particularly eye movements, and the processing of vision and hearing.

Types of Signals

• Chemical signals are molecules that carry messages between cells, organisms, and environments.
• Electromagnetic signals conduct energy through wave-like motion.
• Mechanical signals occur through mechanical forces or pressure.

Eye Anatomy

• The sclera is the white part of the eye, protecting and supporting the eyeball.
• The cornea is the transparent part of the eye covering the iris and pupil, allowing light to enter.
• The pupil is the opening in the center of the iris through which light passes.
• The lens focuses light onto the retina.
• The iris is the colored part of the eye that controls how much light enters.
• The conjunctiva is a thin, clear membrane that covers the white of the eye and the inside of the eyelids.
• The retina is a light-sensitive layer that converts images into electrical signals.
• The optic nerve carries visual information from the retina to the brain.
• The vitreous body is a gel-like substance that fills the space between the lens and the retina.

Endocrine System

• The endocrine system is a network of glands and organs that produce hormones.
• Hormones are released into the bloodstream and travel to cells throughout the body.
• The endocrine system controls growth, development, metabolism, and reproduction.
• Hormones coordinate different functions in the body by carrying messages through the blood.

Hormone-Secreting Organs

• The hypothalamus controls the endocrine system and produces hormones regulating many bodily functions.
• The pituitary gland produces hormones that regulate growth, metabolism, and reproduction.
• The thyroid gland produces hormones regulating metabolism and heart rate.
• The parathyroid glands regulate calcium levels in the blood.
• The pancreas produces digestive juices and hormones like insulin and glucagon that regulate blood sugar levels.
• The adrenal glands produce hormones that regulate blood pressure, metabolism, and the body's response to stress.
• The testes produce testosterone, which is responsible for growth and reproductive functions.
• The ovaries produce estrogen, vital for female sexual and reproductive development.

Types of Hormones

• Estrogen is a female sex hormone that helps develop female sex traits, maintain pregnancy, and regulate menstruation.
• Progesterone prepares breasts for milk production and stimulates the lining of the uterus for fertilization.
• Testosterone is a male hormone important for reproductive organ development and bone health.
• Insulin helps lower blood sugar levels.
• Cortisol helps the body respond to stress, but high levels can lead to anxiety and weight gain.
• Growth hormone influences height and helps build bones and muscles.
• Adrenaline prepares the body for fight-or-flight situations.
• Thyroid hormone regulates metabolism, heart rate, and body temperature.

Hormones and Feedback Loops

• Feedback loops help maintain homeostasis.
• A feedback loop consists of a stimulus, a control center, and an effector.
• Blood glucose levels are regulated by insulin and glucagon.
• Insulin decreases blood sugar by promoting glucose uptake into cells.
• Glucagon increases blood sugar by stimulating the liver to release stored glucose.

Hormone Transport and Receptors

• Hormones enter the bloodstream and are transported to their target site, binding to a receptor.
• Nervous system receptors receive stimuli, facilitating senses.
• Endocrine system receptors are specialized proteins that bind to hormones, causing changes in target cells.