Physiology Exam 4

arteries

carry blood away from the heart
closest to heart
large amounts of elastic and fibrous connective tissue; large amounts of smooth muscle
can withstand high blood pressure
volume varies with contraction and relaxation

veins

carry blood to the heart
large lumens with thin walls
less connective tissue and smooth muscle than arteries
comparatively lower blood pressure than in arteries
vessels are furthest from the heart

Pericardium

3 layer membrane around heart that protects, connects, and secretes lubricant

vena cava

2 (superior and inferior)
bring blood from the body to the heart

pulmonary arteries

exception to naming rule (carrying deoxygenated blood away from the heart)
carry blood from the heart (right ventricle) to the lung

pulomonary veins

exception to naming rule (carrying oxygenated blood to the heart)
carry blood from the lungs to the heart (left atrium)

aorta

main artery
transport blood from the heart (left ventricle) to the body

AtrioVentricular valves

separate the atria from the ventricles

Semilunar valves

separate the ventricles from the aorta and pulmonary artery

path of blood flow

vena cava
right atrium and right AV valve
right ventricle and pulmonary semilunar valve
pulmonary arteries to lungs
pulmonary veins from lungs
left atrium to left AV valve
left ventricle to aortic semilunar valve
exit through aorta

pulmonary circulation

begins with deoxygenated blood returned from the body to the right atrium of the heart where it is pumped out from the right ventricle to the lungs

systemic circulation

oxygenated blood through pulmonary veins to left atrium to left ventricle and out through aorta to the body

diastole

relaxation of the muscle to allow the chambers of the heart to fill with blood

systole

contraction of the muscle that pushes about 60% of the blood from the chamber

What are key differences in tissue composition and blood pressure gradient between arterial and
venous side of circulation?

blood pressure in arteries is much higher than in veins due to receiving blood from the heart after contraction
arteries are thicker; veins have less smooth muscle and connective tissue

myocardial

cardiac muscle cells
striated, only have 1 nucleus per cell, branched, connected by intercalated disk (desmosomes and gap junctions)

desmosomes

provide structure and adhesion

gap junctions

provide rapid cell-cell communication

Autorhythmic cells

pacemakers
generate action potentials, signal for contraction
smaller and fewer contractile fibers compared to contractile cells
do not have organized sarcomeres

Cardionyocytes

contractile cells
striated fibers organized into sarcomeres

How does the anatomy of the cardiac conduction system contribute to the pathway of electrical
signaling and resulting coordination of blood pumping?

action potential waits for ventricles to fill before going on to the atrioventricular node
atria contracts a second before the ventricles so their blood empties into the ventricles before the ventricles contract

What is the main cellular feature that makes pacemaker signals automatically fire action
potentials?

depolarization-repolarization cycle is continuous; no stable resting period
ion funny channels that let both Na+ and K+ through

cellular mechanism causing the charge plateau

Ca2+ channels and fast K+ channels close
creates plateau where the cell cannot depolarize again

contractile cardiac muscle cells

more "normal" mechanism of action potentials
lower resting potential, longer peak because of Ca2+ entry

electrocardiogram (ECG)

summed electrical activity of all heart cells
SA nose sets pace of heart beat at 70 bpm

P-wave

depolarization of atria

QRS complex

wave of ventricular depolarization and atrial repolarization

T-wave

repolarization of ventricle

cardiac muscle cells

striated; sarcomeres; heart muscle; uninucleate, shorter branching fibers; gap junctions and intercalated disks; pacemaker potential

skeletal muscle cells

striated; sarcomeres; attached to bone; multinucleate, large cylindrical fibers; gap junctions

smooth muscle cells

smooth; no sarcomeres; forms the walls of hollow organs and tubes; uninucleate, small spindle-shaped fibers; longer myofibrils; pacemaker potential

What type of muscles help control blood flow thru blood vessels?

vascular smooth muscle

“blood pressure reservoir”

arteries -> thick walled, help in regulating blood flow and the blood pressure

"variable resistance”

arterioles
the resistance in the circulatory system that is used to create blood pressure, the flow of blood and is also a component of cardiac function

blood volume reservoir

veins, nearly 60% of total volume in human volume is in the veins
can be mobilized to boost cardiac output

arterioles

smaller than arteries; move blood from arteries to capillaries
contain little connective tissue; large amount of circular smooth muscle
constricts to close, relaxes to open
contributes to body temperature homeostasis and oxygen regulationc

capillaries

location of exchange
smallest and most numerous blood vessels
no muscle or connective tissue
consist of lumen formed by epithelial tissue; single cell layer thick
simple structure allows exchange of materials (nutrients and wastes) between cells and blood
lowest density in cartilage and subcutaneous tissues
highest density in muscles and glands

continuous capillaries

endothelial cells joined with leaky junctions
junctions allow water and small dissolved solutes to pass through
found in muscle, connective tissue, and neural tissue

fenestrated capillaries

large pores
found in kidneys and intestines

Transcytosis

brings proteins and macromolecules across endothelium
some vesicles may fuse to create temporary channels

venules

transport blood from capillaries to veins
smaller than veins; no visible to the naked eye
contain little connective tissue and little smooth muscle
some exchange with cells here

Do capillaries vasodialate?

No, capillaries can not dilate or constrict

What is the role of the lymphatic system with respect to capillary exchange?

lymphatic system get fluid lost by the capillaries back to the circulatory system

What is the most important function of capillaries and what are some cellular features that can
aid this function?

allow the exchange of nutrients and wastes between the blood and the tissue cells, together with the interstitial fluid
hydrostatic pressure from heart forces things out on arterial side
osmotic pressure dominates on venus side allowing for reabsorption

What is a skeletal muscle pump and what function does it serve?

help maintain venous return and consequently cardiac output by compressing underlying veins in order to increase blood flow back to the heart

plasma

55% of blood and 92% of that is water
made up of water, ions, organic molecules, trace elements and vitamins, gases

Cells in blood

45% of blood is cellular elements
red blood cells, white blood cells, platelets, and cell fragments

Erthrocytes

most abundant cell in body (about 5 billion per ml)
in humans, lack nuclei, mitochondia, and ribosomes
primary function in to transport oxygen and CO2 accomplished with the iron-based protein hemoglobinhe

hemoglobin

heme groups form a ring with iron to carry O2
each hemoglobin molecule can carry 4 O2 molecules
iron is necessary to make heme group

Leukocytes

only fully functional cells in our circulation
involved in immune response
jobs are to recognize and destroy pathogens, make antibodies, cause inflammation

Platelets

fragments of bone marrow cells (megakaryocytes) that have broken off
smaller than erythrocytes (no nucleus, have mitochondria and protein vesicles)
less numerous
important in blood clotting

hemostasis

process to prevent and stop bleeding

What is special about platelets?

platelets are important as they form clots to stop bleeding

How are platelets formed?

produced from very large bone marrow cells called megakaryocytes

Vasocontraction

first step of hemostasis
vessel constricts due to paracrine release
damaged cells release chemicals telling neighboring cells to contract
less blood flow = less blood loss

Platelet plug formation

step 2a of hemostasis
inactive platelets become active platelets to clog vessel wall
platelets will not adhere to intact endothelium; exposed collagen triggers platelet plug formation

Coagulation

step 2b of hemostasis
clot formation
fibriogen to make a ne to trap RBC
need anticoagulations to prevent infarcation

infarction

tissue deprived of blood by a clot

Vessel repair

third step of hemostasis
clot dissolves via plasmin

ventilation

movement of air in/out of lungs (breathing)

respiration

exchange of gases (oxygen and CO2)

internal respiration

exchange of gases between systemic circulation and tissue
provides O2 to cell/mitochondria and removes CO2

external respiration

exchange of gases between blood and air
occurs between alveoi (lungs) and pulmonary capillaries
main function of our respiratory system

why do we breathe?

to make it easier for internal tissues to exchange gases

bronchi

carry air to and from your lungs
screen out foreign particles

bronchioles

carry air to the alveoli

alveoli

where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out

pleural sacs

membrane that wraps around the lungs and connects the lungs to the thoracic wall
between the layers, there is fluid that creates a suction that keeps the sac connected to the chest
if sac is punctured, causes a collapsed lung

How many sources of blood do the lungs have?

2 sources of blood for lungs
pulmonary circulation: delivers unoxygenated blood to lungs
Bronchial circulation: supplies oxygenated blood to supporting tissues of lungs (connetive tissues, bronchi, and bronchioles); part of systemic circulation

4 steps of gas exchange

1. pulmonary ventilation: moving air into and out of the lungs

2. external respiration: diffusion of gases between the alveoli and the blood of the pulmonary capillaries

3. Transport: transport of oxygen and carbon dioxide between the lungs and tissues

4. Internal respiration: diffusion of gases between the blood of the systemic capillaries and cells

Additional functions of respiratory system

1. vocalization

2. defense against pathogens (cilia, mucus, macrophages)

3. maintaining body pH (selective loss or retention of CO2)

4. dissipating water and heat (unavoidable loss through breathing)

What is mucociliary clearance?

self-clearing mechanism of the airways in the respiratory system
removing inhaled particles or pathogens before they can reach the delicate tissue

What is the main site of gas exchange?

the millions of alveoli in the lungs and the capillaries that envelop them.

Type 1 alveolar cells

thin, primary site of gas exchange

Type 2 alveolar cells

cuboidal, produce surfactant

surfactant

phospholipids reduce surface tension, prevent collapse

How does ventilation work?

The air moves through the passages because of pressure gradients that are produced by contraction of the diaphragm and thoracic muscles.

What is the main muscle of inspiration and what does its contraction do to the lungs?

diaphragm
when the diaphragm contracts, the lungs expand to increase lung volume and bring air in
when the diaphragm relaxes it pushes up, lungs volume decreases and pushes air out

What are some factors affecting pulmonary ventilation?

1. air pressure gradient between atmosphere and alveoli (increase pressure gradient = increase ventilation)

2. airway resistance (decrease resistance = increase ventilation)

What is the main function of the urinary system?

to filter blood and create urine as a waste by-product

other functions of urinary system

removal of wastes
water and ion homeostasis
gluoneogensis

functional anatomy of urinary system

kidney (produce urine)
Uter (transport urine to bladder)
Urinary bladder (stores urine)
Urethra (conduct urine to outside environment)

nephron

functional unit of kidneys (about 1 million per kidney)

Why do we form urine?

adjusts blood composition
filter out water, metabolic wastes, and a few solutes
reabsorb water, nutrients, and essential ions