Part 1 Flashcards

Question

Cardio-respiratory physiology- Avian Upper respiratory system comprised of 5 things:

Answer 1

1-incomplete hard plate 2. choana 3. choanal papillae 4. infundibular cleft 5. Glottis

Answer 2

Choana * Slit-like opening in hard palate * Internal nares, opens to nasal passages and conchae

Answer 3

Choanal papillae * Epithelial projects into choana * Lost with infection, Vit A deficiency

Answer 4

Infundibular cleft * Opens to eustachian tubes

Answer 5

Glottis opens at the base of tongue -not covered by epiglottis

Answer 6

* Upper respiratory system * Trachea * Complete, signet-shaped cartilage * Slight overlap for flexibility * Larger diameter lumen * Decreased resistance * Increased length * Increased tracheal dead space volume * Variations * Clinical significance?

Answer 7

* Syrinx * Vocal apparatus * Modified tracheal cartilages form 2 membranes * Located around tracheal bifurcation ** see slide for more info.

Answer 8

Paleopulmonic neopulmonic no

Answer 9

* Paleopulmonic. * Main gas exchanging bronchi * Long and lie parallel to each other * One-way air flow, caudal to cranial **see slide for more info

Answer 10

* Neopulmonic * Short and anastomose profusely * Bidirectional air flow **see slide for more info

Answer 11

* Lower respiratory system * Lungs * Fixed position * Minimal change with respiration * Clinical significance: Dorsal and lateral recumbency may decrease lung volume

Answer 12

* Air sacs (typically 9, 8 paired, 1 single) cranial caudal

Answer 13

* Air sacs (typically 9, 8 paired, 1 single) * Cranial group: cervical, clavicular, anterior thoracic

Answer 14

* Caudal group: caudal thoracic and abdominal **see slides for detailed info

Answer 15

* Similar in structure to mammals, but thinner * Smaller diameter of air capillaries * More air capillaries in given space = greater gas exchange * Unidirectional air flow in most lungs (paleopulmonic system) * Blood flow is at 90 degrees

Answer 16

* Cross-current flow * Parabronchi and blood vessels at 90-degree angle * Air in lungs continuously being exposed to different (fresh) vessels * Decreasing oxygen tension meets unsaturated hemoglobin

Answer 17

* Two breath cycle * First inhalation * Air through trachea to caudal air sacs * First exhalation * From caudal air sacs into lungs * Second inhalation * Through lungs into cranial air sacs * Second exhalation * From cranial air sacs out through trachea * Animation of air sacs and breathing: * https://youtu.be/kWMmyVu1ueY

Answer 18

Since the air sacs are the only significant volume-compliant structures within the body cavity, their volume also increases. As pressure within the air sacs becomes negative relative to ambient atmospheric pressure, air flows from the atmosphere into the pulmonary system. As a result of inspiratory valving (see below), during inspiration there is no or little flow in the ventrobronchi that connect the parabronchi and the intrapulmonary bronchus and, as a result, the inspired gas continues caudally through the intrapulmonary bronchus. A portion of the gas crosses the neopulmonic lung and continues into the caudal thoracic and abdominal air sacs, while an equal portion goes to the dorsobronchi and thence across the paleopulmonic lung (Fig. 3a and Fig. 3b). During contraction of the expiratory muscles the internal volume of the thoracoabdominal cavity decreases, pressure within the air sacs increases, and gas flows out of the caudal thoracic and abdominal air sacs, passes across the neopulmonic lungs to the paleopulmonic lungs and thence out the ventrobronchi and trachea to the environment (Fig. 3a and Fig. 3b). Gas flow from the cranial air sacs does not pass back through the parabronchi but goes to the ventrobronchi, the trachea and thence to the environment. During expiration there is little or no flow in the intrapulmonary bronchus as a result of expiratory valving (see above).

Answer 19

The avian respiratory system is unique as birds have small lungs, that have little change in volume when breathing, and air sacs, which act as bellows but do not participate in gas exchange. This segregation of ventilation and gas exchange helps to increase the total gas exchange surface area. The bellows system allows continuous gas flow as opposed to 'in and out' tidal flow of mammals. Birds have no diaphragm--instead the horizontal septum separates the lungs from the viscera. This septum plays no active role in respiration but passively helps to displace the viscera during breathing.

Answer 20

Flight and the ability to fly at altitude means that birds have much higher oxygen demands than mammals. Avian lungs are 10 times more efficient than mammalian lungs in capturing oxygen due to the following modifications: thin blood gas barrier cross-current blood flow one way air flow rigid lung

Answer 21

Thin blood-gas barrier: the air capillaries of the lung (equivalent to the mammalian alveoli) are finer and more numerous and the blood gas barrier is very thin. This is possible because, unlike mammalian lungs which have to expand and contract with every breath, the fixed avian lungs require little interstitial tissue for added strength.

Answer 22

Cross-current blood flow: the blood flow is at right angles to air flow giving a cross current exchange system. This means that blood flow is always at right angles no matter which way the air is flowing. Cross current exchange allows more efficient absorption of oxygen without incurring high levels of carbon dioxide in the blood.

Answer 23

One way air flow: the air flow through the lungs is unidirectional as opposed to 'in and out tidal flow' of mammals. The parabronchi being tubes and not dead end sacs like alveoli allows for continuous gas exchange in the avian lung and it may explain why birds can fly at high altitudes.

Answer 24

Rigid lung: the fact that the lungs are rigid and play no role in ventilation means that there is 20% more area for gas exchange than in mammals.

Answer 25

* Kidneys divided into three divisions * Cranial * Cranial to the external iliac artery * Middle * Between the external iliac artery and the ischiatic artery * Caudal * Caudal to the ischiatic artery

Answer 26

* Avian kidneys * No defined cortex, medulla, or renal pelvis. * 2 types of nephrons * Avian glomerulus has a similar structure and function to its mammalian counterpart. * Hypotonic urine produced at this point

Answer 27

2 types of nephrons * Reptilian type * Nephrons are smaller and more numerous, with only a short, poorly defined intermediate segment between the proximal and distal convoluted tubules with no loop of Henle. * Mammalian type * Mammalian type has cortical proximal and convoluted tubules and a loop with thin and thick segments

Answer 28

* Avian urine specific gravity is typically between 1.005 and 1.020 g/mL because of birds' decreased capacity for concentrating urine * WHY? **see slide here for more information

Answer 29

* Renal portal system receive blood from * Caudal mesenteric vein * Blood from hindgut * Ischiatic vein * Internal vertebral venous sinus * Blood from vertebral column * Internal iliac vein * Blood from leg region

Answer 30

* Ring of vasculature (aka renal portal system) * Cranial and caudal renal portal veins that branch off the left and right external iliac veins and left and right common iliac veins. **see slide for more info

Answer 31

* Common iliac vein * Valve responsible for diverting blood away from or to the kidneys. * Innervated by adrenergic and acetylcholine recepters

Answer 32

* Blood flow to kidneys * Parasympathetic stimulation via acetylcholine * Valve closure = blood flow into the parenchyma of the kidney.

Answer 33

Blood flow to caudal vena cava (skips kidney) * Sympathetic stimulation via norepinephrine and epinerphrine * Valve open = Blood flow directly into vena cava to ensure venous return to heart during flight

Answer 34

* Bird droppings three components * Urine * Urates * Feces

Answer 35

* Avian ureter * Lined by mucus-secreting pseudostratified epithelium * Facilitates the excretion of urates in colloidal suspension * Starts at the cranial division of the kidney * Courses caudally * Branches to the middle and caudal renal lobes ending in the urodeum

Answer 36

* Uric acid is the main nitrogen waste product * Protein  amino acids + uric acid (“big picture”)

Answer 37

* Small molecule that can freely filtered by glomerulus

Answer 38

* Proximal tubule * Primarily transported here by * Renal portal system  venous blood to the peritubular capillary plexuses

Answer 39

* Urates have the potential for crystal formation in proximal tube or ureter * Occurs when concentration of urates secreted into the lumen increases past its solubility limit

Answer 40

* Risk of sludge or obstruction * Normal patient hydration provides a GFR sufficient to reduce the risk of possible sludge formation or obstruction This is a common finding in free-ranging birds found in a dehydrated and debilitated state.

Answer 41

* Stored in urodeum

Answer 42

Possible to move from the urodeum by retroperistalsis into the large intestine or colon (+/- cecum) * Water reabsorption * Electrolyte homeostasis * Nitrogen recycling * Energy source creation

Answer 43

* Energy source creation * Albumin  degraded to amino acids, dipeptides, tripeptides  bacteria use to produce SCFAs

Answer 44

* Retroperistalsis controlled by tonicity of fluid within the GI tract * 200 mOsm/kg or higher than that of plasma, retrograde peristalsis is significantly slowed or stops

Answer 45

continuous seasonal inderterminate determinate

Answer 46

* Types of breeders: * Continuous * Reproduce throughout the year

Answer 47

* Seasonal * Reproduce in a particular season

Answer 48

* Indeterminate * Respond to removal or addition of eggs during the laying period by laying extra eggs or curtailing laying

Answer 49

* Determinate * Number of eggs in clutch determined at onset of laying and unchanged by removal or addition of eggs

Answer 50

* Brood patch * Females and males

Answer 51

* Testes within coelomic cavity * Dimensions of testis increase with sexual activity * In seasonal birds and especially in some passerines, testicular mass can increase 300 to 500 times * Increased length and diameter of the seminiferous tubules and to a greater number of interstitial cells, in response to LH and FSH * Ductus deferens enters dorsal wall of urodeum

Answer 52

* Most birds have functioning left ovary and oviduct * Right side of the reproductive tract only develops in the beginning of the embryonic phase and remains vestigial * Unknown why unilateral development occurs * One hypothesis: Reduction of body weight to improve the ability to fly

Answer 53

* Ovary * Follicle hierarchy * After ovulation fails no functional corpus luteum * Persistent cells may secrete hormones during regression; however, can lead to cystic follicles

Answer 54

* Oviduct can be divided in five portions: * Infundibulum * Magnum * Isthmus * Uterus * Vagina

Answer 55

* Infundibulum * Proximal opening in oviduct * Responsible for capture of ovulated ovum * Left abdominal air sac surrounds ovary except caudally * Acts as conduit for ovulated ovum to “fall” into opening of the infundibulum * Site of fertilization * Sperm penetration must occur before the albumen is laid down * ~15 minute window (chickens) * Thin layer of dense albumen * Chaliziferous layer, immediately surrounds yolk after secreted * Clinical Relevance: * Egg yolk peritonitis or egg-related coelomitis

Answer 56

* Magnum * Location where majority of albumen is added * Ovum remains here for ~2-3 hours

Answer 57

* Isthmus * Formation of the two shell membranes * Inner shell * Outer shell * Only location to produce sulfur-containing amino acids * Important for shell membrane production * Ovum remains here for ~1-2 hours

Answer 58

* Uterus or Shell gland * Two anatomically distinct portions * Cranial portion * Responsible for adding water and electrolytes to albumen * “plumping of the egg” * Distal portion * Pouchlike—site where egg remains for ~20 hours * Creation of shell * Extraction of calcium from bloodstream for formation of shell

Answer 59

* Conduit for egg to pass from oviduct to cloaca * Fossulae spermaticae * Special spermatic crypts for sperm storage up to several weeks

Answer 60

* Oviposition * physical process of laying eggs in birds

Answer 61

* Egg components * Germinal disc * Yolk * Yolk membranes * Albumen * Shell

Answer 62

* Germinal disc * If ovum is fertilized it is termed the blastoderm * Will become embryo

Answer 63

* Lipoproteins and phosphoproteins * Main source of nutrition for developing embryo

Answer 64

* Yolk membranes * 4 membranes * Form a barrier between yolk and albumen * Allows movement of electrolytes

Answer 65

* Albumen * Suspends embryo in relatively aqueous environment * Protein component nutrition source * Antibacterial properties * Dense albumen * Chalaziferous layter * Thin albumen

Answer 66

* Chalaza * Twisted strands of ovomucin fibers * “spring-like” * Helps hold yolk steady in center of egg

Answer 67

* Two shell membranes * Testa (inner shell membrane) * an organic matrix with calcite, a crystalline form of calcium carbonate. * Cuticle (outer shell membrane) * Water repellent, reduces evaporation loss, forms a barrier for microorganisms

Answer 68

* Air cell at blunt end * Produced as egg cools after being laid * Shape related to hen’s pelvis * Color variations * Mostly from 2 pigments * Red-brown porphyrins * Blue-green biliverdins * Involved in gas exchange

Answer 69

* Each egg typically represents ~10%-20% of the total body calcium

Answer 70

* 2 main sources of calcium: * Bone * Dietary calcium

Answer 71

* The relative importance depends on the availability of dietary calcium. * Diet contains 2% calcium, then medullary bone contributes 30% to 40% of the calcium * Bone contribution higher at night or lower calcium diets

Answer 72

* The highly labile reservoir found in the medullary bone contains enough calcium for 1 egg

Answer 73

* Dietary calcium essential for replenishing medullary bone reservoir

Answer 74

* Parathyroid hormone (PTH) * Calcitonin * Vitamin D3 (calcitriol) * Sex hormones

Answer 75

* Responses within minutes vs hours in mammals

Answer 76

* PTH * Produced by parathyroid gland * Only chief cells, oxyphil cells absent * Promotes calcium absorption from bone * Induces rapid changes in calcium osteoclast activity and calcium transfer by osteoblasts and osteocytes

Answer 77

* Produced by ultimobranchial glands * Anatomically distinct asymmetrical paired glands positioned caudal to the parathyroid glands in the thoracic inlet * 2 cell types (both actively produce calcitonin) * Principal cells (similar to mammalian thyroid C- cells) * Morphologically distinct endocrine cell type, with larger intracytoplasmic granules

Answer 78

* Role of calcitonin in avian calcium homeostasis is still controversial * Stems from administration of calcitonin to eucalcemic birds does not create hypocalcemia

Answer 79

* Calcitriol (1,25-(OH)2-D3) * Increases absorption of calcium across the duodenum and jejunum wall * Mainly by calbindin

Answer 80

* With PTH is responsible for calcium mobilization from medullary bone

Answer 81

* Appears essential for translocation of calcium across the oviductal wall * Similar or identical calbindin protein is also present in the distal portion of the uterus (oviduct) of domestic fowl, with levels rising during egg laying * Note: it is believed that oviductal calbindin production is controlled mostly by sex hormones and not by 1,25-(OH)2-D3, as the production of the intestinal calbindin

Answer 82

* Estrogen * Affects calcium metabolism * Mostly related to increased calcium storage, mobilization, and transportation

Answer 83

* Increased estrogen causes osteoblasts to produce medullary bone * Labile source of calcium when dietary supply is insufficient * Complete mineralization can only occur if calcitriol levels are adequate * Most prominent in the pelvic limb long bones (femur and tibiotarsus) * Can also occur in the thoracic limb long bones (humerus, radius, and ulna) and in other areas

Answer 84

Decreased estrogen causes osteoblasts to produce lamellar cortical bone (medullary bone disappears)

Answer 85

Although intramuscular injections in the legs are not routinely given in avian species, it is important to understand the function of the renal portal system, particularly when using potentially nephrotoxic drugs or drugs that may be cleared by the kidneys.