Lecture 9 - Fatty Acid Metabolism - PowerPoint PPT Presentation

1 / 51
About This Presentation
Title:

Lecture 9 - Fatty Acid Metabolism

Description:

Title: Lecture 9 - Fatty Acid Metabolism Author: win7 Keywords: OPA Last modified by: MRT Document presentation format: Custom Other titles: Times New Roman Arial ... – PowerPoint PPT presentation

Number of Views:139
Avg rating:3.0/5.0
Slides: 52
Provided by: win751
Category:

less

Transcript and Presenter's Notes

Title: Lecture 9 - Fatty Acid Metabolism


1
(No Transcript)
2
Isfahan University of Technology Isfahan, Iran
3
Rumen and reticulum properties
  • The ruminoreticular fold partially separates the
    reticulum and cranial sac of the rumen.
  • Pillars divide the rumen to dorsal and ventral
    parts.

4
  • The dorsal part of rumen is divided to
  • Cranial sac
  • Dorsal sac
  • Caudodorsal blind sac
  • The ventral part of the rumen is divided to
  • The ventral sac
  • The caudoventral blind sac

Rumen and reticulum properties
5
Ruminoreticular wall structure
  • Highly vascularized connective tissue core is in
    the mucosal layer of the finger-like papillae
  • Epithelium is involved in the absorption of
    short-chain fatty acids.

6
  • In the reticulum the mucosal layer contains
    laminae.
  • Conical projections (papillae) are found on the
    surface of laminae.
  • The stratified squamous epithelium of reticulum
    also absorb short-chain fatty acids.

Ruminoreticular wall structure
7
Ruminoreticular wall structure
  • The reticulum has a role in mechanical digestion
    of food.
  • Myenteric plexus can be found between the
    muscularis externa layers.

8
Blood circulation of forestomachs
  • Celiac artery supply the blood flow to
    forestomach and the most part of abomasum.
  • The venous blood drains into the hepatic portal
    vein.

9
Innervations and the receptors
  • The innervations of fore stomachs
  • Vagal nerves (101 afferent/efferent ratio)
  • Splanchnic nerves (31 afferent/efferent ratio)

10
Innervations and the receptors
  • The vagal nerves transmit sensory information
    from two known kinds of sensory receptors
  • Tension receptors
  • Epithelial/mucosal receptors

11
Innervations and the receptors
  • The splanchnic nerves transmit sensory
    information from
  • Serosal receptors
  • Possibly tension receptors

12
  • The movements serve to
  • Mix the ingesta
  • Aid in eructation of gas
  • Propel fluid and fermented foodstuffs into the
    omasum.
  • A cycle of contractions occurs 1 to 3 times per
    minute.

Ruminoreticular motilities
13
Ruminoreticular motilities
  • Two types of contractions are identified
  • Primary contractions
  • Secondary contractions

14
Ruminoreticular motilities
  • Typical primary cycle consist of
  • Biphasic (double) contraction of the reticulum
  • Caudally moving monophasic contraction of the
    dorsal ruminal sac
  • A contraction of the ventral ruminal sac

15
  • Secondary cycle may occur and consist of
    sequential contractions of
  • The caudoventral ruminal blind sac
  • A cranially moving contraction of the
    caudodorsal ruminal blind sac followed by the
    middorsal ruminal sac
  • A contraction of the ventral sac.

Ruminoreticular motilities
16
(No Transcript)
17
Ruminoreticular motilities
  • When ingesta enter the foestomach, heavy objects
    fall into the reticulum and lighter material
    enters the rumen.
  • Added to this mixture are voluminous quantities
    of gas produced during fermentation.

18
Ruminoreticular motilities
19
Ruminoreticular motilities
  • The forestomachs possess a rich enteric nervous
    system.
  • Contractions coordination need the central
    input.
  • Motility centers in the brainstem control both
    the rate and strength of contraction via vagal
    efferents.

20
Ruminoreticular motilities
  • There are also vagal afferents from the rumen to
    the motility centers which allow stretch
    receptors and chemoreceptors in the rumen to
    modulate contractility.

21
Ruminoreticular motilities
  • Feeble intrinsic contractions responsible for
    the smooth muscle tone in the forestomach wall
    arise from nervous activity in its intrinsic
    nerve networks.

22
Ruminoreticular motilities
  • The gastric centers do not have spontaneous
    activity and need to be driven by
  • Excitatory inputs
  • Inhibitory inputs

23
Ruminoreticular motilities
  • The principal inputs to the gastric centers are
    from
  • Forestomachs
  • Abomasum
  • Duodenum by way of vagus nerves

24
Stimulus
Effect
Projections
Receptors
25
Stimulus
Effect
Projections
Receptors
26
Stimulus
Effect
Projections
Receptors
27
  • The known sensory receptor mechanisms are
    responsible for the vagal inputs.
  • The tension receptors are located in the muscle
    layer of different parts.
  • The epithelial receptors are located closed to
    the basement membrane of the luminal epithelium
    of the forestomachs.

Ruminoreticular motilities
28
  • Conditions inside the rumen can significantly
    affect motility.
  • Acidic ruminal contents
  • High roughage diet

Ruminoreticular motilities
29
  • Ruminants are well known for "cud chewing
  • It provides effective mechanical breakdown of
    roughage and increases substrate surface area.
  • Rumination is a unique characteristic of
  • True ruminants (deer, giraffes, and bovidae)
  • Pseudoruminants (camels and llamas).

Rumination and its components
30
Rumination and its components
  • Rumination occurs in resting.
  • The highest incidences of rumination occur during
    afternoon and middle of the night.
  • Many lactating ruminants ruminate while they are
    suckling their young or are being milked.

31
Rumination and its components
  • The time spent ruminating by a given animal
    depends on
  • The texture of the food
  • The amount of food ingested
  • Cattle may ruminate from 35 to 80 minutes per
    kilogram of roughage consumed.

32
Rumination and its components
  • Pharmacological agents have been used to examine
    the physiological mechanisms involved in evoking
    rumination.
  • Volatile fatty acids
  • Catecholamines
  • Gastric hormones
  • Opioids
  • Autacoids

33
Rumination and its components
  • Rumination is centrally mediated by the "gastric
    centers located at
  • Medulla oblongata
  • Ventral hypothalamic area
  • Tactile stimulation of the reticular and ruminal
    epithelia is a powerful stimulus for rumination.

34
Rumination and its components
  • Sensory information from digesta that is
    perceived in pillars
  • Digesta texture
  • Digesta consistency
  • Rumen fill

35
Rumination and its components
36
Rumination and its components
  • Four phases of a rumination cycle
  • Regurgitation
  • Remastication
  • Reinsalivation
  • Reswallowing
  • Regurgitation starts with an inspiration effort.

37
Rumination and its components
  • The bolus is carried into the mouth by reverse
    peristalsis.
  • Antiperistaltic waves of regurgitation passes
    over the esophagus at a velocity of 0.2 m per
    second.

38
Rumination and its components
  • In about two seconds, the "retained" bolus has
    the fluid squeezed out of it.
  • This fluid is immediately swallowed, and the
    remainder is chewed, reinsalivated, and
    subsequently swallowed.

39
Rumination and its components
  • Slower and more regular rate in remastication
    phase

40
Rumination and its components
41
Rumination and its components
  • The rate and duration of rumination chewing are
    controlled
  • The texture (coarseness)
  • Quantity of the food

42
Rumination and its components
  • The reinsalivation phase of rumination coincides
    with the remastication phase.
  • Rumination saliva and ingestion saliva are
    secreted at about the same rate and about 2.5
    times the resting rate.

43
Eructation
  • Eructation is the physiological process of
    expelling ruminoreticular gases
  • Carbon dioxide, 65
  • Methan, 25
  • Nitrogen, 7
  • Oxygen, 0.5
  • Hydrogen, 0.2
  • Hydrogen sulfide, 0.01.

44
Eructation
  • The eructation is associated with almost every
    secondary ruminal contraction.
  • Eructated gas travels up the esophagus at 160 to
    225 cm per second
  • Interestingly, a majority is actually first
    inspired into the lungs, then expired.

45
Eructation
  • A large portion of the eructated gases is
    inspired and recycled into the organism by
    absorption into the lungs.

46
Eructation
  • The rumen raft is the site of origin of most of
    the gases of fermentation.
  • When dorsal surface of raft splits, releasing of
    free gas into the gas layer occur.
  • Not much of the gas is absorbed, and most must
    be eliminated by eructation.

47
Eructation
  • If the gas layer reaches the cardia and clear it
    of fluid, the eructation mechanism is evoked.
  • Eructation is a vagovagal reflex, with centers
    in the medulla ablongata.
  • Mechanical receptors to detect distention are
    present in
  • Rumen dorsal sac
  • Reticular groove
  • Around the cardia and esophagus

48
Eructation
  • The primary type of rumen contraction always
    follows the biphasic reticular contraction and
    spread caudally.
  • In cattle
  • 66 with the secondary type of rumen
    contraction,
  • 20 with the primary type.

49
Eructation
  • In sheep
  • 3 no dependent rumen motility
  • 37 with secondary-type rumen contractions
  • 60 with the time with the primary type

50
Strategies for lower methane emission
  • Increasing the efficiency in which animals use
    nutrients to produce milk or meat.
  • Rumen modifiers such as ionophores improve dry
    matter intake efficiency and suppress acetate
    production, which results in reducing the amount
    of hydrogen released.

51
Strategies for lower methane emission
  • The grinding and pelleting of forages can reduce
    emissions by 40 .
  • Dietary fats have the potential to reduce CH4 up
    to 37.
Write a Comment
User Comments (0)
About PowerShow.com