human and animal physiology Flashcards
what are the two methods that food can be digested
mechanical digestion and chemical digestion
mechanical digestion
chewing (mouth)
churning (stomach)
movement of food
peristalsis
segmentation
chemical digestion
stomach acids
bile
enzymes
where do macromolecules begin to digest
carbohydrates in the mouth
proteins in the stomach
lipids in the intestines
nucleic acids, the pancreas release nucleases to digest them
structure of small intestine
serosa
muscle layer
submucosa
mucosa
structure of villi
microvilli proteins single epithelial layer intestinal gland rich blood supply lacteals smooth muscle serosa
structure features of villi epithelium
tight junctions
micro villi
mitochondria
Pinocytotic Vesicles
membrane transport mechanisms
simple diffusion
facilitated diffusion
osmosis
active transport
endocytosis
involves the invagination of the plasma membrane to create an internal vesicle containing extracellular material, energy dependent process
where is starch digestion initiated
initiated in the salivary glands in the mouth and continued in pancreatic amylase in the intestines.
role of the pancreas in the breakdown of starch
It produces the enzyme amylase which is released from exocrine glands (acinar cells) into the intestinal tract
It produces the hormones insulin and glucagon which are released from endocrine glands (islets of Langerhans) into the blood
how do hormones such as insulin and glucagon regulate the concentration of glucose?
insulin lowers blood glucose levels by increasing glycogen synthesis and storage in the liver and adipose tissues
Glucagon increases blood glucose levels by limiting the synthesis and storage of glycogen by the liver and adipose tissues
what is the core function of the digestive system?
to break down large molecules into smaller subunits that can be absorbed by cells
arteries and veins:
arteries pump blood from the heart
veins pump blood back to the heart
The reason why there are two sets of atria and ventricles is because there are two distinct locations for blood transport
the left side of the heart pumps oxygenated blood around body
the right side of the heart pumps deoxygenated blood to the lungs (pulmonary circulation)
why does the left side of the hear have a thicker muscular pump?
because it needs much more blood to pump to the rest of the body, therefore, needs higher pressure.
what is the function of arteries?
to pump high blood pressure to the body tissues and organs and lungs.
structure of arteries
narrow lumen
a thick wall containing an outer layer of collagen to prevent the artery from rupturing under the high pressure
contains an inner layer of muscle and elastic fibres to help maintain pulse flow (it can contract and stretch)
function of muscle fibre in arteries
help to form a rigid arterial wall that is capable of withstanding the high blood pressure without rupturing
function of elastic fibre in arteries
allow the arterial wall to stretch and expand upon the flow of a pulse through the lumen
what is the function of capillaries
is to exchange materials between the cells in tissues and blood travelling at low pressure
structure of capillaries
They have a very small diameter (~ 5 µm wide) which allows passage of only a single red blood cell at a time (optimal exchange)
The capillary wall is made of a single layer of cells to minimise the diffusion distance for permeable materials
They are surrounded by a basement membrane which is permeable to necessary materials
They may contain pores to further aid in the transport of materials between tissue fluid and blood
veins function
is to collect the blood from the tissues and convey it at low pressure to the atria of the heart
veins structure
They have a very wide lumen (relative to wall thickness) to maximise blood flow for more effective return
They have a thin wall containing less muscle and elastic fibres as blood is flowing at a very low pressure (~ 5 – 10 mmHg)
veins possess valves to prevent backflow and stop the blood from pooling at the lowest extremities
sinotrial node SAN
primary pacemaker- controlling the rate at which the heart beats
function of SAN
sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria and then the walls of the ventricles
function of the atrioventricular node AVN
sends signals down the septum via a nerve bundle (Bundle of His)
The Bundle of His innervates nerve fibres (Purkinje fibres) in the ventricular wall, causing ventricular contraction
nerves connected to the medulla that affect the heart rate:
The sympathetic nerve releases the neurotransmitter noradrenaline (a.k.a. norepinephrine) to increase heart rate
The parasympathetic nerve (vagus nerve) releases the neurotransmitter acetylcholine to decrease heart rate
what is the function of the hormone adrenaline and where is released from
Adrenaline increases heart rate by activating the same chemical pathways as the neurotransmitter noradrenaline and it is released from the adrenal glands.
diastole
atria and ventricles relaxed
blood flows into heart from veins
AV valves opened
SL valves closed
atrial systole
atria contracts ventricles relaxed blood push into atria AV valves open SL valves closed
ventricular systole
atria relaxed ventricles contracts blood pushed into arteries AV valves closed SL valves open
coronary arteries
the blood vessels that surround the heart and nourish the cardiac tissue to keep the heart working
Atherosclerosis (coronary occlusion)
is the hardening and narrowing of the arteries due to the deposition of cholesterol
consequences of coronary occlusion
Atherosclerosis can lead to blood clots which cause coronary heart disease when they occur in coronary arteries
Risk Factors for Coronary Heart Disease
advancing age sex- male increased in ostrogen level smoking obesity genetics diseases diet exercise
first line of defense
skin
mucous membrane
clotting (homeostasis)
is the mechanism by which broken blood vessels are repaired when damaged
There are two key components of a blood clot :
platelets and insoluble fibrin strands
function of platelets
Platelets undergo a structural change when activated to form a sticky plug at the damaged region
function of insoluble fibrin strands
Fibrin strands form an insoluble mesh of fibres that trap blood cells at the site of damage
Coronary thrombosis
the formation of a clot within the blood vessels that supply and sustain the heart tissue
second line of defense
phagocytes
what are phagocytes
the process by which solid materials (such as pathogens) are ingested by a cell
third line of defense
lymphocytes
what are b-lymphocytes
are antibody-producing cells that recognise and target a particular pathogen fragment (antigen)
Helper T lymphocytes (TH cells)
are regulator cells that release chemicals (cytokines) to activate specific B lymphocytes
antibiotics
compounds that kill or inhibit the growth of bacteria
An example of an antibiotic resistant strain of bacteria
golden staph
human immune deficiency
is a retrovirus that infects helper T cells, disabling the body’s adaptive immune system
The processes involved in physiological respiration are
Ventilation: The exchange of air between the atmosphere and the lungs – achieved by the physical act of breathing
Gas Exchange: The exchange of oxygen and carbon dioxide between the alveoli and bloodstream (via passive diffusion)
Cell Respiration: The release of energy (ATP) from organic molecules – it is enhanced by the presence of oxygen (aerobic)
purpose of ventilation
a ventilation system is needed to maintain a concentration gradient in alveoli
structure of alveolus
– They have a very thin epithelial layer (one cell thick) to minimise diffusion distances for respiratory gases
– They are surrounded by a rich capillary network to increase the capacity for gas exchange with the blood
– They are roughly spherical in shape, in order to maximise the available surface area for gas exchange
– Their internal surface is covered with a layer of fluid, as
dissolved gases are better able to diffuse into the bloodstream
inhalation
Diaphragm muscles contract, causing the diaphragm to flatten and increase the volume of the thoracic cavity
External intercostals contract, pulling ribs upwards and outwards (expanding chest)
Additional muscle groups may help pull the ribs up and out (e.g. sternocleidomastoid and pectoralis minor)
exhalation
Diaphragm muscles relax, causing the diaphragm to curve upwards and reduce the volume of the thoracic cavity
Internal intercostal muscles contract, pulling ribs inwards and downwards (reducing breadth of chest)
Abdominal muscles contract and push the diaphragm upwards during forced exhalation
Additional muscle groups may help pull the ribs downwards (e.g. quadratas lumborum)
emphysema
is a lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls
how does excessive affect ventilation
Increase ventilation rate (a greater frequency of breaths allows for a more continuous exchange of gases)
Increase tidal volume (increasing the volume of air taken in and out per breath allows for more air in the lungs to be exchanged)
what are neurons
specialised cells that function to transmit electrical impulses within the nervous system
three basic components of neurons
dendrite
axon
cell body (soma)
what is the myelin sheath
the myelin sheath surrounds the axon to improve the conduction speed of electrical impulses along the axon, but require additional space and energy
what is resting potential
the difference in charge across the membrane when a neuron is not firing
when in resting potential?
the inside of the neuron is more negative relative to the outside
what is action potential?
are the rapid changes in charge across the membrane that occur when a neuron is firing
what are the three stages of action potential
depolarization, repolarization and a refractory period
depolarization
refers to a sudden change in membrane potential – usually from a (relatively) negative to positive internal charge
repolarization
efers to the restoration of a membrane potential following depolarisation (i.e. restoring a negative internal charge
refractory period
refers to the period of time following a nerve impulse before the neuron is able to fire again
nerve impulses
are action potentials that move along the length of an axon as a wave of depolarisation
synapses
physical gaps that separate neurons from each other
neurotransmitters
chemical messengers released from neurons and function to transmit signals across the synaptic cleft
diabetes
is a metabolic disorder that results from a high blood glucose concentration over a prolonged period
type 1 diabetes
does not produce insulin
since a kid
caused by the destruction of B-cells
type 2 diabetes
does not respond to insulin production
caused by the down regulation of insulin receptors
acquired through age
thyroxin
secreted by the thyroxin gland, increase metabolic rate
increases heat production
melatonin
produced by the pineal gland, allows you to sleep in which it synchronizes the cardiac rhythms including sleep timing and blood pressure regulation
leptin
produced by adipose cells, causes appetite inhibition and hence reduced food intake.
men reproductive hormone
testosterone
female reproductive hormone
estrogen and progesterone
menstrual hormones
anterior pituitaries and ovary
anterior pituitarias
FSH - stimulates follicular growth stimulates estrogen secretion
LH - causes ovulation
Ovaries
estrogen - thickens uterine lining, inhibits FSH and LH
progesterone- thickens uterine lining, inhibits FSH and LH
key events in menstruation cycle
- follicular phase
- ovulation
- luteal phase
- menstruation
ligaments
bone to bone
tendons
bone to muscle
synovial joints
ball and socket pivot saddle hinge plane condyloid
