1. Physiology Homeostasis: digestive, respiratory, circulatory, & excretory systems

2. Physiology Homeostasis = the maintenance of stable internal conditions in spite of changes in the external environment. –Circulatory system –Respiratory system –Digestive system –Excretory system

3. Circulatory System The circulatory system functions as the body’s “transportation highway” for the following substances: Nutrients – come from the food we eat Oxygen – comes from the air we breath Metabolic waste – created during some body processes Hormones – come from glands in our body and are the trigger for certain body functions Heat – helps to cool us off or heat us up depending on what we need

4. Circulatory System The circulatory system is composed of a few important parts: Heart – the pump that sends blood moving through the body Arteries – blood vessels that send oxygenated blood to the body from the heart Veins – blood vessels that send deoxygenated blood to the heart from the body Capillaries – small blood vessels that allow exchange of substances from the blood to the body and from the body to the heart

5. Circulatory System

7. The heart is the muscular pump that cycles your blood. It is composed of 4 “chambers”: –left & right atrium and left & right ventricle The atrium is responsible for receiving blood into the heart. The ventricle is responsible for pumping blood out of the heart.

8. Circulatory System: breakdown To the heart: –Veins –Deoxygenated blood (in general) –atrium Away from the heart: –Arteries –Oxygenated blood (in general) –ventricle

10. Circulatory System Components that make up the blood: –Plasma = liquid portion of blood –Red blood cells (erythrocytes) = responsible for carrying oxygen Note: rbc’s have no nucleus! –White blood cells (leukocytes) = defend the body against disease Note: there is 1 wbc for every 600 rbc! –Platelets (thrombocytes) = help to clot blood Note: become shaped like stars when clotting!

11. Blood Cells

12. Red Blood Cell

13. White Blood Cell

14. Platelet

15. Respiratory System

17. –Pharynx = passageway for both air and food. –Larynx (voice box) = passageway for air only. –Trachea (windpipe) = long tube leading to lungs. Note: wrapped in rings of cartilage. –Bronchus s. (bronchi p. ) = two tubes separating from trachea, leading to each lung. –Bronchiole = smaller branches of bronchi. –Alveoli = found at end of bronchioles, clusters of air sacs where gasses are exchanged

18. Respiratory System How do we breath? –The diaphragm, the flat muscle underneath our lungs works by creating low pressure within our lungs. By contracting (inhalation) it moves down, creating more space in the lungs and lower pressure. This forces air to rush in to our lungs. When it relaxes (exhalation) it moves back up, forcing air out of our lungs.

19. Breathing

20. Digestive System The digestive system is responsible for breaking down our food and extracting the nutrients and fluids from it. I believe you already know most of the organs of the digestive system so we will concentrate on those that you may not be familiar with.

22. Digestive System Amylase = enzymes that begin the breakdown of carbohydrates. These are contained in your saliva. Esophagus = long tube that connects mouth to stomach. Food doesn’t just fall into the stomach, it is pushed down through peristaltic motion:

23. peristalsis

24. Digestive System The stomach breaks down food into smaller pieces with the help of gastric fluids: HCl (hydrochloric acid) – breaks protein bonds Pepsin – unfolds proteins into single strands –Note: stomach is 3 million times more acidic than your bloodstream!

25. Digestive System The small intestine is responsible for the majority of digestion and absorbing nutrients into your bloodstream. The pancreas, liver and gall bladder all secrete digestive enzymes into the small intestine, which help finish digestion by converting carbohydrates into monosaccharides, proteins into amino acids, and lipids into fatty acids.

26. Digestive System The small intestine absorbs nutrients more effectively with the help of villi. These increase the surface area of the small intestine so that there are more spaces for nutrients to be absorbed.

27. villi villus

28. Digestive System Finally, the large intestine or colon is responsible for extracting water and mineral ions from the remaining material. All indigestible material is then excreted as feces; first compacted in the rectum, then expelled through the anus.

29. Length of Digestive Tract Total = 8 m (26 ft) – about 2.3 days Mouth = 8 cm (3 in.) / 5-30 s Pharynx/esophagus = 25 cm (10 in.) / 5-10 s Stomach = 15 cm (6 in.) / 2-6 hours Small intestine = 4-6 m (13-20 ft) / 3-6 h Large intestine = 1.2 m (4 ft) / up to 2 d

31. Excretory System The kidneys are the “filters” of blood. Also, when our bodies are metabolizing or processing nucleic acids and proteins, nitrogen is usually left over and must be gotten rid of. Nitrogen will form ammonia in our bodies which is toxic.

32. Excretory System The liver will convert ammonia to urea, which is much less toxic. Once this happens it is transferred to the kidneys so that it can be removed from the body. The kidney has a few major structures: –pyramid –nephron

33. Kidney

34. Excretory System As blood flows through the kidneys is goes through three main phases: Filtration = all non-useful substances are allowed to pass through glomerulus and Bowman’s capsule, and useful substances are returned to the body with the blood. Reabsorption & Secretion = any useful substance that got by filtration is reabsorbed and non useful substances are secreted. Urine formation = water, urea and salts are then emptied into ureter.