chapter 31: internal fluids

what is the general purpose of our circulatory and respiratory systems and what major process is involved in all of them?

general purpose is homeostasis

• how we get and move oxygen

• how organisms move nutrients plus move/get rid of metabolic wastes

major process in both: diffusion

contrast open and closed circulatory systems

open circulatory system

• lack complete vessel networks

• blood (or hemolymph) flows into a cavity (hemocoel), bathing organs directly at lower pressure

closed circulatory system

• confine blood within vessels (veins, arteries, capillaries), allowing for fast, high-pressure circulation

• all vertebrate systems are closed

list the components of vertebrate blood

plasma — water (90%)

• some solids (proteins, hormones, and glucose)

• gases — oxygen stored in red blood cell, CO₂ transported in blood as ions

formed elements — blood cells and platelets

describe hemostasis (process of forming a clot)

hemostasis → how we decrease blood loss

• platelets → other formed element in the blood, helps clotting occur

process of forming a clot:

• damaged blood vessels — collagen fibers hanging inside smooth vessel

• platelets bind to fibers to form a plug/clot

• platelets and injured tissue release clotting factors

• clotting factors to convert prothrombin to thrombin

• thrombin converts fibrinogen to fibrin

• fibrin meshwork is created and platelets contract to pull together

(clotting factors — >=13 identified)

distinguish between single vs double circulation and which vertebrate groups have single or double circulation (a.k.a. single and double circuit)

single circuit: blood travels from heart → goes to gills → gets O₂ → goes to systemic system → back to heart

• ex. fish → heart only receives blood once; deoxygenated blood (in fish)

  • heart has 2 chambers

double circuit:

• pulmonary — heart → lungs → heart

• systemic — heart → body → heart

  • mammals, birds, and crocodiles — 4 chamber heart (2 atria, 2 ventricle)

  • amphibians and most reptiles have 3 chamber heart (2 atrium, single ventricle)

    • some mixing in ventricle chamber

• blood pressure can be different in two chambers in 2 chambers

describe the structure of the human heart, and how blood flows through the heart (chambers and valves)

structure: **take picture and modify on goodnotes**

blood flow:

1. blood comes from inferior vena cava (deoxygenated blood from lower body) or superior vena cava (deoxygenated blood from upper body) into superior right atrium

2. goes into right ventricle (contains papillary muscles) via tricuspid valve

3. goes into pulmonary semilunar valve → left pulmonary arteries (arteries going to the lungs (pulmonary))

4. blood is now oxygenated and comes back via pulmonary veins (veins coming from lungs) into the left atrium

5. goes into left ventricle via bicuspid valve

6. travels up through the aorta, which goes down and behind the heart, which then leads oxygenated blood to the lower body

how is cardiac rhythm is maintained?

excitation (maintains cardiac rhythm):

it starts with pacemaker cells → specialized myogenic (muscle cells) with leaky VGNaIC

• does not require outside stimulus to open Na channels

• heart can contract on its own without input from CNS or ANS — needs blood for nutrients Na, O₂

• found in 3 places: SA (sinoatrial node), AV (atrioventricular node), Bundle of His (purkinje fibers)

sinoatrial (SA) node → pacemaker cells here do not contract but rather initiate depolarization — continuous with fibers in atrial muscle

• sends impulse through the right atrium and across to left atrium

• impulse triggers AV node

• AV node sends signal to Bundle of His

• Bundle of His splits into left and right branches

• Purkinje fibers — branch off nerves and extends through outer wall of ventricle

contraction:

• atrium → contracts from top down (atrial systole)

• ventricle → contracts from bottom up (ventricle systole)

• both contract at the same time

describe heart contraction/heart sounds as it relates to the EKG (ECG)

ECG (electro-cardiogram) → measures heart electrical activity during atrial and ventricular systole (contraction)

heart contraction:

• P — atrial depolarization, atria systole

• QRS — ventricular depolarization, ventricular systole (atrial repolarization)

• T — ventricular repolarization, ventricle relax

heart sounds:

• lub → A-V valves Bicuspid (mitral) and Tricuspid closing

  • ventricles contract

• dub → pulmonary and aortic semilunar closing

  • ventricles relax/atria contract

describe congestive heart failure (left and right side)

congestive heart failure → damage to heart

right side symptoms:

• blood from body backs up (usually inferior vena cava) into legs

left side symptoms:

• blood pools in lungs

• shortness of breath (crackly breathing)

define blood pressure

blood pressure → the force of blood pushing against the walls of the arteries as the heart pumps the blood around the body

typical blood pressure measures systemic bp

• ventricular systole and diastole

• ~120 mm Hg systolic b.p.

• ~80 mm Hg diastolic b.p.

systole → muscles contracted

• when elasticity of the arteries declines with age, systolic bp increases (same amount of blood, smaller space, increased pressure)

diastole → muscles relaxed

• when elasticity of the arteries declines with age, diastolic bp decreases (vessels stay wider longer, large vessel with less amounts of blood so pressure is less)

discuss the capillary exchange. what substances pass across the capillary wall and what’s the significance? what factors are involved in exchange of substances across capillaries in tissues? illustrate changes in the various pressures along the length of a capillary using a graph.

exchange → forcing out of arteries and into veins all due to hydrostatic pressure and osmotic potential

• hydrostatic pressure (blood) → pressure exerted by a fluid at rest (static) due to gravity

  • drops over length of capillary because of frictional resistance to blood flow against vessel walls

• osmotic pressure → minimum pressure needed to stop water (or other solvent) from flowing across a semipermeable membrane into a more concentrated solution

  • rises at the end of the capillary because water is filtered out of the plasma into the tissue space along the length of the capillary

substances that pass across capillary wall

• oxygen, water, and nutrients (like glucose, amino acids, and lipids) moves into tissues

• CO₂, urea, and other metabolic wastes pass into blood

• passes through primarily through diffusion

vital for maintaining homeostasis, provides essential nutrients and oxygen to tissues, while removing waste products like CO₂ and urea

describe Kwashiorkor food deficiency and relate the swollen characteristic to exchange of fluids in capillaries

Kwashiorkor disease → severe form of malnutrition caused by inadequate protein intake

• affects osmotic potential

• more fluid leaves, less fluid returns

  • low blood protein reduces osmotic pressure, preventing fluid from returning to capillaries and forcing it into tissues

• leads to edema

describe the function of the vertebrate lymphatic system

function → maintains fluid balance by draining excess fluid from tissues

• recovers fluids that are not returned to venous capillaries (if not lymphatic)

• lymph drains into veins of lower neck

• lymph nodes (immune system)

  • areas of lymphatic tissue with immune cells

  • filters fluid and checks fluids for foreign objects, bacteria, viruses, etc.

describe the structures and functions of the human respiratory system (muscles associated with breathing, what drives our desire to breathe)

glottis → the part of the larynx consisting of the voice box

epiglottis → flexible, leaf-shaped flap of cartilage located behind the tongue at the top of the larynx (voice box)

human lung structure:

1. trachea

2. bronchus

3. bronchioles

4. alveoli

muscles associated with breathing → diaphragm and external intercostal muscles

• inhale: diaphragm contracts → thoracic cavity volume increases thus expanding lung → pressure inside air space of lungs is negative, causing suction and drawing air in → lungs fill and rib cage expands

• exhale: diaphragm muscles relax → pressure inside air space of lungs is higher, forcing air out

desire to breath comes from build up of CO₂ lowering pH which stimulates desire to breath

be able to determine the amount of oxygen delivered to the tissues using an oxygen saturation curve for hemoglobin. what is the Bohr effect and how does it affect the saturation curve?

oxygen saturation curve → shows how much oxygen is delivered

Bohr effect (CO₂ effect) → decrease in pH causes hemoglobin to have reduced affinity (strength of binding interaction) for oxygen, tissues have a great affinity for O₂

• build up of CO₂ in systemic tissues of body → decrease of pH in blood

• decrease in pH → reduced attraction for O₂ in blood

• therefore, a greater % is delivered to tissues

if given saturation curves for other pigments like myoglobin, etc., determine which has the highest affinity. also, be able to use the saturation curves of fetal and maternal hemoglobin to show why it is advantageous for the unborn child to have hemoglobin with a higher affinity for oxygen relative to the mother’s hemoglobin

myoglobin has the highest affinity — found in cardiac and skeletal muscle

• hemoglobin is pigment found in the blood

• as O₂ is given up by bloodstream, muscles have stronger affinity to hold onto it to use it for muscles contraction

human fetal hemoglobin has higher attraction than human maternal hemoglobin

• in placenta, capillaries get close and O₂ and nutrients diffuse from maternal to fetal

list the 3 ways carbon dioxide is carried by blood. most of the CO₂ is carried in the blood in what form?

some carried as carbaminohemoglobin (23-25%) — an amino acid

some in dissolved state (5-7%)

most converted as bicarbonate ion (~70%)

Fick’s law as it relates to various processes of diffusion

Q = DA (c1-c2)

L

Q = rate of diffusion

simple squamous epithelium maximizes diffusion by minimizing diffusion distance (L)

alveoli increases surface area (A)

compare arteries and veins with regard to structure, movement of blood, and the oxygen content of blood being carried

arteries → carries high-pressure, oxygen-rich blood away from the heart through thick, muscular, elastic walls

• has more smooth muscle than veins

• blood is under higher pressure

• smooth muscles contract and relax, helping to maintain pressure

• when left ventricle:

  • contracts → arteries expand

  • relaxes → arteries contract

veins → carries low-pressure, oxygen-poor blood towards the heart using thin walls and one-way valves to prevent backflow

• has smooth muscle

• not under a lot of pressure

• usually carrying deoxygenated blood back to heart (systemic)

• more superficial — closer to surface

define medical terms given in lecture associated with the circulatory system like embolus, etc.

1. thrombus → stationary clot

2. embolus → detached clot

acute coronary syndrome (ACS) → affects coronary arteries bringing O₂ to the heart

3. ischemia → decreased blood flow to region of the body (due to embolus)

• heart does not receive blood flow it needs

4. angina (pectoralis) → chest pain due to ischemia to the heart

5. myocardial infarction (heart attack) → a blockage of the coronary arteries that carry oxygenated blood to heart tissues

• infarct → any tissue damage due to disruption of blood supply

• circumflex redundancy → multiple arteries surround heart to maintain blood flow if blockage

6. balloon angioplasty → open up artery to increase blood flow

7. aneurysm → weakening and localized dilation in the wall of a blood vessel

8. stroke → blockage or hemorrhage of capillary in brain

• brain aneurysm -- bursts = hemorrhagic stroke

the medical moments covered in lecture

jaundice → build-up of bilirubin in circulatory system

• trauma of childbirth — broken vessels

  • hemoglobin needs broken down; UV light makes bilirubin more water soluble, breaks it down

• adult — liver damage cannot remove bilirubin

bruise coloring

1. red → recent; red blood cells in bruised site

2. purple/blue → to 5 days; area with little oxygen due to damaged blood vessels

3. green → 5-7 days, biliverdin

4. yellow → >7 days, bilirubin