Medical Physiology Exam 3 Review

Hemodynamics

physical principles of blood flow based on pressure and resistance

Arteries

carries blood away from the heart at high pressure

Arterioles

small vessels that receive blood from the arteries, shunts blood where needed

capillary beds

sites of chemical exchange[fluid, nutrients, hormones] between the blood and interstitial fluid

Venules

small vessels that gather blood from the capillaries into the veins

Veins

Blood vessels that carry blood back to the heart, very low pressure

blood pressure

the pressure that is exerted by the blood against the walls of blood vessels

arterial blood pressure

rises when ventricles contract, falls when ventricles relax

systemic circulation

The branch of the circulatory system that supplies all body organs and then returns oxygen-poor blood to the right atrium via the veins.

pulmonary circulation

The passage of venous blood from the right atrium of the heart through the right ventricle and pulmonary arteries to the lungs where it is oxygenated and its return via the pulmonary veins to enter the left atrium and participate in systemic circulation.

3 Basic principles of Circulation

1. Rate of blood flow to tissue based on tissue need.

2. Cardiac output is altered by sum of all local tissue flows

3. Arterial pressure regulation can operate

Factors affecting blood pressure

cardiac output, peripheral resistance, blood volume

Factors affecting circulation

-pressure differences that drive the blood flow

-velocity of blood flow

-volume of blood flow

-blood pressure

-resistance to flow

-venous return

laminar blood flow

type of blood flow not resulting in audible sound; defined by streamline flow or flow in parallel layers without turbulence

turbulent blood flow

type of blood flow resulting in audible sound; defined by chaotic flow due to variations of pressure and velocity

blood viscosity

The stickiness of the blood due to formed elements and plasma proteins.

Hematocrit

The percent of the volume of whole blood that is composed of red blood cells as determined by separation of red blood cells from the plasma usually by centrifugation.

What is the normal amount of hematocrit?

40%

Anemia

A condition in which the blood is deficient in red blood cells, in hemoglobin, or in total volume.

Vascular Distensibility

increase in volume / increase in pressure x original volume

vascular compliance

increase in volume/increase in pressure

blood transfusion

does not dramatically affect pressure

RBCs

erythrocytes; red blood cells; transport oxygen to body tissues

WBCs

white blood cells or leukocytes, defend against infection

Platelets

thrombocytes; cell fragments in the blood that are essential for blood clotting (coagulation)

Plasma

Liquid part of blood, made mostly of water, in which oxygen, nutrients, and minerals are dissolved

Formed elements of blood

red blood cells, white blood cells, platelets

The liquid portion of blood that comprises 55% of the blood's volume is called:

plasma

CBC (complete blood count)

a set of tests that include all WBC, RBC and platelet measurements.

Fibrinogen

blood clotting

serum

liquid portion of the blood that remains after clotting

Globulins

antibodies

Albumins

smallest and most abundant

Contribute to viscosity and osmolarity; influence blood pressure, flow, and fluid balance

What is the shape of a red blood cell?

biconcave disc

Why are red blood cells biconcave?

To increase the surface area for oxygen absorption

What is the lifespan of a RBC?

120 days

What organ removes damaged or old blood cells?

spleen

List the functions of blood

Carry O2 from lungs to tissues

Carbonic Anhydrase (CO2 transport)

Acid-Base buffering of whole blood

How many RBC's per microliter of blood

4-6 million

spleen

An organ that is part of the lymphatic system; it produces lymphocytes, filters the blood, stores blood cells, and destroys old blood cells.

red pulp

the region of the spleen composed of blood-filled venous sinuses and thin plates of splenic tissue (cords), which consist of red blood cells and various white blood cells

white pulp

lymphocytes, macrophages surrounding small branches of splenic artery

Erythropoiesis

production of red blood cells

bone marrow

A soft tissue inside the bone that produces blood cells

Hemopoiesis

the production of blood cells and platelets, which occurs in the bone marrow

Leukopoiesis

production of white blood cells

Proerythroblast

developing red cell before immature red blood cell

basophilic erythroblast

Phase I of red blood cell formation that produces ribosome synthesis (no hemoglobin)

polychromatophilic erythroblast

Day 3 of RBC maturation, cell gets red color

Reticulocyte

immature erythrocyte

Reticulocyte count

Assessment of bone marrow function

Erythropoietin (EPO)

hormone secreted by the kidney to stimulate the production of red blood cells by bone marrow

What happens if blood oxygen is low?

leads to hypoxia, which is a decrease in oxygen at the tissue level

Erythropoietin is what type of feedback loop?

negative

Hemoglobin

iron-containing protein in red blood cells that carries oxygen for delivery to cells

How many chains does hemoglobin have?

4 (2 alpha and 2 beta)

1 hemoglobin equals

4 oxygen

RBC can carry how many oxygen molecules?

1 BILLION

What gas fights with oxygen to bind with iron?

Carbon monoxide

How much O2 does 1 hemoglobin molecule carry at 100% saturation?

4 O2 molecules

Iron Cycle

Iron (Fe) is also recycled made possible by the plasma carrier, transferrin. Tissue macrophages (primarily in the spleen) break down ingested erythrocytes and return iron to the bloodstream directly or after storing it as a ferritin or hemosiderin.

gas exchange

the process by which oxygen is transported to cells and carbon dioxide is transported from cells

What is respiration?

the exchange of gases between the atmosphere, blood, and cells

pulmonary ventilation

movement of air into and out of the lungs

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

What is the flow of blood through the heart?

Superior and inferior vena cava, right atrium, tricuspid valve, rt ventricle, pulmonary valve, pulmonary artery, lungs (picks up oxygen), pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, aorta, to the body

What is the main site of respiration?

Alveoli are considered the main spot for respiration within the lungs

pulmonary edema

accumulation of fluid in the lungs

pleural membrane

double-layered serous membrane that encloses and protects each lung

Is the diaphragm active during inhalation or exhalation?

Inhalation

If you increase the pressure in the abdomen....

it drives stability and mobility for the rest of the body

intercostal muscles

Muscles which move the rib cage during breathing

During normal inhalation, what muscles are active?

External intercostals and diaphragm

lung compliance

expansibility of the lung

surfacant

Lowers surface tension, preventing alveoli from collapsing

Without surfactant

the surface tension of the liquid in the alveoli would be greater and the alveoli would collapse

gas exchange happens in the

alveolus, which exchanges with the pulmonary capillaries

Tidal Volume (TV)

volume of air inhaled or exhaled in a normal breath

Inspiratory Reserve Volume (IRV)

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation

expiratory reserve volume

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation

Residual Volume (RV)

Amount of air remaining in the lungs after a forced exhalation

Vital Capacity (VC)

The difference between the minimum and maximum volume of air in the lungs (TLC-RV)

COPD (chronic obstructive pulmonary disease)

A group of lung diseases that block airflow and make it difficult to breathe.

Emphysema

a condition in which the air sacs of the lungs are damaged and enlarged, causing breathlessness.

Fibrosis

Repair by dense fibrous connective tissue (scar tissue)

bronchitis

inflammation of the bronchial tubes, entrapment of air in alveoli

Someone with a restrictive lung disorder would have

lower total lung capacity

Each alveolus is surrounded by

capillaries

respiratory membrane

where gas exchange occurs between the air on the alveolar side and the blood on the capillary side; the alveolar and capillary walls form the respiratory membrane

What are the 6 layers of the respiratory membrane from air to blood?

1. Surfactant

2. Alveolar epithelial

3. Basement membrane

4. Interstitial space

5. Capillary basement membrane

6. Capillary endothelial membrane

Thickened respiratory membrane

decreased alveolar gas exchange- pulmonary edema, pneumonia

Emphysema is characterized by alveoli damage where several merge into larger air spaces, What effect would this have on gas exchange?

Decreased due to reduced surface area for gas exchange to occur

gas diffusion

occurs across the respiratory membrane between alveoli and capillaries, and across capillary walls between blood and other tissues

Carbon dioxide is ____ in cell and _______ in system blood capillary.

higher in cell, lower in system blood capillary

partial pressure of oxygen

higher in the alveoli than the pulmonary artery

PO2

160 mmHg

If the PO2 in the alveolus is 140 mmHg, will O2 diffuse, and if so, in what direction?

Yes, move from higher to lower due to a higher level of pressure in the alveolus

Factors affecting rate of diffusion

1. Thickness of respiratory membrane

2. Surface area

3. Diffusion coefficient of gas

4. Partial pressure difference between two sides of the membrane

venous pump

skeletal muscles surrounding the veins can contract to move blood by squeezing the veins

venous valves

prevent backflow of blood; most abundant in veins of limbs

Bohr effect

a decrease in the amount of oxygen associated with hemoglobin and other respiratory compounds in response to a lowered blood pH resulting from an increased concentration of carbon dioxide in the blood.