HBS 2025 Final Review - Neurology, Endocrinology, and Circulation

Flashcards for HBS 2025 Final Review

Neuron Function

Polarity of the membrane changes as Na+ rushes into the cell during depolarization. K+ entering causes repolarization. Na+ K+ channel brings the cell back to resting potential.

Action Potential

Resting potential, depolarization (Na+ channels open), repolarization (K+ channels open). Ca++ enters the axon terminus, releasing neurotransmitters into the synapse.

Neurotransmitter Action

Diffuse across the synapse to bind to receptors on the postsynaptic neuron or neuromuscular junction. At the postsynaptic dendrite, neurotransmitters open Na+ channels and depolarize the neuron.

Neuromuscular Junction

Acetylcholine binds to the acetylcholine receptor, causing the release of Ca++ from the sarcoplasmic reticulum, which binds to troponin, allowing muscle contraction.

Multiple Sclerosis

Loss of myelin sheath, leading to weak muscles and paralysis, characterized by relapsing symptoms.

Alzheimer's Disease

Loss of brain cells, resulting in severe memory loss.

Parkinson's Disease

Loss of dopamine-producing cells, leading to tremors, and difficulty in moving and speaking.

Amyotrophic Lateral Sclerosis (ALS)

Death of motor neurons, without affecting sensory or cognitive functions.

Huntington's Disease

Hereditary autosomal dominant gene causing death of brain cells, characterized by Huntington's chorea (uncontrollable movements).

Epilepsy

Uncontrolled electrical activity in the brain, leading to seizures or temporary unresponsiveness.

Endocrine Glands

Secrete hormones directly into the bloodstream to reach target tissues/organs, differing from exocrine glands that secrete through ducts.

Pituitary Gland

Master gland signaled by the hypothalamus, secreting hormones like ACTH, prolactin, oxytocin, FSH, TSH, ADH, HGH, LH, and MSH to influence other glands and tissues.

Thyroid Gland

Produces thyroxine (T4) and triiodothyronine (T3), which control metabolism.

Parathyroid gland

Controls calcium levels by secreting parathyroid hormone (parathormone).

Adrenal Glands

Produce cortisol, adrenaline, noradrenaline, and aldosterone.

Pancreas

Secretes insulin (from Beta cells) to lower blood sugar and glucagon (from Alpha cells) to raise blood sugar.

Type 1 Diabetes

Autoimmune disorder; deficiency in insulin production from death or damage to the pancreatic beta-cells.

Type 2 Diabetes

Insulin resistance; cells become less sensitive or responsiveness to insulin and/or the body does not produce enough insulin.

Hormonal Control of Reproduction

Hypothalamus releases GnRH, causing the pituitary to release FSH and LH, which stimulate the testes (testosterone) or ovaries (estrogen, progesterone).

Heart Anatomy

Four chambers, vessels entering/exiting, blood flow patterns (e.g., vena cava to right atrium). Left ventricle has the thickest wall.

Heart Valves

Tricuspid (right atrium to right ventricle), Bicuspid/Mitral (left atrium to left ventricle), Pulmonary (right ventricle to pulmonary artery), Aortic (left ventricle to aorta).

Coronary Arteries

Supply the heart muscle with blood. Blockage can cause angina or myocardial infarction (heart attack).

Arteries vs. Veins

Arteries: thick walls with muscle and elastic fibers. Veins: thinner walls, less muscle, one-way valves. Capillaries: one-cell thick.

Varicose Veins

Damaged valves, causing blood pooling in vessels, leading to potential blood clots.

Normal Pulse Rate

60-100 bpm; tachycardia (higher) caused by stress, exercise, etc.; bradycardia (lower) caused by relaxation, medication, etc.

Systolic Pressure

Higher pressure when blood is 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.

Heartbeat Sounds

First sound: atrial valves (tricuspid, mitral) closing. Second sound: pulmonary and aortic valves snapping shut.

Cardiac Health Assessment

Pulse rate, blood pressure, cardiac output (pulse rate x stroke volume), echocardiogram, EKG, arteriograms.

Peripheral Circulation Assessment

Pulse, Doppler studies, ankle-brachial index (ABI), arteriograms.