Exam 3, Human Physiology

What are the functions of the skeletal system?

Support, protect organs, movement, blood cell production, mineral storage.

What is compact bone?

Dense, outer layer of bone that has osteons, which are cylinders surrounding central canals.

What is spongy bone?

Bone found inside the ends of long bones, characterized by trabeculae and red marrow.

What is an osteon?

The structural unit of compact bone.

What is an osteocyte?

A mature bone cell.

What is a lacuna?

A small space where an osteocyte lives.

What does the central canal contain?

Blood vessels and nerves.

What is yellow marrow?

Bone marrow that stores fat.

What is red marrow?

Bone marrow that is responsible for making blood cells.

What is the periosteum?

The outer covering of a bone.

What is the bone matrix composed of?

Calcium phosphate and collagen.

What is ossification?

The process by which cartilage turns into bone.

What role do chondrocytes have in bone development?

They form cartilage.

What do osteoblasts do?

They build bone.

What regulates growth in bones?

Growth hormone (GH), estrogen, and testosterone.

When does bone growth stop?

After the epiphyseal plates close.

What factors influence bone remodeling?

Exercise and hormones.

What do osteoblasts and osteoclasts do?

Osteoblasts build bone while osteoclasts break it down.

What is the function of parathyroid hormone (PTH)?

It increases calcium levels in the blood.

What is the function of calcitonin?

It lowers calcium levels in the blood.

What are the four characteristics of muscles?

Contractile, extensible, elastic, excitable.

What is the insertion in muscle anatomy?

The movable end of the muscle.

What is the origin in muscle anatomy?

The fixed end of the muscle.

What is a tendon?

A structure that connects muscle to bone.

What are synergistic muscles?

Muscles that work together.

What are antagonistic muscles?

Muscles that oppose each other.

What is the structure hierarchy of muscles?

Muscle → fascicles → muscle fibers → myofibrils → sarcomeres.

What are actin and myosin?

Actin is a thin filament, and myosin is a thick filament.

What are the steps of muscle contraction?

1. Cross-bridge forms (myosin binds actin) 2. Power stroke (head pulls actin) 3. Detachment (ATP binds myosin) 4. Reset (ATP → ADP + P).

What is the role of ATP in muscle contraction?

It powers the detachment and reset of myosin.

What is light exercise characterized by?

Aerobic exercise, which uses oxygen.

What occurs during intense exercise?

Anaerobic exercise, utilizing creatine phosphate.

What does tropomyosin do?

Blocks actin binding sites.

What is the function of troponin?

Binds calcium and moves tropomyosin.

What is the sarcoplasmic reticulum (SR)?

A structure that stores and releases calcium.

What are T-tubules?

Structures that transmit action potentials in muscle cells.

What are fast muscle fibers characterized by?

Powerful contractions for short bursts.

What are slow muscle fibers known for?

Endurance and sustained contractions.

What is muscle tone?

A slight, constant contraction of muscles.

What is a motor unit?

A single neuron and all the muscle fibers it controls.

What are the functions of blood?

Transport, protection, and regulation.

What is plasma?

The liquid component of blood, consisting of water, proteins, nutrients, and waste.

What are formed elements in blood?

Red blood cells, white blood cells, and platelets.

What do all formed elements come from?

Stem cells in red marrow.

What is the clotting process?

Platelets → thrombin → fibrin (forms net) → plasmin dissolves clot.

What are neutrophils?

First responders in the immune response.

What are lymphocytes?

T and B cells involved in the immune response.

What do monocytes become?

They become macrophages.

What do eosinophils fight?

Parasites.

What do basophils release?

Histamine during allergic responses.

What happens to red blood cells (RBCs) as they mature?

They lose their nucleus and become packed with hemoglobin.

What is hemoglobin?

A protein that binds oxygen using iron.

What is the lifespan of red blood cells?

Approximately 120 days, cut short due to lack of a nucleus.

Where are old red blood cells recycled?

In the liver and spleen.

What do kidneys produce to increase red blood cell production?

Erythropoietin (EPO).

What are the blood types based on antigens?

A: A antigens, anti-B antibodies; B: B antigens, anti-A antibodies; AB: A & B antigens, no antibodies (universal recipient); O: No antigens, anti-A & anti-B (universal donor).

What does Rh factor indicate?

Rh positive has Rh antigen; Rh negative mother with Rh positive baby can lead to complications in later pregnancies.

What is breathing?

The process of air moving in and out of the lungs.

What is external respiration?

The gas exchange that occurs between the lungs and blood.

What is gas transport?

The movement of O2 and CO2 in the blood.

What is internal respiration?

The gas exchange that occurs between blood and tissues.

What is the function of the larynx?

It acts as the voice box.

What does the epiglottis do?

It blocks the trachea when swallowing.

What is the function of the nose in the respiratory system?

It filters and moistens the air.

What are the trachea, bronchi, and bronchioles?

They are air passages in the respiratory system.

What is the role of alveoli?

Sites of gas exchange within the lungs.

What is the airflow order in the respiratory system?

Nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.

What closes during swallowing?

The epiglottis covers the glottis.

What happens to vocal cords during quiet breathing?

They remain relaxed.

What happens to vocal cords during speech?

They are tightened.

What keeps airways open in the trachea and bronchi?

Cartilage rings.

What controls the diameter of bronchioles?

Smooth muscle.

What happens during inhalation?

The diaphragm moves down, reducing pressure and allowing air to enter.

What happens during exhalation?

The diaphragm moves up, increasing pressure and pushing air out.

How is oxygen primarily transported in the body?

Mostly on hemoglobin.

How is carbon dioxide primarily transported in the body?

As bicarbonate (HCO3-), bound to hemoglobin, and dissolved in plasma.

What does the medulla do in relation to breathing?

It detects high levels of CO2 and H+ and increases the breathing rate.