BIPN  100    Human  Physiology  1  Bill Kristan, Ph.D.

Pacific Hall 3122A 534-4760 wkristan@ucsd.edu (put BIPN 100 in the subject line)

Sections, TAs: Section Day Time Location TA . A02 Fri 8:00-8:50am WLH 2206 If needed A06 Fri 11:00-11:50am SEQUO 148 Winjet Chou A07 Fri 12:00-12:50pm SEQUO 147 Saatchi Patell A08 Fri 1:00-1:50pm WLH 2115 Justine Liang A09 Fri 2:00-2:50pm WLH 2206 Hao Shi A10 Fri 3:00-3:50pm HSS 1128A If needed A01 Mon 9:00-9:50am WLH 2115 Tim Macaulay A03 Mon 4:00-4:50pm WLH 2208 Mallorie Nguyen A04 Mon 5:00-5:50pm WLH 2208 Donel Purcella A05 Mon 6:00-6:50pm WLH 2115 Kyra Rashid

Dr. K’s Office hours: Tuesdays: 2:30-3:30 PM (in office: 3122A Pacific Hall) Fridays: 11:00 AM-noon (meeting room: 3501 Pacific Hall)

WEB SITE: http://classes.biology.ucsd.edu/bipn100B.FA15/ Has the following : 1. General information. 2. The syllabus. 3. Outlines of each lecture, including all figures used in the lecture; [updated by Monday morning for each week’s lectures]. 4. A problem set for each week (added by Thursday). 5. Midterm exams and keys from 2011, 2012. 6. Announcements about exams, policy, etc.

PODCASTS OF LECTURES: podcast.ucsd.edu

BIPN  100    Human  Physiology  1  Bill Kristan, Ph.D.

Pacific Hall 3122A 534-4760 wkristan@ucsd.edu (put BIPN 100 in the subject line)

WHAT’S HAPPENING? Check the Announcements section of the course website, or come to lecture.

EXAM SCHEDULE Midterms: Thursday, October 22 (7:00-8:20 PM)

Thursday, November 19 (7:00-8:20 PM) Final exam: Wednesday, December 9 (11:30 AM to 2:30 PM)

(Exam locations will be announced in class and on the course website)

BOOKS ON RESERVE: in the BioMed Library.

PROBLEM SETS: the same sort of questions and problems as those on exams. Their intent: to learn to explain observations by physiological mechanisms. Great way to prepare for exams: do the problem sets in writing, on paper. Each week, the solutions to the questions will be:

(a) discussed in sections, and (b) posted on the course website.

TEXT: Human Physiology: An Integrated Approach, 7th edition, by Dee Silverthorn (2016), although the 6th edition (2013) will also be OK. (The syllabus lists readings in both editions.)

GRADES ~90% of grade from lecture material, ~10% from readings.

Lists Terms you should know ~25 terms the start of each set of lecture notes;

• you should be able to define them. • the IAs and Dr. K should be able to use them without defining them.

Improvement can help--

final exam is comprehensive; doing better on the final can raise your grade.

LECTURE OUTLINES Intended to facilitate note-taking.

Don’t hold Dr. K responsible for sticking to the order, or for saying everything in the notes.

Will be on the web site by Monday for the week’s lectures.

Terms you should know: mechanistic explanation, teleological explanation, correlation, necessity, sufficiency, "milieu interior," homeostasis, allostasis, input signal, output signal, independent variable, dependent variable, feedback system, negative feedback, controlled variable, sensor, set point, comparing unit, controller, neutral (dead) zone, high-gain, low-gain, positive feedback, perturbation, indirectly controlled component, control, regulation.

I. Physiology as a science. A. Physiology is the study of the function of organ systems and how they interact.

Physiology depends on knowing molecular and cell biology, as well as physics and chemistry but emphasizes the interactions among cells, tissues, and organs.

LECTURE #1: Introduction: homeostasis; negative feedback and positive feedback

Dictionary.com: the branch of biology dealing with the functions and activities of living organisms and their parts.

B. Like any science, Physiology can explain how things happen, not why they happen.

. 1. Mechanistic explanation: addresses mechanisms that cause the effect. It answers questions that ask “How....?” a. These explanations discuss events that happened before the observation being explained. b. Here are two examples: i. The mammalian heart rate increases when sympathetic neurons innervating heart muscle fibers increase their firing rate. ii. A neuron produces an action potential when voltage-gated sodium channels open.

2. Teleological explanation: addresses the consequences of an event. (Telos means "end," and a teleological explanation is based on the ends--or effects--of the event). These explanations answer “Why....?” questions.

a. This kind of explanation focuses on events that follow in time the thing you are explaining. b. Here are two examples:

i. Running makes your heart rate increase because your muscles need more oxygen. ii. Neurons produce action potentials because they need to send signals over long distances

3. Be sure to give mechanistic explanations, not teleological ones, in this course!

D. Experimental science looks for causal relationships: does A cause B? • it uses 3 major approaches:

5. Further experiments could show that these conclusions are incomplete, or even wrong, either because the experiment was done badly or because of incomplete information.

4. From these experiments, we conclude: a. the light switch turns on the light

3. Sufficiency (or “activation”): with everything else held constant, turning on A produces B. a. Flipping the light switch up and down turns the light on and off.

2. Necessity (or “inhibition” or “ablation” or “knock out”): when A is eliminated, B never occurs. a. If you disable the light switch with the light off, the light never goes on.

1. Correlation: A and B occur in a particular order (A then B) under many conditions; for example: a. The light switch is up whenever the light is on.

b. Whenever there is electrical activity in the PBN in a rat’s brain, the rat inhales.

b. If you anesthetize the PBN in a rat’s brain, the rat stops inhaling.

b. If you electrically stimulate the rat’s PBN at a faster rate, it inhales at the faster rate.

b. electrical activity in the rat PBN causes inhalation

II. The focus of this class will be on physiological systems; i.e., how different parts of the body work together to regulate normal function.

Fig. 1.1

A. Rene Descartes (17th century French mathematician, philosopher, and physiologist), explained reflexes (e.g., pulling one’s finger away from a flame, Fig. 1.1) as mechanisms to “preserve the body’s well-being”.

• the mechanism was wrong, but the concept was right!

B. A 19th century, French physiologist named Claude Bernard found evidence that conditions inside an animal’s body are often quite different from conditions outside the body. He wrote, "The constancy of the internal environment (“milieu interior”) is required for a free and independent life”

E. The major mechanism for maintaining a variable at a nearly constant value is negative feedback.

D. Today, physiologists also talk about allostasis, because physiological values can change as conditions change a. For example, heart rate and body temperature go up during vigorous exercise. b. The new value is still very much under control; it is controlled around this new value.

C. A 20th century American physiologist named Walter Cannon studied many complex mechanisms that animals use to maintain the inside of their bodies in a different state from the external world. 1. He called the maintenance of relatively constant internal conditions homeostasis. (from Latin “homeo” meaning “alike”, or “same” and Greek “stasis” meaning “remains in place”.) 2. In fact, there normally are variations in all physiological measures over time, but in a healthy animal, the variations are relatively small and the average value remains constant.

• Another example: your blood [Na+] is nearly the same whether you drink distilled or salty water. • Example: the temperature inside your body is currently ~25-30˚F higher than the room air.

Fig. 1.2

+ means that the two components change in the same direction: if #1 decreases, #2 also decreases; if #1 goes up, #2 goes up. In other words, #1 turns on #2.

- means that the two components change in opposite directions: if # 3 decreases, #1 increases if #3 goes down, #1 goes up. In other words, #3 turns off #1.

Feedback system

Input Output

Input

Output Fig. 1.3 means

+ Input Output Fig. 1.4

Input

Output means

_ Input Output

Input

Output means Fig. 1.5

(Independent variable)

(Dependent variable)

If the temperature is higher than the set point (too warm), S – T < 0

If the temperature is lower than the set point (too cold), S – T > 0

--the furnace turns off

--the furnace turns on.

+

_

+

Comparing unit

(thermostat)

Temperature sensed

Controller (furnace)

Controlled variable

(air temp.)

Sensor (thermometer)

Set point (thermostat

setting)

+ +

A furnace and thermostat regulate temperature by a negative feedback system

Fig. 1.6

A furnace regulates when a temperature is too cold.

_+

_

+

Comparing unit

(thermostat)

Controller (air conditioner)

Controlled variable

(air temperature)

Sensor (thermometer)

Set point

(thermostat setting)

If the temperature is higher than the set point (too warm), S – T < 0 --the air conditioner turns on.

If the temperature is lower than the set point (too cold), S – T > 0 --the air conditioner turns off.

An air conditioner regulates when a temperature is too warm.

Controlling an air conditioner with a thermostat is also a negative feedback system

Fig. 1.7

_

Fig. 1.8

_

+

Using a single diagram to show how both a furnace and an air conditioner regulate the temperature around a set point.

+

_

+

Comparing unit

(thermostat)

Temperature sensed

Controller (furnace)

Controlled variable

(air temp.)

Sensor (thermometer)

Set point (thermostat

setting)

+

_ Controller

(air conditioner)

Each of the loops can be considered individually......

......by following the arrows around a single loop:

_

+Too hot: +

_

+

Comparing unit

(thermostat)

Temperature sensed

Controller (furnace)

Controlled variable

(air temp.)

Sensor (thermometer)

Set point (thermostat

setting)

+

_ Controller

(air conditioner)

+

_

+

Comparing unit

(thermostat)

Temperature sensed

Controller (furnace)

Controlled variable

(air temp.)

Sensor (thermometer)

Set point (thermostat

setting)

+

_ _

+Too cold:

Controller (air conditioner)

Fig. 1.8

_

+

Using a single diagram to show how both a furnace and an air conditioner regulate the temperature around a set point.

+

_

+

Comparing unit

(thermostat)

Temperature sensed

Controller (furnace)

Controlled variable

(air temp.)

Sensor (thermometer)

Set point (thermostat

setting)

+

_ Controller

(air conditioner)

To work properly, the set points for the furnace and the air conditioner should not be the same value.

• there is always a neutral zone or dead zone built into the system.

_

+

+

_

+

Comparing unit (in hypothalamus)

Temperature sensed

Controller (shivering)

Controlled variable

(body temp.)

Sensor (body temperature sensory neurons)

Set point (comfortable body temp.)

+

_ Controller (sweating)

Humans have comparable systems for controlling their “core” body temperature.

We have other ways to control body temp (e.g., amount of clothing, skin vasodilation), but shivering and sweating are the major ones.

Other mammals use different mechanisms (e.g., dogs shiver, but they pant rather than sweat).

Fig. 1.9

Examples of positive feedback loops.

This one has no negative signs:

Fig. 1.10 Component

#1 Component

#3 Component

#2 + +

+

This one has two negative signs that effectively cancel each other:

Fig. 1.11

Component #1

Component #3

Component #2

+

_

_