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Year 2 NSF > Reptiles 1 > Flashcards

Reptiles 1 Flashcards

1
Q

Thermoregulation of reptiles

A
  1. controlled by hypothalamus
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2
Q

What are the 2 main mechanisms of acquiring heat?

A

o Heliothermy - heat gain from direct solo radiation

o Thigmothermy - heat gain from a direct warm object in environment

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3
Q

How is the CV system involved in heat regulation?

A
  1. High temp: HR + vasodilation increases = warm blood to periphery
  2. Low temp: HR + vasodilation reduces = warm blood retained in core
  3. Lungs can be bypassed by means of a (right to left) shunt, meaning reduced heat loss by evaporation
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4
Q

Behavioural means to manage thermoregulation

A

o Body position and shape
o Burrowing/Hiding/shade seeking
o Pigmentation

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5
Q

What is unique about the reptile metabolism?

Which factors influence the metabolic rate in reptiles?

A

Vs other animals metabolism is much slower than animals of similar size

  1. Diet
  2. Size
  3. Body temperature
  4. species
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6
Q

Reptiles utilise mainly aerobic respiration but can switch to anaerobic during extensive exercise. What are the consequences of this?

A 
1. 
loads of lactic acid produced
2. which reduces blood pH, more acidic
3. in tuen means less affinity to oxygen
4. so NEED a recovery period after
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7
Q

Light required

A
  1. UVA – 320-400nm required for normal feeding behaviour, reproduction
  2. UVB – 290-320nm required for conversion of Vit D3 in skin and Ca
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8
Q

Why is dietary calcium to phosphate ration so important?

A

1.5:1 to 2:1
• When plasma calcium levels are insufficient to support neuromuscular activity Para Thyroid Hormone acts to mobilise calcium from bony stores, causes
o Metabolic Bone Disease one of the commonest reasons for presentation at the vets

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9
Q

Important to know about reptiles and bones

A
  1. They lack the haversian bone system of mammals

2. so bone healing is slow (2-18 months)

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10
Q

Skull of reptiles

A

2 Skull types seen

  1. Diapsid - snakes/ lizards/ tuatara/ crocodilia
  2. ANApsid - chelonia
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11
Q

Integument of reptiles

A
  1. largest “organ” of the body
  2. Heals more slowly than mammals
  3. HAs 3 layers
  4. Undergoes ecdysis
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12
Q

What is dysecdysis

A
  1. abnormal shedding of outer skin, often indicating suboptimal husbandry
  2. failure to shed
  3. require humidity and shedding surfaces to do so
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13
Q

Talk about Ecdysis

A

o Shedding of old skin
o Controlled by thyroid gland
o Can be complete (snakes) or patchy (lizards)

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14
Q

Talk about the 3 layers of reptile skin

A
  1. Stratum corneum – heavily keratinised
  2. Intermediate layer – stratum germinativum cells at varying stages of development
  3. Stratum germinativum (stratum basale) – cuboidal cells which undergo mitosis to form the cells of the intermediate layer
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15
Q

CV system:
RBC
What % weight does blood take
Heart chambers

A

RBC - nucleated
8-10% body weight
Heart is 3 chambered in most reptiles, crocs have 4!

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16
Q

HEART

A
  1. • Although most reptiles only have ‘one’ ventricle it is subdivided by muscular ridges
    • Mixing of oxygenated and deoxygenated blood does occur but is kept to a minimum through timing of contractions and division of chambers
    • During breath holding pressure in the lungs increases
    • This causes the majority of blood to bypass the pulmonary circulation
    • Blood enters aortic arches and bypasses the lungs
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17
Q

Renal Portal system

A

• External iliac veins (carrying blood draining from hind limbs) enter a large renal portal vein
o Most of blood flows directly into the kidney
• 2 issues with this in terms of drug administration
o Avoid injecting potentially nephrotoxic agents into tail or caudal extremities
o Consider implications of this with other therapeutic agents also
o Some drugs may be flushed out of system before they have the chance to take effect

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18
Q

Respiratory system

A
  1. Easily identifiable larynx
  2. Trachea to paired lungs EXCEPT snakes where left is vestigial or absent
  3. NO diaphragm
  4. Right lung is simple sac structure with reticular pattern of ridges to inc SA for GExchange
  5. 3 phases to respiration - expiration, inhalation, rest phase - can last long periods)
19
Q

Lungs plays a role in what

A
  1. respiration
  2. Buoyancy
    o Vocalisation
    o Display
20
Q

How does temp affect respiratory system?

A
  1. acts as a controlling factor

2. Inc temp inc oxygen demand and reduces pulmonary resistance

21
Q

When medicating snakes what to consider

A

Renal portal system so

  1. drug may be metabolised and leave circulation before reached body
  2. if giving nephrotoxic drugs means will go to the kidney unchanged
22
Q

What affects the rate of digestion in reptiles?

A

o Stops below 7°C (important in hibernation) o oral medication less effective!
o Slows if unwell (so oral medication can be less effective)
o Diet – herbivore digestion slower and less efficient

23
Q

Talk about stomach and SI

A 
1. Stomach
o Simple, muscular walls
2. Small intestine
o Short compared with mammals
o Secretion of digestive enzymes from mucosa, pancreas, liver and gall bladder
24
Q

What is unique to reptile teeth

A
  1. NO periodontal ligament

2. Polyphydonty - process whereby teeth are replaced throughout life as get damaged

25
Q

What are the types of teeth reptiles have

A
  1. Acrodont
    a. Attached to crest of bone, no socket, no periodontal ligament (v easily damaged)
    b. Seen in waterdragons and chameleons
  2. Pleurodont
    a. Attached to medial aspect of jaw bone with an eroded lingual aspect of tooth.
    b. See bulge at bottom
  3. Thecodont
    a. Crocodiles only, in a socket but with no periodontal ligament
26
Q

GI broadly

A
  1. generally shorter and simpler that mammalian
  2. The herbivores have large caecum adn colon for fermentation
  3. mouth:
    - Chelonia, horny keratinous beaks, no teeth
    - Mucus secreting glands for moisten and lubricating food.
    - No chewing done in reptiles
    - Snakes – some modified to venom glands
27
Q

Talk about large intestine

A
  1. mainly utilised in absorption of XS fluid.
  2. dependent on lifestyle e.g. herbivore, large caecum
  3. Terminated in cloaca
28
Q

Talk about cloaca

A

Three compartments:
o Coprodeum – receives faecal waste from the colon
o Urodeum – receives ureters and products of reproductive tract
o Proctodeum – common storage area for both before expulsion

29
Q

How do they excrete urine

A

excreted as uric acid as the end product of protein catabolism

30
Q

Where are the kidneys located.

What do reptiles have adn not have in terms of kidney

A

caudal coelomic cavity
DONT HAVE: renal pelvis, no loop of henle and no renal pyramids
DO HAVE glomerulus, proximal, intermediate and distal tubule

31
Q

Talk about bladder in the diff species

A

• Bladder present in chelonia and most lizards
o No bladder in snakes (although some have a rudimentary pouch!)
o Ureters open directly into cloaca

32
Q

Water intake, loss and consesrvation

A
  1. INTAKE: through eating and drinking. Some species have the ability to absorb water through cloaca (hence water bathing tortoises etc)
  2. LOSS: usual ways
  3. CONSERVATION: o Minimal through kidneys
    o Cloacal reflux into colon/bladder
    o Uric acid excretion
    o Renal portal system
    o Reduced glomerular filtration
33
Q

Reptile egg

A

o Egg shells are leathery rather than calcified and brittle
o System of membranes for protection
o Water resistant but allows some gas exchange

34
Q

Reproductive strategies

A
  1. Fertilisation always internal

2. Sperm can be stored for several months

35
Q

Different types of egg laying

A
  1. OVIPAROUS
    o Lay eggs which develop outside the body
    o Fertilisation can be internal (all reptiles) or external
    o Yolk is source of nutrients for developing embryo
    o 2-3 clutches/breeding season
  2. VIVIPAROUS (sometimes referred to as ovoviviparous!)
    o Eggs hatched internally and young born ‘live’
    o Gestation 6wks – 6 months
    o Some have placental type exchange of nutrients
    o Developing young can compress maternal GI tract
36
Q

What age do chelonia, small lizards and large lizards and snakes reach sexual maturity?

A

o Chelonia 3-8 years
o Small lizards 1-2 years
o Large lizards and snakes 2-3 years

37
Q

How is sex determined

A
  1. Heteromorphic sex chromosomes Females ZW Male ZZ

2. Temperature related sex determination. Turtles higher temps = females, lizards oppo

38
Q

Male repro tract

A

• Testes located internally, on right close to vena cava, on left close to left adrenal gland
• Like birds, increase in size and activity during the breeding season
• Lizards and snakes
o Paired extracloacal hemipenes – everted during mating
• Chelonia
o Single phallus – developed from proctodeum – protruded during mating
• BOTH MAY PROLAPSE – common problem

39
Q

Female repro

A 
•	Ovaries contain a number of follicles (as with birds)
•	2 functional oviducts comprising of
o	Infundibulum, uterine tube, isthmus, uterus and vagina
•	Open into
o	Urodeum
•	3 phases to cycle
o	Quiescent
o	Vitteline
o	Gravid
40
Q

Vision

A

o Fused transparent eyelids - the spectacle = don’t blink
o Pineal gland has role in light detection
o No consensual pupillary light response - shine light in one eye won’t affect other
o Iris skeletal muscle so no response to atropine

41
Q

Olfaction

A

o Jacobsons (vomeronasal) organ – detects pheromones

42
Q

Tongue

A

o Taste and touch Receptors on tongue and oral epithelium

43
Q

Auditory

A

o Only crocodiles have external ears –
o tympanic membrane outer margin in others
o Short open eustachian tube
o Single middle ear bone – collumella
o Transmits vibrations from air and ground (via quadrate bone of skull

44
Q

3rd eye?!?!?!

A
  • Parietal eye/third eye
  • No role in vision
  • Detects light
  • Found on top of head between two lateral eyes
  • Doesn’t look like an eye – modified scale!

Year 2 NSF (10 decks)

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