Physiology unit 3

What are the four hormone classifications based on chemical structure and what are some examples?

What are the four hormone classifications based on chemical structure and what are some examples?

amino acid derivatives (water soluble):

-thyroid hormone

-epinephrine

proteins and polypeptides:

-antidiuretic hormone

-insulin

steroids (lipid soluble):

-progesterone

-testosterone

-cortisol

fatty acids derivatives:

What are the hormone secretion classifications and how do they differ?

1. Autocrine

•Hormone acts on cells that released it

2. Paracrine

•Hormone acts on nearby tissue

3. Endocrine

•Hormone acts on distant target

What are the common aspects shared by all hormones?

•Blood born

•Receptors on/in target cells

•Specific effect on target cell

•Can be turned off

What are the different types of interactions when more than one hormone acts at the same target and how do they differ?

Synergistic - additive or complementary

Permissive - hormone increases responsiveness of different hormone

Priming effect - hormone presence increases sensitivity/effect of same hormone

Antagonistic - oppositive effects

-e.g. insulin (increase in glucose stores) & glucagon (decrease in glucose stores)

What are the factors which determine the half-life of hormones?

accumulation in tissues, active metabolites, and receptor interactions

What is the mechanism of action of steroid hormones?

Steroid hormones pass through the cell membrane of the target cell. The receptor bound steroid hormone travels into the nucleus and binds to another specific receptor on the chromatin.

What are the differences between the two second messenger mechanisms of water-soluble hormone action?

1. 2nd messenger - adenylate cyclase

Membrane receptor binding

Intracellular g-protein

subunit dissociation

Subunit activates adenylate cyclase

Forms cAMP from ATP

cAmp activates protein kinase

protein kinase phosphorylates (adds a phosphate) specific enzymes

Enzymes activated or inhibited

2. PIP-Ca++ second messenger

Membrane receptor binding

G-protein dissociates intracellularly

Activates phospholipase C (PLC)

Releases inositol trisphosphate (IP3) from lipid

IP3 releases Ca2+ from endoplasmic reticulum

Ca2+ activates calmodulin

Calmodulin has a variety of effects

What does the second messenger cascade have on intracellular action?

Amplified intracellular effect

What are the differences between the anterior and posterior pituitary in terms of how they operate?

Anterior pituitary

•Blood born factors from hypothalamus trigger hormone release

Posterior pituitary

•Axonal txport from hypothalamus (production) to post. pit. (release)

What are the general types of hormones released by hypothalamus?

The thyrotropin-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), growth hormone-releasing hormone (GHRH), corticotropin-releasing hormone (CRH), somatostatin, and dopamine are released from the hypothalamus into the blood and travel to the anterior pituitary.

What are the general types of hormones released by the pituitary?

tropic (travel & stimulate)

What are the specific hormones released by the hypothalamus?

CRH, GnRH, and TRH

What are the specific hormones released by the pituitary?

- Growth hormone (GH)

- Thyroid stimulating hormone (TSH)

- Adrenocorticotropic hormone (ACTH)

- Follicle stimulating hormone (FSH)

- Leuteinizing hormone (LH)

- Prolactin (PRL)

Which hypothalamic hormones control the anterior pituitary and which specific hormones are released?

•TRH - thyrotropin releasing hormone

•CRH - corticotropin releasing hormone

•GnRH - gonadotropin releasing hormone

•DA (dopamine) - prolactin inhibiting hormone

•Somatostatin - inhibits growth hormone release

What are some hormones whose release is not controlled by the pituitary?

insulin, glucagon, thyroid (T3 & T4), parathyroid (PTH), cortisol, epinephrine, norepinephrine, and calcitonin

How does feedback control of hormones work to control hormone action?

Final hormone (e.g. cortisol) feeds back to inhibit hypothalamus (releasing hormones) and AP (stimulating hormones)

Which class of hormones are released by the adrenal cortex and which hormone triggers their release?

corticosteroids in response to ACTH

What are the actions of mineralocorticoids, glucocorticoids a sex steroids?

Mineralocorticoids: Na+ & K+ regulation by kidney tubules Glucocorticoids: Regulate glucose metabolism (catabolic)

Sex steroids: Supplement production by gonads

What hormones are released from the adrenal medulla?

catecholamines (epinephrine and norepinephrine)

Which hormones are released from the thyroid?

triiodothyronine (T3) and thyroxine (T4)

What is their action and what hormone controls their release?

regulation of your weight, energy levels, internal temperature, skin, hair, nail growth, metabolism and the thyroid-stimulating hormone (TSH) controls their release

How does lack of iodine cause a goiter?

Lack of iodine causes low T3 and T4 levels which then causes low negative feedback which then causes excess TSH leading to hypothyroidism and goiter. Also causes enlargement in the thyroid

What hormone is released from the parathyroid gland and what are its actions? What triggers its release?

PTH - parathyroid hormone

-stimulates osteoclasts

-increase vitamin D3 production in kidney

Decrease in blood Ca++ leads to release

What are the steps in Vit. D formation and what are the actions of Vit. D?

Steps:

-converted in skin by sunlight

-hydroxylated in liver

-2nd hydroxylation in kidney (active form)

Actions:

- increase in intestinal Ca++ and phosphate absorption

- increase in Ca++ reabsorption by kidney

- increase in blood Ca++

From where is calcitonin released?

From thyroid C cells

What causes the release of calcitonin and what are its actions?

Increase in blood Ca++ leads to calcitonin release

Actions:

- inhibits osteoclasts

- increase in urinary excretion of Ca++

- decrease in blood Ca++

What triggers the release of glucagon and what are the actions of?

1. release

- decrease in plasma glucose

- detected by islets

2. actions

- decrease glucose uptake

-increase in glycogen breakdown (glycogenolysis)

- increase in lipolysis

- increase in protein breakdown

- increase in blood glucose

What triggers the release of insulin what are the actions?

1. Release

• Increase in plasma glucose

•Detected by islets

•Insulin release

•Parasympathetics also trigger release

2. Insulin actions

• Increase in cellular glucose uptake

•Via increase in glucose transport protein fusion w/ cell membrane

• Increase in glycogen formation

• Increase in adipose formation

• Increase in protein formation

• Decrease in blood glucose

Which hormone is released from the pineal gland?

melatonin

What triggers melatonin release and what are its actions?

inhibits GnRH release (decrease in LH and FSH)

to promote sleep

What are the major components of whole blood and what are the relative percentages of each?

Plasma - 55% of whole blood

Water - 90% of plasma

Proteins - 8% of plasma weight

Albumins - 60% of plasma weight

What are some examples of different types of plasma proteins and which is the most common?

Albumins: most common protein

antibodies, clotting factors, peptide hormones

What is the difference between serum and plasma?

Serum is plasma without the clotting factors, and minus plasma proteins

What are the formed elements in the blood and what are the roles of each?

platelets: involved in clotting, contact damaged surface and rupture, release contents, causes additional platelet sticking, platelet plug formed

erythrocytes (RBC): O2 carrier

leukocytes (WBC): granulocytes and agranulocytes

What are the differences between granulocytes and agranulocytes?

both have granuloes, but only granulocytes can be stained by dyes

What is the production pathway common to all formed elements?

Same hematopoietic stem cell differentiates into all

What are the antigens and antibodies which determine blood type?

antigens tell you which blood you are, antibodies tell you which blood you aren't

Antibodies:

O - A&B antibodies

A - B antibodies

B - A antibodies

AB - no antibodies

Antigens:

O - everyone has this

A - determines "A" blood type

B - determines "B" blood type

What are the roles of the atria and ventricles? Where does each receive blood from and pump blood to?

atria receive from systemic and pulmonary blood, ventricles release to systemic and pulmonary blood

In what ways is the right ventricle different from the left ventricle?

right
-thin vs the left
-pumps to pulmonary trunk (artery)
left
-thicker
-pumps to aorta (artery)

What is the pulmonary circuit and what is the systemic circuit? What are the differences?

Pulmonary circuit
-from right heart to lungs
-returns to left heart
-relatively low pressure (15 mm Hg)
Systemic Circuit
-from left heart thru body
-returns to right heart
-100 mm Hg

What is the pathway of blood flow through the heart, lungs and body?

Blood comes into the right atrium from the body, moves into the right ventricle and is pushed into the pulmonary arteries in the lungs. After picking up oxygen, the blood travels back to the heart through the pulmonary veins into the left atrium, to the left ventricle and out to the body's tissues through the aorta.

When in each part of the pathway is the blood oxygenated or deoxygenated?

Systemic circulation carries oxygenated blood from the left ventricle, through the arteries, to the capillaries in the tissues of the body. From the tissue capillaries, the deoxygenated blood returns through a system of veins to the right atrium of the heart.

What are the layers of the pericardium?

fibrous and serous

What is the myocardium?

the muscular tissue of the heart.

What are the properties of cardiac muscle?

striated, single nucleus, involuntary, branched, heart muscle

how does the cardiac action potential differ from other action potentials in the body?

the cardiac action potential is not initiated by nervous activity

What is the endocardium?

-innermost layer of the heart
-smooth endothelial sheet

What are the different valves in the heart and where is each found?

atrioventricular (AV) valves: right - tricuspid; left - bicuspid
semilunar (SL) valves: aortic and pulmonary, ventricular exits

How do chordae tendineae and papillary muscles assist valve function?

chordae tendineae anchors valve cusps to papillary muscles
papillary muscles protrude from ventricle walls and contracts before ventricles, which prevents blood from slamming against strium wall

When do each valve open and close?

Systole
-AV valves close
-SL valves open (semilunar)
Diastole
-SL valves close
-AV valves open

Where does blood enter and exit from the coronary circulation?

The blood enters the heart's right atrium and is pumped to your right ventricle, which in turn pumps the blood to your lungs.

What is the conduction pathway through the heart?

1. SA node
2. atrial depolarization
3. atrioventricular node (AV)
4. AV bundle
5. rt. and left bundle branches
6. purkinje fibers
7. cardiac muscle

At what site does depolarization begin and what are the subsequent pathway parts to the cardiac muscle?

The wave of depolarization begins in the right atrium, and the impulse spreads across the superior portions of both atria and then down through the contractile cells. The contractile cells then begin contraction from the superior to the inferior portions of the atria, efficiently pumping blood into the ventricles.

What are the parts of the cardiac pressure cycle and what happens during each part?

-Isovolumetric contraction: pressure increases, AV valves snap shut
-Ventricular pressure exceeds aortic: SL valves open
-Ventricles empty: pressure increases then decreases, SL valves shut
-Isovolumetric relaxation: all valves shut
-Atrial exceeds ventricular pressure: AV valves open, ventricles fill
-Atrial contraction: ventricles topped off

What is the equation for cardiac output?

heart rate x stroke volume

What factors control HR and SV?

The three primary factors that regulate SV are preload, afterload and contractility. Heart rate (HR) also affects SV. Changes in HR alone inversely affects SV.

How do the sympathetic and parasympathetic nervous systems differ in how they affect heart function?

sympathetics increase HR, increase strength of contraction, increased conduction speed through heart
parasympathetics decrease HR

What are preload and afterload, and what factors affect each?

Preload is the initial stretching of the cardiac myocytes (muscle cells) prior to contraction. It is related to ventricular filling. Afterload is the force or load against which the heart has to contract to eject the blood.

What is ejection fraction?

stroke volume/end diastolic volume

What is the Frank-Starling Law?

- Increased ventricles stretch -> contraction force -> increased SV
- Enhances sympathetics
- Ejection fraction - % EDV pumped out of heart (~ 60%)

Where is extrinsic innervation of the heart controlled?

medulla

Which areas have which ANS functions?

Cardioacceleratory center: SYMP fibers projected
To SA (sinoatrial) and AV (atrioventricular) nodes

Cardioinhibitory center: PARASYMP fibers projected
To SA and AV nodes

How are arteries structured different than veins?

arteries are larger, more elastic, and have more pressure

What are the different arterial and venous vessels? Where are each found and what are their roles in circulating blood?

1. Arterial end
•Hydrostatic > osmotic pressure
•Net movement out (more)
2. Venous end
•Osmotic > hydrostatic pressure
•Net movement in (less, ~ 9/10)

Which vessels have the greatest effect on peripheral resistance?

small arteries and arterioles

What are the different types of capillaries?

continuous, fenestrated, sinusoidal

What are the osmotic and hydrostatic factors which make fluid movement into and out of capillaries different as they pass through from the arterial end to the venous end of the capillary?

Osmotic pressure is determined by the difference in the proteins present in the blood and interstitial tissue. Hydrostatic pressure is higher at the arterial end, and materials are pushed out. Hydrostatic pressure is lower than osmotic pressure at the venule end, and materials are moved into the capillary.

What are the differences in fluid movement in the arterial and venous ends?

hydrostatic pressure forces fluid out of the capillary, osmotic pressure draws fluid back in

What is an anastomosis?

The connections between blood vessels that provide an alternate route.

What are the variables in the flow equation and which is most important when it comes to control of circulation in the body?

P = pressure
r = radius (big factor)
L = length
n = viscosity

What is the overall equation for blood pressure?

BP = CO x PR
blood pressure
cardiac output
peripheral resistance

Where are baroreceptors found and how do they work to control blood pressure?

-Carotid sinus
-Aortic arch

What are their inputs and outputs and what are the effects of their output?

-Send signals to medulla
-increase in pressure ->increase in output

Specially how does the body compensate for the blood pressure change when going from laying to standing?

-blood moves down the body
-decrease in BP, less baroreceptor firing
-increase in sympathetic output
-decrease in parasympathetic output
-PR? increase, vasoconstriction
-BP? increase; reestablish blood pressure

What are systolic and diastolic pressure and what is the heart doing when each occurs?

Systolic is when the heart contracts and diastolic is when the heart relaxes
Systolic = 120 mmHg
Diastolic = 80 mmHg

How is MAP calculated using systolic and diastolic pressure? What is pulse pressure?

Mean arterial pressure
•What body regulates
•MAP = 1/3 pulse pressure + diastolic

What are the differences between intrinsic and extrinsic regulation?

extrinsic: neurons, adrenal medulla, cholinergic sympathetic fibers, vasodilation in GI, genitals, and salivary
intrinsic: paracrine, autoregulation, and hyperemia

With extrinsic, which branch of the ANS is involved? How do a and b receptors work to control vasoconstriction and vasodilation?

1.Sympathetics
- Neurons:
•Release norepi.
• a receptors close to neurons
•Trigger vasoconstriction
- Adrenal medulla:
•Circulating epi. & norepi.
• b receptors away from neurons
•Trigger vasodilation
- Cholinergic sympathetic fibers:
•Release ACh in arterioles
•Vasodilate during fight or flight
2. Parasympathetics
Vasodilation in:
•Digestive tract
•Genetalia
•Salivary glands

What are the different types of local/intrinsic regulation and how does each work?

Paracrine: substance release by vessel endothelial cells
Autoregulation: smooth muscle constricts in response to increased pressure
Hyperemia: increased blood flow

Which variables in the diffusion equation are the most important in the design/construction of the lung to have the ability to achieve enough diffusion to sustain life?

Qs = quantity of solute diffusing (mol/cm2)
t = time (sec)
Ds = diffusion coefficient (ease of passage) (1/sec)
A = area (cm2) most important
Cs = concentration (mol/l)
x = distance (cm)

What is the difference between bulk flow and diffusion? What places does each occur?

Bulk flow = move the air, inhale air
Diffusion = due to conc. gradient
from lung to blood

What is the difference between internal and external respiration?

External respiration- oxygen and carbon dioxide exchange between lungs and blood stream
internal respiration- oxygen and carbon dioxide exchange between tissue cells and blood stream

Why is it important for the upper airways to create turbulence and stir the air past the respiratory epithelium?

Ensures more collisions with the respiratory epithelium in the nasal cavity (mucociliary clearance can occur). Also ensures air is warmed and humidified.

How is the respiratory constructed to enable it to help clean inhaled air?

mucosa and cilia work together to trap debris and move it towards the throat where it can be swallowed

How do the airways change in their construction from the trachea to the bronchioles?

trachea splits into left and right primary bronci splits into 2 and 3 branches (respectively), slpits into tertiary bronchi which divides repeatedly and gets progressively smaller where they split into broncioles

How does smoking affect the cilia and what effect does this have?

paralyzes and eventually destroys cilia, no mucous movement to throat, moved by coughing instead

What happens to the cross sectional area and airflow velocity as airways branch into smaller airways within the lung?

the air velocity is decreased

What are the smallest conduction airways?

terminal bronchioles

What occurrence/process makes the respiratory zone "respiratory?"

gas exchange. Alveolar ventilation and gas exchange occur as oxygen moves down its conc. gradient and into the red blood cells

Which structures allow the lung to have a large surface area? What other important characteristic do they have to enable diffusion?

Alveoli gives larger surface area

What are the layers of the air-blood barrier?

- Alveolar epithelium cells (inside)
- Basal lamina of alveolar epithelium
- Basal lamina of capillary epithelium
- Endothelial cells of capillaries
- Other CT cells that surround these layers (outside)

What is the Law of Laplace?

decrease in radius = increase in surface tension forces

Why does this law make surfactant important?

because surfactant reduces surface tension leading to an increase in the radius
• Lipoprotein secreted by lung
• Reduces surface tension
• Decreases work of inflation

What are the pleural sacs, pleural space, and the visceral and parietal pleura?

pleural sac: fluid filled sac, surrounds each lung
visceral pleura: against lung
parietal pleura: against chest wall
pleural space: inside pleural sac

What is the difference between a negative pressure and a positive pressure?

Higher air pressures are positive, and lower air pressures are negative.

Which type of pressure is found in the intrapleural space and why is it important?

A negative pressure
Holds lung open

How does Boyle's law relate to inspiration and expiration?

When the volume of the lungs changes, the pressure of the air in the lungs changes in accordance with Boyle's Law

How do intrapleural and intrapulmonary pressures change during inhalation and exhalation?

at rest: Pip < Palv = Patm
-4 < 0 = 0
inhale: Pip < Palv < Patm
-6 < -1 < 0
exhale: Pip < Palv > Patm
-3 < +3 > 0