Animal Form and Function

Tissues Tissues are groups of cells that have a common structure and function The tissues are organized into organs groups of organs that work together make up an organ system

Tissues there are 4 major types of tissues in animals Epithelial – sheets of cells that cover the body, lines organs, and protects. Connective – scattered cells with extracellular matrix (cartilage, tendons, ligaments, bone, blood)

Tissues Muscle – responsible for all types of body movement (made of fibers of proteins called actin and myosin) skeletal muscle cardiac muscle smooth muscle Nervous – made of nerve cells called neurons that transmit signals from one part of body to another

Control and Regulation For animal survival 2 organ systems specialize in control and coordination 1.Endocrine System – releases (chemical) hormones into bloodstream to cause specific effects 2.Nervous System – transmits (electrical) signals to specific locations. Only nuerons, muscle cells, and endocrine cells receive signals

Homeostasis Homeostasis (maintaining a constant internal environment) is the function of most of the organ systems negative feedback systems – is when the animal responds in a way to reverse a change (ie. In exercise the body sweats to cool body) positive feedback systems – is when the animals responds to amplify a change (ie. In birth, the pressure of baby’s head causes uterus to open)

Thermoregulation Animals are loosely grouped into 2 categories based on how they maintain body temperature Ectotherm – animals maintain heat from their environment (cold- blooded) Endotherm – animals generate their own heat (warm-blooded)

Respiratory System Animal cells require oxygen. These cells rely on the respiratory system to deliver oxygen and remove carbon dioxide There are several gas exchange mechanisms in animals Direct with environment – some animals are small enough that every cell is in contact (our close enough to the surface) with the outside environment [ie. flatworms]

Gills – gills are evaginated (outgrowths) that create a large surface area. Some are unprotected, others are protected like fish where water enters mouth and passes over the gills to exchange gases. Tracheae – chitin-lined tubes in insects. Permeates gas exchange through holes called spiraceles

Lungs – invaginated structures, or cavities in the body of the animal. Spiders have book lungs, which are stacks of membranes

Gas Exchange in Humans Nose, Pharynx, Larynx – air enters the nose and through the nasal cavity (pharynx & larynx) ** larynx is the “voice box” Trachea – after passing larynx air enter a cartilage-lined tube, trachea ** to separate food and air is a small flap, epilottis Bronchi, Bronchioles – trachea branches into 2 bronchi which continue to branch off into bronchioles Alveolus – each branchiole branch ends with a blood capillary covered sac called alveolus

Gas Exchange in Humans Diffusion between alveolar chambers and blood – oxygen diffuses past several membranes into blood ** carbon dioxide diffuses in the opposite direction Bulk flow of oxygen – oxygen is transported through body by red blood cells (RBC). ** RBC has hemoglobin which is a protein that bonds to oxygen Diffusion between blood and cells – blood capillaries permeate the body. Oxygen diffuses out of RBC across capillaries and several membranes to enter cells Bulk flow of carbon dioxide – most carbon dioxide made in cells is diffused back into bloodstream and is carried to the lungs by the plasma (liquid portion of blood)

Gas Exchange in Humans More information: Air is drawn into the lungs by a contraction of the diaphram (a muscle under lungs) Air is pushed out of the lungs when the diaphragm relaxes Chemoreseptors in the brain monitor pH levels in blood and increases or slows down respiration accordingly ** carbon dioxide in blood is slightly acidic

Circulatory System Large organisms require a transport system to deliver oxygen and nutrients and to remove waste and carbon dioxide There are two types of circulatory systems to accomplish this transport Open Circulatory System – pumps blood into an internal cavity called a hemocoel (aka sinuses) which bathe tissues with a oygen and nutrient-rich fluid, hemolymph. The hemolymph returns to the heart via holes called ostia. found in insects & most mollusks

Circulatory System Closed Circulatory System – is where the oxygen and nutrient-rich blood is carried in vessels found in annelids (worms), some mollusks (octopus/squid), and vertebrates In a closed circulatory system, blood is carried away from the heart through arteries with brach off into arterioles that eventually forms capillaries From capillaries, blood returns to the heart through small vessels called venules, that meet together to form veins.

Human Heart