1. Dr K’s office hours: In office Tuesdays 2:30 - 3:30 PM `(In office: 3122A Pacific Hall) Group This Friday 11:30 - 12:30 (Meeting room: 3501 Pacific Hall)

2. Dr K’s problem-solving session: Thurs. 5-6 in 3500 Pacific Hall (NOT Wed this week—that’s a holiday).

3. Grading errors? 1. Check the answer key on the web site. 2. Talk to the appropriate TA (see “# graded” below) by Wed, Nov. 11. 3. For all grade changes, turn in a written description of the error(s) to Dr. K, along with exam, by Fri. Nov. 13. ***Dr. K may re-grade the whole exam***

4. Pick up graded exams: If you signed the waiver, outside the elevator of the third floor of Pacific Hall. If you did not sign the waiver, from Dr. K after class or at office hours.

5. TA sections, office hours:      

BIPN100    Human  Physiology  1                  Bill  Kristan,  Ph.D.  

. Section IA # graded Office Hour . Fri 11:00-11:50am SEQUO 148…..Winjet Chou……....(3)…..Wed 3-3:50 pm……...HSS 1145B Fri 12:00-12:50pm SEQUO 147…...Saatchi Patell…….(7)…..Wed 1-1:40 pm……...Muir Woods Fri 1:00-1:50pm WLH 2115 ….. Justine Liang….….(4)…..Tues 10-10:50 am…..Hi Thai Fri 2:00-2:50pm WLH 2206 …….Hao Shi……………(2)…...Fri 3-3:50 pm………...HSS 1128A Mon 9:00-9:50am WLH 2115……. Tim Macaulay....….(8)…...Tues 12:30-1:20 pm…Mandeville Cart Mon 4:00-4:50pm WLH 2208……. Mallorie Nguyen….(6).....Thurs 2-2:50 pm…….Goody's Market Mon 5:00-5:50pm WLH 2208……..Donel Purcella……(5)..…Mon 3:30-4:20 pm…..Price Center East, SR 2 Mon 6:00-6:50pm WLH 2115……...Kyra Rashid………(1)…..Thurs 10-10:40 am…Revelle Com. Lounge

How to interpret ECG recordings

In all cases, “current flow vector” means a depolarization; during repolarization, the recordings have the opposite polarity.

Fig. 14.15(d) of Silverthorn, 6th edition

Normal: ventricular (R) wave largest in lead II

If the heart axis is shifted to the right: the ventricular (R) wave is largest in lead III, and negative in lead I.

From Berne & Levy Physiology, 6th ed., Fig. 16-28

If the heart axis is shifted to the left: the ventricular (R) wave largest in lead I, and negative in lead III

• Caused by hypertrophy (increased thickness) of the right ventricle

• Caused by hypertrophy (increased thickness) of the left ventricle

Uses of ECG: 2. Limb leads can detect changes in thickness of ventricles.

Fig 16-31 in Berne & Levy Physiology, 6th ed.

First-degree: prolonged P-R

Second-degree: drop-out of some QRS complexes

Third-degree (complete): P and QRS independent

Uses of ECG: 3. Can detect conducting system block.

Uses of ECG: 3. Can detect conducting system block.

Silverthorn: Figure 14-23, 5th edition, and Fig. 14.15(h) of 6th edition

Grand summary: Electrical & mechanical events of the cardiac cycle

Silverthorn, 6th edition; Fig. 14.18

lub dub

Effects of Epi, muscle stretch on stroke volume

Cardiac autoregulation (Starling Law of the Heart)

Starling’s Law of the Heart: increased atrial filling (from venous return) increases cardiac output. Cause: cardiac muscle contracts more strongly when stretched.

Plot peak contraction vs. ventricular volume for a number of atrial volumes:

. increased atrial filling

. decreased atrial filling

Starling’s experiment:

Results from Starling’s experiment:

Stro

ke v

olum

e (m

l)

decreased atrial filling: smaller contraction

increased atrial filling: larger contraction

normal filling

....is the same as the first part of the length-tension curve for skeletal muscle

Pea

k of

the

cont

ract

ion

The length-force curve for cardiac muscle....

. increased atrial filling

. decreased atrial filling

....is the same as the first part of the length-tension curve for skeletal muscle

Pea

k of

the

cont

ract

ion

The length-force curve for cardiac muscle....

. increased atrial filling

. decreased atrial filling

500

Effects of Epi, muscle stretch on stroke volume

Ventricular volume

Venous return +

Ventricle

Muscle stretch +

Ventricular muscle

Muscle contraction

+

Ventricular muscle

_

Stroke volume +

Ventricle

As drawn, this is a negative feedback

Here’s Starling’s Law as a feedback diagram:

, but it can be positive feedback.

The length-tension (stretch/contraction) curve for cardiac muscle is complex:

Muscle stretch

Muscle contraction +

Ventricular muscle

At low stretch, it is positive:

Muscle stretch

Muscle contraction _

Ventricular muscle

but at high stretch, it is negative:

Venous return

Ventricular volume

Muscle stretch

Muscle contraction

Stroke volume

+ +

+

_ +

Ventricle Ventricular muscle

Ventricular muscle

Ventricle

This means that Starling’s Law is negative feedback at normal venous return….

Venous return

Ventricular volume

Muscle stretch

Muscle contraction

Stroke volume

+ _

+

_ +

Ventricle Ventricular muscle

Ventricular muscle

Ventricle

but it becomes becomes positive feedback when the venous return is abnormally high:

Lecture 13: Hemodynamics

Leucocytes = white blood cells (WBCs)

Erythrocytes = red blood cells (RBCs)

Serum = plasma with clotting proteins (fibrinogen) removed

Hematocrit = percentage of blood volume that is cellular.

Components of blood

(From Fig. 13.12)

(From Fig. 13.10)

Figure 15-1 Functional model of the cardiovascular system. (Silverthorn, 5th ed)

Control of pressure and flow in the cardiovascular system

The pressure exerted by a fluid drops as it flows through a tube