Systems Physiology Unit 3

Major endocrine glands

Hypothalamus/pituitary, thyroid, adrenal, pancreas

Secondary endocrine glands

any organ/tissue producing and releasing hormones

Hormones

chemical messengers sent by endocrine glands

Lipid soluble receptors

hormone diffuses through plasma membrane, slower response but longer lasting, gene transcription

Water soluble receptors

hormones bind to membrane receptors, faster response but short lived, second messenger pathways

Second messenger pathway

reception → transduction → response

Hormonal stimulation

release of a hormone in response to another hormone

Humoral stimulation

Release of a hormone in response to changes in level of nutrient or ion in the blood

Nervous system stimulation

release of a hormone in response to stimulation by the nervous system

Posterior Pituitary Gland

hypothalamic nuclei produce Oxytocin (OT) and Vasopressin or antidiuretic hormone (ADH)

ADH major roles in the PNS

maintain body fluid tonicity and maintain blood pressure

Anterior pituitary gland

releases thyroid-stimulating hormone (TSH) and Adrenocorticotropic hormone (ACTH)

Aldosterone

enhances water and sodium retention in the kidneys

Cortisol

causes increased glucose availability, increases efficiency of epinephrine and norepinephrine

HPA axis

the connection between NS and endocrine system’s coordinated response to stress, primary role is to regulate the response to acute stress

Hyperthyroidism

increases oxygen consumption and metabolic heat production, increase protein catabolism and may cause muscle weakness, hyperexcitable reflexes and psychological distubances, influences beta-1 adrenergic receptors in the heart

Hypothyroidism

absence of negative feedback increases TSH secretion, slows metabolic rate and oxygen consumption, decreases protein synthesis, slowed heart rate

Parathyroid hormone

helps maintain calcium levels

Pericardium

double-layered membrane that encases the heart

Parietal layer (pericardium)

outer layer of the pericardium, surrounds the roots of the heart’s major blood vessels and is attached by ligaments to the spinal column, diaphragm, and other parts of the body

Visceral layer (pericardium)

inner layer of the pericardium, attached to the heart muscle

Pericardial fluid

fills the space between the two layers of the pericardium, reduces friction from the heart’s movements

Two types of cardiac cells

conducting cells, contractile cells

Conducting cells

about 1% of the cardiac cells, form the conduction system of the heart, function like neurons

Contracting cells

99% of the cardiac cells, respond to signals from the conducting cells, triggers systole and diastole

Intrinsic Conducting Pathway

hearts own conduction system, consists of conducting cardiac cells specialized to initiate and distribute impulses throughout the heart, results in depolarization and repolarization in an orderly and sequential manner

Sinoatrial node (SAN)

controls the heart’s rhythm of contraction/relaxation, often called the pacemaker or sinus node

Atrioventricular node (AVN)

part of the heart’s intrinsic conduction system

MAP = ?

Cardiac Output x Perfusion resistance

MAP range

60 - 100 mmHg

Arterial baroreceptors

found in the carotid sinus and aortic arch, act through a negative feedback system to maintain the MAP in the ideal range

Vasomotor center

a cluster of sympathetic neurons in the medulla that controls changes in the diameter of blood vessels

Cardiac center

a cluster of sympathetic neurons in the medulla that controls changes in heart rates and contractility forces inotropy

Hypotension

low blood pressure, can lead to cardiogenic shock (circulatory shock)

Hypertension

high blood pressure, can lead to coronary artery disease, myocardial infarction, stroke