ANIMAL SYSTEMS 1

Body organization • Unicellular

• Multicellular simple

• Multicellular complex-rely on folded and branched internal surfaces to facilitate exchange of materials

Levels of organization• cells tissues organs systems• Tissues are composed of cells with a common structure and function• Cells are held together with a sticky matrix

• There are 4 types of tissues:

1. Epithelial-covers outside of body and lines organs and cavities

• Cells are tightly joined• Simple or stratified• Shape may be squamous,

columnar or cuboidal

2. Connective-binds and supports other tissues• Composed of a few cells in a matrix• Connective tissue is made of 3 kinds of fibers:

a. Collagen fibers-collagen is the most abundant animal protein, these fibers are non-elastic and do not tear easily

b. Elastic fibers-long threads of elastin protein that provide a rubbery quality c. Reticular fibers-thin and branched, they join connective tissue to adjacent tissue

• Types of connective tissue:a. Looseb. Adiposec. Fibrousd. Cartilagee. Bonef. blood

3. Muscular-long cells called fibers that are capable of contracting

-most abundant tissue in animals-muscle contractions use much of the energy produced in respiration

4. Nervous-senses -sense stimuli-transmits signals-mostly concentrated in the brain

Staying warm or cool:• Endothermic-produce heat from inside, includes birds,

mammals, some fish and some insects• Body coverings help retain heat (fur, fat layers)• High metabolic rate (80% can go to heat)• Modify behavior (migrate, hibernate)• Panting • Seeking shade• Huddling• Shedding• Thicker fur• Nocturnal

• Ectothermic-gain heat from external sources, includes most fish, amphibians, reptiles• Body coverings help retain heat-scales• Modify behavior (basking)• Fanning wings• Nocturnal

Homeostasis • Maintaining the internal environment

• Body temperature • Water-salt balance• Carbon dioxide• Glucose• pH

Homeostatic control:Negative feedback

1. Sensor2. Control center

• Negative feedback-a change causes the control center to counteract any further changesPrevents small changes from becoming too big

• Positive feedback-a change causes the control center to increase the responseExample-labor

Digestive system• Obtaining food

• Filter feeders-sift small particles from water (baleen whales)• Fluid feeders-parasites that tap into the vascular system of host• Substrate feeders-live on the material they eat (maggots)• Bulk feeders-bite off chunks or whole organism

Essential NutrientsMust be preassembled as the animal cannot make them

1. Amino acids-need 20 to make all proteins, about half are essential.• Protein deficiency is the most

common type of malnutrition in humans

2. Fatty acids-deficiencies are rare3. Vitamins-organic, need very small amounts, 13 are essential

• Water soluable-excess excreted in urine• Fat soluable-excess stored and may be toxic (A, D, E, K)

4. Minerals-inorganic, too much may cause toxic side effects

Food Processing 1. Ingestion-eating2. Digestion-breaking down food to small molecules3. Enzymatic hydrolysis-splitting large molecules4. Absorption of small molecules5. Elimination of undigested waste

Complete digestive system• Consists of two openings-mouth and anus• Long tube with specialized structures

Structures of digestion• Mouth-saliva moistens food and makes it slippery,

contains the enzyme amylase to break down starch• Teeth make food smaller• Pharynx-throat• Larynx-contains vocal cords

• Esophagus-muscular tube that carries food to the stomach

• Food is pushed down by waves of muscle contractions called peristalsis

• No food is digested in the esophagus

• Stomach, j shaped elastic sac, stores and mixes food with gastric juices• HCl- ph = 2, the acid breaks down the matrix that holds cells

together and kills most bacteria• Pepsin-enzyme that breaks down proteins• Sphincters (circular muscles) keep food inside until consistency of

thick milkshake

The stomach is coated with a mucus lining that protects it from acid• Even so, the stomach lining is constantly eroded and replaces itself every 3

days

• Accessory organs• Liver-makes bile• Gall bladder-stores bile

Pancreas--secretion acts as a pH buffer, bile acts as a detergent (emulsifies fat)

• Small intestine• 6 meters long• Most of the breakdown and

absorption occurs here• Duodenum-first 25 cm,

juices from pancreas, liver, gall bladder and intestine are added here

Absorption in the small intestine• Has huge surface area (300 m2 or size of tennis court)

• Folds with projections called villi• Each villus has microvilli• Inside each villus is a network of

capillaries and lymph vessels

• Large intestine (colon)• 1.5 m long• Cecum is pouch at the beginning

where appendix attaches• Recovers water, waste becomes solid• Contains harmless bacteria (some produce vitamins)• Rectum is end portion where waste is stored until elimination

Problems Eating disorders

1. Anorexia-refusing to eat enough to be healthy2. Bulimia-overeating and purging3. Binge eating-overeating without purging

Diabetes4. Type I-no insulin is produced by the pancreas5. Type 2-insulin resistance (cells do not take up glucose even if

insulin is present), associated with obesity

High cholesterol leads to cardiovascular disease

Circulatory system• Open systems-blood bathes organs directly, no vessels• Closed systems-all blood is contained in vessels

Double loop systemA. The heart

-size of a fist-4 chambered

2 thin walled atria serve as receiving chambers2 thick walled ventricles serve as pumping chambers

-chambers separated by valves to prevent backflow

• Cardiac cycle-one complete sequence of filling and contracting

• Heart rhythm• SA node (pacemaker)-specialized cells that set the rate

• Located in wall of right atrium• AV node spreads signal throughout heart

• Located in wall between right atrium and right ventricle

Produces electrical currents recorded as EKG

B. Blood vessels-arteries are 3 layers with thick muscle, extra strength is needed for uneven speed and pressures-veins are also 3 layers but thinner, flow is mainly due to skeletal muscle contractions.valves prevent backflow

-capillaries-one cell thick, allows exchange of material between blood and fluid around cells

Capillaries in the heart, brain, and kidneys are always filled to capacity. Others may be diverted as needed.

For example, after a meal capillaries in digestive tract are full, while exercising capillaries in muscles are full.

• Blood pressure-created by force of blood pushing against vessel walls• Greater in arteries than veins• Contraction pressure is called systole• Relaxation pressure is called diastole

• Healthy: 120 systole 80 diastole

C. Blood composition• Plasma-liquid portion of blood, 90% water with dissolved ions,

proteins, antibodies, clotting factors, nutrients, waste, hormones, CO2, O2

• RBC (erythrocytes)-transport oxygen, most numerous of thecells, disk shape helps perform

function, lack nuclei, contain hemoglobin

• WBC (leukocytes)-fight infection• Platelets-cell fragments, no nuclei, help clot blood

Problems 1. Cardiovascular disease-caused by a combination of

lifestyle and geneticsa. atherosclerosis-deposits of cholesterol thicken and harden artery walls. It narrows the opening and causes platelets to adhere triggering a clot

b. hypertension (high blood pressure)-promotes atherosclerosis and increases risk of heart attack and stroke

c. heart attack-death of part of heartdue to blockage and loss of oxygen

d. stroke-death of nerve tissue due to blocked vessels in brain

Respiratory system• Uptake of oxygen from environment and release of carbon

dioxide into environment• Requires a respiratory surface

• Must by moist, thin and have a large surface area

1. Nasal cavities warm, filter and moisten air2. Larynx-contain vocal cords, opening is covered with

epiglottis when swallowing3. trachea-windpipe, held open with rings of cartilage

4. bronchi-tubes into each lung5. bronchioles-smaller and smaller branches6. alveoli-air sacs where exchange takes place7. diaphragm-breathing muscle

• Breathing is controlled by two areas of the brain: the medulla oblongata and the pons• It is a response to change in pH of the blood

Problems 1. Bronchitis2. Laryngitis3. Emphysema4. Lung cancer

Excretory system• Types of animal waste:

• Ammonia-very toxic, animal must have lots of water to dilute it. Common in aquatic species. Requires the least amount of energy to produce

• Urea-less toxic, can be stored, found in land animals because it requires less water to dilute

• Uric acid-nontoxic, nonsoluble, excreted as dry paste, found in birds, insects and many reptiles. Requires the most energy to produce

• Steps in excretion:• Filtration• Reabsorption• Secretion• Excretion

1. Kidneys-bean shaped, reddish brown, fist sized 1. Made of millions of filtering units called nephrons2. Cortex-outer region3. Medulla-cone shaped regions between cortex and pelvis4. Pelvis-hollow chamber where urine collects

2. Ureter3. Bladder-elastic sac4. Urethra-tube to exit the body

Control of excretion1. Antidiuretic hormone (ADH)

-produced in the hypothalamus-increases water reabsorbtion, reduces urine volume-released when water is lost through sweating or eating salty foods

2. AldosteroneProduced by adrenal glandsCauses reabsorbsion of salt and water increasing blood pressure and volumereleased when there is a drop in blood pressure

3. Atrial natriuretic factor-released by the walls of the atria -inhibits salt reabsorption and reduces aldosterone releasereleased in response to an increase in blood volume

Problems • Kidney stones• Urinary tract infections• Gout • Drugs and toxins