anat 3 organ system 1

Integumentary System — Definition

Body’s outer layer, includes skin, hair, nails, sweat, and sebaceous glands (produce oil, released as sebum).

Integumentary System — Functions

Provide protection, prevent water loss/gain, synthesize Vitamin D, thermoregulation (sweat, vasodilation/constriction), sense pain, temperature, touch, and pressure through sensory receptors.

Skeletal System — Definition

The skeleton, composed of bones, joints, ligaments, and cartilage, divided into axial and appendicular skeletons.

Skeletal System — Axial Skeleton

Contains the skull, hyoid, vertebral column, and thoracic cage.

Skeletal System — Appendicular Skeleton

Composed of upper and lower limbs, and the pelvic girdle.

Skeletal System — Functions

Support & protection of body framework, hematopoiesis (blood-cell production in bone marrow), mineral storage (calcium and phosphorus), and movement.

Muscular System — Definition

Produces body movement and generates heat through muscle contraction, making up approximately 40% of total body mass.

Muscular System — Types of Muscles

Cardiac muscle, skeletal muscle, and smooth muscle.

Cardiac Muscle

Involuntary, striated muscle found only in the heart.

Skeletal Muscle

Voluntary, striated muscle, comprising approximately 40% of body mass, makes up muscles you move, such as biceps and thigh muscles.

Smooth Muscle

Involuntary, non-striated muscle that makes up the walls of organs.

Nervous System — Definition & Functions

Regulatory system responsible for responding to sensory stimuli, controlling muscles and some glands, and is responsible for consciousness, intelligence, and memory.

Nervous System — Divisions

Anatomically: Central Nervous System (CNS) and Peripheral Nervous System (PNS); Functionally: Somatic Nervous System and Visceral/Autonomic Nervous System.

Central Nervous System (CNS)

Consists of the brain and spinal cord.

Peripheral Nervous System (PNS)

Consists of 12 pairs of cranial nerves, 31 pairs of spinal nerves, and associated ganglia.

Somatic Nervous System

Responsible for voluntary muscle control.

Visceral/Autonomic Nervous System

Includes sympathetic (fight/flight) and parasympathetic (rest/digest) divisions, both with sensory (afferent) and motor (efferent) components.

Sensory/Afferent Components

Receive information from the external world and body, including touch, pain, temperature, vibration, pressure, and proprioception.

Motor/Efferent Components

Generate and execute movements.

Nervous System — Cell Types

Includes neuroglial cells and neurons.

Neuroglial Cells — Function

Support, nourish, protect, and maintain neurons.

Neurons — Function

Specialized cells that receive and transmit electrical signals.

Neuron — Main Parts

Cell body (soma), dendrites, axon.

Dendrites

Receive signals from other neurons or sensory receptors and carry them toward the cell body.

Axon

Carries electrical impulses away from the cell body.

Cell Body (Soma)

Contains the nucleus and most of the organelles required for the neuron’s metabolism.

Endocrine System — Definition

A system of glands that secrete hormones directly into the bloodstream.

Endocrine System — Functions

Regulates growth and development, metabolism, reproduction, fluid/electrolyte balance, and stress responses.

Major Endocrine Glands

Includes pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, pineal gland, thymus, and ovaries/testes.

Pituitary Gland

Often called the 'master gland'; controls many other endocrine glands and regulates growth, reproduction, and water balance.

Thyroid Gland

Produces thyroid hormones that regulate metabolism, growth, and development.

Parathyroid Glands

Regulate blood calcium levels through parathyroid hormone (PTH).

Adrenal Glands

Located above the kidneys; produce hormones involved in stress, blood pressure, metabolism, and salt/water balance.

Pancreas — Endocrine Function

Produces insulin (lowers blood glucose) and glucagon (raises blood glucose).

Pineal Gland

Produces melatonin, which helps regulate the sleep-wake cycle.

Thymus

Important for development and maturation of T lymphocytes (T cells).

Reproductive Glands (Gonads)

Ovaries produce estrogen and progesterone; testes produce testosterone.

Cardiovascular System — Definition

Consists of the heart, blood, and blood vessels.

Cardiovascular System — Main Functions

Transport oxygen, transport nutrients, remove waste products, transport hormones, regulate temperature, and maintain homeostasis.

Heart — Function

Muscular pump that circulates blood throughout the body.

Heart — Four Chambers

Includes right atrium, right ventricle, left atrium, and left ventricle.

Right Atrium

Receives deoxygenated blood from the body through the superior and inferior vena cava.

Right Ventricle

Pumps deoxygenated blood to the lungs through the pulmonary artery.

Left Atrium

Receives oxygenated blood from the lungs through the pulmonary veins.

Left Ventricle

Pumps oxygenated blood to the body through the aorta.

Arteries

Carry blood away from the heart.

Veins

Carry blood toward the heart.

Capillaries

Tiny blood vessels where exchange of gases, nutrients, and waste occurs between blood and tissues.

Respiratory System — Function

Responsible for gas exchange; takes in oxygen and removes carbon dioxide.

Major Respiratory Structures

Includes nose/nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, lungs, and alveoli.

Alveoli

Tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged between air and blood.

Diaphragm

Main muscle of respiration; contracts during inhalation and relaxes during exhalation.

Digestive System — Function

Breaks food down into nutrients that can be absorbed and used by the body.

Main Digestive Tract

Includes mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.

Stomach — Function

Stores and mechanically/chemically digests food, particularly proteins.

Small Intestine — Function

Main site of digestion and nutrient absorption.

Large Intestine — Function

Absorbs water and electrolytes and forms/stores feces.

Liver — Digestive Function

Produces bile, which helps digest fats.

Gallbladder

Stores and concentrates bile and releases it into the small intestine.

Urinary System — Functions

Removes metabolic waste, regulates water and electrolytes, helps regulate blood pressure, and maintains acid-base balance.

Main Urinary Organs

Includes kidneys, ureters, urinary bladder, and urethra.

Kidneys

Filter the blood and produce urine.

Ureters

Carry urine from the kidneys to the bladder.

Urinary Bladder & Urethra

Bladder stores urine; urethra carries urine from the bladder to the outside of the body.