Study Guide Info Flashcards
what are the cardiac muscle fibres that cause heart contraction?
autorhythmic fibres
identify each step involved in heart contraction.
electrical impulse travels through the cardiac conduction system each cycle.
- Sino-atrial node
- Through the atra
- Atrio-ventricular node
- Atrio-ventricular bundle
- Right and left bundle branches
- Purkinje fibres
what factors affect cardiac output?
stroke volume and heart rate
identify and define the factors that regulate stroke volume.
- preload: the degree of stretch on the heart before it contracts
- a greater preload on cardiac muscle fibres increases their force of contraction - contractility: the forcefulness of contraction individual ventricular muscle fibres
- afterload: the pressure that must be exceeded before ejection of blood from the ventricles can occur
describe regulation of heart rate.
The most important regulatory factor of heart rate are the autonomic system and hormones released by the adrenal medulla
which blood vessels can and cannot constrict or dilate?
arteries can constrict or dilate to adjust the rate of blood flow
arterioles regulate resistance and undergo vasoconstriction and vasodilation
venules and veins have less elastic tissue and less smooth muscle than arteries. they are not designed to withstand great pressure.
how is blood pressure regulated?
the medulla oblangata contains a cardiovascular centre, which is a group of neurons that regulate heart rate, contractility and blood vessel diameter.
hypothalamus also contains cardiovascular centre (sympathetic output only)
baroreceptors: pressure-sensitive sensory receptors that are located in large arteries in the neck and chest. they send impulses to the cardiovascular centre to help regulate BP.
explain what happens when blood pressure decreases.
- BP decreases
- baroreceptors send input to cardiovascular centre
- increased sympathetic, decreased parasympathetic output
- increased secretion of norepinephrine and epinephrine from adrenal medulla
- increased stroke volume and heart rate lead to increased cardiac output
- constriction of blood vessels increases systemic vascular resistance
return to homeostasis when increased vascular resistance brings BP back to normal
what type of cells are involved in innate immunity?
Natural killer cells - kill infected cells by releasing granules that contain perforin and granzymes
Phagocytes - ingest foreign particulate matter
identify and describe the primary cells that are involved in adaptive immunity.
lymphocytes - T cells and B cells
cell-mediated: cytotoxic T cells
- directly attack invading antigens by releasing lethal lytic chemicals that kill cells on contact
- effective against intracellular pathogens
antibody-mediated: B cells transform into plasma cells which synthesis nd secrete specific proteins called antibodies
- a given antibody can bind to and inactive a specific antigen
- effective against extracellular pathogens
identify and describe additional cells that are involved in adaptive immunity.
helper T cells: control the humeral response of B cells, produce interleukins and promote cell multiplication
suppressor T cells: damp down immune response
memory B and T: recognise antigens and generate large quantities of antibodies
describe the innate immune system
it is present at birth and includes defence mechanisms that provide general protection against invasion by a wide range of pathogens
first line of defence: physical barriers such as skin, sweat, mucous membranes, sebaceous glands, tears, saliva
second line of defence: immune cells or substances that treat all foreign cells in the same way: phagocytes, natural killer cells, inflammation, fever
describe the adaptive immune system
involves activation of specific lymphocytes that combat a particular pathogen or foreign substance
the ability of the body to defend itself against specific invading agents
has both specificity and memory and may be cell-mediated or antibody-mediated
what are the key features of inflammation and why does this occur?
inflammation is a non-specific localised tissue response to tissue damage which has occurred through injury or infection.
the four signs and symptoms of inflammation are:
1. redness (due to vasodilation)
2. heat (due to increased blood supply)
3. swelling (due to increased vascular permeability and accumulation of exudate)
4. pain (due to increased pressure on nerve endings from swelling)
define ‘tropic hormone’.
a hormone that is produced in one endocrine gland and regulates the secretion of a hormone in another endocrine gland.
Identify the tropic hormones that are produced in the anterior pituitary.
Human growth hormone Thyroid stimulating hormone Follicle stimulating hormone Leutinising hormone Adrenocorticotropic hormone
what is the human growth hormone?
stimulates the liver, bone, muscle, cartilage and other tissues to synthesise and secrete insulin-like growth factors
what is the thyroid stimulating hormone?
stimulates the thyroid to produce thyroid hormones
what is the adrenocorticotropic hormone?
stimulates the adrenal cortex to produce cortisol
