BIOM20002 Lecture Notes - Lecture 55: Adrenal Gland, Juxtaglomerular Apparatus, Internal Bleeding

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plumdeer622

15 Sep 2018

School

University of Melbourne

Department

Biomedicine

Course

BIOM20002

Professor

All

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Document Summary

Usually defined in terms of inadequate oxygen delivery to the body due to circulatory failure. (as distinct from respiratory failure) Almost invariably associated with low blood pressure (but not necessarily low cardiac output). Blood pressure easy to measure and understand - (cid:862)lo(cid:449) (cid:271)lood pressure(cid:863) a surrogate ter(cid:373) for shock in this lecture. Blood pressure (bp) = cardiac output (co) x peripheral resistance (pr) Cardiac output (co) = heart rate x stroke volume. Slows the normal rate of sa node (100-120bpm) to give normal resting heart beat (60-70bpm) Catecholamines secreted by adrenal glands increase heart rate. Ventricular end-diastolic volume (preload): volume in left ventricle at end of diastole. Cardiac contractility: force with which heart muscle contracts. Resistance against which ventricle has to contract: afterload. In this lecture we consider only systemic circuit. Frank-starling curve: an optimal level of ventricular filling that allows cardiac muscle to contract with most force. Adrenal glands: adrenaline acts on 2-receptors - vasodilation)

Related Questions

c) How going from laying to standing affects arterial blood pressure in the head region?

When we are laying down the Mean Arterial Pressure (MAP) is at the same level of the heart which is about 100 mm Hg. When we try to stand up from the lying position, our head is placed above our heart and gravity starts to pull the blood back downwards to our heart and feet. Return of venous blood is reduced and this leads to a decrease in cardiac stroke volume and decline in mean arterial pressure which is reduced to 60-70 mm Hg. This decreases the flow of blood to head. In response to this reduction in arterial blood pressure in the brain, parasympathetic nervous system is withdrawn and sympathetic nervous system is activated to pump more blood to head region via increased heart rates.

d) How the baroreceptors reflex explains the higher HRs during standing

When a person stands up, baroreceptor reflexes are rapidly activated to restore arterial pressure so that mean arterial pressure normally is not reduced by more than a few mmHg when a person is standing compared to lying down. However, in order to maintain this normal mean arterial pressure, the person who is standing upright has increased systemic vascular resistance (sympathetic mediated), decreased venous compliance (due to sympathetic activation of veins), decreased stroke volume (due to decreased preload), and increased heart rate (baroreceptor-mediated tachycardia).

Question 1 (1 point)Save Question 1Save
Which of the following will increase blood flow to a given regionof the body?

A smaller pressure gradient between the arteries and thatregion.

Vasoconstriction of the arterioles feeding that region.

An increase in blood viscosity via dehydration.

An increase in diameter of the arterioles feeding the region.
Question 2 (1 point)Save Question 2Save
Which of the following statements pertaining to the innervation ofthe heart is TRUE?

The heart is directly activated by the somatic nervoussystem.

The heart muscle is directly activated by the autonomic nervoussystem.

NE released by sympathetic neurons binds to beta-adrenergicreceptors and increases heart rate.

ACh released by parasympathetic neurons binds to nicotinicreceptors and decreases heart rate.
Question 3 (1 point)Save Question 3Save
The prolonged depolarization in cardiac myocytes is due primarilyto which channel type?

Voltage-gated sodium channels

Voltage-gated potassium channels

Funny (F-type) sodium channels

Long-lasting (L-type) calcium channels
Question 4 (1 point)Save Question 4Save
Which of the following statements about the pacemaker potentialgenerated by the SA node is FALSE?

Its intrinsic rate is about 70 depolarizations per minute.

The rate of depolarization can be affected by autonomicinnervation.

Funny (F-type) sodium channels play a role in the gradualdepolarization.

In the complete absence of extrinsic input (hormones or neurons),the SA node will continue to depolarize
Question 5 (1 point)Save Question 5Save
Match the description in the left hand column with the terms in theright hand column that BEST correspond (one match per term, allselections are used).

The period of the cardiac cycle when the heart is contracting

The period during diastole when the pressure in the atria exceedsthe pressure in the ventricles.

The period during systole when all heart valves are closed.

The difference between end-diastolic volume and end-systolicvolume.

The period of the cardiac cycle when the heart is relaxing.

1.
Systole
2.
Diastole
3.
Stroke volume
4.
Isovolumetric contraction
5.
Ventricular filling

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BIOM20002 Lecture Notes - Lecture 55: Adrenal Gland, Juxtaglomerular Apparatus, Internal Bleeding

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