lecture 17, 18 oct 2005 -...
Post on 08-Aug-2020
0 Views
Preview:
TRANSCRIPT
1
1
Lecture 17, 18 Oct 2005Chapter 20-24
Circulation, Oxygen and Carbon Dioxide TransportVertebrate Physiology
ECOL 437 (aka MCB 437, VetSci 437)
University of ArizonaFall 2005
instr: Kevin Boninet.a.: Kristen Potter
2
1. Circulation 2. Heart Muscle3. Heart Function4. Diving Response
Reading of Text:Start with Chapters 23 & 24(skip the invert material if you like)Next week we will discuss 21 & 22(read Chapter 20 quickly)EXAM THURSDAY, Paper Drafts today
12-10 Randall et al.
2
3
AZDStar18 Oct 2005
4
Short QuizECOL 43706 Oct 2005
1. Draw a graph that represents the length-tension curve.
2. Explain, mechanistically, why the curve above has the shape it does.
3. Describe two characteristics that differ between muscle fiber types.
4. Explain what ryanodine and dihydropyridine receptors are and what they do.
Include Name and Lab time
2.326s.d.1min9max3.5median3.679mean
2 points
2 points
3 points
3 points
3
5
(Eckert, 12-4)To
Lungs
From body
To BodyviaAORTA
FromLungs
Mammalian Heart
Chordae tendinae
6
Cardiac Muscle (the other striated muscle)
-Small muscle fiber cells with only one nucleus
-Individual fibers are connected to neighbors electronically via gap junctions
-Two types of fibers:1. Contractile (similar to skeletal muscle)2. Conducting (including pacemaker cells)
Do not contract, but transmit electrical signal
-Cardiac contraction myogenic (arises within heart)Can be influenced by autonomic nervous system(alpha, beta adrenoreceptors increase [Ca2+])
-Long-lasting AP with long plateau phase, and longrefractory period - why?
4
7
Cardiac Muscle (the other striated muscle)
-Intracellular calcium from SR and across plasma membrane (unlike in skeletal)
-Dihydropyridine receptors in T-tubules arevoltage-activated calcium channels
-Ryanodine receptors then release more calcium from SR into the cytoplasm (calcium-induced calcium release)
-During relaxation, Calcium pumped actively back into SR and out across plasma membrane
8
Vertebrate Circulation (too big for diffusion!)
Divided into Central and Peripheral
Heart is main propulsive organ
Arterial system-distributes blood-regulates pressure
Capillaries-transfer between blood and tissues
Venous system-return blood to heart-storage reservoir
Focus on Mammalian Circulation with some exceptions
5
9Knut Schmidt_Nielsen 1997
Gravityand BP
10
Circulatory Roles and Components
Valves control direction of blood flow
Smooth muscle controls diameter of peripheral vessels, thereby altering resistance and flow to different tissues
Sherwood 1997
6
11
Vander 2001
Circulatory Roles and Components
-Gases (CO2, O2)-Nutrients-Waste-Hormones-Antibodies-Salts-etc.
-TemperatureRegulation
RBCs
-Blood volume 5-10% of body volume
12
gills simple (and linear):1. Blood goes to gills2. O2-rich blood goes to tissues3. O2-poor blood goes to heart4. Blood gets pumped back to gills
lungs more complex because get 2 circuits in parallel:1. Pulmonary circuit (lower pressure)2. Systemic circuit (higher pressure)
Development of Terrestrial Circulatory System:
7
13Hill et al. 2004, Fig. 23.3
Spongy vs. Compact Myocardium
14
Fish Circulation through gills
(Eckert, 12-16)
8
15
Addition of lungs more complicated (Eckert, 12-16)
Watervs.air
16
Two parallel closed circuits:
1. Pulmonary(lower press.)
2. Systemic
(Eckert, 12-3) Note venousreservoir
Mammalian Circulation
9
17
9-3, Sherwood 1997
Tissue Beds in Parallel, not Series
All cells within 2-3 cells of a capillaryCan control amount of flow to each tissue independently
18
In addition to Heart,
Blood also moved via1. Elastic recoil of arteries2. Squeezing of vessels during body movement3. Peristaltic contractions of smooth muscle in vessels
10
19
(Eckert, 12-4)ToLungs
From body
To BodyviaAORTA
FromLungs
Mammalian Heart
Chordae tendinae
20
14-14,
Vander 2001
Mammalian HeartNo valves as Enter
Atria
11
21
Amphibians and Reptiles (except crocodilians) with3 chambers (= one ventricle, two atria)
- incomplete ventricular septum
- BUT separate rich and poor blood
- AND alter pressure in systemic and pulmonary
- able to alter flow to systemic or pulmonary circuit
Non-Mammalian Heart Examples:
22
Amphibians:
only vertebrates where O2 poor blood to skin(as well as to lungs)
adults with paired pulmocutaneous arteriesdivide into two branches1. Pulmonary2. Cutaneous (to flanks and dorsum)
skin provides 20-90% O2 uptake30-100% CO2 release
Cardiovascular System
12
23
FROG Heart
conus arteriosusw/ spiral valve
trabeculae(create channels)
role of Tb and HR
CardiovascularSystem
Pough et al., 2001Fig 6-8
Gets poor
Gets rich
24
Reptilian Heart (not crocs)
(no conus arteriosus, no spiral valve)
2 systemic arches and one pulmonary arteryfrom single ventricle
BUT, single ventricle functions as THREE
3-chambered heart anatomically5-chambered heart functionally
Cardiovascular System RAA = right aortic archLAA = left aortic archPA = pulmonary artery
Muscular Ridge
Pough et al., 2001Fig 6-9a
RA = right atriumLA = left atrium
13
25
Pough et al., 2001Fig 6-9
Reptilian Heart (not crocs) not “primitive”
RAA = right aortic archLAA = left aortic archPA = pulmonary artery
Muscular RidgeCP = cavum pulmonaleCV = cavum venosumCA = cavum arteriosum
IVC = intraventricular canalAVV = atrioventricular valve
1
22
1 4
2
55
6
77
3-chambered heart anatomically5-chambered heart functionally
Muscular Ridge
3
26
R to LO2 poor to systemic via aortic arches(short delay between valves opening)
L to RO2 rich to pulmonary artery(longer delay between valves opening)
Reptilian and Amphibian Circulation
Cardiac Shunts (in 3-chambered heart)
1. temperature regulation2. breath holding (diving, turtle in shell, inflated lizards)3. stabilize O2 content of blood when breathe intermittently
14
27
Mammalian fetus:
Ductus arteriosus (R -> L shunt, lung bypass)-pulmonary artery to systemic arch-when lung inflate resistance down (pulm)-when lose placental circ. resistance up (syst)-closes at birth
Foramen ovale (interatrial shunt R -> L)-hole in wall between atria-closes at birth
28
Bird chick:
Chorioallantois= network of vessels under
shell surface
Interatrial septum-R -> L shunt, lung bypass-closes after hatching
15
29
Vander 2001
Electrical Activity in the Mammalian Heart
Influenced by autonomic NS
RALA
LVRV
30
Sherwood 1997
Cardiac Cells electronically linked by Gap Junctions
(except from atrial to ventricular cells…)
16
31
Vander 2001
Electrical Activity in the Mammalian Heart
32
Recall AP and refractory period differences…
(Eckert, 12-7)
17
33
Vander 2001
Types of Cardiac Cells:
A. Contractile
B. Conducting
~ autorhythmic
~ fast-conducting
SA nodeAV node
InternodalInteratrialBundle of HisPurkinjeEtc.
34
Sherwood 1997
18
35
Types of Cardiac Cells:
A. Contractile
B. Conducting
- 1° autorhythmic
-1° fast-conducting
SA nodeAV node
Pacemakers:
-Normally HR driven by SA node
-Others are Latentpacemakers
-Called Ectopicpacemaker when node other than SA driving HR
InternodalInteratrialBundle of HisPurkinjeEtc.
36
Sherwood 1997
~ SA node ~ latent rate
Sherwood 1997
19
37
Sherwood 1997
SA
AV
other
The
Hea
rt R
ate
Trai
n
oops
38
9-11, Sherwood 1997
Autorhythmic Cardiac Muscle (e.g. SA node)
~Transient Ca2+
channels
K+, Na+
Which way would you
alter channel permeabilitiesto speed or slow HR??
20
39
Sherwood 1997
Vander 2001Contractile Cardiac MuscleCa2+ current maintains plateau
40
(Eckert, 12-8)
(Q,R,S masks atrial repolarization)
21
41
(Eckert, 12-8)
4214-25, Vander 2001
WiggersDiagram
Valves open/close where pressure curves cross
760 mmHg = 1 atm= 9.8 m blood
1:2
22
43
Sherwood 1997
Atrial Kick
Heart filled ~same with increased HR
44
Sherwood 1997
Vander 2001
Frank-Starling Curve
Systole = Ventricular Emptying
Diastole = Ventricular Filling (rest)
23
45(Eckert, 12-13)
Heart Work Loops
46
Cardiac Output:
CO = cardiac output (ml/min from 1 ventricle)
SV = stroke volume (ml/beat from 1 ventricle)
= EDV – ESV (end-diastolic – end-systolic volume)
HR = heart rate (beats/min)
CO = HR x SV
- Heart can utilize different types of energy sources (unlike brain)
MABP = CO x TPRMABP = DP + 1/3(SP-DP)
24
47
HR control
Parasympathetic vs. Sympathetic
(Eckert, 12-5)
48Knut Schmidt_Nielsen 1997
Gravityand BP
25
49
Knut Schmidt_Nielsen 1997
Exercise
OxygenConsumptionX 20
Cardiac Output 6x
50
Peripheral Circulation
- Endothelium lining vessels- Middle layer with smooth muscle (esp. arteries)- Outer fibrous layer
Capillaries with ~ only Endothelium
26
51
(Eckert,12-26)
52
Peripheral Circulation
Compliance vs. Elasticity
~ Veins vs. Arteries
Volume Reservoir vs. Pressure Reservoir
27
53
Volume Reservoir vs. Pressure Reservoir
14-34, Vander 2001
(Eckert, 12-27)~Constant P and Q at Capillaries!
54
Venous System
- low pressure (11 mm Hg or less)
- thin walled veins with less muscle
- more compliant and less elastic
- valves
- blood moved by skeletal muscle (and smooth)
- breathing creates vacuum (low pressure) in chest to aid blood flow to heart
top related