Overview of Neurology, Endocrine, and Circulatory Systems

Motor Neuron

Carry signals from the CNS to muscles or glands to cause a response (movement, secretion, etc.).

Direction of Signal (Motor Neuron)

Away from the brain and spinal cord.

Examples (Motor Neuron)

Neurons that tell your leg to move or your heart to beat.

Location (Motor Neuron)

Found in the spinal cord and connected to muscles or glands in the PNS.

Multipolar

A type of neuron characterized by multiple extensions from the cell body. (motor neuron)

Sensory Neuron

Carry information from sensory receptors to the central nervous system (CNS).

Direction of Signal (Sensory Neuron)

Toward the brain and spinal cord.

Examples (Sensory Neuron)

Touch receptors in skin.

Location (Sensory Neuron)

Found in sensory organs and peripheral nervous system (PNS).

Unipolar

A type of neuron characterized by a single extension from the cell body. (sensory neuron)

Interneuron

Connect sensory and motor neurons and process information within the CNS.

Direction of Signal (Interneuron)

Neither strictly afferent or efferent - they integrate and relay signals.

Examples (Interneuron)

Neurons in the brain or spinal cord that process stimuli and decide how to respond.

Location (Interneuron)

Entirely within the CNS (brain and spinal cord).

Bipolar

A type of neuron characterized by two extensions from the cell body. (interneuron)

Neuron

A specialized nerve cell that functions as the body's information messenger.

Resting State

The state of a neuron when the membrane potential is -70 mV.

Depolarization Phase

The phase where the membrane potential changes from -50 mV to +30 mV.

Threshold

The membrane potential level at approximately -50 mV where voltage-gated Na+ channels open rapidly.

Peak of Action Potential

The point where voltage-gated Na+ channels inactivate and voltage-gated K+ channels fully open.

Repolarization Phase

The phase where the membrane potential returns from +30 mV back down toward -70 mV.

Hyperpolarization Phase

The phase where the membrane potential reaches -80 mV due to prolonged opening of K+ channels.

Return to Resting State

The process where K+ channels close and the Na+/K+ pump restores and maintains resting membrane potential.

Multiple Sclerosis

A condition characterized by the loss of myelin sheath leading to weak muscles and paralysis.

Alzheimer's

Loss of brain cells leading to severe memory loss.

Parkinson's

Loss of dopamine producing cells causing tremors, difficulty moving and speaking.

ALS

Death of motor neurons but doesn't affect sensory or mind.

Huntington's

Hereditary autosomal dominant gene causing death of brain cells.

Huntington's chorea

Uncontrollable movements associated with Huntington's disease.

Epilepsy

Uncontrolled electrical activity in the brain causing seizures or temporary unresponsiveness.

Endocrine Glands

Ductless glands that release hormones directly into the bloodstream.

Products made by Endocrine Glands

Hormones (chemical messengers).

Delivery Method of Endocrine Glands

Hormones are secreted into the blood, which carries them to distant target organs or tissues.

Examples of Endocrine Glands

Pituitary gland - growth hormone (GH), ACTH; Thyroid gland - thyroxine (T4), triiodothyronine (T3); Adrenal glands - cortisol, adrenaline; Pancreas (endocrine part) - insulin, glucagon; Ovaries/Testes - estrogen, testosterone.

Exocrine Glands

Glands that release their product through ducts to the outside of the body or into a body cavity.

Products made by Exocrine Glands

Enzymes, mucus, sweat, saliva, digestive juices, etc.

Delivery Method of Exocrine Glands

Secretions are transported via ducts directly to the target site (e.g., skin, mouth, digestive tract).

Examples of Exocrine Glands

Salivary glands - saliva; Sweat glands - sweat; Lacrimal glands - tears.

Hypothalamus

Has both endocrine and neurologic function and signals the pituitary gland.

Pituitary

Is the master gland that secretes to other glands (e.g., ACTH to adrenals, Prolactin to breast tissue).

Thyroid

Makes thyroxine, which controls metabolism.

Parathyroid

Makes parathormone which controls calcium.

Thymus

Involved in the immune system.

Adrenals

Makes cortisol, adrenaline, noradrenaline, and aldosterone.

Testes or ovaries

Makes testosterone, estrogen, and progesterone.

Pineal

Makes melatonin, which regulates sleep.

Pancreas

Makes insulin and glucagon for blood sugar control.

The levels of control for thyroxine

Hypothalamus releases TRH which acts on pituitary to release TSH, which acts on thyroid to release T3 and T4, increasing metabolic rate.

The Levels of control for glucose in blood

High glucose triggers insulin release from B cells in pancreas, increasing glucose uptake in cells; low glucose triggers glucagon release from alpha cells in pancreas, causing glycogen hydrolysis.

Type 1 Diabetes

Autoimmune condition where the immune system destroys insulin-producing beta cells in the pancreas.

Type 2 Diabetes

Condition where the body becomes resistant to insulin or doesn't produce enough insulin.

Treatment

Managed with lifestyle changes, oral medications, and sometimes insulin.

Prevention

Often preventable or delayed with healthy diet, exercise, and weight control.

GnRH

Hormone released by the hypothalamus that causes the pituitary to release FSH and LH.

FSH

Follicle-stimulating hormone that acts on the ovaries in females to produce estrogen and progesterone.

LH

Luteinizing hormone that acts on Leydig cells in males and ovaries in females.

Testosterone

Hormone released by the testes in response to LH.

Estrogen

Hormone produced by the ovaries in response to FSH.

Progesterone

Hormone produced by the ovaries in response to FSH.

SVC

Superior vena cava; brings deoxygenated blood to the right atrium.

IVC

Inferior vena cava; brings deoxygenated blood to the right atrium.

Tricuspid Valve

Valve that allows blood to flow from the right atrium to the right ventricle.

Right Ventricle

Chamber that pumps deoxygenated blood through the pulmonary valve to the lungs.

Pulmonary Valve

Valve that allows deoxygenated blood to flow from the right ventricle to the pulmonary arteries.

Pulmonary Arteries

Carry deoxygenated blood to the lungs for oxygenation.

Pulmonary Veins

Carry oxygenated blood back to the heart and enter the left atrium.

Left Atrium

Chamber that receives oxygenated blood from the pulmonary veins.

Bicuspid/Mitral Valve

Valve that allows blood to flow from the left atrium to the left ventricle.

Left Ventricle

Chamber that pumps oxygenated blood through the aortic valve into the aorta.

Aortic Valve

Valve that allows oxygenated blood to flow from the left ventricle into the aorta.

Coronary Arteries

Supply the heart muscle with blood.

Angina

Chest pain caused by reduced blood flow to the heart muscle.

Heart Attack (myocardial infarction)

Condition caused by blocked coronary arteries leading to heart muscle damage.

Varicose Veins

Damaged valves that cause blood to pool in vessels and can lead to blood clots.

Capillaries

Blood vessels that are one cell thick to allow for diffusion.

Pulse Rate

Normal is 60-100 beats per minute; athletes may have a lower rate.

Systolic Pressure

Higher pressure caused by blood being pushed out of the left ventricle into the aorta.

Diastolic Pressure

Lower pressure when the heart is relaxed and blood is not pushing against artery walls.

Cardiac Output

Calculated as pulse rate x stroke volume.

Echocardiogram

An ultrasound to check the heart's actions.

EKG

Test to check the electrical activity of the heart.

Arteriograms

Test to check the blood flow to the cardiac arteries.

Ankle Brachial Index (ABI)

Test to check if blood pressure and blood are getting to the arms and legs.

Doppler Studies

Test to hear where the blockages are.