The Respiratory System

Transcription

1 Human Anatomy III: Respiratory, Urinary & Digestive Systems The Respiratory System Major functions include: Obtaining oxygen Removing carbon dioxide Maintenance of ph balance Respiration may be accomplished in a variety of ways Animals small enough use diffusion; no specialized organs Directly through the skin (again, via diffusion) Gills (for aquatic animals) Tracheal tubes (insects) Lungs (terrestrial vertebrates) Basic Anatomy of the Respiratory System I Clockwise from upper left: tracheae in a grasshopper; book lungs in a spider; tracheal gills in an aquatic insect larva Air enters through the nose Inside nose the air is warmed and moistened From the nose it enters the pharynx Junction point where oral and nasal passages meet It then passes over the larynx, or voice box Within larynx are the vocal cords 1

2 Basic Anatomy of the Respiratory System II 2

3 The Alveoli Alveoli are the capillaries of the lung; gas exchange occurs here rather than in bronchi or bronchioles Oxygen moves out of the alveoli Carbon dioxide moves into the alveoli Alveoli resemble a bunch of grapes at the end of bronchioles Each alveolus is covered in a thin film of water and a surfactant Gas exchange can t occur without water Surfactants keep an alveolus from sticking to itself and collapsing during breathing The Pleural Cavity The lungs sit within a space called the pleural cavity Normally, the outer surface of the lungs sticks to the inner surface of the pleural lining Puncturing the cavity causes a pneumothorax Air gets in and lungs collapse 3

4 Breathing: Inspiration In the first part of breathing, air is taken into the lungs This is an active process and occurs when: The diaphragm is lowered The rib cage expands These two steps increase the lung volume, which lowers the pressure within the lungs compared to the outside pressure Thus, air moves in! Breathing: Expiration In the second part of breathing, air is pushed out of the lungs This is a passive process and occurs when: The diaphragm is raised The rib cage contracts These two steps decrease the lung volume, which raises the pressure within the lungs compared to the outside pressure Thus, air moves out! Normal breathing rates in humans are breaths per minute Control of Breathing 4

5 Respiration in Birds Most vertebrates mix incoming and outgoing air Thus, some oxygen is lost and some carbon dioxide retained Birds have a unique breathing pathway to avoid this Air flows in only one direction Involves a number of air sacs to store air before or after it goes to lungs Respiration in Fishes Most fish exchange gases primarily with gills (a few have lungs) Use counter-current exchange to increase efficiency Water has less oxygen than does air Blood and water flow in opposite directions The Urinary System Major functions are: To rid body of waste material, primarily excess water, excess ions, and nitrogenous waste To maintain fluid and ion balance To maintain ph balance To maintain blood volume In humans, urea is the nitrogenous waste product Formed when proteins are broken down The urinary system forms part of the excretory system, along with the lower part of the digestive system 5

6 Basic Anatomy of the Urinary System Kidneys lie along the rear of the body, on either side of the spine Kidneys filter the blood and produce a mix of water and waste called urine The ureter is a tube which connects the kidneys and The bladder is a muscular storage organ which holds the urine Can hold up to 800 ml under normal conditions Urine leaves the bladder and exits the body through the urethra In males, urethra also connects to reproductive organs; not true in females Most non-mammals have a common exit for the excretory and reproductive systems called the cloaca Kidney Structure 6

7 Urine Formation Blood from capillaries is first filtered and the resulting fluid collected (in the glomerulus and Bowman s capsule) This fluid moves through a series of tubes (the proximal and distal tubules, the loop of Henle) Water and ions are reabsorbed as needed by diffusion or active transport Capillaries around tubules gather up reabsorbed water and ions Finally, fluid exits nephron and collects in renal pelvis Stones result from a buildup of material in the renal medulla Usually made of calcium oxalate crystals If large enough (above 2-3 mm) cause pain as they move through ureter Usually painless after they reach bladder Kidney Stones Control of the Urinary System Several hormones control rate of water retention in the kidneys Most important of these is antidiuretic hormone, or ADH ADH increases reabsorption of water by making the tubules more leaky Diuretics, such as caffeine, can interfere with these hormones Increase fluid loss 7

8 The Digestive System Major functions are: To break down large food particles and absorb nutrients To excrete solid waste material (feces) To help maintain water balance More primitive animals have a digestive system where food and wastes move through the same opening (the gastrovascular cavity) Most animals have a digestive system where food enters and wastes exit through separate openings (a complete digestive system) The Journey of a Food Bolus! Digestion begins with the mouth Teeth mechanically break down large bites into small pieces Adult humans have 32 teeth 8 incisors to cut or tear 4 cuspids (canines) for cutting 8 premolars (bicuspids) and 12 molars for crushing Carbohydrate breakdown begins due to amylase produced by salivary glands After this, food moves into the pharynx via the process of swallowing 8

9 The Journey of a Bolus II! The Stomach Further breaks down food, mainly carbohydrates and proteins, to produce chyme Stomach possesses sphincters at either end to prevent backflow into throat or early entry to intestines Cardiac (lower esophageal) sphincter to throat Pyloric sphincter to intestines Lining of stomach is heavily folded into rugae Cells in rugae make hydrochloric acid and pepsin (an enzyme to break down proteins ph of stomach is usually 2 (no food) to 4 (with food) Also produces amylases The Small Intestine 9

10 The Pancreas Lies near the stomach and connects to duodenum Produces a large amount of digestive enzymes which enter small intestine Amylases for carbohydrates Proteases for protein Lipases for lipids (fats) Also produces the hormones insulin and glucagon, which help regulate blood sugar levels The Liver Largest organ by weight in the body Produces bile, which is stored in the gall bladder or enters SI Bile helps break apart fat globules so that lipase can act on them to break them down Converts and stores simple sugars to regulate blood sugar level Completes breakdown of proteins to amino acids and urea Removes toxins from blood Digests old RBCs; parts of hemoglobin enter bile 10

11 Liver is made up of around 100,000 lobules, which filter blood from intestines The Large Intestine Thicker and shorter (~1.5 m) than small intestine Aids in reabsorption of water About 95% of water entering intestines is reabsorbed Absorption of some material Assisted by a dense gut flora (bacteria) These also produce several vitamins (K, B 5 ) Compaction and excretion of solid waste material Largest segment is the colon Cecum is a pouch-like region that attaches to small intestine Rectum is the muscular tube that exits body at the anus 11