BSC-2010 Lecture Notes - Lecture 11: Stethoscope, Arteriole, Basophil

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2 Dec 2016

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Physiology — the science of biological function
Function: has a strutural (anatomical) basis… at the organ, cellular & molecular levels
Homeostasis — maintaining a constant internal environment
It applies to organisms
Hierarchical levels of structural organization in a complex - emergent properties
Convergent evolution in fast swimmers
Physical laws (hydrodynamics in this case) constrain the evolution of biological
Direct exchange with the environment
Physical constraint in simple, multicellular organisms (no circulatory system)
Distance over which diusion is an eect transport mechanism (at least for small
molecules) —> high surface area to volume ration
Internal exchange surfaces of complex animals
In humans, or very very large cells, diusion is not an ecient process
It cannot supply all of the oxygen and food and nutrient molecules that you need,
and it cannot remove all of the carbon dioxide that you need….
You need a respiratory system and circulatory system to function adequately
Circulatory System
It circulates the nutrients (from digestion) around in the blood
The circulatory system is central to the respiratory and excretory system
Respiratory System
It releases CO2 through the respiratory system, and circulates O2 throughout the
body through the circulatory system
Excretory System
Gets rid of the waste molecules
Includes the kidneys
Structure and Function in Animal Tissues: Epithelial Tissues
These are the types of tissues open and interacting to/with the environment
Digestive system
Respiratory system
Simple vs. Stratified
Simple - one layer
Stratified - many man cells
Examples include the lining of the mouth and the skin itself
Typically are cells exposed to the environment because of
abrasion and cells rubbing o
Squamous vs. Cuboidal vs. Columnar
Cuboidal - cube like structure
Typically associated with the excretory system
Columnar - column like structure
Typically associated with the digestive system
Squamous - flat cells
Found where diusion typically occurs
*Pseudo stratified columnar - not a single layer, but not stratified in the
sense that it has many layers
Note the structural polarity
There is a very clear orientation in their molecular function
Structure and Function in Animal Tissues: Muscle Tissue
Skeletal Muscles
Allow you to move, allow you to lift thing, allow you to chew
Voluntary movements
Make up a great deal of the body’s muscles
Has to do with the contractile elements of the skeletal muscle
The largest type of muscle cells
Cardiac Muscles
Cells tend to be quite a bit smaller than the skeletal fibers
Reflect a high degree of organization of the contractive proteins
Involuntary movement, you don’t have to think about your heart beating
for it to beat
Smooth Muscles
They are called smooth because they do not have striations
The smooth muscles are the smallest type of muscle cells
Found in many places in the body; tends to be found in places where the
motions occur on their own
In an involuntary nature
Example: digestive system
Structure and Function in Animal Tissues: Nervous Tissue
Consists of dendrites, cell body, and axon
Take in information at the dendrites
Information transmitted along the neuron and to other cells through
the axon
An electrosignal travels down the axon; called an action potential
Glial Cells
Structure and Function in Animal Tissues: Connective Tissues
Sparse population of cells scattered through an ECM
Examples include: bones, adipose tissue, cartilage tissue, collagenous fiber, fibrous
connective tissue, and blood
Adipose tissue - a fat tissue that stores lipids
Blood - considered a connective tissue because of the cell type it derives from; it
also connects all parts of the body by circulating
Organ Systems in Mammals - Main Components and Functions
Digestive System
Main components:
Mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, anus
Main functions:
Food processing - ingestion, digestion, absorption, elimination
Circulatory System
Main components:
Heart, blood vessels, blood
Main functions:
Internal distribution of materials
Respiratory System
Main components:
Lungs, trachea, other breathing tubes
Main functions:
Gas exchange - uptake of oxygen; disposal of carbon dioxide
Immune and Lymphatic System
Main components:
Bone marrow, lymph nodes, thymus, spleen, lymph vessels
Main functions:
Body defense - fighting against infections and cancer
Excretory System
Main components:
Kidneys, ureters, urinary bladder, urethra
Main functions:
Disposal of metabolic waters; regulation of osmotic balance of blood
Endocrine System
Main components:
Pituitary, thyroid, pancreas, adrenal, and other hormone-secreting glands
Main functions:
Coordination of body activities - such as digestion and metabolism
Reproductive System
Main components:
Ovaries or testes and associated organs
Main functions:
Nervous System
Main components:
Brain, spinal cord, nerves, sensory organs
Main functions:
Coordination of body activities; detection of stimuli and formulation of
responses to them
Integumentary System
Main components:
Skin and its derivatives (hair, claws, skin, glands)
Main functions:
Protection against mechanical injury, infection, dehydration;
Skeletal System
Main components:
Skeleton - bones, tendons, ligaments, cartilage
Main functions:
Body support, protection of internal organs, movement
Muscular System
Main components:
Skeletal muscles
Main functions:
Locomotion and other movement
Not that many dierent cell types in an individual, but all came from one fertilized egg
cell, with one genome (DNA sequence): dierentiation
Communication and Control in Complex Organisms
Signaling in the endocrine and nervous systems
Chemical vs. Electrical + Chemical
Insulin Secretion - Endocrine/ chemical signaling
There is a signal in your blood that triggers how much insulin is needed to
be released
Your pancreas releases the insulin which travels in the blood, and certain
cell types respond to the insulin
Neurons - Electrical signal
One neuron can initiate an electrical signal
*note: there are mechanical signals also
Circulatory System
Concentration gradient is driving force for transport of small molecules (e.g.
glucose, Ca2+) over short distances (e.g., minimum dimension of a cell)
Pump (heart) generates hydrostatic pressure to transport (bulk flow) blood (or
hemolymph) to all cells of a complex organism
Internal exchange surfaces of complex animals
Open and closed circulatory systems
An open circulatory system
A closed circulatory system
Single versus Double circulation in vertebrates
Single circulation: Fish
Heart chambers - 2
Double circulation: Amphibian
Heart chambers - 3
Double circulation: Mammal
Heart chambers - 4
The mammalian cardiovascular system
Superior vena cava
Pulmonary artery
Capillaries: endothelium
Like a simple squamous epithelium
Allows for the diusion of small molecules
Pulmonary veins
Right atrium // left atrium
Right ventricle // left ventricle
Inferior vena cava
The human cardiac cycle:
(1) Atrial and ventricular diastole
(2) Atrial systole and ventricular diastole
(3) Ventricular systole and atrial diastole
Electrical control of human heart rhythm and one component of cardiac output
(1) Signals (yellow) from SA node spread through atria
(2) Signales are delayed at the AV node
(3) Bundle branches pass signals to heart apex
(4) Signals spread through ventricles
Cardiac output (ml/min) = heart rate (beats/min) x stroke volume (ml/beat)
Mammalian Heart: A closer look — TRACE THE PATH OF BLOOD THROUGHOUT THE
The structure of blood vessels: 3 main components
(1) Connected tissue layer on the outside
Adds strength and structure as well as elasticity
(2) Smooth muscle
When it contract, is constricts the artery
(3) Internal layer - Endothelium
Only one cell thick
Influences the contractile or relaxation of the muscle
The arteries tend to have quite a bit of smooth muscle; the pressure here is the highest
They deal with major pressure as well as pressure fluctuations
They must have some elasticity in them
Small diameter
Makes up a capillary bed
Allows for the diusion of oxygen and carbon dioxide
Their functions is to keep the blood moving in one direction so that you do not
have backwards blood flow
The interrelationship of cross-sectional area of blood vessels, blood flow velocity, and blood
Blood pressure = hydrostatic pressure
As blood moves through the ….
Aorta: the blood pressure is quite high
Diastolic 80 // Systolic 120
Arteries: the blood velocity is pretty fast
Arterioles: the blood velocity decreases
Capillaries: major decrease in blood velocity; this will be significant for the
delivery of nutrients
Venues & veins: pressure continues to drop
The systemic blood pressure varies in a time dependent manner
Blood pressure is the driving force that moves blood through the circulatory system
*** IMPORTANT graph
Measurement of blood pressure
(1) Cu inflated with air
Pressure in cu greater than 120 mm Hg
Artery closed
(2) Pressure in cu drops below 130 mm Hg
Sounds audible in stethoscope
This means that the pressure in the cu is about equal to the pressure in
the arteries
You get turbulent flow of the blood
This is the systolic pressure
(3) Pressure in cu below 70 mm Hg
Sounds stop
This is your diastolic pressure
* systolic/diastole (units = mm Hg)
Systolic is the higher one, typical number is 120
The blood pressure that you’re measuring in the brachial artery should be pretty close
to what the blood pressure is in the heart
CV functional implication from variation in systolic and diastolic BP
Control of blood flow in capillary beds
Blood flow itself is controlled very often at the level of individual capillary beds
When the sphincters are relaxed… blood flows
Delivers oxygen to the parts of the body in need
When the sphincters are contracted… this reduces blood flow
Increased peripheral resistance
Peripheral Resistance
Whether the sphincters are controlled ore relaxed aects this
Blood flow in veins
Direction of blood flow in vein - towards the heart
Has valves
These ensure that blood flows in only one direction
Most important valves would be found in your legs
Moves blood down to your feet but also responsible for moving blood up
to your head and back to your heart
There is less pressure moving the blood back up again
There are also skeletal nucleases (like in the legs)
When they contract it squeezes the veins
Pushes the blood out of the open valve
Skeletal muscles are an accessory pump in the circulatory system
Composition of mammalian blood — a complex fluid that is a specialized connective tissue
Plasma = 55 %
Major functions:
Ions (blood electrolytes_
Includes sodium, potassium, calcium, magnesium, chloride, and
Major functions:
Osmotic balance
pH buering
Regulation of membrane permeability
Plasma proteins
Includes albumin, immunoglobulins (antibodies),
Major functions:
Osmotic balance (albumin)
pH buering (albumin)
Defense (immunoglobulins)
Lipid transort (apolipoproteins)
Clotting (fibrinogen)
Substances transported by the blood:
Nutrients (such as glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Cellular elements = 45 %
Cell Type:
Leukocytes (white blood cells)
Number per uL of blood
Defense and immunity
Number per uL of blood
Blood clotting
Erythrocytes (red blood class)
Number per uL of blood
Transport of O2 and some CO2
Fluid exchange between capillaries (across endothelium) and the interstitial fluid
Human lymph nodes and vessels
Lymphatic system returns some intestinal fluid to the cardiovascular system
Role in cardiovascular system and helps protect against infection (role in immune
Dierentiation of blood cells
Stem cells (in bone marrow)
Lymphoid stem cells
Lymphocytes - B cells and T cells
Antibody production
Myeloid stem cells
RBCs = erythrocytes
Biconcave shape (high SA:vol)
Anaerobic metabolism
No mitochondria
O2 transport via hemoglobin (Hb)
> 10^8 molecules per RBC
Clotting (coagulation)
Neutrophils, basophils, monocytes, eosinophils
Heart attack (myocardial infarction) - blockage of heart (coronary) arteries
Stroke (“brain attack”) - blockage or rupture of arteries supplying brain
Risk factors:
Hypertension (high blood pressure)
High cholesterol/triglycerides
Dietary fat
Low density lipoproteins (LDLs) (“bad cholesterol”)
Note “good cholesterol” = high density lipoproteins (HDLs)
Sedentary lifestyle
What makes “bad” cholesterol (LDL) “bad”, and “good” cholesterol (HDL) “good” for your
cardiovascular system?
Inflammation is the first response of the immune system to infection or irritation
LDL is pro-inflammatory
HDL is anti-inflammatory
Atherosclerotic plaques develop in a blood vessels wall, in part, in response to
LDLs inflammatory signals
Inserting a stent to widen an obstructed artery
(1) A stent and a ballon are inserted into an obstructed artery
(2) Inflating the ballon expands the stent, widening the artery
(3) The ballon is removed, leaving the stent in place
Increased blood flow
Ballon catheterization
Some stents are medicated (drug-eluting stents) to prevent/slow regrowth of the
blocking plaque
Gas Exchange
Internal exchange surfaces of complex animals
Diversity in the structure of gills, external body surfaces function in gas exchange in aquatic
Diverse structures, but common feature: large surface area
The structure and function of fish gills:
Countercurrent exchange - note the O2 gradient throughout the gill
It is a highly eective mechanism for increasing the amount of O2 taken up
by the water
The gradient always allows for water to be taken up
The mammalian respiratory system
Moist surface for gas exchange
Large surface area
Loading and unloading of respiratory gases:
(1) Inhaled air
(2) Alveolar spaces
(3) Pulmonary viens and systemic arteries
(4) Body tissues
(5) Pulmonary arteries and systemic veins
(6) Exhaled air
Partial pressure of a gas:
Atmospheric pressure of all gasses = 760 mm Hg
PO2 = 21%
PO2 = (.21)(760) = 160 mm Hg
Oxygen dislocation curves for hemoglobin at human body temperature (37 C)
Mechanics of breathing (ventilation): Negative pressure breathing
Rip cage expands as rib muscles contract
Diaphragm contracts
Rib cage gets smaller as rib muscles relax
Diaphragm relaxes (moves up)
Tidal Volume = normal breath
Total Lung Volume = vital capacity + residual volume
Carbon Dioxide (CO2) transport in the blood
Enzyme: carbonic anhydrase
Catalysts reactions
pH buering: Hb and carbonic acid/bicarbonate
CO2 transport
7% dissolved in plasma
Dissolved in plasma as bicarbonate (HCO3)
5% bound to Hb
Homeostatic control of breathing - homeostasis = maintaining internal balance
Normal blood pH = about 7.4
Blood pH falls due to rising levels of CO2 in tissues (such as when exercising)
Medulla detects decrease in pH of cerebrospinal fluid
Sensors in major blood vessels detect decrease in blood pH
Medulla receives signals from major blood vessels
Signals from medulla to rib muscles and diaphragm increase rate and depth of
Blood CO2 level falls and pH rises
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