Overview of Body Systems Biology for Majors
Organs and Organ Systems • An organ is made up of tissues that work together to perform a specific function for the body as a whole • Groups of organs that perform related functions are organized into organ systems, which perform more general functions
Maintaining Homeostasis Organ systems work together to help the body maintain homeostasis: • The cardiovascular, urinary, and lymphatic systems all help the body control water balance • The cardiovascular, integumentary (skin and associated structures), respiratory, and muscular systems work together to help the body maintain a stable internal temperature • The endocrine system is the control center for regulating blood calcium homeostasis
Blood Calcium • Calcium ions are used for the heartbeat, the contraction of muscles, the activation of enzymes, and cellular communication • The parathyroid and thyroid glands of the endocrine system detect changes in blood calcium levels • When the parathyroid glands detect low blood calcium levels, the skeletal, urinary, and digestive systems all act as effectors to achieve this goal through negative feedback.
Blood Glucose • The endocrine functions of the pancreas and liver coordinate efforts to maintain normal blood glucose levels • The nervous and digestive systems also play a role in maintaining blood glucose levels by prompting you to eat, which raises blood glucose levels
The Endocrine System Major endocrine glands. (Male left, female on the right.) • Pineal gland • Pituitary gland • Thyroid gland • Thymus • Adrenal gland • Pancreas • Ovary • Testis
Sensory System Exteroceptors Interoceptors blood pressure dropping changes in glucose and pH levels • Vision • Hearing • Touch • Equilibrium • Chemoreception: • Gustation • Olfaction
The Olfactory System The Olfactory Nerve leads to the brain
Cell Maintenance Systems • The circulatory, respiratory, and digestive systems provide the nutrients and energy your cells need to live • The immune system protects these cells from pathogens
Functions of the Respiratory System There are four processes of respiration. They are: • Breath or ventilation • External Respiration, which is the exchange of gases (oxygen and carbon dioxide) between inhaled air and the blood. • Internal Respiration, which is the exchange of gases between the blood and tissue fluids. • Cellular Respiration The respiratory system also: • Regulates of Blood pH, which occurs in coordination with the kidneys, • Defends against microbes • Controls body temperature due to loss of evaporate during expiration
Types of Muscle • Smooth muscle is involuntary muscle found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, ureters, bladder, and blood vessels. Smooth muscle cells contain only one nucleus and no striations • Cardiac muscle is involuntary muscle that is striated in structure and appearance with only one nucleus. Cardiac muscle is found only within the heart • Skeletal muscle is voluntary muscle anchored by tendons to the bone and is used move. Skeletal muscle cells are multinucleated and striated
Functions of the skeletal muscle include: • Support of the body • Aids in bone movement • Helps maintain a constant temperature throughout the body • Assists with the movement of cardiovascular and lymphatic vessels through contractions • Protection of internal organs and contributing to joint stability
Types of Bones • Long bones have a long longitudinal axis (right). • Short bones have a short longitudinal axis and are more cube-like. • Flat bones are thin and curved such as some of the bones of the skull. • Irregular bones are often found in groups and have a variety of shapes and sizes.
Integumentary System • consists of the skin, hair, nails, the subcutaneous tissue below the skin, and assorted glands • The skin protects the body from harmful substances and prevents the loss of fluids
Mammary Glands Mammary glands are the exocrine glands that, in the female mammal, produce milk for the sustenance of the young.
Practice Question Why is the reproductive system a control system rather than a cell maintenance one?
Quick Review • Discuss how different body systems interact with one another • Describe the nervous, endocrine, reproductive, and sensory systems • Describe the circulatory, immune, respiratory, and digestive systems • Describe the muscular, skeletal, and integumentary systems