Human Anatomy and Physiology Quiz

Muscles and Skin

• The skin is the largest organ, varying in thickness across different areas.
• It acts as a barrier against pathogens, chemicals, radiation, and physical injury (protection).
• Skin helps regulate body temperature through sweat and blood flow (regulation).
• Contains nerve endings sensitive to touch, pain, temperature, and pressure (sensation).
• Synthesizes vitamin D when exposed to sunlight (metabolism).
• Plays a role in the body's immune response (immune defense).

Structure of the Skin

• Consists of two main layers: epidermis and dermis.
• Epidermis: The outer, thinner layer composed of epithelial tissue, lacks blood vessels (avascular).
• Dermis: The inner, thicker layer with blood vessels (vascular).

Epidermis

• The outermost layer, chiefly keratinized stratified squamous epithelium.
• Keratinocytes: The most abundant cells, filled with keratin, form a protective barrier.
• Melanocytes: Produce melanin, the skin's pigment.
• Langerhans cells: Part of the immune defense system, combating pathogens.
• Tactile epithelial cells (Merkel cells): Detect touch sensations.

Dermis

• The deeper layer composed of dense irregular connective tissue.
• Contains collagen and elastic fibers for strength and elasticity.
• Cells like fibroblasts, macrophages, and adipocytes are present.
• Contains blood vessels, nerves, glands, and hair follicles.

Subcutaneous Layer (Hypodermis)

• Not part of the skin, lying beneath the dermis.
• Composed of loose connective tissue and adipose tissue.
• Attaches skin to underlying tissues and organs.
• Plays important roles in heat insulation, energy storage, anchoring, and cushioning.

Appendages of the Skin

• Nails
• Hair follicles
• Sebaceous glands
• Sweat glands

The Nails

• Keratinized plates on the dorsal surfaces of fingers and toes.
• The proximal edge is the nail root.
• Nail folds surround and overlap the nail.
• The nail bed is the skin surface covered by the nail.

Hair and Hair Follicles

• Distributed across the body surface, excluding the palms and soles.
• Hair follicles are invaginations of the epidermis, where hairs grow out.
• Parts include the hair shaft, hair follicle, sebaceous glands, arrector pili muscle, and hair bulb.
• Sebaceous glands produce sebum to moisturize and protect hair and scalp.
• Arrrector pili muscles contract to create goosebumps.

Sebaceous Glands

• Situated beneath the skin surface of hair follicles.
• Produce sebum, an oily substance, to maintain hair flexibility.
• Lubricates the surface epidermis around the follicle opening.

Sweat Glands

• Long, tubular glands scattered over the body surface, excluding red lips margins (lips), nail beds, and genital area.
• Most deeply penetrating structures among epidermal appendages.
• Produce sweat to regulate body temperature and resist pathogens.

Types of Muscles

• Skeletal, Smooth, and Cardiac muscles.
• Tables describing main features, location, type of cells, and histology for each muscle are given in the original document.

Skeletal Muscle Terminology

• Agonist muscles initiate a particular movement (primary and responsible)
• Antagonist muscles oppose the agonist.
• Prime mover is another term used for the agonist, emphasizing its main role.
• Synergists assist an agonist in the action, helping stabilize joints to improve efficiency.

Skeletal Muscle Terminology (Attachments)

• Origin: Muscle attachment that moves the least.
• Insertion: Muscle attachment that moves the most.
• Belly: The fleshy portion of the muscle.
• Tendons: Tough, fibrous tissues that connect muscles to bones.
• Aponeurosis: Flat, sheet-like fibrous tissues that connect muscles.

Thorax

• Region between the neck and abdomen.
• Separated from the neck superiorly and abdomen inferiorly by diaphragm.
• Protects lungs and heart, provides attachment points for muscles of the thorax, upper extremities, abdomen and back.

Thoracic Cavity

• Contains the mediastinum which encompasses structures like the heart, major vessels, thymus, and lymph nodes.
• Contains two pleural cavities (one for each lung).
• Divided into the superior mediastinum and pleural cavities that house the lungs.

The Thoracic Wall

• Formed by the thoracic part of the vertebral column, sternum and costal cartilages, ribs, intercostal spaces, suprapleural membrane and diaphragm.

Chest Wall

• Includes skin (dermis and epidermis), superficial fascia (subcutaneous tissue, support, and protection), and respiratory accessory muscles.

Intercostal Spaces

• Consist of three layers of intercostal muscles (external, internal, innermost) supporting respiration, arranged in a specific order of Intercostal vein, artery, and nerve (VAN).
• Contains intercostal nerves and blood vessels that run between muscle layers.

Pleura

• Double-layered membrane surrounding the lungs.
• Visceral pleura: Coats the lungs, mirroring their contours.
• Parietal pleura: Lines the chest wall and diaphragm.
• Pleural cavity: Space between the membranes filled with lubricating fluid, reducing friction.

Pleura (Functions)

• Lubrication: Allows smooth lung movement during breathing.
• Pressure Regulation: Maintains negative pressure in the pleural cavity essential for lung expansion.
• Protection: Creates a barrier against infection and other irritants.

Cardiovascular System

• Composed of the heart, blood vessels, and blood.
• The heart acts as a pump pushing blood to organs, tissues, and cells.
• Blood delivers oxygen and nutrients to cells, removes carbon dioxide and waste products.
• Blood travels through arteries, arterioles, capillaries, venules, and veins.

Heart

• A muscular organ (250-400 grams) pyramidal in shape, located within the pericardium behind the sternum
• Comprised of four chambers forming two separate pumps
• The right atrium is separated from the right ventricle by the tricuspid valve
• The left atrium is separated from the left ventricle by the bicuspid (mitral) valve
• The pulmonary valve separates the right ventricle from the pulmonary artery
• The aortic valve separates the left ventricle from the aorta

Pericardium

• Fibrous-serous sac enveloping the heart and the roots of the great vessels in the middle mediastinum.
• Restricts excessive heart movement, functioning as a lubricated container, and protecting to prevent friction.

Heart Wall

• Composed of epicardium (serous pericardium) which externally covers the heart, myocardium (cardiac muscle), and endocardium (contains endothelium lining the inner surface of the heart).
• Allows smooth heart actions.

Heart Valves

• Tricuspid valve: between right atrium and right ventricle
• Pulmonary valve: between right ventricle and pulmonary artery
• Mitral (bicuspid) valve: between left atrium and left ventricle
• Aortic valve: between left ventricle and aorta

Arterial Supply of the Heart

• Provided by the right and left coronary arteries branching from the ascending aorta immediately above the aortic valve.
• Branches spread over the heart's surface.

Conducting System of the Heart

• Responsible for the rhythmic contraction of the heart at ~70-90 beats/minute.
• The process in the conducting system, originates spontaneously, and the atria contract first, followed by the ventricles (a slight delay).
• Allows time for the atria to empty their blood into the ventricles before ventricles contract

Major Blood Vessels

• Aorta, brachiocephalic trunk, left common carotid artery, left subclavian artery, pulmonary arteries, superior vena cava, inferior vena cava, and pulmonary veins.

Blood Circulation

• Oxygen-rich blood from lungs enters the heart, then circulates to the body
• Oxygen-poor blood from the body enters the heart, then circulates to the lungs.

Lungs

• Two organs in the thoracic cavity responsible for gas exchange.
• Divided into lobes and segments, separated by fissures.
• The original document contains diagrams of locations, structures, and functionality.

Bronchial Tree

• Trachea divides into right and left main bronchi.
• Carina separates the main bronchi openings
• Main bronchi branch into lobar (secondary) bronchi.
• Lobar bronchi further divide into segmental bronchi, then bronchioles.
• Bronchioles lead to alveolar ducts and alveoli (site of gas exchange).

Lung Lobes and Fissures

• Lungs are divided into lobes (superior, middle, inferior), with fissures (oblique and horizontal) separating them.

Blood Supply

• Pulmonary arteries carry deoxygenated blood from the heart to the lungs to become oxygenated.
• Pulmonary veins carry oxygenated blood from the lungs to the heart .
• Bronchial arteries deliver oxygenated blood to lung tissues.

Gas Exchange

• Exchange of oxygen and carbon dioxide between alveoli and capillaries takes place in lung alveoli.