Lec 1. Introduction to Physiology

Physiology

Is the study of functions of organisms

Structural levels of organisms

* Atoms/ molecules
* Cells
* Tissues
* Organ
* Organ systems
* Organisms

Atoms/ molecules

Atoms are building blocks of matter that bond together to form compounds or molecules

Cells

Basic units of life formed by molecules

Tissues

A group of cell working together

Organs

Different types of tissues combine together to perform a function

Organ system

Several types of organ work together

Organisms

Several organ systems work together

Explain the figure

1. Start with air: air from external environment that has O2 comes to the body while CO2 comes out. Occurs at the lungs => respiratory system
2. O2 goes into blood vessels in circle movement and continues to circulate in order to pump the heart => called a circular system that circulate bloods, nutrients, O2 around, and it delivers to different cells such as nerves, muscles cells, etc…Also, 2 ways communication between cells and circulatory systems
3. Blood goes around that has filtered at kidney. Filtration occurs that creates filtrate which will travel through and then eventually concentrate because of re-absorption. Filtered into urine => urinary/ or renal system
4. Nutrients, water, inorganic ions go into the tube and happens:


1. Secretion (ex: digestive enzymes)
2. Absorption: nutrients absorb into circulatory system, and distributes to other areas like muscles and other cells in the body
3. Unabsorbed materials go down along the tube, also known as feces => digestive system

External Environment

* Components outside the body
* Ex: good (air, nutrients, water, inorganic ions); bad (urine: coming out from urine systems; and feces: coming from digestive systems that undigested materials)

Internal environment

* Components inside the body
* Ex: cell, fluid

How to separate external vs. internal environment?

* Separated them by:
* Epithelium:
* Ex: obvious (skin) >< hard to separate (lining lungs, intestinal tract, and kidney tubules)

Describe internal vs. external parts in previous figure?

* O2 in the lungs, food in stomach = part of external environment
* Until food absorbed into the body and bloodstream = internal environment
* Kidney: urine is formed from filtration and stored in the bladder. The fluid inside the bladder is an external environment

Define major concept

* Human body requires contact with the external environment
* Problems: Not all cells are in direct contact w/ external environment
* Solutions: fluid compartments => allows for cell communications (eg: one cell is filled w/ fluid, and another cell is filled w/ fluid. The fluids between them can move in and out of the cells, meaning components to be shared and communicated)

What is fluid compartments?

Total body water (TBW): volume of water contained in all the body’s compartments

How many types of fluid compartments?

1. Intracellular fluid (ICF)
2. Extracellular fluid (ECF)

Homeostasis

* Maintenance of a relatively constant internal environment (meaning to keep internal environment balance)
* Unifying them in physiology
* Disruption occurs → body no longer at ease → it’s decreased → disease

How does the body maintain the homeostasis?

Regulatory responses to maintain homeostasis

How many homeostasis control systems and their characteristics?

Two classes:

* Intrinsic/ Local controls: Inherent in an organ (ex: blood vessel can open/close by itself)
* Extrinsic/ systematic controls:
* regulatory mechanisms initiated outside organ
* involved a lot of long distance systems: uses endocrine and nervous systems
* ex: blood vessels open up by a hormone or electrical impulses caused by a neuron → called extrinsic control since blood vessels are regulated by the outside using other systems

What are advantages of extrinsic control?

* Coordinate response from several organs → common goal (eg: rather just having blood vessels control itself, the endocrine and nervous system can control the blood vessels but also control the heart and the lungs at the same time to coordinate or achieve a common goal)

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What are regulated variables?

* Conditions regulated by homeostatic control
* Ex: temp, pH, salinity, dissolved gas conc., nutrient and waste conc.

What is the set point? Give examples?

* Is the range for a regulated variable that the body wants to maintain
* ex:
* body temp: 37C
* blood glucose: 100 mg/ml
* Blood pH: 7.35-7.45

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What will happen if set out go out of range? Give example.

* error signals: deviation from the set point
* ex: if body temp is supposed to be 37C, but it climbs to 39C, then 2 degree deviation is error signal
* once you have error signal, it will take a homeostatic response

List components of homeostatic response?

1. Stimulus: deviation/or changes from set point (error signal)
2. Sensor: detects stimulus
3. Integrating center


1. receives inputs from receptors
2. determines needed output to effectors
3. usually is the nervous system
4. Effectors: receives output to respond to stimulus

Describe how homeostatic response takes place in the example of driving watermelon juice everyday?

Blood glucose level is normal. Drinking watermelon juice causes glucose level increases, causing error signals:


1. Stimulus: glucose from watermelon juice
2. Sensor: beta cells of pancreas which detect the increase of glucose level in blood
3. Integrating center: beta cells of pancreas which take information of high blood glucose levels and determine the need output (insulin). Insulin goes to blood and binds to effectors (muscle cells, adipose tissues, liver cells,…) since output communicates to the effectors
4. Effectors: after receiving insulin, the effectors respond to the glucose levels by uptaking glucose and remove it from the blood, lowering your blood glucose and getting back to the initial set point

What is feedback?

Response made after change detected

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How many types of feedbacks?

Two types:

* Negative feedback
* Positive feedback

What is negative feedback? Give examples.

* response moves the system in the opposite direction of the initial change
* stabilizing: keeps things at a particular set point since whenever deviation sets a particular direction, the responses move it the opposite direction
* More common in the body
* Ex:
* Blood glucose level (fig: initial change is increase blood glucose, but the response is decrease blood glucose in opposite direction)
* Regulate body temp
* body temp goes up → responses move temp down
* cold → temp down → response move temp up → shivering

What is positive feedback? Give examples.

* Response moves the system in the same direction as the inital changes
* Directional
* Less common
* Ex:
* Childbirth: keeps increasing oxytocin until done in delivery of the baby
* Ovulation

What is diabetes?

* Blood glucose levels: cannot be regulated normally
* Urine volume: urine draws water away from your body and dehydrates, causing urine to be higher volume => Diabetes people usually urinate more frequently

What are results of diabetes?

* Excessive thirst
* Excessive fluid loss
* Eventually all body system affected

How many types of diabetes?

4 types:

* Diabetes Mellitus Type I
* Diabetes Mellitus Type II
* Gestational Diabetes
* Diabetes Insipidus

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What is diabetes mellitus I?

* Inadequate insulin production (generally in younger)
* (eg: insulin produced by beta cells in pancreas. For some reasons, the immune system starts to attack the beta cells, meaning they no longer have many beta cells and resulting in inadequate insulin production. Since you don’t produce enough beta cells in pancreas, the glucose is to high, leading to diabetes)
* Insulin dependent

What is diabetes mellitus type II?

* Body cells lose response to insulin
* Non-insulin dependent
* Most common

What is gestational diabetes?

* Temporary loss of sensitivity to insulin due to hormonal changes

What is diabetes insipidus?

* Inadequate antidiuretic hormone secretion → high urine volume
* Rare
* Anti-diurectic is a hormone that stops urinating, hence it makes you re-absorb your fluids more. No issues w/ insulin or glucose levels, but it’s about high urine volume

How can you develop diabetes?

* Obesity:
* High fat content relative to lean body mass
* Body mass index (BMI): 30-39
* BMI = body weight (kg) / height (m^2)
* Sedentary lifestyle (inactive lifestyle)

What is intracellular fluid? (ICF)

Fluid inside the cells

What is extracellular fluid (ECF)? How many types of ECF?

1. fluids outside cells
2. includes:


1. Plasma: liquid (non-cellular) portion of blood


1. ex: blood vessel has red blood cell and fluid surrounding those red blood cells. This fluid is called plasma and it’s a type of ECF
2. Interstitial fluid (ISF): fluid surrounding cells anywhere in the body, but not in blood vessel

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