I. Cell Physiology

Physiology

· normal processes or functions of living thing

Two Main Goal of Physiology

[1] Understand and predict the body's response to stimuli

[2] Understand how the body maintains conditions within a narrow range of values in the presence of a continually changing

Structural and Functional Organization of the Body

chemical, cell, tissue, organ, organ system, organism

Major Organ Systems

- Integumentary
- Skeletal
- Muscular
- Nervous
- Endocrine
- Circulatory
- Lymphatic
- Immune
- Respiratory
- Digestive
- Urinary
- Reproductive

Characteristics of Life

(1) organization,
(2) metabolism,
(3) responsiveness,
(4) growth,
(5) development,
(6) reproduction

Organization

· Condition in which the parts of an organism have specific relationships to each other and parts interact to perform specific function

Disruption of this organized state can result in

· loss of functions and death

Ex:
1. Tetanic Contraction of Muscle
2. Heart Cardiac Arrest

Cardio-Pulmonary Circulation

blood circulation through the heart and lungs

Pulmonary Circulation

Tissues - [Gas Exchange; carry deoxygenated blood]
Venules -
Veins -
Vena Cava -
Right Atrium - Tricuspid Valve
Right Ventricle - Pulmonary Valve
Pulmonary Artery - carry deoxygenated blood
Lungs [Gas Exchange from Alveoli; carry oxygenated blood] -
Pulmonary Veins - carry oxygenated blood
Left Atrium - Bicuspid Valve

Systemic Circulation

Pulmonary Veins - carry oxygenated blood
Left Atrium - Bicuspid Valve
Left Ventricle - Aortic Valve
Aorta - Largest Artery
Arterioles - Smaller Artery
Capillaries - site of nutrient exchange
Venules -
Veins -
Target Tissues - supply oxygenated blood; becomes deoxygenated after

Metabolism

· Sum of all chemical and physical changes taking place in an organism.

Example:
Catabolic and Anabolic Metabolism

Anabolic

Building up of smaller molecules into even larger molecules
Ex: Gluconeogenesis and Glycogenolysis

Catabolic

Broken down of larger molecules into its monomer
Ex: Glycolysis and Glycogenesis

Glycolysis

Oxidation of glucose to pyruvate [anaerobic] and acetyl coa [aerobic]

· Aerobic and Anaerobic Conditions
· Occurs in Cytoplasm
· Utilizes Glucose
· End Product
o 2 ATP's [4 ATP's]
o 2 NADH
o 2 Pyruvate

Glycolysis Pathway

Glucose -
Glucose 6-phosphate -
Fructose 6-phosphate -
Fructose 1,6-biphosphate -
[Dehydroxyacetone phosphate -
Gllyceraldehyde-3-phosphate]

1,3-biphosphoglycerate -
3-phosphoglycerate -
2- phosphoglycerate -
Phosphoenolpyruvate -
Pyruvate -

Glycogenesis

Synthesis of glycogen from glucose, when glucose level is high

Glycogenolysis

Degradation of glycogen into glucose when glucose is in short supply

Gluconeogenesis

Formation of glucose from non-carbohydrate compounds including pyruvate, lactate, glycerol, glycerol phosphate and amino acids.

Responsiveness

· Ability of an organism to sense changes in its external or internal environment and make the adjustments that help maintain its life

Ex:
A. NA-K+ Pump
B. Vasodilation - in response to increase muscle activity
C. Gas Exchange

Vasodilation

· BV increased in Diameter
· Increased Permeability of Blood Vessels - has an easy capillary exchange or gas exchange
· Decreases resistance to blood flow
· Increases the blood flow

Gas Exchange

Diffusion which requires Electron Chemical Gradient
· Depends on Concentration Gradient that runs from higher concentration to lower concentration.
· Result: Blood Becomes Oxygenated
o Increase O2; Decrease CO2 [exhaled]

Growth

· Results in an increase in size of all or part of the organisms

Development

· Includes the changes an organism undergoes through time
· It begins with fertilization and ends at death

Reproduction

Formation of new cells or new organisms

Homeostasis

· Homeo - the same + stasis - standing

· Existence and maintenance of a relatively constant environment within the body

· It is the property of a system to try to maintain constancy in the face of external perturbations

Variables

temperature, volume and chemical content

Deviation of Set Point

· cells do not function normally and can even die. Disease disrupts homeostasis and sometimes result to death.

Example
- Exceeds Upper Limit [Hyperthermia]
- Lower than the Lower Limit [Hypothermia]

Types of Body Fluid

ICF (Intracellular Fluid)
ECF (Extracellular Fluid)

ICF (Intracellular Fluid)

the fluid inside our cells. most protein located here. [2/3]
· K, Mg, and Phosphate

ECF (Extracellular Fluid)

all body fluids other then ones inside our cells. subdivided by location.

Two Types of ECF
A. Intercellular (Interstitial)
· In between cells

B. Intravascular (Plasma - fluid component of blood)
· Inside the blood vessel (blood)
· Na, Cl, Bicarbonate, 02, Glucose and CO2

ECF Transport System : The Circulatory System - Two Stages

· 1st Stage: movement of blood through the body in the blood vessel [Pulmonary]

· 2nd Stage: movement of fluid between the blood capillaries and the cells [Systemic]

· Na and K can free pass-through

Ion Channel

· Plasma Protein cannot due to several factors

o Size (Large Molecules)
o Charge (Negatively Charge)

Under pathologic condition, plasma protein can move outside the space, called

EDEMA FORMATION or Pamamanas

EDEMA FORMATION happens when

· There is a decrease in diameter of BV
· Increase resistance, causing
· Decrease Blood Flow, causing
· Increased Time of the blood to be stocked - causing leaking in Interstitial Space
· Increased fluid in the Interstitial Space introduces EDEMA causing PAMAMANAS

Diffusion

· is caused by kinetics motion of molecules in both the plasma and the interstitial fluid

Origin of Nutrients in the ECF

-Respiratory: O2
-GI: carbs, fatty and amino acids
-Liver: detoxification

Glucose in the Liver can undego

1. Glycogenesis - conversion of glucose into Glycogen - stored carbohydrate

2. Glycolysis - [aerobic metabolism] conversion of glucose into Pyruvate - then into Acetyl CoA to further produces ATP

3. Lactate - [anaerobic metabolism] conversion of pyruvate without the presence oxygen to provide energy.

However, excess lactate is not good. Thus, it needs to be converted back to glucose via blood to the Liver.

Will undergo Cori Cycle to converts lactate into pyruvate [lactose dehydrogenase] then into glucose [gluconeogenesis].

Glucose produced by the liver can be transported by the blood into the muscle.

Removal of Metabolic End Products

- lungs (CO2) through exhalation or respiration
- kidneys (urea, uric acid, excess of some ions)
- GI tract
- liver

Kidney's Nephron Pathway

Afferent Arterioles
Glomerulus [Filtration]
Efferent Arterioles
Peritubular Capillaries

Filtrate

H2O, Cl, Na, K, Glu, AA, Urea
[moves through the PCT - Loop of Henle - DCT - Collecting Duct - production of waste urine]

Direction of Reabsorption and Secretion

Reabsorption - From Renal Tubule to Blood [molecules that are needed by the body]

Secretion - From Blood to Renal Tubule [molecules that are for excretion]

Regulation of Body Function

nervous system and hormonal system

Nervous System

Types of Nervous System
A. Somatic NS - conscious control; skeletal system
B. Autonomic NS - unconscious control; cardiovascular, respiratory and digestive system

Autonomic NS - unconscious control

a. Sympathetic
Fight or Flight Mechanism - prepares the body into a stressful situation - increased heart rate

b. Parasympathetic
Rest and Digest - control Heart and GIT

Heart

Sympathetic NS
Increase heart contractility - result into an increase heart rate
[response to exercise]

Parasympathetic NS
Slows contractility and decrease the heart rate

In response to Exercise

Increased Muscle Activity;
Increased CO2; Decrease O2 [stimuli]
Detected by chemoreceptor
Sensory Neuron - transmit info the CNS
CNS decides Sympathetic NS
· Target Organ: Heart
· [1] Increased Muscle Contractility
· [2] Increased Heart Rate - supply blood to tissues; resulted to an Increase Oxygen and Decrease Carbon Dioxide
· [3] Increased Respiratory Rate

GIT

Sympathetic NS
Production of thick viscous saliva;
Inhibits the contraction of smooth muscle;
Adrenal Rush

Parasympathetic NS
Supports digestion;
increase production of thin copious saliva
supports the contraction of smooth muscle

Hormonal System

· Endocrine glands that secrete chemical substance called Hormones

Hormones are produced by Ductless Glands

Difference between Nervous and Hormonal Systems

Hormonal
Muscular and secretory activities
Slow speed of action
Longer duration of action - due the presence of hormone

Nervous
Metabolic function
Fast and immediate action
Short duration of action

The Body's 2 Control Systems

Nervous and Endocrine System
· allow for 4 different types of biological reflexes
o Simple (pure) nervous
o Simple (pure) endocrine
o Neurohormone
o Neuroendocrine

Control System of the Body

1. Genetic Control System

2. Control system that operates within the organ to control function of individual portion of the organ

3. Control system that operates throughout the entire body to control interrelation between organs

a. e.g. Respiratory System operating with nervous system to regulate concentration of carbon dioxide in ECF

b. e.g. Liver and Pancreas regulate the concentration of glucose in the ECF

c. e.g. Kidney regulates concentration of H, Na, K, phosphate and other ions in the ECF

Liver and Pancreas

If there is an increase GLUCOSE

[Beta Cells of Pancreatic Islets] - type of ductless glands
- release INSULIN [a type of hormone which lowers down the rate of glucose in the blood]

Insulin - moves with blood through the Liver
- Insulin creates a transported - GLUT4 which creates a pathway for glucose to enter the liver.

- Glucose in the liver is converted to glycogen via glycogenesis, thereby regulating the rate of glucose in the blood

Diabetes Mellitus

insulin is not secreted adequately or tissues are resistant to its effects

Diabetes Mellitus
Type 1 - Genetic Cause
Type 2 - Insulin Resistance [insulator does not work]

Causes: [1] No Insulin produces
[2] there is resistance to insulin

Kidney

organ that removes urea, excess water, and other waste products from the blood and passes them to the ureter.

involved in Acid Base Balance

Metabolic Acidosis

- increased level of acid in blood (circulating)
· Increase Hydrogen = Decrease in pH Acid
· CO2 is the source of Hydrogen
· Through Co2 + H20 = H2OO3 where H is hydrogen and HCO3 is Bicarbonate
· Can be removed through secretion in kidney via Urine
· Lowers down the level of hydrogen - which maintains homeostasis

Metabolic Alkalosis

- low level of acid in blood
· Decrease Hydrogen = Increase in pH Acid
· Kidney reabsorbs hydrogen that adds in the blood

Two types of Homeostatic Feedback Loops (Systems)

1. Negative (loop) Feedback Mechanism
· Homeostatic - maintenance of constancy

2. Positive (Loop) Feedback Mechanisms
· Not homeostatic - makes the certain deviation greater

Components of Feedback Loops

1. Receptor: monitors the value of some variable
Ex: Chemoreceptor; Thermoreceptor; Baroreceptor; Mechanoreceptor

2. Control Center: establishes the set point
Ex: Nervous System

3. Effector: can change the value of the variable
Ex: Heart; Lungs

4. Stimulus
deviation from the set point; detected by the receptor

5. Response
produced by the effector

Reflex

1. Response Loop
2. Feedback Loop

Purpose: keep system near a "Set Point"
o Maintain the value within the normal range

Responses at Two Levels

1. Cellular Response at Target Cells
· opening or closing of the channels
· modification of an enzyme

2. Systemic Response at Organizational Level
· vasodilation or vasoconstriction
· increase or decrease in blood pressure

Negative Feedback

a mechanism of response in which a stimulus initiates reactions that reduce the stimulus

· Nature of Most Control System
· Negate the initiating factors or stimulus

Examples:
regulation of blood pressure, body temperature, and blood sugar levels

Regulation of Blood Pressure

· Low BP - detects by Baroreceptor - transmit to Sensory Neuron - then the CNS [cardio regulatory center] - Motor Neuron - Target Tissue [Response: Relaxation of Arterial Wall]

Decrease in Blood Pressure

Relaxation of Arterial Wall [Autoregulatory Response]
· Results in Vasodilation
· Increase Diameter of BV
· Decreases the Resistance
· Decreases Blood Pressure
· Better Blood Flow - which maintains the supply to the tissues

Rise in Blood Pressure

Constriction of Arterial Wall
· Increase Blood Pressure;
· Causes Turbulent Flow; disturbed flow of blood
· Factor that causes Aneurysm - which weakens the vascular wall
· Result in Vasoconstriction
· Decrease the Diameter of BV
· Increase the Resistance
· Decreases the Blood Flow - limit the increase blood flow

Atherosclerosis

- block deposition of LDL; cholesterol; calcium deposits.
· Decrease the diameter - leads to High Blood Pressure
· Causes Turbulent Flow of Blood
· Sclerosis - means Narrowing

Positive Feedback

A physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change.

· Also known as vicious cycle
· When a deviation occurs, the response is to make the deviation greater
· Does not lead to stability but to instability and often death

Examples:
Blood Clotting, Child Birth, Generation of Nerve Impulse

Blood Clothing

Causes Muscular Spasm
· Contraction of Muscular Wall;
· Which causes Vasoconstriction

VASOCONSTRICTION
· Decrease Diameter of BV
· Increase Resistance to BF
· Decrease Blood Flow
· Aims to create a PLATELET PLUG - as temporary seal before the recruitment of blood clothing factors
· Creates Fibril Cloth - which permanently seal the damage area
o Does not cause hemorrhage

Childbirth

Causes Cervical Stretch - mechanical stimulus - transmit to Sensory Neuron - to CNS [Hypothalamus] - produces Oxytocin - will be given to Posterior Pituitary Gland - which secreted the hormone Oxytocin - through the bloodstream - to the Reproductive System Part - Uterus - Oxytocin causes contraction; pushing fetus down to the vaginal canal that causes Cervical Stretch.

Harmful Effects of Positive Feedback

[1] After Hemorrhage
[2] Blood Pressure Drops
[3] Hearts Ability to Pump Blood

half

Response loop is of -reflex

cellular response at target cells

-opening or closing of channels

-modification of an enzyme

Systemic response at organizational level

vasodilation or vasoconstriction

increase or decrease in blood pressure

Receptor

-monitors The value of some variable

control center

-establishes the set point

Effector

can change the value of the variable

stimulus

deviation from the set point, detected by the receptor

Response

produced by the effector