Physiology Exam 4

arteries

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